#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: PACKAGE VERSION\n"
"POT-Creation-Date: 2018-12-08 14:49-0200\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"

#. Put one translator per line, in the form NAME <EMAIL>, YEAR1, YEAR2
msgctxt "_"
msgid "translator-credits"
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:32
msgid "FreeBSD Developers' Handbook"
msgstr ""

#. (itstool) path: info/author
#: book.translate.xml:35
msgid "<orgname>The FreeBSD Documentation Project</orgname>"
msgstr ""

#. (itstool) path: info/pubdate
#. (itstool) path: info/releaseinfo
#: book.translate.xml:37 book.translate.xml:146
msgid ""
"$FreeBSD: head/en_US.ISO8859-1/books/developers-handbook/book.xml 51938 2018-"
"06-30 10:45:14Z eadler $"
msgstr ""

#. (itstool) path: info/copyright
#: book.translate.xml:39
msgid ""
"<year>2000</year> <year>2001</year> <year>2002</year> <year>2003</year> "
"<year>2004</year> <year>2005</year> <year>2006</year> <year>2007</year> "
"<year>2008</year> <year>2009</year> <year>2010</year> <year>2011</year> "
"<year>2012</year> <year>2013</year> <year>2014</year> <year>2015</year> "
"<year>2016</year> <year>2017</year> <year>2018</year> <holder>The FreeBSD "
"Documentation Project</holder>"
msgstr ""

#. (itstool) path: legalnotice/title
#: book.translate.xml:64
msgid "Copyright"
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:66
msgid ""
"Redistribution and use in source (XML DocBook) and 'compiled' forms (XML, "
"HTML, PDF, PostScript, RTF and so forth) with or without modification, are "
"permitted provided that the following conditions are met:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:73
msgid ""
"Redistributions of source code (XML DocBook) must retain the above copyright "
"notice, this list of conditions and the following disclaimer as the first "
"lines of this file unmodified."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:79
msgid ""
"Redistributions in compiled form (transformed to other DTDs, converted to "
"PDF, PostScript, RTF and other formats) must reproduce the above copyright "
"notice, this list of conditions and the following disclaimer in the "
"documentation and/or other materials provided with the distribution."
msgstr ""

#. (itstool) path: important/para
#: book.translate.xml:88
msgid ""
"THIS DOCUMENTATION IS PROVIDED BY THE FREEBSD DOCUMENTATION PROJECT \"AS "
"IS\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, "
"THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR "
"PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD DOCUMENTATION PROJECT "
"BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR "
"CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF "
"SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS "
"INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN "
"CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) "
"ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION, EVEN IF ADVISED OF "
"THE POSSIBILITY OF SUCH DAMAGE."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:105
msgid "FreeBSD is a registered trademark of the FreeBSD Foundation."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:107
msgid ""
"Apple, AirPort, FireWire, iMac, iPhone, iPad, Mac, Macintosh, Mac OS, "
"Quicktime, and TrueType are trademarks of Apple Inc., registered in the U.S. "
"and other countries."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:112
msgid ""
"IBM, AIX, OS/2, PowerPC, PS/2, S/390, and ThinkPad are trademarks of "
"International Business Machines Corporation in the United States, other "
"countries, or both."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:116
msgid ""
"IEEE, POSIX, and 802 are registered trademarks of Institute of Electrical "
"and Electronics Engineers, Inc. in the United States."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:119
msgid ""
"Intel, Celeron, Centrino, Core, EtherExpress, i386, i486, Itanium, Pentium, "
"and Xeon are trademarks or registered trademarks of Intel Corporation or its "
"subsidiaries in the United States and other countries."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:123
msgid "Linux is a registered trademark of Linus Torvalds."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:125
msgid ""
"Microsoft, IntelliMouse, MS-DOS, Outlook, Windows, Windows Media and Windows "
"NT are either registered trademarks or trademarks of Microsoft Corporation "
"in the United States and/or other countries."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:129
msgid ""
"Motif, OSF/1, and UNIX are registered trademarks and IT DialTone and The "
"Open Group are trademarks of The Open Group in the United States and other "
"countries."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:133
msgid ""
"Sun, Sun Microsystems, Java, Java Virtual Machine, JDK, JRE, JSP, JVM, "
"Netra, OpenJDK, Solaris, StarOffice, SunOS and VirtualBox are trademarks or "
"registered trademarks of Sun Microsystems, Inc. in the United States and "
"other countries."
msgstr ""

#. (itstool) path: legalnotice/para
#: book.translate.xml:138
msgid ""
"Many of the designations used by manufacturers and sellers to distinguish "
"their products are claimed as trademarks. Where those designations appear in "
"this document, and the FreeBSD Project was aware of the trademark claim, the "
"designations have been followed by the <quote>™</quote> or the <quote>®</"
"quote> symbol."
msgstr ""

#. (itstool) path: abstract/para
#: book.translate.xml:149
msgid ""
"Welcome to the Developers' Handbook. This manual is a <emphasis>work in "
"progress</emphasis> and is the work of many individuals. Many sections do "
"not yet exist and some of those that do exist need to be updated. If you are "
"interested in helping with this project, send email to the <link xlink:href="
"\"http://lists.FreeBSD.org/mailman/listinfo/freebsd-doc\">FreeBSD "
"documentation project mailing list</link>."
msgstr ""

#. (itstool) path: abstract/para
#: book.translate.xml:155
msgid ""
"The latest version of this document is always available from the <link xlink:"
"href=\"@@URL_RELPREFIX@@/index.html\">FreeBSD World Wide Web server</link>. "
"It may also be downloaded in a variety of formats and compression options "
"from the <link xlink:href=\"https://download.freebsd.org/ftp/doc/\">FreeBSD "
"FTP server</link> or one of the numerous <link xlink:href="
"\"@@URL_RELPREFIX@@/doc/en_US.ISO8859-1/books/handbook/mirrors-ftp."
"html\">mirror sites</link>."
msgstr ""

#. (itstool) path: part/title
#: book.translate.xml:165
msgid "Basics"
msgstr ""

#. (itstool) path: info/title
#. (itstool) path: sect1/title
#: book.translate.xml:174 book.translate.xml:428
msgid "Introduction"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:176 book.translate.xml:2642
msgid ""
"<personname><firstname>Murray</firstname><surname>Stokely</surname></"
"personname><contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:177
msgid ""
"<personname><firstname>Jeroen</firstname><surname>Ruigrok van der Werven</"
"surname></personname>"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:183
msgid "Developing on FreeBSD"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:185
msgid ""
"So here we are. System all installed and you are ready to start programming. "
"But where to start? What does FreeBSD provide? What can it do for me, as a "
"programmer?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:189
msgid ""
"These are some questions which this chapter tries to answer. Of course, "
"programming has different levels of proficiency like any other trade. For "
"some it is a hobby, for others it is their profession. The information in "
"this chapter might be aimed toward the beginning programmer; indeed, it "
"could serve useful for the programmer unfamiliar with the FreeBSD platform."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:198
msgid "The BSD Vision"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:200
msgid ""
"To produce the best <trademark class=\"registered\">UNIX</trademark> like "
"operating system package possible, with due respect to the original software "
"tools ideology as well as usability, performance and stability."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:207
msgid "Architectural Guidelines"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:209
msgid "Our ideology can be described by the following guidelines"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:215
msgid ""
"Do not add new functionality unless an implementor cannot complete a real "
"application without it."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:220
msgid ""
"It is as important to decide what a system is not as to decide what it is. "
"Do not serve all the world's needs; rather, make the system extensible so "
"that additional needs can be met in an upwardly compatible fashion."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:228
msgid ""
"The only thing worse than generalizing from one example is generalizing from "
"no examples at all."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:233
msgid ""
"If a problem is not completely understood, it is probably best to provide no "
"solution at all."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:238
msgid ""
"If you can get 90 percent of the desired effect for 10 percent of the work, "
"use the simpler solution."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:243
msgid "Isolate complexity as much as possible."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:247
msgid ""
"Provide mechanism, rather than policy. In particular, place user interface "
"policy in the client's hands."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:252
msgid "From Scheifler &amp; Gettys: \"X Window System\""
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:256
msgid "The Layout of <filename>/usr/src</filename>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:259
msgid ""
"The complete source code to FreeBSD is available from our public repository. "
"The source code is normally installed in <filename>/usr/src</filename> which "
"contains the following subdirectories:"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:269
msgid "Directory"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:270
msgid "Description"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:276
msgid "<filename>bin/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:277
msgid "Source for files in <filename>/bin</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:282
msgid "<filename>cddl/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:283
msgid "Utilities covered by the Common Development and Distribution License"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:288
msgid "<filename>contrib/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:289
msgid "Source for files from contributed software."
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:294
msgid "<filename>crypto/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:295
msgid "Cryptographical sources"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:299
msgid "<filename>etc/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:300
msgid "Source for files in <filename>/etc</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:304
msgid "<filename>gnu/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:305
msgid "Utilities covered by the GNU Public License"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:310
msgid "<filename>include/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:311
msgid "Source for files in <filename>/usr/include</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:315
msgid "<filename>kerberos5/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:316
msgid "Source for Kerberos version 5"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:320
msgid "<filename>lib/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:321
msgid "Source for files in <filename>/usr/lib</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:325
msgid "<filename>libexec/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:326
msgid "Source for files in <filename>/usr/libexec</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:330
msgid "<filename>release/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:331
msgid "Files required to produce a FreeBSD release"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:336
msgid "<filename>rescue/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:337
msgid "Build system for the <filename>/rescue</filename> utilities"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:343
msgid "<filename>sbin/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:344
msgid "Source for files in <filename>/sbin</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:348
msgid "<filename>secure/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:349
msgid "Contributed cryptographic sources"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:353
msgid "<filename>share/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:354
msgid "Source for files in <filename>/usr/share</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:358
msgid "<filename>sys/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:359
msgid "Kernel source files"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:363
msgid "<filename>tests/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:364
msgid "The FreeBSD test suite"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:368
msgid "<filename>tools/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:369
msgid "Tools used for maintenance and testing of FreeBSD"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:374
msgid "<filename>usr.bin/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:375
msgid "Source for files in <filename>/usr/bin</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:379
msgid "<filename>usr.sbin/</filename>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:380
msgid "Source for files in <filename>/usr/sbin</filename>"
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:396
msgid "Programming Tools"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:399
msgid ""
"<personname> <firstname>James</firstname> <surname>Raynard</surname> </"
"personname> <contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:406
msgid ""
"<personname> <firstname>Murray</firstname> <surname>Stokely</surname> </"
"personname>"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:416 book.translate.xml:2648 book.translate.xml:4571
#: book.translate.xml:9138
msgid "Synopsis"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:418
msgid ""
"This chapter is an introduction to using some of the programming tools "
"supplied with FreeBSD, although much of it will be applicable to many other "
"versions of <trademark class=\"registered\">UNIX</trademark>. It does "
"<emphasis>not</emphasis> attempt to describe coding in any detail. Most of "
"the chapter assumes little or no previous programming knowledge, although it "
"is hoped that most programmers will find something of value in it."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:430
msgid ""
"FreeBSD offers an excellent development environment. Compilers for C and C++ "
"and an assembler come with the basic system, not to mention classic "
"<trademark class=\"registered\">UNIX</trademark> tools such as <command>sed</"
"command> and <command>awk</command>. If that is not enough, there are many "
"more compilers and interpreters in the Ports collection. The following "
"section, <link linkend=\"tools-programming\">Introduction to Programming</"
"link>, lists some of the available options. FreeBSD is very compatible with "
"standards such as <acronym><trademark class=\"registered\">POSIX</"
"trademark></acronym> and <acronym>ANSI</acronym> C, as well with its own BSD "
"heritage, so it is possible to write applications that will compile and run "
"with little or no modification on a wide range of platforms."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:443
msgid ""
"However, all this power can be rather overwhelming at first if you have "
"never written programs on a <trademark class=\"registered\">UNIX</trademark> "
"platform before. This document aims to help you get up and running, without "
"getting too deeply into more advanced topics. The intention is that this "
"document should give you enough of the basics to be able to make some sense "
"of the documentation."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:450
msgid ""
"Most of the document requires little or no knowledge of programming, "
"although it does assume a basic competence with using <trademark class="
"\"registered\">UNIX</trademark> and a willingness to learn!"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:457
msgid "Introduction to Programming"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:459
msgid ""
"A program is a set of instructions that tell the computer to do various "
"things; sometimes the instruction it has to perform depends on what happened "
"when it performed a previous instruction. This section gives an overview of "
"the two main ways in which you can give these instructions, or "
"<quote>commands</quote> as they are usually called. One way uses an "
"<firstterm>interpreter</firstterm>, the other a <firstterm>compiler</"
"firstterm>. As human languages are too difficult for a computer to "
"understand in an unambiguous way, commands are usually written in one or "
"other languages specially designed for the purpose."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:472
msgid "Interpreters"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:474
msgid ""
"With an interpreter, the language comes as an environment, where you type in "
"commands at a prompt and the environment executes them for you. For more "
"complicated programs, you can type the commands into a file and get the "
"interpreter to load the file and execute the commands in it. If anything "
"goes wrong, many interpreters will drop you into a debugger to help you "
"track down the problem."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:482
msgid ""
"The advantage of this is that you can see the results of your commands "
"immediately, and mistakes can be corrected readily. The biggest disadvantage "
"comes when you want to share your programs with someone. They must have the "
"same interpreter, or you must have some way of giving it to them, and they "
"need to understand how to use it. Also users may not appreciate being thrown "
"into a debugger if they press the wrong key! From a performance point of "
"view, interpreters can use up a lot of memory, and generally do not generate "
"code as efficiently as compilers."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:493
msgid ""
"In my opinion, interpreted languages are the best way to start if you have "
"not done any programming before. This kind of environment is typically found "
"with languages like Lisp, Smalltalk, Perl and Basic. It could also be argued "
"that the <trademark class=\"registered\">UNIX</trademark> shell "
"(<command>sh</command>, <command>csh</command>) is itself an interpreter, "
"and many people do in fact write shell <quote>scripts</quote> to help with "
"various <quote>housekeeping</quote> tasks on their machine. Indeed, part of "
"the original <trademark class=\"registered\">UNIX</trademark> philosophy was "
"to provide lots of small utility programs that could be linked together in "
"shell scripts to perform useful tasks."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:507
msgid "Interpreters Available with FreeBSD"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:509
msgid ""
"Here is a list of interpreters that are available from the FreeBSD Ports "
"Collection, with a brief discussion of some of the more popular interpreted "
"languages."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:513
msgid ""
"Instructions on how to get and install applications from the Ports "
"Collection can be found in the <link xlink:href=\"@@URL_RELPREFIX@@/doc/"
"en_US.ISO8859-1/books/handbook/ports-using.html\">Ports section</link> of "
"the handbook."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:519
msgid "<acronym>BASIC</acronym>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:522
msgid ""
"Short for Beginner's All-purpose Symbolic Instruction Code. Developed in the "
"1950s for teaching University students to program and provided with every "
"self-respecting personal computer in the 1980s, <acronym>BASIC</acronym> has "
"been the first programming language for many programmers. It is also the "
"foundation for Visual Basic."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:530
msgid ""
"The Bywater Basic Interpreter can be found in the Ports Collection as "
"<package>lang/bwbasic</package> and the Phil Cockroft's Basic Interpreter "
"(formerly Rabbit Basic) is available as <package>lang/pbasic</package>."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:539
msgid "Lisp"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:542
msgid ""
"A language that was developed in the late 1950s as an alternative to the "
"<quote>number-crunching</quote> languages that were popular at the time. "
"Instead of being based on numbers, Lisp is based on lists; in fact, the name "
"is short for <quote>List Processing</quote>. It is very popular in "
"<acronym>AI</acronym> (Artificial Intelligence) circles."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:550
msgid ""
"Lisp is an extremely powerful and sophisticated language, but can be rather "
"large and unwieldy."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:553
msgid ""
"Various implementations of Lisp that can run on <trademark class="
"\"registered\">UNIX</trademark> systems are available in the Ports "
"Collection for FreeBSD. GNU Common Lisp can be found as <package>lang/gcl</"
"package>. CLISP by Bruno Haible and Michael Stoll is available as "
"<package>lang/clisp</package>. For CMUCL, which includes a highly-optimizing "
"compiler too, or simpler Lisp implementations like SLisp, which implements "
"most of the Common Lisp constructs in a few hundred lines of C code, "
"<package>lang/cmucl</package> and <package>lang/slisp</package> are "
"available respectively."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:569
msgid "Perl"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:572
msgid ""
"Very popular with system administrators for writing scripts; also often used "
"on World Wide Web servers for writing <acronym>CGI</acronym> scripts."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:576
msgid ""
"Perl is available in the Ports Collection as <package>lang/perl5.24</"
"package> for all FreeBSD releases."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:583
msgid "Scheme"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:586
msgid ""
"A dialect of Lisp that is rather more compact and cleaner than Common Lisp. "
"Popular in Universities as it is simple enough to teach to undergraduates as "
"a first language, while it has a high enough level of abstraction to be used "
"in research work."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:592
msgid ""
"Scheme is available from the Ports Collection as <package>lang/elk</package> "
"for the Elk Scheme Interpreter. The MIT Scheme Interpreter can be found in "
"<package>lang/mit-scheme</package> and the SCM Scheme Interpreter in "
"<package>lang/scm</package>."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:603
msgid "Icon"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:606
msgid ""
"Icon is a high-level language with extensive facilities for processing "
"strings and structures. The version of Icon for FreeBSD can be found in the "
"Ports Collection as <package>lang/icon</package>."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:615
msgid "Logo"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:618
msgid ""
"Logo is a language that is easy to learn, and has been used as an "
"introductory programming language in various courses. It is an excellent "
"tool to work with when teaching programming to smaller age groups, as it "
"makes creation of elaborate geometric shapes an easy task."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:625
msgid ""
"The latest version of Logo for FreeBSD is available from the Ports "
"Collection in <package>lang/logo</package>."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:632
msgid "Python"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:635
msgid ""
"Python is an Object-Oriented, interpreted language. Its advocates argue that "
"it is one of the best languages to start programming with, since it is "
"relatively easy to start with, but is not limited in comparison to other "
"popular interpreted languages that are used for the development of large, "
"complex applications (Perl and Tcl are two other languages that are popular "
"for such tasks)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:644
msgid ""
"The latest version of Python is available from the Ports Collection in "
"<package>lang/python</package>."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:651
msgid "Ruby"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:654
msgid ""
"Ruby is an interpreter, pure object-oriented programming language. It has "
"become widely popular because of its easy to understand syntax, flexibility "
"when writing code, and the ability to easily develop and maintain large, "
"complex programs."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:660
msgid ""
"Ruby is available from the Ports Collection as <package>lang/ruby25</"
"package>."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:666
msgid "Tcl and Tk"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:669
msgid ""
"Tcl is an embeddable, interpreted language, that has become widely used and "
"became popular mostly because of its portability to many platforms. It can "
"be used both for quickly writing small, prototype applications, or (when "
"combined with Tk, a GUI toolkit) fully-fledged, featureful programs."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:676
msgid ""
"Various versions of Tcl are available as ports for FreeBSD. The latest "
"version, Tcl 8.5, can be found in <package>lang/tcl87</package>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:685
msgid "Compilers"
msgstr ""

#. (itstool) path: footnote/para
#: book.translate.xml:693
msgid "If you run it in the shell, you may get a core dump."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:687
msgid ""
"Compilers are rather different. First of all, you write your code in a file "
"(or files) using an editor. You then run the compiler and see if it accepts "
"your program. If it did not compile, grit your teeth and go back to the "
"editor; if it did compile and gave you a program, you can run it either at a "
"shell command prompt or in a debugger to see if it works properly.<_:"
"footnote-1/>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:696
msgid ""
"Obviously, this is not quite as direct as using an interpreter. However it "
"allows you to do a lot of things which are very difficult or even impossible "
"with an interpreter, such as writing code which interacts closely with the "
"operating system—or even writing your own operating system! It is also "
"useful if you need to write very efficient code, as the compiler can take "
"its time and optimize the code, which would not be acceptable in an "
"interpreter. Moreover, distributing a program written for a compiler is "
"usually more straightforward than one written for an interpreter—you can "
"just give them a copy of the executable, assuming they have the same "
"operating system as you."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:709
msgid ""
"As the edit-compile-run-debug cycle is rather tedious when using separate "
"programs, many commercial compiler makers have produced Integrated "
"Development Environments (<acronym>IDE</acronym>s for short). FreeBSD does "
"not include an IDE in the base system, but <package>devel/kdevelop</package> "
"is available in the Ports Collection and many use <application>Emacs</"
"application> for this purpose. Using <application>Emacs</application> as an "
"IDE is discussed in <xref linkend=\"emacs\"/>."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:723
msgid "Compiling with <command>cc</command>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:725
msgid ""
"This section deals with the <application>gcc</application> and "
"<application>clang</application> compilers for C and C++, since they come "
"with the FreeBSD base system. Starting with FreeBSD 10.X <command>clang</"
"command> is installed as <command>cc</command>. The details of producing a "
"program with an interpreter vary considerably between interpreters, and are "
"usually well covered in the documentation and on-line help for the "
"interpreter."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:734
msgid ""
"Once you have written your masterpiece, the next step is to convert it into "
"something that will (hopefully!) run on FreeBSD. This usually involves "
"several steps, each of which is done by a separate program."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:741
msgid ""
"Pre-process your source code to remove comments and do other tricks like "
"expanding macros in C."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:746
msgid ""
"Check the syntax of your code to see if you have obeyed the rules of the "
"language. If you have not, it will complain!"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:752
msgid ""
"Convert the source code into assembly language—this is very close to machine "
"code, but still understandable by humans. Allegedly."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:758
msgid ""
"Convert the assembly language into machine code—yep, we are talking bits and "
"bytes, ones and zeros here."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:764
msgid ""
"Check that you have used things like functions and global variables in a "
"consistent way. For example, if you have called a non-existent function, it "
"will complain."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:771
msgid ""
"If you are trying to produce an executable from several source code files, "
"work out how to fit them all together."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:777
msgid ""
"Work out how to produce something that the system's run-time loader will be "
"able to load into memory and run."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:783
msgid "Finally, write the executable on the filesystem."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:787
msgid ""
"The word <firstterm>compiling</firstterm> is often used to refer to just "
"steps 1 to 4—the others are referred to as <firstterm>linking</firstterm>. "
"Sometimes step 1 is referred to as <firstterm>pre-processing</firstterm> and "
"steps 3-4 as <firstterm>assembling</firstterm>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:793
msgid ""
"Fortunately, almost all this detail is hidden from you, as <command>cc</"
"command> is a front end that manages calling all these programs with the "
"right arguments for you; simply typing"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:798
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc foobar.c</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:800
msgid ""
"will cause <filename>foobar.c</filename> to be compiled by all the steps "
"above. If you have more than one file to compile, just do something like"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:804
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc foo.c bar.c</userinput>"
msgstr ""

#. (itstool) path: footnote/para
#: book.translate.xml:810
msgid ""
"In case you did not know, a binary sort is an efficient way of sorting "
"things into order and a bubble sort is not."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:806
msgid ""
"Note that the syntax checking is just that—checking the syntax. It will not "
"check for any logical mistakes you may have made, like putting the program "
"into an infinite loop, or using a bubble sort when you meant to use a binary "
"sort.<_:footnote-1/>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:814
msgid ""
"There are lots and lots of options for <command>cc</command>, which are all "
"in the manual page. Here are a few of the most important ones, with examples "
"of how to use them."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:821
msgid "<option>-o <replaceable>filename</replaceable></option>"
msgstr ""

#. (itstool) path: footnote/para
#: book.translate.xml:828
msgid "The reasons for this are buried in the mists of history."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:826
msgid ""
"The output name of the file. If you do not use this option, <command>cc</"
"command> will produce an executable called <filename>a.out</filename>.<_:"
"footnote-1/>"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:833
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cc foobar.c</userinput>               "
"<lineannotation>executable is a.out</lineannotation>\n"
"<prompt>%</prompt> <userinput>cc -o foobar foobar.c</userinput>     "
"<lineannotation>executable is foobar</lineannotation>"
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:840
msgid "<option>-c</option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:843
msgid ""
"Just compile the file, do not link it. Useful for toy programs where you "
"just want to check the syntax, or if you are using a <filename>Makefile</"
"filename>."
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:848
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc -c foobar.c</userinput>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:851
msgid ""
"This will produce an <firstterm>object file</firstterm> (not an executable) "
"called <filename>foobar.o</filename>. This can be linked together with other "
"object files into an executable."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:860
msgid "<option>-g</option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:863
msgid ""
"Create a debug version of the executable. This makes the compiler put "
"information into the executable about which line of which source file "
"corresponds to which function call. A debugger can use this information to "
"show the source code as you step through the program, which is "
"<emphasis>very</emphasis> useful; the disadvantage is that all this extra "
"information makes the program much bigger. Normally, you compile with "
"<option>-g</option> while you are developing a program and then compile a "
"<quote>release version</quote> without <option>-g</option> when you are "
"satisfied it works properly."
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:877
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc -g foobar.c</userinput>"
msgstr ""

#. (itstool) path: footnote/para
#: book.translate.xml:884
msgid ""
"Note, we did not use the <option>-o</option> flag to specify the executable "
"name, so we will get an executable called <filename>a.out</filename>. "
"Producing a debug version called <filename>foobar</filename> is left as an "
"exercise for the reader!"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:880
msgid "This will produce a debug version of the program. <_:footnote-1/>"
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:894
msgid "<option>-O</option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:897
msgid ""
"Create an optimized version of the executable. The compiler performs various "
"clever tricks to try to produce an executable that runs faster than normal. "
"You can add a number after the <option>-O</option> to specify a higher level "
"of optimization, but this often exposes bugs in the compiler's optimizer."
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:905
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc -O -o foobar foobar.c</userinput>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:908
msgid "This will produce an optimized version of <filename>foobar</filename>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:914
msgid ""
"The following three flags will force <command>cc</command> to check that "
"your code complies to the relevant international standard, often referred to "
"as the <acronym>ANSI</acronym> standard, though strictly speaking it is an "
"<acronym>ISO</acronym> standard."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:922
msgid "<option>-Wall</option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:925
msgid ""
"Enable all the warnings which the authors of <command>cc</command> believe "
"are worthwhile. Despite the name, it will not enable all the warnings "
"<command>cc</command> is capable of."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:933
msgid "<option>-ansi</option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:936
msgid ""
"Turn off most, but not all, of the non-<acronym>ANSI</acronym> C features "
"provided by <command>cc</command>. Despite the name, it does not guarantee "
"strictly that your code will comply to the standard."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:945
msgid "<option>-pedantic</option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:948
msgid ""
"Turn off <emphasis>all</emphasis> <command>cc</command>'s non-<acronym>ANSI</"
"acronym> C features."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:955
msgid ""
"Without these flags, <command>cc</command> will allow you to use some of its "
"non-standard extensions to the standard. Some of these are very useful, but "
"will not work with other compilers—in fact, one of the main aims of the "
"standard is to allow people to write code that will work with any compiler "
"on any system. This is known as <firstterm>portable code</firstterm>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:963
msgid ""
"Generally, you should try to make your code as portable as possible, as "
"otherwise you may have to completely rewrite the program later to get it to "
"work somewhere else—and who knows what you may be using in a few years time?"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:969
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cc -Wall -ansi -pedantic -o foobar foobar.c</"
"userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:972
msgid ""
"This will produce an executable <filename>foobar</filename> after checking "
"<filename>foobar.c</filename> for standard compliance."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:978
msgid "<option>-l<replaceable>library</replaceable></option>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:981
msgid "Specify a function library to be used at link time."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:984
msgid ""
"The most common example of this is when compiling a program that uses some "
"of the mathematical functions in C. Unlike most other platforms, these are "
"in a separate library from the standard C one and you have to tell the "
"compiler to add it."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:990
msgid ""
"The rule is that if the library is called "
"<filename>lib<replaceable>something</replaceable>.a</filename>, you give "
"<command>cc</command> the argument <option>-l<replaceable>something</"
"replaceable></option>. For example, the math library is <filename>libm.a</"
"filename>, so you give <command>cc</command> the argument <option>-lm</"
"option>. A common <quote>gotcha</quote> with the math library is that it has "
"to be the last library on the command line."
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1002 book.translate.xml:1045
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc -o foobar foobar.c -lm</userinput>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1005
msgid ""
"This will link the math library functions into <filename>foobar</filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1008
msgid ""
"If you are compiling C++ code, use <command>c++</command>. <command>c++</"
"command> can also be invoked as <command>clang++</command> on FreeBSD."
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1013
#, no-wrap
msgid "<prompt>%</prompt> <userinput>c++ -o foobar foobar.cc</userinput>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1016
msgid ""
"This will both produce an executable <filename>foobar</filename> from the "
"C++ source file <filename>foobar.cc</filename>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1024
msgid "Common <command>cc</command> Queries and Problems"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1029
msgid ""
"I am trying to write a program which uses the <function>sin()</function> "
"function and I get an error like this. What does it mean?"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1034
#, no-wrap
msgid ""
"/var/tmp/cc0143941.o: Undefined symbol `_sin' referenced from text segment"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1039
msgid ""
"When using mathematical functions like <function>sin()</function>, you have "
"to tell <command>cc</command> to link in the math library, like so:"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1052
msgid ""
"All right, I wrote this simple program to practice using <option>-lm</"
"option>. All it does is raise 2.1 to the power of 6."
msgstr ""

#. (itstool) path: informalexample/programlisting
#: book.translate.xml:1057
#, no-wrap
msgid ""
"#include &lt;stdio.h&gt;\n"
"\n"
"int main() {\n"
"	float f;\n"
"\n"
"	f = pow(2.1, 6);\n"
"	printf(\"2.1 ^ 6 = %f\\n\", f);\n"
"	return 0;\n"
"}"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1068
msgid "and I compiled it as:"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1071
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc temp.c -lm</userinput>"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1074
msgid "like you said I should, but I get this when I run it:"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1078
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>./a.out</userinput>\n"
"2.1 ^ 6 = 1023.000000"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1082
msgid "This is <emphasis>not</emphasis> the right answer! What is going on?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1087
msgid ""
"When the compiler sees you call a function, it checks if it has already seen "
"a prototype for it. If it has not, it assumes the function returns an "
"<type>int</type>, which is definitely not what you want here."
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1097
msgid "So how do I fix this?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1101
msgid ""
"The prototypes for the mathematical functions are in <filename>math.h</"
"filename>. If you include this file, the compiler will be able to find the "
"prototype and it will stop doing strange things to your calculation!"
msgstr ""

#. (itstool) path: informalexample/programlisting
#: book.translate.xml:1108
#, no-wrap
msgid "#include &lt;math.h&gt;\n"
"#include &lt;stdio.h&gt;\n"
"\n"
"int main() {\n"
"..."
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1115
msgid "After recompiling it as you did before, run it:"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1119
#, no-wrap
msgid "<prompt>%</prompt> <userinput>./a.out</userinput>\n"
"2.1 ^ 6 = 85.766121"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1123
msgid ""
"If you are using any of the mathematical functions, <emphasis>always</"
"emphasis> include <filename>math.h</filename> and remember to link in the "
"math library."
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1132
msgid ""
"I compiled a file called <filename>foobar.c</filename> and I cannot find an "
"executable called <filename>foobar</filename>. Where has it gone?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1139
msgid ""
"Remember, <command>cc</command> will call the executable <filename>a.out</"
"filename> unless you tell it differently. Use the <option>-"
"o <replaceable>filename</replaceable></option> option:"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1146
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc -o foobar foobar.c</userinput>"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1153
msgid ""
"OK, I have an executable called <filename>foobar</filename>, I can see it "
"when I run <command>ls</command>, but when I type in <command>foobar</"
"command> at the command prompt it tells me there is no such file. Why can it "
"not find it?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1162
msgid ""
"Unlike <trademark class=\"registered\">MS-DOS</trademark>, <trademark class="
"\"registered\">UNIX</trademark> does not look in the current directory when "
"it is trying to find out which executable you want it to run, unless you "
"tell it to. Type <command>./foobar</command>, which means <quote>run the "
"file called <filename>foobar</filename> in the current directory.</quote>"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1173
msgid ""
"I called my executable <filename>test</filename>, but nothing happens when I "
"run it. What is going on?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1179
msgid ""
"Most <trademark class=\"registered\">UNIX</trademark> systems have a program "
"called <command>test</command> in <filename>/usr/bin</filename> and the "
"shell is picking that one up before it gets to checking the current "
"directory. Either type:"
msgstr ""

#. (itstool) path: informalexample/screen
#: book.translate.xml:1185
#, no-wrap
msgid "<prompt>%</prompt> <userinput>./test</userinput>"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1188
msgid "or choose a better name for your program!"
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1194
msgid ""
"I compiled my program and it seemed to run all right at first, then there "
"was an error and it said something about <errorname>core dumped</errorname>. "
"What does that mean?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1201
msgid ""
"The name <firstterm>core dump</firstterm> dates back to the very early days "
"of <trademark class=\"registered\">UNIX</trademark>, when the machines used "
"core memory for storing data. Basically, if the program failed under certain "
"conditions, the system would write the contents of core memory to disk in a "
"file called <filename>core</filename>, which the programmer could then pore "
"over to find out what went wrong."
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1213
msgid "Fascinating stuff, but what I am supposed to do now?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1218
msgid ""
"Use <command>gdb</command> to analyze the core (see <xref linkend="
"\"debugging\"/>)."
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1225
msgid ""
"When my program dumped core, it said something about a "
"<errorname>segmentation fault</errorname>. What is that?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1231
msgid ""
"This basically means that your program tried to perform some sort of illegal "
"operation on memory; <trademark class=\"registered\">UNIX</trademark> is "
"designed to protect the operating system and other programs from rogue "
"programs."
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1236
msgid "Common causes for this are:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1240
msgid "Trying to write to a <symbol>NULL</symbol> pointer, eg"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:1243
#, no-wrap
msgid "char *foo = NULL;\n"
"strcpy(foo, \"bang!\");"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1248
msgid "Using a pointer that has not been initialized, eg"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:1251
#, no-wrap
msgid "char *foo;\n"
"strcpy(foo, \"bang!\");"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1254
msgid ""
"The pointer will have some random value that, with luck, will point into an "
"area of memory that is not available to your program and the kernel will "
"kill your program before it can do any damage. If you are unlucky, it will "
"point somewhere inside your own program and corrupt one of your data "
"structures, causing the program to fail mysteriously."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1264
msgid "Trying to access past the end of an array, eg"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:1267
#, no-wrap
msgid "int bar[20];\n"
"bar[27] = 6;"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1272
msgid "Trying to store something in read-only memory, eg"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:1275
#, no-wrap
msgid "char *foo = \"My string\";\n"
"strcpy(foo, \"bang!\");"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1278
msgid ""
"<trademark class=\"registered\">UNIX</trademark> compilers often put string "
"literals like <literal>\"My string\"</literal> into read-only areas of "
"memory."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1284
msgid ""
"Doing naughty things with <function>malloc()</function> and "
"<function>free()</function>, eg"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:1288
#, no-wrap
msgid "char bar[80];\n"
"free(bar);"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1291
msgid "or"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:1293
#, no-wrap
msgid "char *foo = malloc(27);\n"
"free(foo);\n"
"free(foo);"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1299
msgid ""
"Making one of these mistakes will not always lead to an error, but they are "
"always bad practice. Some systems and compilers are more tolerant than "
"others, which is why programs that ran well on one system can crash when you "
"try them on an another."
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1309
msgid ""
"Sometimes when I get a core dump it says <errorname>bus error</errorname>. "
"It says in my <trademark class=\"registered\">UNIX</trademark> book that "
"this means a hardware problem, but the computer still seems to be working. "
"Is this true?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1317
msgid ""
"No, fortunately not (unless of course you really do have a hardware "
"problem…). This is usually another way of saying that you accessed memory in "
"a way you should not have."
msgstr ""

#. (itstool) path: question/para
#: book.translate.xml:1326
msgid ""
"This dumping core business sounds as though it could be quite useful, if I "
"can make it happen when I want to. Can I do this, or do I have to wait until "
"there is an error?"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1333
msgid "Yes, just go to another console or xterm, do"
msgstr ""

#. (itstool) path: answer/screen
#: book.translate.xml:1335
#, no-wrap
msgid "<prompt>%</prompt> <userinput>ps</userinput>"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1337
msgid "to find out the process ID of your program, and do"
msgstr ""

#. (itstool) path: answer/screen
#: book.translate.xml:1340
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>kill -ABRT <replaceable>pid</replaceable></"
"userinput>"
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1342
msgid ""
"where <parameter><replaceable>pid</replaceable></parameter> is the process "
"ID you looked up."
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1346
msgid ""
"This is useful if your program has got stuck in an infinite loop, for "
"instance. If your program happens to trap <symbol>SIGABRT</symbol>, there "
"are several other signals which have a similar effect."
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1351
msgid ""
"Alternatively, you can create a core dump from inside your program, by "
"calling the <function>abort()</function> function. See the manual page of "
"<citerefentry><refentrytitle>abort</refentrytitle><manvolnum>3</manvolnum></"
"citerefentry> to learn more."
msgstr ""

#. (itstool) path: answer/para
#: book.translate.xml:1356
msgid ""
"If you want to create a core dump from outside your program, but do not want "
"the process to terminate, you can use the <command>gcore</command> program. "
"See the manual page of <citerefentry><refentrytitle>gcore</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry> for more information."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:1368
msgid "Make"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1371
msgid "What is <command>make</command>?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1373
msgid ""
"When you are working on a simple program with only one or two source files, "
"typing in"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1376
#, no-wrap
msgid "<prompt>%</prompt> <userinput>cc file1.c file2.c</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1378
msgid ""
"is not too bad, but it quickly becomes very tedious when there are several "
"files—and it can take a while to compile, too."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1382
msgid ""
"One way to get around this is to use object files and only recompile the "
"source file if the source code has changed. So we could have something like:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1386
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cc file1.o file2.o</userinput> … "
"<userinput>file37.c</userinput> …"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1388
msgid ""
"if we had changed <filename>file37.c</filename>, but not any of the others, "
"since the last time we compiled. This may speed up the compilation quite a "
"bit, but does not solve the typing problem."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1393
msgid ""
"Or we could write a shell script to solve the typing problem, but it would "
"have to re-compile everything, making it very inefficient on a large project."
""
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1397
msgid ""
"What happens if we have hundreds of source files lying about? What if we are "
"working in a team with other people who forget to tell us when they have "
"changed one of their source files that we use?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1402
msgid ""
"Perhaps we could put the two solutions together and write something like a "
"shell script that would contain some kind of magic rule saying when a source "
"file needs compiling. Now all we need now is a program that can understand "
"these rules, as it is a bit too complicated for the shell."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1408
msgid ""
"This program is called <command>make</command>. It reads in a file, called a "
"<firstterm>makefile</firstterm>, that tells it how different files depend on "
"each other, and works out which files need to be re-compiled and which ones "
"do not. For example, a rule could say something like <quote>if "
"<filename>fromboz.o</filename> is older than <filename>fromboz.c</filename>, "
"that means someone must have changed <filename>fromboz.c</filename>, so it "
"needs to be re-compiled.</quote> The makefile also has rules telling make "
"<emphasis>how</emphasis> to re-compile the source file, making it a much "
"more powerful tool."
msgstr ""

#. (itstool) path: footnote/para
#: book.translate.xml:1426
msgid ""
"They do not use the <filename>MAKEFILE</filename> form as block capitals are "
"often used for documentation files like <filename>README</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1420
msgid ""
"Makefiles are typically kept in the same directory as the source they apply "
"to, and can be called <filename>makefile</filename>, <filename>Makefile</"
"filename> or <filename>MAKEFILE</filename>. Most programmers use the name "
"<filename>Makefile</filename>, as this puts it near the top of a directory "
"listing, where it can easily be seen.<_:footnote-1/>"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1433
msgid "Example of Using <command>make</command>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1435
msgid "Here is a very simple make file:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1437
#, no-wrap
msgid "foo: foo.c\n"
"	cc -o foo foo.c"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1440
msgid "It consists of two lines, a dependency line and a creation line."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1443
msgid ""
"The dependency line here consists of the name of the program (known as the "
"<firstterm>target</firstterm>), followed by a colon, then whitespace, then "
"the name of the source file. When <command>make</command> reads this line, "
"it looks to see if <filename>foo</filename> exists; if it exists, it "
"compares the time <filename>foo</filename> was last modified to the time "
"<filename>foo.c</filename> was last modified. If <filename>foo</filename> "
"does not exist, or is older than <filename>foo.c</filename>, it then looks "
"at the creation line to find out what to do. In other words, this is the "
"rule for working out when <filename>foo.c</filename> needs to be re-compiled."
""
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1456
msgid ""
"The creation line starts with a <token>tab</token> (press <keycap>tab</"
"keycap>) and then the command you would type to create <filename>foo</"
"filename> if you were doing it at a command prompt. If <filename>foo</"
"filename> is out of date, or does not exist, <command>make</command> then "
"executes this command to create it. In other words, this is the rule which "
"tells make how to re-compile <filename>foo.c</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1465
msgid ""
"So, when you type <userinput>make</userinput>, it will make sure that "
"<filename>foo</filename> is up to date with respect to your latest changes "
"to <filename>foo.c</filename>. This principle can be extended to "
"<filename>Makefile</filename>s with hundreds of targets—in fact, on FreeBSD, "
"it is possible to compile the entire operating system just by typing "
"<userinput>make world</userinput> in the appropriate directory!"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1474
msgid ""
"Another useful property of makefiles is that the targets do not have to be "
"programs. For instance, we could have a make file that looks like this:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1478
#, no-wrap
msgid "foo: foo.c\n"
"	cc -o foo foo.c\n"
"\n"
"install:\n"
"	cp foo /home/me"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1484
msgid "We can tell make which target we want to make by typing:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1487
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>make <replaceable>target</replaceable></"
"userinput>"
msgstr ""

#. (itstool) path: para/buildtarget
#: book.translate.xml:1492 book.translate.xml:1501 book.translate.xml:1504
msgid "install"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1489
msgid ""
"<command>make</command> will then only look at that target and ignore any "
"others. For example, if we type <userinput>make foo</userinput> with the "
"makefile above, make will ignore the <_:buildtarget-1/> target."
msgstr ""

#. (itstool) path: para/buildtarget
#: book.translate.xml:1499
msgid "foo"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1495
msgid ""
"If we just type <userinput>make</userinput> on its own, make will always "
"look at the first target and then stop without looking at any others. So if "
"we typed <userinput>make</userinput> here, it will just go to the <_:"
"buildtarget-1/> target, re-compile <filename>foo</filename> if necessary, "
"and then stop without going on to the <_:buildtarget-2/> target."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1504
msgid ""
"Notice that the <_:buildtarget-1/> target does not actually depend on "
"anything! This means that the command on the following line is always "
"executed when we try to make that target by typing <userinput>make install</"
"userinput>. In this case, it will copy <filename>foo</filename> into the "
"user's home directory. This is often used by application makefiles, so that "
"the application can be installed in the correct directory when it has been "
"correctly compiled."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1514
msgid ""
"This is a slightly confusing subject to try to explain. If you do not quite "
"understand how <command>make</command> works, the best thing to do is to "
"write a simple program like <quote>hello world</quote> and a make file like "
"the one above and experiment. Then progress to using more than one source "
"file, or having the source file include a header file. <command>touch</"
"command> is very useful here—it changes the date on a file without you "
"having to edit it."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1525
msgid "Make and include-files"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1527
msgid ""
"C code often starts with a list of files to include, for example stdio.h. "
"Some of these files are system-include files, some of them are from the "
"project you are now working on:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1532
#, no-wrap
msgid "#include &lt;stdio.h&gt;\n"
"#include \"foo.h\"\n"
"\n"
"int main(...."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1537
msgid ""
"To make sure that this file is recompiled the moment <filename>foo.h</"
"filename> is changed, you have to add it in your <filename>Makefile</"
"filename>:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1541
#, no-wrap
msgid "foo: foo.c foo.h"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1543
msgid ""
"The moment your project is getting bigger and you have more and more own "
"include-files to maintain, it will be a pain to keep track of all include "
"files and the files which are depending on it. If you change an include-file "
"but forget to recompile all the files which are depending on it, the results "
"will be devastating. <command>clang</command> has an option to analyze your "
"files and to produce a list of include-files and their dependencies: "
"<option>-MM</option>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1552
msgid "If you add this to your Makefile:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1554
#, no-wrap
msgid "depend:\n"
"	cc -E -MM *.c &gt; .depend"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1557
msgid ""
"and run <userinput>make depend</userinput>, the file <filename>.depend</"
"filename> will appear with a list of object-files, C-files and the include-"
"files:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1561
#, no-wrap
msgid "foo.o: foo.c foo.h"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1563
msgid ""
"If you change <filename>foo.h</filename>, next time you run <command>make</"
"command> all files depending on <filename>foo.h</filename> will be "
"recompiled."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1567
msgid ""
"Do not forget to run <command>make depend</command> each time you add an "
"include-file to one of your files."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1572
msgid "FreeBSD Makefiles"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1574
msgid ""
"Makefiles can be rather complicated to write. Fortunately, BSD-based systems "
"like FreeBSD come with some very powerful ones as part of the system. One "
"very good example of this is the FreeBSD ports system. Here is the essential "
"part of a typical ports <filename>Makefile</filename>:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1581
#, no-wrap
msgid ""
"MASTER_SITES=   ftp://freefall.cdrom.com/pub/FreeBSD/LOCAL_PORTS/\n"
"DISTFILES=      scheme-microcode+dist-7.3-freebsd.tgz\n"
"\n"
".include &lt;bsd.port.mk&gt;"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1586
msgid ""
"Now, if we go to the directory for this port and type <userinput>make</"
"userinput>, the following happens:"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1591
msgid ""
"A check is made to see if the source code for this port is already on the "
"system."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1596
msgid ""
"If it is not, an FTP connection to the URL in <symbol>MASTER_SITES</symbol> "
"is set up to download the source."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1602
msgid ""
"The checksum for the source is calculated and compared it with one for a "
"known, good, copy of the source. This is to make sure that the source was "
"not corrupted while in transit."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1609
msgid ""
"Any changes required to make the source work on FreeBSD are applied—this is "
"known as <firstterm>patching</firstterm>."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1615
msgid ""
"Any special configuration needed for the source is done. (Many <trademark "
"class=\"registered\">UNIX</trademark> program distributions try to work out "
"which version of <trademark class=\"registered\">UNIX</trademark> they are "
"being compiled on and which optional <trademark class=\"registered\">UNIX</"
"trademark> features are present—this is where they are given the information "
"in the FreeBSD ports scenario)."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1624
msgid ""
"The source code for the program is compiled. In effect, we change to the "
"directory where the source was unpacked and do <command>make</command>—the "
"program's own make file has the necessary information to build the program."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:1632
msgid ""
"We now have a compiled version of the program. If we wish, we can test it "
"now; when we feel confident about the program, we can type <userinput>make "
"install</userinput>. This will cause the program and any supporting files it "
"needs to be copied into the correct location; an entry is also made into a "
"<database>package database</database>, so that the port can easily be "
"uninstalled later if we change our mind about it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1643
msgid ""
"Now I think you will agree that is rather impressive for a four line script!"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1646
msgid ""
"The secret lies in the last line, which tells <command>make</command> to "
"look in the system makefile called <filename>bsd.port.mk</filename>. It is "
"easy to overlook this line, but this is where all the clever stuff comes "
"from—someone has written a makefile that tells <command>make</command> to do "
"all the things above (plus a couple of other things I did not mention, "
"including handling any errors that may occur) and anyone can get access to "
"that just by putting a single line in their own make file!"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1656
msgid ""
"If you want to have a look at these system makefiles, they are in <filename>/"
"usr/share/mk</filename>, but it is probably best to wait until you have had "
"a bit of practice with makefiles, as they are very complicated (and if you "
"do look at them, make sure you have a flask of strong coffee handy!)"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1665
msgid "More Advanced Uses of <command>make</command>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1667
msgid ""
"<command>Make</command> is a very powerful tool, and can do much more than "
"the simple example above shows. Unfortunately, there are several different "
"versions of <command>make</command>, and they all differ considerably. The "
"best way to learn what they can do is probably to read the "
"documentation—hopefully this introduction will have given you a base from "
"which you can do this."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1675
msgid ""
"The version of make that comes with FreeBSD is the <application>Berkeley "
"make</application>; there is a tutorial for it in <filename>/usr/share/doc/"
"psd/12.make</filename>. To view it, do"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1680
#, no-wrap
msgid "<prompt>%</prompt> <userinput>zmore paper.ascii.gz</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1682
msgid "in that directory."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1684
msgid ""
"Many applications in the ports use <application>GNU make</application>, "
"which has a very good set of <quote>info</quote> pages. If you have "
"installed any of these ports, <application>GNU make</application> will "
"automatically have been installed as <command>gmake</command>. It is also "
"available as a port and package in its own right."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1691
msgid ""
"To view the info pages for <application>GNU make</application>, you will "
"have to edit <filename>dir</filename> in the <filename>/usr/local/info</"
"filename> directory to add an entry for it. This involves adding a line like"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1697
#, no-wrap
msgid " * Make: (make).                 The GNU Make utility."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1699
msgid ""
"to the file. Once you have done this, you can type <userinput>info</"
"userinput> and then select <guimenuitem>make</guimenuitem> from the menu (or "
"in <application>Emacs</application>, do <userinput>C-h i</userinput>)."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:1708
msgid "Debugging"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1711
msgid "The Debugger"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1713
msgid ""
"The debugger that comes with FreeBSD is called <command>gdb</command> "
"(<application>GNU debugger</application>). You start it up by typing"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1717
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>gdb <replaceable>progname</replaceable></"
"userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1719
msgid ""
"although many people prefer to run it inside <application>Emacs</"
"application>. You can do this by:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1722
#, no-wrap
msgid ""
"<userinput>M-x gdb RET <replaceable>progname</replaceable> RET</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1724
msgid ""
"Using a debugger allows you to run the program under more controlled "
"circumstances. Typically, you can step through the program a line at a time, "
"inspect the value of variables, change them, tell the debugger to run up to "
"a certain point and then stop, and so on. You can even attach to a program "
"that is already running, or load a core file to investigate why the program "
"crashed. It is even possible to debug the kernel, though that is a little "
"trickier than the user applications we will be discussing in this section."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1734
msgid ""
"<command>gdb</command> has quite good on-line help, as well as a set of info "
"pages, so this section will concentrate on a few of the basic commands."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1738
msgid ""
"Finally, if you find its text-based command-prompt style off-putting, there "
"is a graphical front-end for it (<package>devel/xxgdb</package>) in the "
"Ports Collection."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1743
msgid ""
"This section is intended to be an introduction to using <command>gdb</"
"command> and does not cover specialized topics such as debugging the kernel."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1749
msgid "Running a Program in the Debugger"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1751
msgid ""
"You will need to have compiled the program with <option>-g</option> to get "
"the most out of using <command>gdb</command>. It will work without, but you "
"will only see the name of the function you are in, instead of the source "
"code. If you see a line like:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1757
#, no-wrap
msgid "… (no debugging symbols found) …"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1759
msgid ""
"when <command>gdb</command> starts up, you will know that the program was "
"not compiled with <option>-g</option>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1762
msgid ""
"At the <command>gdb</command> prompt, type <userinput>break main</userinput>."
" This will tell the debugger that you are not interested in watching the "
"preliminary set-up code in the program being run, and that it should stop "
"execution at the beginning of your code. Now type <userinput>run</userinput> "
"to start the program—it will start at the beginning of the set-up code and "
"then get stopped by the debugger when it calls <function>main()</function>. "
"(If you have ever wondered where <function>main()</function> gets called "
"from, now you know!)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1773
msgid ""
"You can now step through the program, a line at a time, by pressing "
"<command>n</command>. If you get to a function call, you can step into it by "
"pressing <command>s</command>. Once you are in a function call, you can "
"return from stepping into a function call by pressing <command>f</command>. "
"You can also use <command>up</command> and <command>down</command> to take a "
"quick look at the caller."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1781
msgid ""
"Here is a simple example of how to spot a mistake in a program with "
"<command>gdb</command>. This is our program (with a deliberate mistake):"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1785
#, no-wrap
msgid ""
"#include &lt;stdio.h&gt;\n"
"\n"
"int bazz(int anint);\n"
"\n"
"main() {\n"
"	int i;\n"
"\n"
"	printf(\"This is my program\\n\");\n"
"	bazz(i);\n"
"	return 0;\n"
"}\n"
"\n"
"int bazz(int anint) {\n"
"	printf(\"You gave me %d\\n\", anint);\n"
"	return anint;\n"
"}"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1802
msgid ""
"This program sets <symbol>i</symbol> to be <literal>5</literal> and passes "
"it to a function <function>bazz()</function> which prints out the number we "
"gave it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1807
msgid "When we compile and run the program we get"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1809
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cc -g -o temp temp.c</userinput>\n"
"<prompt>%</prompt> <userinput>./temp</userinput>\n"
"This is my program\n"
"anint = 4231"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1814
msgid "That was not what we expected! Time to see what is going on!"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1817
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>gdb temp</userinput>\n"
"GDB is free software and you are welcome to distribute copies of it\n"
" under certain conditions; type \"show copying\" to see the conditions.\n"
"There is absolutely no warranty for GDB; type \"show warranty\" for details.\n"
"GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, "
"Inc.\n"
"(gdb) <userinput>break main</userinput>				<lineannotation>Skip the set-up "
"code</lineannotation>\n"
"Breakpoint 1 at 0x160f: file temp.c, line 9.	<lineannotation>gdb puts "
"breakpoint at main()</lineannotation>\n"
"(gdb) <userinput>run</userinput>					<lineannotation>Run as far as main()</"
"lineannotation>\n"
"Starting program: /home/james/tmp/temp		<lineannotation>Program starts "
"running</lineannotation>\n"
"\n"
"Breakpoint 1, main () at temp.c:9		<lineannotation>gdb stops at main()</"
"lineannotation>\n"
"(gdb) <userinput>n</userinput>						<lineannotation>Go to next line</"
"lineannotation>\n"
"This is my program				<lineannotation>Program prints out</lineannotation>\n"
"(gdb) <userinput>s</userinput>						<lineannotation>step into bazz()</"
"lineannotation>\n"
"bazz (anint=4231) at temp.c:17			<lineannotation>gdb displays stack frame</"
"lineannotation>\n"
"(gdb)"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1834
msgid ""
"Hang on a minute! How did <symbol>anint</symbol> get to be <literal>4231</"
"literal>? Did we not we set it to be <literal>5</literal> in "
"<function>main()</function>? Let us move up to <function>main()</function> "
"and have a look."
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1839
#, no-wrap
msgid ""
"(gdb) <userinput>up</userinput>					<lineannotation>Move up call stack</"
"lineannotation>\n"
"#1  0x1625 in main () at temp.c:11		<lineannotation>gdb displays stack "
"frame</lineannotation>\n"
"(gdb) <userinput>p i</userinput>					<lineannotation>Show us the value of i</"
"lineannotation>\n"
"$1 = 4231					<lineannotation>gdb displays 4231</lineannotation>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1844
msgid ""
"Oh dear! Looking at the code, we forgot to initialize <symbol>i</symbol>. We "
"meant to put"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1847
#, no-wrap
msgid ""
"<lineannotation>…</lineannotation>\n"
"main() {\n"
"	int i;\n"
"\n"
"	i = 5;\n"
"	printf(\"This is my program\\n\");\n"
"<lineannotation>…</lineannotation>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1855
msgid ""
"but we left the <literal>i=5;</literal> line out. As we did not initialize "
"<symbol>i</symbol>, it had whatever number happened to be in that area of "
"memory when the program ran, which in this case happened to be "
"<literal>4231</literal>."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:1862
msgid ""
"<command>gdb</command> displays the stack frame every time we go into or out "
"of a function, even if we are using <command>up</command> and <command>down</"
"command> to move around the call stack. This shows the name of the function "
"and the values of its arguments, which helps us keep track of where we are "
"and what is going on. (The stack is a storage area where the program stores "
"information about the arguments passed to functions and where to go when it "
"returns from a function call)."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1875
msgid "Examining a Core File"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1877
msgid ""
"A core file is basically a file which contains the complete state of the "
"process when it crashed. In <quote>the good old days</quote>, programmers "
"had to print out hex listings of core files and sweat over machine code "
"manuals, but now life is a bit easier. Incidentally, under FreeBSD and other "
"4.4BSD systems, a core file is called <filename><replaceable>progname</"
"replaceable>.core</filename> instead of just <filename>core</filename>, to "
"make it clearer which program a core file belongs to."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1887
msgid ""
"To examine a core file, start up <command>gdb</command> in the usual way. "
"Instead of typing <command>break</command> or <command>run</command>, type"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1891
#, no-wrap
msgid ""
"(gdb) <userinput>core <replaceable>progname</replaceable>.core</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1893
msgid ""
"If you are not in the same directory as the core file, you will have to do "
"<userinput>dir /path/to/core/file</userinput> first."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1897
msgid "You should see something like this:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1899
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>gdb a.out</userinput>\n"
"GDB is free software and you are welcome to distribute copies of it\n"
" under certain conditions; type \"show copying\" to see the conditions.\n"
"There is absolutely no warranty for GDB; type \"show warranty\" for details.\n"
"GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, "
"Inc.\n"
"(gdb) <userinput>core a.out.core</userinput>\n"
"Core was generated by `a.out'.\n"
"Program terminated with signal 11, Segmentation fault.\n"
"Cannot access memory at address 0x7020796d.\n"
"#0  0x164a in bazz (anint=0x5) at temp.c:17\n"
"(gdb)"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1911
msgid ""
"In this case, the program was called <filename>a.out</filename>, so the core "
"file is called <filename>a.out.core</filename>. We can see that the program "
"crashed due to trying to access an area in memory that was not available to "
"it in a function called <function>bazz</function>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1918
msgid ""
"Sometimes it is useful to be able to see how a function was called, as the "
"problem could have occurred a long way up the call stack in a complex "
"program. <command>bt</command> causes <command>gdb</command> to print out a "
"back-trace of the call stack:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1924
#, no-wrap
msgid ""
"(gdb) <userinput>bt</userinput>\n"
"#0  0x164a in bazz (anint=0x5) at temp.c:17\n"
"#1  0xefbfd888 in end ()\n"
"#2  0x162c in main () at temp.c:11\n"
"(gdb)"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1930
msgid ""
"The <function>end()</function> function is called when a program crashes; in "
"this case, the <function>bazz()</function> function was called from "
"<function>main()</function>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1936
msgid "Attaching to a Running Program"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1938
msgid ""
"One of the neatest features about <command>gdb</command> is that it can "
"attach to a program that is already running. Of course, that assumes you "
"have sufficient permissions to do so. A common problem is when you are "
"stepping through a program that forks, and you want to trace the child, but "
"the debugger will only let you trace the parent."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1945
msgid ""
"What you do is start up another <command>gdb</command>, use <command>ps</"
"command> to find the process ID for the child, and do"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:1949
#, no-wrap
msgid "(gdb) <userinput>attach <replaceable>pid</replaceable></userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1951
msgid "in <command>gdb</command>, and then debug as usual."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1953
msgid ""
"<quote>That is all very well,</quote> you are probably thinking, <quote>but "
"by the time I have done that, the child process will be over the hill and "
"far away</quote>. Fear not, gentle reader, here is how to do it (courtesy of "
"the <command>gdb</command> info pages):"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:1959
#, no-wrap
msgid ""
"<lineannotation>…</lineannotation>\n"
"if ((pid = fork()) &lt; 0)		/* _Always_ check this */\n"
"	error();\n"
"else if (pid == 0) {		/* child */\n"
"	int PauseMode = 1;\n"
"\n"
"	while (PauseMode)\n"
"		sleep(10);	/* Wait until someone attaches to us */\n"
"	<lineannotation>…</lineannotation>\n"
"} else {			/* parent */\n"
"	<lineannotation>…</lineannotation>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1971
msgid ""
"Now all you have to do is attach to the child, set <symbol>PauseMode</"
"symbol> to <literal>0</literal>, and wait for the <function>sleep()</"
"function> call to return!"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:1978
msgid "Using Emacs as a Development Environment"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:1981
msgid "Emacs"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1983
msgid ""
"Emacs is a highly customizable editor—indeed, it has been customized to the "
"point where it is more like an operating system than an editor! Many "
"developers and sysadmins do in fact spend practically all their time working "
"inside Emacs, leaving it only to log out."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:1990
msgid ""
"It is impossible even to summarize everything Emacs can do here, but here "
"are some of the features of interest to developers:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:1996
msgid ""
"Very powerful editor, allowing search-and-replace on both strings and "
"regular expressions (patterns), jumping to start/end of block expression, "
"etc, etc."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2002
msgid "Pull-down menus and online help."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2006
msgid "Language-dependent syntax highlighting and indentation."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2011
msgid "Completely customizable."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2015
msgid "You can compile and debug programs within Emacs."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2020
msgid ""
"On a compilation error, you can jump to the offending line of source code."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2025
msgid ""
"Friendly-ish front-end to the <command>info</command> program used for "
"reading GNU hypertext documentation, including the documentation on Emacs "
"itself."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2031
msgid ""
"Friendly front-end to <command>gdb</command>, allowing you to look at the "
"source code as you step through your program."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2037
msgid "And doubtless many more that have been overlooked."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2039
msgid ""
"Emacs can be installed on FreeBSD using the <package>editors/emacs</package> "
"port."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2043
msgid ""
"Once it is installed, start it up and do <literal>C-h t</literal> to read an "
"Emacs tutorial—that means hold down <keycap>control</keycap>, press "
"<keycap>h</keycap>, let go of <keycap>control</keycap>, and then press "
"<keycap>t</keycap>. (Alternatively, you can use the mouse to select "
"<guimenuitem>Emacs Tutorial</guimenuitem> from the <guimenu>Help</guimenu> "
"menu.)"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2051
msgid ""
"Although Emacs does have menus, it is well worth learning the key bindings, "
"as it is much quicker when you are editing something to press a couple of "
"keys than to try to find the mouse and then click on the right place. And, "
"when you are talking to seasoned Emacs users, you will find they often "
"casually throw around expressions like <quote><literal>M-x replace-s RET foo "
"RET bar RET</literal></quote> so it is useful to know what they mean. And in "
"any case, Emacs has far too many useful functions for them to all fit on the "
"menu bars."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2062
msgid ""
"Fortunately, it is quite easy to pick up the key-bindings, as they are "
"displayed next to the menu item. My advice is to use the menu item for, say, "
"opening a file until you understand how it works and feel confident with it, "
"then try doing C-x C-f. When you are happy with that, move on to another "
"menu command."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2069
msgid ""
"If you cannot remember what a particular combination of keys does, select "
"<guimenuitem>Describe Key</guimenuitem> from the <guimenu>Help</guimenu> "
"menu and type it in—Emacs will tell you what it does. You can also use the "
"<guimenuitem>Command Apropos</guimenuitem> menu item to find out all the "
"commands which contain a particular word in them, with the key binding next "
"to it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2077
msgid ""
"By the way, the expression above means hold down the <keysym>Meta</keysym> "
"key, press <keysym>x</keysym>, release the <keysym>Meta</keysym> key, type "
"<userinput>replace-s</userinput> (short for <literal>replace-string</"
"literal>—another feature of Emacs is that you can abbreviate commands), "
"press the <keysym>return</keysym> key, type <userinput>foo</userinput> (the "
"string you want replaced), press the <keysym>return</keysym> key, type bar "
"(the string you want to replace <literal>foo</literal> with) and press "
"<keysym>return</keysym> again. Emacs will then do the search-and-replace "
"operation you have just requested."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2090
msgid ""
"If you are wondering what on earth <keysym>Meta</keysym> is, it is a special "
"key that many <trademark class=\"registered\">UNIX</trademark> workstations "
"have. Unfortunately, PC's do not have one, so it is usually <keycap>alt</"
"keycap> (or if you are unlucky, the <keysym>escape</keysym> key)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2096
msgid ""
"Oh, and to get out of Emacs, do <command>C-x C-c</command> (that means hold "
"down the <keysym>control</keysym> key, press <keysym>x</keysym>, press "
"<keysym>c</keysym> and release the <keysym>control</keysym> key). If you "
"have any unsaved files open, Emacs will ask you if you want to save them. "
"(Ignore the bit in the documentation where it says <command>C-z</command> is "
"the usual way to leave Emacs—that leaves Emacs hanging around in the "
"background, and is only really useful if you are on a system which does not "
"have virtual terminals)."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:2109
msgid "Configuring Emacs"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2111
msgid ""
"Emacs does many wonderful things; some of them are built in, some of them "
"need to be configured."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2114
msgid ""
"Instead of using a proprietary macro language for configuration, Emacs uses "
"a version of Lisp specially adapted for editors, known as Emacs Lisp. "
"Working with Emacs Lisp can be quite helpful if you want to go on and learn "
"something like Common Lisp. Emacs Lisp has many features of Common Lisp, "
"although it is considerably smaller (and thus easier to master)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2122
msgid ""
"The best way to learn Emacs Lisp is to download the <link xlink:href=\"ftp://"
"ftp.gnu.org/old-gnu/emacs/elisp-manual-19-2.4.tar.gz\">Emacs Tutorial</link>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2125
msgid ""
"However, there is no need to actually know any Lisp to get started with "
"configuring Emacs, as I have included a sample <filename>.emacs</filename>, "
"which should be enough to get you started. Just copy it into your home "
"directory and restart Emacs if it is already running; it will read the "
"commands from the file and (hopefully) give you a useful basic setup."
msgstr ""

#. (itstool) path: sect2/title
#. (itstool) path: example/title
#: book.translate.xml:2134 book.translate.xml:2202
msgid "A Sample <filename>.emacs</filename>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2136
msgid ""
"Unfortunately, there is far too much here to explain it in detail; however "
"there are one or two points worth mentioning."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2142
msgid ""
"Everything beginning with a <literal>;</literal> is a comment and is ignored "
"by Emacs."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2147
msgid ""
"In the first line, the <literal>-*- Emacs-Lisp -*-</literal> is so that we "
"can edit <filename>.emacs</filename> itself within Emacs and get all the "
"fancy features for editing Emacs Lisp. Emacs usually tries to guess this "
"based on the filename, and may not get it right for <filename>.emacs</"
"filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2157
msgid ""
"The <keysym>tab</keysym> key is bound to an indentation function in some "
"modes, so when you press the tab key, it will indent the current line of "
"code. If you want to put a <token>tab</token> character in whatever you are "
"writing, hold the <keysym>control</keysym> key down while you are pressing "
"the <keysym>tab</keysym> key."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2167
msgid ""
"This file supports syntax highlighting for C, C++, Perl, Lisp and Scheme, by "
"guessing the language from the filename."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2173
msgid ""
"Emacs already has a pre-defined function called <function>next-error</"
"function>. In a compilation output window, this allows you to move from one "
"compilation error to the next by doing <command>M-n</command>; we define a "
"complementary function, <function>previous-error</function>, that allows you "
"to go to a previous error by doing <command>M-p</command>. The nicest "
"feature of all is that <command>C-c C-c</command> will open up the source "
"file in which the error occurred and jump to the appropriate line."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2186
msgid ""
"We enable Emacs's ability to act as a server, so that if you are doing "
"something outside Emacs and you want to edit a file, you can just type in"
msgstr ""

#. (itstool) path: listitem/screen
#: book.translate.xml:2190
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>emacsclient <replaceable>filename</"
"replaceable></userinput>"
msgstr ""

#. (itstool) path: footnote/para
#: book.translate.xml:2193
msgid ""
"Many Emacs users set their <envar>EDITOR</envar> environment to "
"<literal>emacsclient</literal> so this happens every time they need to edit "
"a file."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2192
msgid "and then you can edit the file in your Emacs!<_:footnote-1/>"
msgstr ""

#. (itstool) path: example/programlisting
#: book.translate.xml:2204
#, no-wrap
msgid ""
";; -*-Emacs-Lisp-*-\n"
"\n"
";; This file is designed to be re-evaled; use the variable first-time\n"
";; to avoid any problems with this.\n"
"(defvar first-time t\n"
"  \"Flag signifying this is the first time that .emacs has been evaled\")\n"
"\n"
";; Meta\n"
"(global-set-key \"\\M- \" 'set-mark-command)\n"
"(global-set-key \"\\M-\\C-h\" 'backward-kill-word)\n"
"(global-set-key \"\\M-\\C-r\" 'query-replace)\n"
"(global-set-key \"\\M-r\" 'replace-string)\n"
"(global-set-key \"\\M-g\" 'goto-line)\n"
"(global-set-key \"\\M-h\" 'help-command)\n"
"\n"
";; Function keys\n"
"(global-set-key [f1] 'manual-entry)\n"
"(global-set-key [f2] 'info)\n"
"(global-set-key [f3] 'repeat-complex-command)\n"
"(global-set-key [f4] 'advertised-undo)\n"
"(global-set-key [f5] 'eval-current-buffer)\n"
"(global-set-key [f6] 'buffer-menu)\n"
"(global-set-key [f7] 'other-window)\n"
"(global-set-key [f8] 'find-file)\n"
"(global-set-key [f9] 'save-buffer)\n"
"(global-set-key [f10] 'next-error)\n"
"(global-set-key [f11] 'compile)\n"
"(global-set-key [f12] 'grep)\n"
"(global-set-key [C-f1] 'compile)\n"
"(global-set-key [C-f2] 'grep)\n"
"(global-set-key [C-f3] 'next-error)\n"
"(global-set-key [C-f4] 'previous-error)\n"
"(global-set-key [C-f5] 'display-faces)\n"
"(global-set-key [C-f8] 'dired)\n"
"(global-set-key [C-f10] 'kill-compilation)\n"
"\n"
";; Keypad bindings\n"
"(global-set-key [up] \"\\C-p\")\n"
"(global-set-key [down] \"\\C-n\")\n"
"(global-set-key [left] \"\\C-b\")\n"
"(global-set-key [right] \"\\C-f\")\n"
"(global-set-key [home] \"\\C-a\")\n"
"(global-set-key [end] \"\\C-e\")\n"
"(global-set-key [prior] \"\\M-v\")\n"
"(global-set-key [next] \"\\C-v\")\n"
"(global-set-key [C-up] \"\\M-\\C-b\")\n"
"(global-set-key [C-down] \"\\M-\\C-f\")\n"
"(global-set-key [C-left] \"\\M-b\")\n"
"(global-set-key [C-right] \"\\M-f\")\n"
"(global-set-key [C-home] \"\\M-&lt;\")\n"
"(global-set-key [C-end] \"\\M-&gt;\")\n"
"(global-set-key [C-prior] \"\\M-&lt;\")\n"
"(global-set-key [C-next] \"\\M-&gt;\")\n"
"\n"
";; Mouse\n"
"(global-set-key [mouse-3] 'imenu)\n"
"\n"
";; Misc\n"
"(global-set-key [C-tab] \"\\C-q\\t\")	; Control tab quotes a tab.\n"
"(setq backup-by-copying-when-mismatch t)\n"
"\n"
";; Treat 'y' or &lt;CR&gt; as yes, 'n' as no.\n"
"(fset 'yes-or-no-p 'y-or-n-p)\n"
"(define-key query-replace-map [return] 'act)\n"
"(define-key query-replace-map [?\\C-m] 'act)\n"
"\n"
";; Load packages\n"
"(require 'desktop)\n"
"(require 'tar-mode)\n"
"\n"
";; Pretty diff mode\n"
"(autoload 'ediff-buffers \"ediff\" \"Intelligent Emacs interface to diff\" "
"t)\n"
"(autoload 'ediff-files \"ediff\" \"Intelligent Emacs interface to diff\" t)\n"
"(autoload 'ediff-files-remote \"ediff\"\n"
"  \"Intelligent Emacs interface to diff\")\n"
"\n"
"(if first-time\n"
"    (setq auto-mode-alist\n"
"	  (append '((\"\\\\.cpp$\" . c++-mode)\n"
"		    (\"\\\\.hpp$\" . c++-mode)\n"
"		    (\"\\\\.lsp$\" . lisp-mode)\n"
"		    (\"\\\\.scm$\" . scheme-mode)\n"
"		    (\"\\\\.pl$\" . perl-mode)\n"
"		    ) auto-mode-alist)))\n"
"\n"
";; Auto font lock mode\n"
"(defvar font-lock-auto-mode-list\n"
"  (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'lisp-mode 'perl-mode "
"'scheme-mode)\n"
"  \"List of modes to always start in font-lock-mode\")\n"
"\n"
"(defvar font-lock-mode-keyword-alist\n"
"  '((c++-c-mode . c-font-lock-keywords)\n"
"    (perl-mode . perl-font-lock-keywords))\n"
"  \"Associations between modes and keywords\")\n"
"\n"
"(defun font-lock-auto-mode-select ()\n"
"  \"Automatically select font-lock-mode if the current major mode is in font-"
"lock-auto-mode-list\"\n"
"  (if (memq major-mode font-lock-auto-mode-list)\n"
"      (progn\n"
"	(font-lock-mode t))\n"
"    )\n"
"  )\n"
"\n"
"(global-set-key [M-f1] 'font-lock-fontify-buffer)\n"
"\n"
";; New dabbrev stuff\n"
";(require 'new-dabbrev)\n"
"(setq dabbrev-always-check-other-buffers t)\n"
"(setq dabbrev-abbrev-char-regexp \"\\\\sw\\\\|\\\\s_\")\n"
"(add-hook 'emacs-lisp-mode-hook\n"
"	  '(lambda ()\n"
"	     (set (make-local-variable 'dabbrev-case-fold-search) nil)\n"
"	     (set (make-local-variable 'dabbrev-case-replace) nil)))\n"
"(add-hook 'c-mode-hook\n"
"	  '(lambda ()\n"
"	     (set (make-local-variable 'dabbrev-case-fold-search) nil)\n"
"	     (set (make-local-variable 'dabbrev-case-replace) nil)))\n"
"(add-hook 'text-mode-hook\n"
"	  '(lambda ()\n"
"	     (set (make-local-variable 'dabbrev-case-fold-search) t)\n"
"	     (set (make-local-variable 'dabbrev-case-replace) t)))\n"
"\n"
";; C++ and C mode...\n"
"(defun my-c++-mode-hook ()\n"
"  (setq tab-width 4)\n"
"  (define-key c++-mode-map \"\\C-m\" 'reindent-then-newline-and-indent)\n"
"  (define-key c++-mode-map \"\\C-ce\" 'c-comment-edit)\n"
"  (setq c++-auto-hungry-initial-state 'none)\n"
"  (setq c++-delete-function 'backward-delete-char)\n"
"  (setq c++-tab-always-indent t)\n"
"  (setq c-indent-level 4)\n"
"  (setq c-continued-statement-offset 4)\n"
"  (setq c++-empty-arglist-indent 4))\n"
"\n"
"(defun my-c-mode-hook ()\n"
"  (setq tab-width 4)\n"
"  (define-key c-mode-map \"\\C-m\" 'reindent-then-newline-and-indent)\n"
"  (define-key c-mode-map \"\\C-ce\" 'c-comment-edit)\n"
"  (setq c-auto-hungry-initial-state 'none)\n"
"  (setq c-delete-function 'backward-delete-char)\n"
"  (setq c-tab-always-indent t)\n"
";; BSD-ish indentation style\n"
"  (setq c-indent-level 4)\n"
"  (setq c-continued-statement-offset 4)\n"
"  (setq c-brace-offset -4)\n"
"  (setq c-argdecl-indent 0)\n"
"  (setq c-label-offset -4))\n"
"\n"
";; Perl mode\n"
"(defun my-perl-mode-hook ()\n"
"  (setq tab-width 4)\n"
"  (define-key c++-mode-map \"\\C-m\" 'reindent-then-newline-and-indent)\n"
"  (setq perl-indent-level 4)\n"
"  (setq perl-continued-statement-offset 4))\n"
"\n"
";; Scheme mode...\n"
"(defun my-scheme-mode-hook ()\n"
"  (define-key scheme-mode-map \"\\C-m\" 'reindent-then-newline-and-indent))\n"
"\n"
";; Emacs-Lisp mode...\n"
"(defun my-lisp-mode-hook ()\n"
"  (define-key lisp-mode-map \"\\C-m\" 'reindent-then-newline-and-indent)\n"
"  (define-key lisp-mode-map \"\\C-i\" 'lisp-indent-line)\n"
"  (define-key lisp-mode-map \"\\C-j\" 'eval-print-last-sexp))\n"
"\n"
";; Add all of the hooks...\n"
"(add-hook 'c++-mode-hook 'my-c++-mode-hook)\n"
"(add-hook 'c-mode-hook 'my-c-mode-hook)\n"
"(add-hook 'scheme-mode-hook 'my-scheme-mode-hook)\n"
"(add-hook 'emacs-lisp-mode-hook 'my-lisp-mode-hook)\n"
"(add-hook 'lisp-mode-hook 'my-lisp-mode-hook)\n"
"(add-hook 'perl-mode-hook 'my-perl-mode-hook)\n"
"\n"
";; Complement to next-error\n"
"(defun previous-error (n)\n"
"  \"Visit previous compilation error message and corresponding source code."
"\"\n"
"  (interactive \"p\")\n"
"  (next-error (- n)))\n"
"\n"
";; Misc...\n"
"(transient-mark-mode 1)\n"
"(setq mark-even-if-inactive t)\n"
"(setq visible-bell nil)\n"
"(setq next-line-add-newlines nil)\n"
"(setq compile-command \"make\")\n"
"(setq suggest-key-bindings nil)\n"
"(put 'eval-expression 'disabled nil)\n"
"(put 'narrow-to-region 'disabled nil)\n"
"(put 'set-goal-column 'disabled nil)\n"
"(if (&gt;= emacs-major-version 21)\n"
"	(setq show-trailing-whitespace t))\n"
"\n"
";; Elisp archive searching\n"
"(autoload 'format-lisp-code-directory \"lispdir\" nil t)\n"
"(autoload 'lisp-dir-apropos \"lispdir\" nil t)\n"
"(autoload 'lisp-dir-retrieve \"lispdir\" nil t)\n"
"(autoload 'lisp-dir-verify \"lispdir\" nil t)\n"
"\n"
";; Font lock mode\n"
"(defun my-make-face (face color &amp;optional bold)\n"
"  \"Create a face from a color and optionally make it bold\"\n"
"  (make-face face)\n"
"  (copy-face 'default face)\n"
"  (set-face-foreground face color)\n"
"  (if bold (make-face-bold face))\n"
"  )\n"
"\n"
"(if (eq window-system 'x)\n"
"    (progn\n"
"      (my-make-face 'blue \"blue\")\n"
"      (my-make-face 'red \"red\")\n"
"      (my-make-face 'green \"dark green\")\n"
"      (setq font-lock-comment-face 'blue)\n"
"      (setq font-lock-string-face 'bold)\n"
"      (setq font-lock-type-face 'bold)\n"
"      (setq font-lock-keyword-face 'bold)\n"
"      (setq font-lock-function-name-face 'red)\n"
"      (setq font-lock-doc-string-face 'green)\n"
"      (add-hook 'find-file-hooks 'font-lock-auto-mode-select)\n"
"\n"
"      (setq baud-rate 1000000)\n"
"      (global-set-key \"\\C-cmm\" 'menu-bar-mode)\n"
"      (global-set-key \"\\C-cms\" 'scroll-bar-mode)\n"
"      (global-set-key [backspace] 'backward-delete-char)\n"
"					;      (global-set-key [delete] 'delete-char)\n"
"      (standard-display-european t)\n"
"      (load-library \"iso-transl\")))\n"
"\n"
";; X11 or PC using direct screen writes\n"
"(if window-system\n"
"    (progn\n"
"      ;;      (global-set-key [M-f1] 'hilit-repaint-command)\n"
"      ;;      (global-set-key [M-f2] [?\\C-u M-f1])\n"
"      (setq hilit-mode-enable-list\n"
"	    '(not text-mode c-mode c++-mode emacs-lisp-mode lisp-mode\n"
"		  scheme-mode)\n"
"	    hilit-auto-highlight nil\n"
"	    hilit-auto-rehighlight 'visible\n"
"	    hilit-inhibit-hooks nil\n"
"	    hilit-inhibit-rebinding t)\n"
"      (require 'hilit19)\n"
"      (require 'paren))\n"
"  (setq baud-rate 2400)			; For slow serial connections\n"
"  )\n"
"\n"
";; TTY type terminal\n"
"(if (and (not window-system)\n"
"	 (not (equal system-type 'ms-dos)))\n"
"    (progn\n"
"      (if first-time\n"
"	  (progn\n"
"	    (keyboard-translate ?\\C-h ?\\C-?)\n"
"	    (keyboard-translate ?\\C-? ?\\C-h)))))\n"
"\n"
";; Under UNIX\n"
"(if (not (equal system-type 'ms-dos))\n"
"    (progn\n"
"      (if first-time\n"
"	  (server-start))))\n"
"\n"
";; Add any face changes here\n"
"(add-hook 'term-setup-hook 'my-term-setup-hook)\n"
"(defun my-term-setup-hook ()\n"
"  (if (eq window-system 'pc)\n"
"      (progn\n"
";;	(set-face-background 'default \"red\")\n"
"	)))\n"
"\n"
";; Restore the \"desktop\" - do this as late as possible\n"
"(if first-time\n"
"    (progn\n"
"      (desktop-load-default)\n"
"      (desktop-read)))\n"
"\n"
";; Indicate that this file has been read at least once\n"
"(setq first-time nil)\n"
"\n"
";; No need to debug anything now\n"
"\n"
"(setq debug-on-error nil)\n"
"\n"
";; All done\n"
"(message \"All done, %s%s\" (user-login-name) \".\")"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:2491
msgid "Extending the Range of Languages Emacs Understands"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2494
msgid ""
"Now, this is all very well if you only want to program in the languages "
"already catered for in <filename>.emacs</filename> (C, C++, Perl, Lisp and "
"Scheme), but what happens if a new language called <quote>whizbang</quote> "
"comes out, full of exciting features?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2501
msgid ""
"The first thing to do is find out if whizbang comes with any files that tell "
"Emacs about the language. These usually end in <filename>.el</filename>, "
"short for <quote>Emacs Lisp</quote>. For example, if whizbang is a FreeBSD "
"port, we can locate these files by doing"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:2507
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>find /usr/ports/lang/whizbang -name \"*.el\" -"
"print</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2509
msgid ""
"and install them by copying them into the Emacs site Lisp directory. On "
"FreeBSD, this is <filename>/usr/local/share/emacs/site-lisp</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2513
msgid "So for example, if the output from the find command was"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:2516
#, no-wrap
msgid "/usr/ports/lang/whizbang/work/misc/whizbang.el"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2518
msgid "we would do"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:2520
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>cp /usr/ports/lang/whizbang/work/misc/whizbang."
"el /usr/local/share/emacs/site-lisp</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2522
msgid ""
"Next, we need to decide what extension whizbang source files have. Let us "
"say for the sake of argument that they all end in <filename>.wiz</filename>. "
"We need to add an entry to our <filename>.emacs</filename> to make sure "
"Emacs will be able to use the information in <filename>whizbang.el</"
"filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2529
msgid ""
"Find the <symbol>auto-mode-alist entry</symbol> in <filename>.emacs</"
"filename> and add a line for whizbang, such as:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:2533
#, no-wrap
msgid ""
"<lineannotation>…</lineannotation>\n"
"(\"\\\\.lsp$\" . lisp-mode)\n"
"(\"\\\\.wiz$\" . whizbang-mode)\n"
"(\"\\\\.scm$\" . scheme-mode)\n"
"<lineannotation>…</lineannotation>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2539
msgid ""
"This means that Emacs will automatically go into <function>whizbang-mode</"
"function> when you edit a file ending in <filename>.wiz</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2543
msgid ""
"Just below this, you will find the <symbol>font-lock-auto-mode-list</symbol> "
"entry. Add <function>whizbang-mode</function> to it like so:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:2547
#, no-wrap
msgid ""
";; Auto font lock mode\n"
"(defvar font-lock-auto-mode-list\n"
"  (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'whizbang-mode 'lisp-"
"mode 'perl-mode 'scheme-mode)\n"
"  \"List of modes to always start in font-lock-mode\")"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2552
msgid ""
"This means that Emacs will always enable <function>font-lock-mode</function> "
"(ie syntax highlighting) when editing a <filename>.wiz</filename> file."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2556
msgid ""
"And that is all that is needed. If there is anything else you want done "
"automatically when you open up <filename>.wiz</filename>, you can add a "
"<function>whizbang-mode hook</function> (see <function>my-scheme-mode-hook</"
"function> for a simple example that adds <function>auto-indent</function>)."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:2566
msgid "Further Reading"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2568
msgid ""
"For information about setting up a development environment for contributing "
"fixes to FreeBSD itself, please see "
"<citerefentry><refentrytitle>development</refentrytitle><manvolnum>7</"
"manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2574
msgid ""
"Brian Harvey and Matthew Wright <emphasis>Simply Scheme</emphasis> MIT 1994. "
"ISBN 0-262-08226-8"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2581
msgid ""
"Randall Schwartz <emphasis>Learning Perl</emphasis> O'Reilly 1993 ISBN 1-"
"56592-042-2"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2588
msgid ""
"Patrick Henry Winston and Berthold Klaus Paul Horn <emphasis>Lisp (3rd "
"Edition)</emphasis> Addison-Wesley 1989 ISBN 0-201-08319-1"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2595
msgid ""
"Brian W. Kernighan and Rob Pike <emphasis>The Unix Programming Environment</"
"emphasis> Prentice-Hall 1984 ISBN 0-13-937681-X"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2602
msgid ""
"Brian W. Kernighan and Dennis M. Ritchie <emphasis>The C Programming "
"Language (2nd Edition)</emphasis> Prentice-Hall 1988 ISBN 0-13-110362-8"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2609
msgid ""
"Bjarne Stroustrup <emphasis>The C++ Programming Language</emphasis> Addison-"
"Wesley 1991 ISBN 0-201-53992-6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2616
msgid ""
"W. Richard Stevens <emphasis>Advanced Programming in the Unix Environment</"
"emphasis> Addison-Wesley 1992 ISBN 0-201-56317-7"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:2623
msgid ""
"W. Richard Stevens <emphasis>Unix Network Programming</emphasis> Prentice-"
"Hall 1990 ISBN 0-13-949876-1"
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:2640
msgid "Secure Programming"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2650
msgid ""
"This chapter describes some of the security issues that have plagued "
"<trademark class=\"registered\">UNIX</trademark> programmers for decades and "
"some of the new tools available to help programmers avoid writing "
"exploitable code."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:2656
msgid "Secure Design Methodology"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2659
msgid ""
"Writing secure applications takes a very scrutinous and pessimistic outlook "
"on life. Applications should be run with the principle of <quote>least "
"privilege</quote> so that no process is ever running with more than the bare "
"minimum access that it needs to accomplish its function. Previously tested "
"code should be reused whenever possible to avoid common mistakes that others "
"may have already fixed."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2667
msgid ""
"One of the pitfalls of the <trademark class=\"registered\">UNIX</trademark> "
"environment is how easy it is to make assumptions about the sanity of the "
"environment. Applications should never trust user input (in all its forms), "
"system resources, inter-process communication, or the timing of events. "
"<trademark class=\"registered\">UNIX</trademark> processes do not execute "
"synchronously so logical operations are rarely atomic."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:2675
msgid "Buffer Overflows"
msgstr ""

#. (itstool) path: para/indexterm
#. (itstool) path: sect3/indexterm
#: book.translate.xml:2680 book.translate.xml:2899
msgid "<primary>buffer overflow</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2681
msgid "<primary>von Neumann</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2686
msgid "<primary>Morris Internet worm</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2677
msgid ""
"Buffer Overflows have been around since the very beginnings of the von "
"Neumann <xref linkend=\"COD\"/> architecture. <_:indexterm-1/> <_:indexterm-"
"2/> They first gained widespread notoriety in 1988 with the Morris Internet "
"worm. Unfortunately, the same basic attack remains <_:indexterm-3/> "
"effective today. By far the most common type of buffer overflow attack is "
"based on corrupting the stack."
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:2692
msgid "<primary>stack</primary>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:2693
msgid "<primary>arguments</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2700
msgid "<primary>LIFO</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2701
msgid "<primary>process image</primary> <secondary>stack pointer</secondary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2710
msgid "<primary>stack frame</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2711
msgid "<primary>stack pointer</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2720
msgid "<primary>frame pointer</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2721
msgid "<primary>process image</primary> <secondary>frame pointer</secondary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2725
msgid "<primary>return address</primary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2726
msgid "<primary>stack-overflow</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2695
msgid ""
"Most modern computer systems use a stack to pass arguments to procedures and "
"to store local variables. A stack is a last in first out (LIFO) buffer in "
"the high memory area of a process image. When a program invokes a function a "
"new \"stack frame\" is <_:indexterm-1/> <_:indexterm-2/> created. This stack "
"frame consists of the arguments passed to the function as well as a dynamic "
"amount of local variable space. The \"stack pointer\" is a register that "
"holds the current <_:indexterm-3/> <_:indexterm-4/> location of the top of "
"the stack. Since this value is constantly changing as new values are pushed "
"onto the top of the stack, many implementations also provide a \"frame "
"pointer\" that is located near the beginning of a stack frame so that local "
"variables can more easily be addressed relative to this value. <xref linkend="
"\"COD\"/> The return address for function <_:indexterm-5/> <_:indexterm-6/> "
"<_:indexterm-7/> <_:indexterm-8/> calls is also stored on the stack, and "
"this is the cause of stack-overflow exploits since overflowing a local "
"variable in a function can overwrite the return address of that function, "
"potentially allowing a malicious user to execute any code he or she wants."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2734
msgid ""
"Although stack-based attacks are by far the most common, it would also be "
"possible to overrun the stack with a heap-based (malloc/free) attack."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2738
msgid ""
"The C programming language does not perform automatic bounds checking on "
"arrays or pointers as many other languages do. In addition, the standard C "
"library is filled with a handful of very dangerous functions."
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2746
msgid "<function>strcpy</function>(char *dest, const char *src)"
msgstr ""

#. (itstool) path: entry/simpara
#: book.translate.xml:2748 book.translate.xml:2753
msgid "May overflow the dest buffer"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2751
msgid "<function>strcat</function>(char *dest, const char *src)"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2756
msgid "<function>getwd</function>(char *buf)"
msgstr ""

#. (itstool) path: entry/simpara
#: book.translate.xml:2757
msgid "May overflow the buf buffer"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2760
msgid "<function>gets</function>(char *s)"
msgstr ""

#. (itstool) path: entry/simpara
#: book.translate.xml:2761
msgid "May overflow the s buffer"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2764
msgid "<function>[vf]scanf</function>(const char *format, ...)"
msgstr ""

#. (itstool) path: entry/simpara
#: book.translate.xml:2766
msgid "May overflow its arguments."
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2769
msgid "<function>realpath</function>(char *path, char resolved_path[])"
msgstr ""

#. (itstool) path: entry/simpara
#: book.translate.xml:2771
msgid "May overflow the path buffer"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:2774
msgid "<function>[v]sprintf</function>(char *str, const char *format, ...)"
msgstr ""

#. (itstool) path: entry/simpara
#: book.translate.xml:2776
msgid "May overflow the str buffer."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:2782
msgid "Example Buffer Overflow"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2784
msgid ""
"The following example code contains a buffer overflow designed to overwrite "
"the return address and skip the instruction immediately following the "
"function call. (Inspired by <xref linkend=\"Phrack\"/>)"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:2789
#, no-wrap
msgid ""
"#include &lt;stdio.h&gt;\n"
"\n"
"void manipulate(char *buffer) {\n"
"  char newbuffer[80];\n"
"  strcpy(newbuffer,buffer);\n"
"}\n"
"\n"
"int main() {\n"
"  char ch,buffer[4096];\n"
"  int i=0;\n"
"\n"
"  while ((buffer[i++] = getchar()) != '\\n') {};\n"
"\n"
"  i=1;\n"
"  manipulate(buffer);\n"
"  i=2;\n"
"  printf(\"The value of i is : %d\\n\",i);\n"
"  return 0;\n"
"}"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2809
msgid ""
"Let us examine what the memory image of this process would look like if we "
"were to input 160 spaces into our little program before hitting return."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2813
msgid "[XXX figure here!]"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2815
msgid ""
"Obviously more malicious input can be devised to execute actual compiled "
"instructions (such as exec(/bin/sh))."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:2819
msgid "Avoiding Buffer Overflows"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2826
msgid ""
"<primary>string copy functions</primary> <secondary>strncpy</secondary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2830
msgid ""
"<primary>string copy functions</primary> <secondary>strncat</secondary>"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:2842
msgid "<primary>NUL termination</primary>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2821
msgid ""
"The most straightforward solution to the problem of stack-overflows is to "
"always use length restricted memory and string copy functions. "
"<function>strncpy</function> and <function>strncat</function> are part of "
"the standard C library. <_:indexterm-1/> <_:indexterm-2/> These functions "
"accept a length value as a parameter which should be no larger than the size "
"of the destination buffer. These functions will then copy up to `length' "
"bytes from the source to the destination. However there are a number of "
"problems with these functions. Neither function guarantees NUL termination "
"if the size of the input buffer is as large as the <_:indexterm-3/> "
"destination. The length parameter is also used inconsistently between "
"strncpy and strncat so it is easy for programmers to get confused as to "
"their proper usage. There is also a significant performance loss compared to "
"<function>strcpy</function> when copying a short string into a large buffer "
"since <function>strncpy</function> NUL fills up the size specified."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:2852
msgid ""
"Another memory copy implementation exists to get around these problems. The "
"<function>strlcpy</function> and <function>strlcat</function> functions "
"guarantee that they will always null terminate the destination string when "
"given a non-zero length argument."
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:2858
msgid ""
"<primary>string copy functions</primary> <secondary>strlcpy</secondary>"
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:2863
msgid ""
"<primary>string copy functions</primary> <secondary>strlcat</secondary>"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:2868
msgid "Compiler based run-time bounds checking"
msgstr ""

#. (itstool) path: sect3/indexterm
#: book.translate.xml:2870
msgid ""
"<primary>bounds checking</primary> <secondary>compiler-based</secondary>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:2873
msgid ""
"Unfortunately there is still a very large assortment of code in public use "
"which blindly copies memory around without using any of the bounded copy "
"routines we just discussed. Fortunately, there is a way to help prevent such "
"attacks — run-time bounds checking, which is implemented by several C/C++ "
"compilers."
msgstr ""

#. (itstool) path: sect3/indexterm
#: book.translate.xml:2880
msgid "<primary>ProPolice</primary>"
msgstr ""

#. (itstool) path: sect3/indexterm
#: book.translate.xml:2881
msgid "<primary>StackGuard</primary>"
msgstr ""

#. (itstool) path: sect3/indexterm
#: book.translate.xml:2882
msgid "<primary>gcc</primary>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:2884
msgid ""
"ProPolice is one such compiler feature, and is integrated into "
"<citerefentry><refentrytitle>gcc</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry> versions 4.1 and later. It replaces and extends the earlier "
"StackGuard <citerefentry><refentrytitle>gcc</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry> extension."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:2888
msgid ""
"ProPolice helps to protect against stack-based buffer overflows and other "
"attacks by laying pseudo-random numbers in key areas of the stack before "
"calling any function. When a function returns, these <quote>canaries</quote> "
"are checked and if they are found to have been changed the executable is "
"immediately aborted. Thus any attempt to modify the return address or other "
"variable stored on the stack in an attempt to get malicious code to run is "
"unlikely to succeed, as the attacker would have to also manage to leave the "
"pseudo-random canaries untouched."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:2901
msgid ""
"Recompiling your application with ProPolice is an effective means of "
"stopping most buffer-overflow attacks, but it can still be compromised."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:2907
msgid "Library based run-time bounds checking"
msgstr ""

#. (itstool) path: sect3/indexterm
#: book.translate.xml:2909
msgid ""
"<primary>bounds checking</primary> <secondary>library-based</secondary>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:2914
msgid ""
"Compiler-based mechanisms are completely useless for binary-only software "
"for which you cannot recompile. For these situations there are a number of "
"libraries which re-implement the unsafe functions of the C-library "
"(<function>strcpy</function>, <function>fscanf</function>, <function>getwd</"
"function>, etc..) and ensure that these functions can never write past the "
"stack pointer."
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:2923
msgid "libsafe"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:2924
msgid "libverify"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:2925
msgid "libparanoia"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:2928
msgid ""
"Unfortunately these library-based defenses have a number of shortcomings. "
"These libraries only protect against a very small set of security related "
"issues and they neglect to fix the actual problem. These defenses may fail "
"if the application was compiled with -fomit-frame-pointer. Also, the "
"LD_PRELOAD and LD_LIBRARY_PATH environment variables can be overwritten/"
"unset by the user."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:2940
msgid "SetUID issues"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:2942
msgid "<primary>seteuid</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2944
msgid ""
"There are at least 6 different IDs associated with any given process. "
"Because of this you have to be very careful with the access that your "
"process has at any given time. In particular, all seteuid applications "
"should give up their privileges as soon as it is no longer required."
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:2950
msgid "<primary>user IDs</primary> <secondary>real user ID</secondary>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:2954
msgid "<primary>user IDs</primary> <secondary>effective user ID</secondary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2959
msgid ""
"The real user ID can only be changed by a superuser process. The "
"<application>login</application> program sets this when a user initially "
"logs in and it is seldom changed."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2963
msgid ""
"The effective user ID is set by the <function>exec()</function> functions if "
"a program has its seteuid bit set. An application can call "
"<function>seteuid()</function> at any time to set the effective user ID to "
"either the real user ID or the saved set-user-ID. When the effective user ID "
"is set by <function>exec()</function> functions, the previous value is saved "
"in the saved set-user-ID."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:2973
msgid "Limiting your program's environment"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:2975
msgid "<primary>chroot()</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2977
msgid ""
"The traditional method of restricting a process is with the "
"<function>chroot()</function> system call. This system call changes the root "
"directory from which all other paths are referenced for a process and any "
"child processes. For this call to succeed the process must have execute "
"(search) permission on the directory being referenced. The new environment "
"does not actually take effect until you <function>chdir()</function> into "
"your new environment. It should also be noted that a process can easily "
"break out of a chroot environment if it has root privilege. This could be "
"accomplished by creating device nodes to read kernel memory, attaching a "
"debugger to a process outside of the <citerefentry><refentrytitle>chroot</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> environment, or in "
"many other creative ways."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:2992
msgid ""
"The behavior of the <function>chroot()</function> system call can be "
"controlled somewhat with the kern.chroot_allow_open_directories "
"<command>sysctl</command> variable. When this value is set to 0, "
"<function>chroot()</function> will fail with EPERM if there are any "
"directories open. If set to the default value of 1, then <function>chroot()</"
"function> will fail with EPERM if there are any directories open and the "
"process is already subject to a <function>chroot()</function> call. For any "
"other value, the check for open directories will be bypassed completely."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3003
msgid "FreeBSD's jail functionality"
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:3005
msgid "<primary>jail</primary>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3007
msgid ""
"The concept of a Jail extends upon the <function>chroot()</function> by "
"limiting the powers of the superuser to create a true `virtual server'. Once "
"a prison is set up all network communication must take place through the "
"specified IP address, and the power of \"root privilege\" in this jail is "
"severely constrained."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3014
msgid ""
"While in a prison, any tests of superuser power within the kernel using the "
"<function>suser()</function> call will fail. However, some calls to "
"<function>suser()</function> have been changed to a new interface "
"<function>suser_xxx()</function>. This function is responsible for "
"recognizing or denying access to superuser power for imprisoned processes."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3021
msgid "A superuser process within a jailed environment has the power to:"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3025
msgid ""
"Manipulate credential with <function>setuid</function>, <function>seteuid</"
"function>, <function>setgid</function>, <function>setegid</function>, "
"<function>setgroups</function>, <function>setreuid</function>, "
"<function>setregid</function>, <function>setlogin</function>"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3030
msgid "Set resource limits with <function>setrlimit</function>"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3031
msgid "Modify some sysctl nodes (kern.hostname)"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3033
msgid "<function>chroot()</function>"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3034
msgid ""
"Set flags on a vnode: <function>chflags</function>, <function>fchflags</"
"function>"
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3037
msgid ""
"Set attributes of a vnode such as file permission, owner, group, size, "
"access time, and modification time."
msgstr ""

#. (itstool) path: listitem/simpara
#: book.translate.xml:3040
msgid "Bind to privileged ports in the Internet domain (ports &lt; 1024)"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3044
msgid ""
"<function>Jail</function> is a very useful tool for running applications in "
"a secure environment but it does have some shortcomings. Currently, the IPC "
"mechanisms have not been converted to the <function>suser_xxx</function> so "
"applications such as MySQL cannot be run within a jail. Superuser access may "
"have a very limited meaning within a jail, but there is no way to specify "
"exactly what \"very limited\" means."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3053
msgid ""
"<trademark class=\"registered\">POSIX</trademark>.1e Process Capabilities"
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:3055
msgid "<primary>POSIX.1e Process Capabilities</primary>"
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:3056
msgid "<primary>TrustedBSD</primary>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3058
msgid ""
"<trademark class=\"registered\">POSIX</trademark> has released a working "
"draft that adds event auditing, access control lists, fine grained "
"privileges, information labeling, and mandatory access control."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3061
msgid ""
"This is a work in progress and is the focus of the <link xlink:href=\"http://"
"www.trustedbsd.org/\">TrustedBSD</link> project. Some of the initial work "
"has been committed to FreeBSD-CURRENT (cap_set_proc(3))."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:3069
msgid "Trust"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3071
msgid ""
"An application should never assume that anything about the users environment "
"is sane. This includes (but is certainly not limited to): user input, "
"signals, environment variables, resources, IPC, mmaps, the filesystem "
"working directory, file descriptors, the # of open files, etc."
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3077
msgid "<primary>positive filtering</primary>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3078
msgid "<primary>data validation</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3080
msgid ""
"You should never assume that you can catch all forms of invalid input that a "
"user might supply. Instead, your application should use positive filtering "
"to only allow a specific subset of inputs that you deem safe. Improper data "
"validation has been the cause of many exploits, especially with CGI scripts "
"on the world wide web. For filenames you need to be extra careful about "
"paths (\"../\", \"/\"), symbolic links, and shell escape characters."
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3089
msgid "<primary>Perl Taint mode</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3091
msgid ""
"Perl has a really cool feature called \"Taint\" mode which can be used to "
"prevent scripts from using data derived outside the program in an unsafe way."
" This mode will check command line arguments, environment variables, locale "
"information, the results of certain syscalls (<function>readdir()</"
"function>, <function>readlink()</function>, <function>getpwxxx()</"
"function>), and all file input."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:3102
msgid "Race Conditions"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3104
msgid ""
"A race condition is anomalous behavior caused by the unexpected dependence "
"on the relative timing of events. In other words, a programmer incorrectly "
"assumed that a particular event would always happen before another."
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3109
msgid "<primary>race conditions</primary> <secondary>signals</secondary>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3112
msgid ""
"<primary>race conditions</primary> <secondary>access checks</secondary>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3115
msgid "<primary>race conditions</primary> <secondary>file opens</secondary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3118
msgid ""
"Some of the common causes of race conditions are signals, access checks, and "
"file opens. Signals are asynchronous events by nature so special care must "
"be taken in dealing with them. Checking access with <function>access(2)</"
"function> then <function>open(2)</function> is clearly non-atomic. Users can "
"move files in between the two calls. Instead, privileged applications should "
"<function>seteuid()</function> and then call <function>open()</function> "
"directly. Along the same lines, an application should always set a proper "
"umask before <function>open()</function> to obviate the need for spurious "
"<function>chmod()</function> calls."
msgstr ""

#. (itstool) path: chapter/title
#: book.translate.xml:3141
msgid "Localization and Internationalization - L10N and I18N"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:3144
msgid "Programming I18N Compliant Applications"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3145
msgid "<primary>Qt</primary>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3146
msgid "<primary>GTK</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3147
msgid ""
"To make your application more useful for speakers of other languages, we "
"hope that you will program I18N compliant. The GNU gcc compiler and GUI "
"libraries like QT and GTK support I18N through special handling of strings. "
"Making a program I18N compliant is very easy. It allows contributors to port "
"your application to other languages quickly. Refer to the library specific "
"I18N documentation for more details."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3155
msgid ""
"In contrast with common perception, I18N compliant code is easy to write. "
"Usually, it only involves wrapping your strings with library specific "
"functions. In addition, please be sure to allow for wide or multibyte "
"character support."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3161
msgid "A Call to Unify the I18N Effort"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3163
msgid ""
"It has come to our attention that the individual I18N/L10N efforts for each "
"country has been repeating each others' efforts. Many of us have been "
"reinventing the wheel repeatedly and inefficiently. We hope that the various "
"major groups in I18N could congregate into a group effort similar to the "
"Core Team's responsibility."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3170
msgid ""
"Currently, we hope that, when you write or port I18N programs, you would "
"send it out to each country's related FreeBSD mailing list for testing. In "
"the future, we hope to create applications that work in all the languages "
"out-of-the-box without dirty hacks."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3176
msgid ""
"The <link xlink:href=\"http://lists.FreeBSD.org/mailman/listinfo/freebsd-"
"i18n\">FreeBSD internationalization mailing list</link> has been established."
" If you are an I18N/L10N developer, please send your comments, ideas, "
"questions, and anything you deem related to it."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3182
msgid "Perl and Python"
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:3183
msgid "<primary>Perl</primary>"
msgstr ""

#. (itstool) path: sect2/indexterm
#: book.translate.xml:3186
msgid "<primary>Python</primary>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3190
msgid ""
"Perl and Python have I18N and wide character handling libraries. Please use "
"them for I18N compliance."
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:3196
msgid "Localized Messages with POSIX.1 Native Language Support (NLS)"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3198
msgid ""
"<personname><firstname>Gábor</firstname><surname>Kövesdán</surname></"
"personname><contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3204
msgid ""
"Beyond the basic I18N functions, like supporting various input encodings or "
"supporting national conventions, such as the different decimal separators, "
"at a higher level of I18N, it is possible to localize the messages written "
"to the output by the various programs. A common way of doing this is using "
"the POSIX.1 NLS functions, which are provided as a part of the FreeBSD base "
"system."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3212
msgid "Organizing Localized Messages into Catalog Files"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3214
msgid ""
"POSIX.1 NLS is based on catalog files, which contain the localized messages "
"in the desired encoding. The messages are organized into sets and each "
"message is identified by an integer number in the containing set. The "
"catalog files are conventionally named after the locale they contain "
"localized messages for, followed by the <literal>.msg</literal> extension. "
"For instance, the Hungarian messages for ISO8859-2 encoding should be stored "
"in a file called <filename>hu_HU.ISO8859-2</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3223
msgid ""
"These catalog files are common text files that contain the numbered messages."
" It is possible to write comments by starting the line with a <literal>$</"
"literal> sign. Set boundaries are also separated by special comments, where "
"the keyword <literal>set</literal> must directly follow the <literal>$</"
"literal> sign. The <literal>set</literal> keyword is then followed by the "
"set number. For example:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:3230
#, no-wrap
msgid "$set 1"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3232
msgid ""
"The actual message entries start with the message number and followed by the "
"localized message. The well-known modifiers from "
"<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></"
"citerefentry> are accepted:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:3236
#, no-wrap
msgid "15 \"File not found: %s\\n\""
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3238
msgid ""
"The language catalog files have to be compiled into a binary form before "
"they can be opened from the program. This conversion is done with the "
"<citerefentry><refentrytitle>gencat</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry> utility. Its first argument is the filename of the compiled "
"catalog and its further arguments are the input catalogs. The localized "
"messages can also be organized into more catalog files and then all of them "
"can be processed with <citerefentry><refentrytitle>gencat</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3248
msgid "Using the Catalog Files from the Source Code"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3250
msgid ""
"Using the catalog files is simple. To use the related functions, "
"<filename>nl_types.h</filename> must be included. Before using a catalog, it "
"has to be opened with <citerefentry><refentrytitle>catopen</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry>. The function takes "
"two arguments. The first parameter is the name of the installed and compiled "
"catalog. Usually, the name of the program is used, such as "
"<application>grep</application>. This name will be used when looking for the "
"compiled catalog file. The <citerefentry><refentrytitle>catopen</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> call looks for this "
"file in <filename>/usr/share/nls/<replaceable>locale</replaceable>/"
"<replaceable>catname</replaceable></filename> and in <filename>/usr/local/"
"share/nls/<replaceable>locale</replaceable>/<replaceable>catname</"
"replaceable></filename>, where <literal>locale</literal> is the locale set "
"and <literal>catname</literal> is the catalog name being discussed. The "
"second parameter is a constant, which can have two values:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3267
msgid ""
"<literal>NL_CAT_LOCALE</literal>, which means that the used catalog file "
"will be based on <envar>LC_MESSAGES</envar>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3272
msgid ""
"<literal>0</literal>, which means that <envar>LANG</envar> has to be used to "
"open the proper catalog."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3278
msgid ""
"The <citerefentry><refentrytitle>catopen</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> call returns a catalog identifier of type "
"<literal>nl_catd</literal>. Please refer to the manual page for a list of "
"possible returned error codes."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3282
msgid ""
"After opening a catalog <citerefentry><refentrytitle>catgets</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> can be used to "
"retrieve a message. The first parameter is the catalog identifier returned "
"by <citerefentry><refentrytitle>catopen</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry>, the second one is the number of the set, the "
"third one is the number of the messages, and the fourth one is a fallback "
"message, which will be returned if the requested message cannot be retrieved "
"from the catalog file."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3289
msgid ""
"After using the catalog file, it must be closed by calling "
"<citerefentry><refentrytitle>catclose</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry>, which has one argument, the catalog id."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3294
msgid "A Practical Example"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3296
msgid ""
"The following example will demonstrate an easy solution on how to use NLS "
"catalogs in a flexible way."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3299
msgid ""
"The below lines need to be put into a common header file of the program, "
"which is included into all source files where localized messages are "
"necessary:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:3303
#, no-wrap
msgid ""
"\n"
"#ifdef WITHOUT_NLS\n"
"#define getstr(n)	 nlsstr[n]\n"
"#else\n"
"#include &lt;nl_types.h&gt;\n"
"\n"
"extern nl_catd		 catalog;\n"
"#define getstr(n)	 catgets(catalog, 1, n, nlsstr[n])\n"
"#endif\n"
"\n"
"extern char		*nlsstr[];"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3315
msgid ""
"Next, put these lines into the global declaration part of the main source "
"file:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:3318
#, no-wrap
msgid ""
"\n"
"#ifndef WITHOUT_NLS\n"
"#include &lt;nl_types.h&gt;\n"
"nl_catd	 catalog;\n"
"#endif\n"
"\n"
"/*\n"
" * Default messages to use when NLS is disabled or no catalog\n"
" * is found.\n"
" */\n"
"char    *nlsstr[] = {\n"
"        \"\",\n"
"/* 1*/  \"some random message\",\n"
"/* 2*/  \"some other message\"\n"
"};"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3334
msgid ""
"Next come the real code snippets, which open, read, and close the catalog:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:3337
#, no-wrap
msgid ""
"\n"
"#ifndef WITHOUT_NLS\n"
"	catalog = catopen(\"myapp\", NL_CAT_LOCALE);\n"
"#endif\n"
"\n"
"...\n"
"\n"
"printf(getstr(1));\n"
"\n"
"...\n"
"\n"
"#ifndef WITHOUT_NLS\n"
"	catclose(catalog);\n"
"#endif"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:3353
msgid "Reducing Strings to Localize"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:3355
msgid ""
"There is a good way of reducing the strings that need to be localized by "
"using <application>libc</application> error messages. This is also useful to "
"just avoid duplication and provide consistent error messages for the common "
"errors that can be encountered by a great many of programs."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:3361
msgid ""
"First, here is an example that does not use <application>libc</application> "
"error messages:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:3364
#, no-wrap
msgid ""
"\n"
"#include &lt;err.h&gt;\n"
"...\n"
"if (!S_ISDIR(st.st_mode))\n"
"	errx(1, \"argument is not a directory\");\n"
"	  "
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:3371
msgid ""
"This can be transformed to print an error message by reading <varname>errno</"
"varname> and printing an error message accordingly:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:3375
#, no-wrap
msgid ""
"\n"
"#include &lt;err.h&gt;\n"
"#include &lt;errno.h&gt;\n"
"...\n"
"if (!S_ISDIR(st.st_mode)) {\n"
"	errno = ENOTDIR;\n"
"	err(1, NULL);\n"
"}\n"
"	  "
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:3385
msgid ""
"In this example, the custom string is eliminated, thus translators will have "
"less work when localizing the program and users will see the usual "
"<quote>Not a directory</quote> error message when they encounter this error. "
"This message will probably seem more familiar to them. Please note that it "
"was necessary to include <filename>errno.h</filename> in order to directly "
"access <varname>errno</varname>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:3393
msgid ""
"It is worth to note that there are cases when <varname>errno</varname> is "
"set automatically by a preceding call, so it is not necessary to set it "
"explicitly:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:3397
#, no-wrap
msgid ""
"\n"
"#include &lt;err.h&gt;\n"
"...\n"
"if ((p = malloc(size)) == NULL)\n"
"	err(1, NULL);\n"
"	  "
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:3407
msgid "Making use of <filename>bsd.nls.mk</filename>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3409
msgid ""
"Using the catalog files requires few repeatable steps, such as compiling the "
"catalogs and installing them to the proper location. In order to simplify "
"this process even more, <filename>bsd.nls.mk</filename> introduces some "
"macros. It is not necessary to include <filename>bsd.nls.mk</filename> "
"explicitly, it is pulled in from the common Makefiles, such as <filename>bsd."
"prog.mk</filename> or <filename>bsd.lib.mk</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3418
msgid ""
"Usually it is enough to define <varname>NLSNAME</varname>, which should have "
"the catalog name mentioned as the first argument of "
"<citerefentry><refentrytitle>catopen</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> and list the catalog files in <varname>NLS</"
"varname> without their <literal>.msg</literal> extension. Here is an "
"example, which makes it possible to to disable NLS when used with the code "
"examples before. The <varname>WITHOUT_NLS</varname> "
"<citerefentry><refentrytitle>make</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry> variable has to be defined in order to build the program "
"without NLS support."
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:3428
#, no-wrap
msgid ""
"\n"
".if !defined(WITHOUT_NLS)\n"
"NLS=	es_ES.ISO8859-1\n"
"NLS+=	hu_HU.ISO8859-2\n"
"NLS+=	pt_BR.ISO8859-1\n"
".else\n"
"CFLAGS+=	-DWITHOUT_NLS\n"
".endif"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3437
msgid ""
"Conventionally, the catalog files are placed under the <filename>nls</"
"filename> subdirectory and this is the default behavior of <filename>bsd.nls."
"mk</filename>. It is possible, though to override the location of the "
"catalogs with the <varname>NLSSRCDIR</varname> "
"<citerefentry><refentrytitle>make</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry> variable. The default name of the precompiled catalog files "
"also follow the naming convention mentioned before. It can be overridden by "
"setting the <varname>NLSNAME</varname> variable. There are other options to "
"fine tune the processing of the catalog files but usually it is not needed, "
"thus they are not described here. For further information on <filename>bsd."
"nls.mk</filename>, please refer to the file itself, it is short and easy to "
"understand."
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:3462
msgid "Source Tree Guidelines and Policies"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3465 book.translate.xml:3560
msgid ""
"<personname> <firstname>Poul-Henning</firstname> <surname>Kamp</surname> </"
"personname> <contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3472
msgid ""
"<personname> <firstname>Giorgos</firstname> <surname>Keramidas</surname> </"
"personname>"
msgstr ""

#. (itstool) path: chapter/para
#: book.translate.xml:3481
msgid ""
"This chapter documents various guidelines and policies in force for the "
"FreeBSD source tree."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:3485
msgid "Style Guidelines"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3487
msgid "<primary>style</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3489
msgid ""
"Consistent coding style is extremely important, particularly with large "
"projects like FreeBSD. Code should follow the FreeBSD coding styles "
"described in <citerefentry><refentrytitle>style</refentrytitle><manvolnum>9</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>style.Makefile</"
"refentrytitle><manvolnum>5</manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:3496
msgid "<varname>MAINTAINER</varname> on Makefiles"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3498
msgid "<primary>ports maintainer</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3500
msgid ""
"If a particular portion of the FreeBSD <filename>src/</filename> "
"distribution is being maintained by a person or group of persons, this is "
"communicated through an entry in <filename>src/MAINTAINERS</filename>. "
"Maintainers of ports within the Ports Collection express their "
"maintainership to the world by adding a <varname>MAINTAINER</varname> line "
"to the <filename>Makefile</filename> of the port in question:"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:3509
#, no-wrap
msgid ""
"<varname>MAINTAINER</varname>= <replaceable>email-addresses</replaceable>"
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:3512
msgid ""
"For other parts of the repository, or for sections not listed as having a "
"maintainer, or when you are unsure who the active maintainer is, try looking "
"at the recent commit history of the relevant parts of the source tree. It is "
"quite often the case that a maintainer is not explicitly named, but the "
"people who are actively working in a part of the source tree for, say, the "
"last couple of years are interested in reviewing changes. Even if this is "
"not specifically mentioned in the documentation or the source itself, asking "
"for a review as a form of courtesy is a very reasonable thing to do."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3524
msgid "The role of the maintainer is as follows:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3528
msgid ""
"The maintainer owns and is responsible for that code. This means that he or "
"she is responsible for fixing bugs and answering problem reports pertaining "
"to that piece of the code, and in the case of contributed software, for "
"tracking new versions, as appropriate."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3536
msgid ""
"Changes to directories which have a maintainer defined shall be sent to the "
"maintainer for review before being committed. Only if the maintainer does "
"not respond for an unacceptable period of time, to several emails, will it "
"be acceptable to commit changes without review by the maintainer. However, "
"it is suggested that you try to have the changes reviewed by someone else if "
"at all possible."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3547
msgid ""
"It is of course not acceptable to add a person or group as maintainer unless "
"they agree to assume this duty. On the other hand it does not have to be a "
"committer and it can easily be a group of people."
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:3557
msgid "Contributed Software"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3567 book.translate.xml:3975
msgid ""
"<personname> <firstname>David</firstname> <surname>O'Brien</surname> </"
"personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3573
msgid ""
"<personname> <firstname>Gavin</firstname> <surname>Atkinson</surname> </"
"personname>"
msgstr ""

#. (itstool) path: sect1/indexterm
#: book.translate.xml:3582
msgid "<primary>contributed software</primary>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3584
msgid ""
"Some parts of the FreeBSD distribution consist of software that is actively "
"being maintained outside the FreeBSD project. For historical reasons, we "
"call this <emphasis>contributed</emphasis> software. Some examples are "
"<application>sendmail</application>, <application>gcc</application> and "
"<application>patch</application>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3592
msgid ""
"Over the last couple of years, various methods have been used in dealing "
"with this type of software and all have some number of advantages and "
"drawbacks. No clear winner has emerged."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3597
msgid ""
"Since this is the case, after some debate one of these methods has been "
"selected as the <quote>official</quote> method and will be required for "
"future imports of software of this kind. Furthermore, it is strongly "
"suggested that existing contributed software converge on this model over "
"time, as it has significant advantages over the old method, including the "
"ability to easily obtain diffs relative to the <quote>official</quote> "
"versions of the source by everyone (even without direct repository access). "
"This will make it significantly easier to return changes to the primary "
"developers of the contributed software."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3609
msgid ""
"Ultimately, however, it comes down to the people actually doing the work. If "
"using this model is particularly unsuited to the package being dealt with, "
"exceptions to these rules may be granted only with the approval of the core "
"team and with the general consensus of the other developers. The ability to "
"maintain the package in the future will be a key issue in the decisions."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:3618
msgid ""
"Because it makes it harder to import future versions minor, trivial and/or "
"cosmetic changes are <emphasis>strongly discouraged</emphasis> on files that "
"are still tracking the vendor branch."
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:3626
msgid "Vendor Imports with SVN"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3629
msgid ""
"<personname> <firstname>Dag-Erling</firstname> <surname>Smørgrav</surname> </"
"personname> <contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:3639
msgid ""
"This section describes the vendor import procedure with "
"<application>Subversion</application> in details."
msgstr ""

#. (itstool) path: step/title
#: book.translate.xml:3644
msgid "Preparing the Tree"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3646
msgid ""
"If this is your first import after the switch to <acronym>SVN</acronym>, you "
"will have to flatten and clean up the vendor tree, and bootstrap merge "
"history in the main tree. If not, you can safely omit this step."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3651
msgid ""
"During the conversion from <acronym>CVS</acronym> to <acronym>SVN</acronym>, "
"vendor branches were imported with the same layout as the main tree. For "
"example, the <application>foo</application> vendor sources ended up in "
"<filename>vendor/<replaceable>foo</replaceable>/dist/contrib/"
"<replaceable>foo</replaceable></filename>, but it is pointless and rather "
"inconvenient. What we really want is to have the vendor source directly in "
"<filename>vendor/<replaceable>foo</replaceable>/dist</filename>, like this:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3661
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cd vendor/<replaceable>foo</replaceable>/dist/"
"contrib/<replaceable>foo</replaceable></userinput>\n"
"<prompt>%</prompt> <userinput>svn move $(svn list) ../..</userinput>\n"
"<prompt>%</prompt> <userinput>cd ../..</userinput>\n"
"<prompt>%</prompt> <userinput>svn remove contrib</userinput>\n"
"<prompt>%</prompt> <userinput>svn propdel -R svn:mergeinfo</userinput>\n"
"<prompt>%</prompt> <userinput>svn commit</userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3668
msgid ""
"Note that, the <literal>propdel</literal> bit is necessary because starting "
"with 1.5, Subversion will automatically add <literal>svn:mergeinfo</literal> "
"to any directory you copy or move. In this case, you will not need this "
"information, since you are not going to merge anything from the tree you "
"deleted."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:3676
msgid ""
"You may want to flatten the tags as well. The procedure is exactly the same. "
"If you do this, put off the commit until the end."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3681
msgid ""
"Check the <filename>dist</filename> tree and perform any cleanup that is "
"deemed to be necessary. You may want to disable keyword expansion, as it "
"makes no sense on unmodified vendor code. In some cases, it can be even be "
"harmful."
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3687
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>svn propdel svn:keywords -R .</userinput>\n"
"<prompt>%</prompt> <userinput>svn commit</userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3690
msgid ""
"Bootstrapping of <literal>svn:mergeinfo</literal> on the target directory "
"(in the main tree) to the revision that corresponds to the last change was "
"made to the vendor tree prior to importing new sources is also needed:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3695
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cd head/contrib/<replaceable>foo</"
"replaceable></userinput>\n"
"<prompt>%</prompt> <userinput>svn merge --record-only <replaceable>svn_base</"
"replaceable>/vendor/<replaceable>foo</replaceable>/"
"dist@<replaceable>12345678</replaceable> .</userinput>\n"
"<prompt>%</prompt> <userinput>svn commit</userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3699
msgid ""
"where <replaceable>svn_base</replaceable> is the base directory of your "
"<acronym>SVN</acronym> repository, e.g., <literal>svn+ssh://svn.FreeBSD.org/"
"base</literal>."
msgstr ""

#. (itstool) path: step/title
#: book.translate.xml:3705
msgid "Importing New Sources"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3707
msgid ""
"Prepare a full, clean tree of the vendor sources. With <acronym>SVN</"
"acronym>, we can keep a full distribution in the vendor tree without "
"bloating the main tree. Import everything but merge only what is needed."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3713
msgid ""
"Note that you will need to add any files that were added since the last "
"vendor import, and remove any that were removed. To facilitate this, you "
"should prepare sorted lists of the contents of the vendor tree and of the "
"sources you are about to import:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3719
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cd vendor/<replaceable>foo</replaceable>/dist</"
"userinput>\n"
"<prompt>%</prompt> <userinput>svn list -R | grep -v '/$' | sort &gt; ../"
"<replaceable>old</replaceable></userinput>\n"
"<prompt>%</prompt> <userinput>cd ../<replaceable>foo-9.9</replaceable></"
"userinput>\n"
"<prompt>%</prompt> <userinput>find . -type f | cut -c 3- | sort &gt; ../"
"<replaceable>new</replaceable></userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3724
msgid ""
"With these two files, the following command will list removed files (files "
"only in <filename><replaceable>old</replaceable></filename>):"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3728
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>comm -23 ../<replaceable>old</replaceable> ../"
"<replaceable>new</replaceable></userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3730
msgid ""
"While the command below will list added files (files only in "
"<filename><replaceable>new</replaceable></filename>):"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3734
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>comm -13 ../<replaceable>old</replaceable> ../"
"<replaceable>new</replaceable></userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3736
msgid "Let us put this together:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3738
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cd vendor/<replaceable>foo</replaceable>/"
"<replaceable>foo-9.9</replaceable></userinput>\n"
"<prompt>%</prompt> <userinput>tar cf - . | tar xf - -C ../dist</userinput>\n"
"<prompt>%</prompt> <userinput>cd ../dist</userinput>\n"
"<prompt>%</prompt> <userinput>comm -23 ../<replaceable>old</replaceable> ../"
"<replaceable>new</replaceable> | xargs svn remove</userinput>\n"
"<prompt>%</prompt> <userinput>comm -13 ../<replaceable>old</replaceable> ../"
"<replaceable>new</replaceable> | xargs svn add</userinput>"
msgstr ""

#. (itstool) path: warning/para
#: book.translate.xml:3745
msgid ""
"If there are new directories in the new distribution, the last command will "
"fail. You will have to add the directories, and run it again. Conversely, if "
"any directories were removed, you will have to remove them manually."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3752
msgid "Check properties on any new files:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3756
msgid ""
"All text files should have <literal>svn:eol-style</literal> set to "
"<literal>native</literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3762
msgid ""
"All binary files should have <literal>svn:mime-type</literal> set to "
"<literal>application/octet-stream</literal>, unless there is a more "
"appropriate media type."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3769
msgid ""
"Executable files should have <literal>svn:executable</literal> set to "
"<literal>*</literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3775
msgid "There should be no other properties on any file in the tree."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:3781
msgid ""
"You are ready to commit, but you should first check the output of "
"<command>svn stat</command> and <command>svn diff</command> to make sure "
"everything is in order."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3787
msgid ""
"Once you have committed the new vendor release, you should tag it for future "
"reference. The best and quickest way is to do it directly in the repository:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3791
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>svn copy <replaceable>svn_base</replaceable>/"
"vendor/<replaceable>foo</replaceable>/dist <replaceable>svn_base</"
"replaceable>/vendor/<replaceable>foo</replaceable>/<replaceable>9.9</"
"replaceable></userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3793
msgid ""
"To get the new tag, you can update your working copy of <filename>vendor/"
"<replaceable>foo</replaceable></filename>."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:3798
msgid ""
"If you choose to do the copy in the checkout instead, do not forget to "
"remove the generated <literal>svn:mergeinfo</literal> as described above."
msgstr ""

#. (itstool) path: step/title
#: book.translate.xml:3806
msgid "Merging to <emphasis>-HEAD</emphasis>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3808
msgid ""
"After you have prepared your import, it is time to merge. Option <option>--"
"accept=postpone</option> tells <acronym>SVN</acronym> not to handle merge "
"conflicts yet, because they will be taken care of manually:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3813
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cd head/contrib/<replaceable>foo</"
"replaceable></userinput>\n"
"<prompt>%</prompt> <userinput>svn update</userinput>\n"
"<prompt>%</prompt> <userinput>svn merge --accept=postpone "
"<replaceable>svn_base</replaceable>/vendor/<replaceable>foo</replaceable>/"
"dist</userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3817
msgid ""
"Resolve any conflicts, and make sure that any files that were added or "
"removed in the vendor tree have been properly added or removed in the main "
"tree. It is always a good idea to check differences against the vendor "
"branch:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:3823
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>svn diff --no-diff-deleted --old="
"<replaceable>svn_base</replaceable>/vendor/<replaceable>foo</replaceable>/"
"dist --new=.</userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3825
msgid ""
"<option>--no-diff-deleted</option> tells <acronym>SVN</acronym> not to check "
"files that are in the vendor tree but not in the main tree."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:3830
msgid ""
"With <acronym>SVN</acronym>, there is no concept of on or off the vendor "
"branch. If a file that previously had local modifications no longer does, "
"just remove any left-over cruft, such as FreeBSD version tags, so it no "
"longer shows up in diffs against the vendor tree."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3837
msgid ""
"If any changes are required for the world to build with the new sources, "
"make them now — and test until you are satisfied that everything build and "
"runs correctly."
msgstr ""

#. (itstool) path: step/title
#: book.translate.xml:3844
msgid "Commit"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:3846
msgid ""
"Now, you are ready to commit. Make sure you get everything in one go. "
"Ideally, you would have done all steps in a clean tree, in which case you "
"can just commit from the top of that tree. That is the best way to avoid "
"surprises. If you do it properly, the tree will move atomically from a "
"consistent state with the old code to a consistent state with the new code."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:3859
msgid "Encumbered Files"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3861
msgid ""
"It might occasionally be necessary to include an encumbered file in the "
"FreeBSD source tree. For example, if a device requires a small piece of "
"binary code to be loaded to it before the device will operate, and we do not "
"have the source to that code, then the binary file is said to be encumbered. "
"The following policies apply to including encumbered files in the FreeBSD "
"source tree."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3871
msgid ""
"Any file which is interpreted or executed by the system CPU(s) and not in "
"source format is encumbered."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3876
msgid ""
"Any file with a license more restrictive than BSD or GNU is encumbered."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3881
msgid ""
"A file which contains downloadable binary data for use by the hardware is "
"not encumbered, unless (1) or (2) apply to it. It must be stored in an "
"architecture neutral ASCII format (file2c or uuencoding is recommended)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3888
msgid ""
"Any encumbered file requires specific approval from the <link xlink:href="
"\"@@URL_RELPREFIX@@/administration.html#t-core\">Core Team</link> before it "
"is added to the repository."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3894
msgid ""
"Encumbered files go in <filename>src/contrib</filename> or <filename>src/sys/"
"contrib</filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3899
msgid ""
"The entire module should be kept together. There is no point in splitting "
"it, unless there is code-sharing with non-encumbered code."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3905
msgid ""
"Object files are named <filename><replaceable>arch</replaceable>/"
"<replaceable>filename</replaceable>.o.uu&gt;</filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3910
msgid "Kernel files:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3914
msgid ""
"Should always be referenced in <filename>conf/files.*</filename> (for build "
"simplicity)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3920
msgid ""
"Should always be in <filename>LINT</filename>, but the <link xlink:href="
"\"@@URL_RELPREFIX@@/administration.html#t-core\">Core Team</link> decides "
"per case if it should be commented out or not. The <link xlink:href="
"\"@@URL_RELPREFIX@@/administration.html#t-core\">Core Team</link> can, of "
"course, change their minds later on."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3929
msgid ""
"The <firstterm>Release Engineer</firstterm> decides whether or not it goes "
"into the release."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3936
msgid "User-land files:"
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:3941
msgid "<primary>core team</primary>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3940
msgid ""
"The <link xlink:href=\"@@URL_RELPREFIX@@/administration.html#t-core\">Core "
"team</link><_:indexterm-1/> decides if the code should be part of "
"<command>make world</command>."
msgstr ""

#. (itstool) path: para/indexterm
#: book.translate.xml:3948
msgid "<primary>release engineering</primary>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3947
msgid ""
"The <link xlink:href=\"@@URL_RELPREFIX@@/administration.html#t-re\">Release "
"Engineering</link><_:indexterm-1/> decides if it goes into the release."
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:3959
msgid "Shared Libraries"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3962
msgid ""
"<personname> <firstname>Satoshi</firstname> <surname>Asami</surname> </"
"personname> <contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:3969
msgid ""
"<personname> <firstname>Peter</firstname> <surname>Wemm</surname> </"
"personname>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3984
msgid ""
"If you are adding shared library support to a port or other piece of "
"software that does not have one, the version numbers should follow these "
"rules. Generally, the resulting numbers will have nothing to do with the "
"release version of the software."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:3990
msgid "The three principles of shared library building are:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3994
msgid "Start from <literal>1.0</literal>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:3998
msgid ""
"If there is a change that is backwards compatible, bump minor number (note "
"that ELF systems ignore the minor number)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4004
msgid "If there is an incompatible change, bump major number"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4009
msgid ""
"For instance, added functions and bugfixes result in the minor version "
"number being bumped, while deleted functions, changed function call syntax, "
"etc. will force the major version number to change."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4014
msgid ""
"Stick to version numbers of the form major.minor (<replaceable>x</"
"replaceable>.<replaceable>y</replaceable>). Our a.out dynamic linker does "
"not handle version numbers of the form <replaceable>x</replaceable>."
"<replaceable>y</replaceable>.<replaceable>z</replaceable> well. Any version "
"number after the <replaceable>y</replaceable> (i.e., the third digit) is "
"totally ignored when comparing shared lib version numbers to decide which "
"library to link with. Given two shared libraries that differ only in the "
"<quote>micro</quote> revision, <command>ld.so</command> will link with the "
"higher one. That is, if you link with <filename>libfoo.so.3.3.3</filename>, "
"the linker only records <literal>3.3</literal> in the headers, and will link "
"with anything starting with <replaceable>libfoo.so.3</replaceable>."
"<replaceable>(anything &gt;= 3)</replaceable>.<replaceable>(highest "
"available)</replaceable>."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:4033
msgid ""
"<command>ld.so</command> will always use the highest <quote>minor</quote> "
"revision. For instance, it will use <filename>libc.so.2.2</filename> in "
"preference to <filename>libc.so.2.0</filename>, even if the program was "
"initially linked with <filename>libc.so.2.0</filename>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4040
msgid ""
"In addition, our ELF dynamic linker does not handle minor version numbers at "
"all. However, one should still specify a major and minor version number as "
"our <filename>Makefile</filename>s <quote>do the right thing</quote> based "
"on the type of system."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4046
msgid ""
"For non-port libraries, it is also our policy to change the shared library "
"version number only once between releases. In addition, it is our policy to "
"change the major shared library version number only once between major OS "
"releases (i.e., from 6.0 to 7.0). When you make a change to a system library "
"that requires the version number to be bumped, check the <filename>Makefile</"
"filename>'s commit logs. It is the responsibility of the committer to ensure "
"that the first such change since the release will result in the shared "
"library version number in the <filename>Makefile</filename> to be updated, "
"and any subsequent changes will not."
msgstr ""

#. (itstool) path: chapter/title
#: book.translate.xml:4067
msgid "Regression and Performance Testing"
msgstr ""

#. (itstool) path: chapter/para
#: book.translate.xml:4069
msgid ""
"Regression tests are used to exercise a particular bit of the system to "
"check that it works as expected, and to make sure that old bugs are not "
"reintroduced."
msgstr ""

#. (itstool) path: chapter/para
#: book.translate.xml:4073
msgid ""
"The FreeBSD regression testing tools can be found in the FreeBSD source tree "
"in the directory <filename>src/tools/regression</filename>."
msgstr ""

#. (itstool) path: section/title
#: book.translate.xml:4078
msgid "Micro Benchmark Checklist"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4080
msgid ""
"This section contains hints for doing proper micro-benchmarking on FreeBSD "
"or of FreeBSD itself."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4083
msgid ""
"It is not possible to use all of the suggestions below every single time, "
"but the more used, the better the benchmark's ability to test small "
"differences will be."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4089
msgid ""
"Disable <acronym>APM</acronym> and any other kind of clock fiddling "
"(<acronym>ACPI</acronym> ?)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4094
msgid ""
"Run in single user mode. E.g., <citerefentry><refentrytitle>cron</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry>, and other daemons "
"only add noise. The <citerefentry><refentrytitle>sshd</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> daemon can also cause "
"problems. If ssh access is required during testing either disable the SSHv1 "
"key regeneration, or kill the parent <command>sshd</command> daemon during "
"the tests."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4103
msgid ""
"Do not run <citerefentry><refentrytitle>ntpd</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4107
msgid ""
"If <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> events are generated, run "
"<citerefentry><refentrytitle>syslogd</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> with an empty <filename>/etc/syslogd.conf</"
"filename>, otherwise, do not run it."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4114
msgid "Minimize disk-I/O, avoid it entirely if possible."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4118
msgid "Do not mount file systems that are not needed."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4122
msgid ""
"Mount <filename>/</filename>, <filename>/usr</filename>, and any other file "
"system as read-only if possible. This removes atime updates to disk (etc.) "
"from the I/O picture."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4129
msgid ""
"Reinitialize the read/write test file system with "
"<citerefentry><refentrytitle>newfs</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> and populate it from a <citerefentry><refentrytitle>tar</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry> or "
"<citerefentry><refentrytitle>dump</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> file before every run. Unmount and mount it before starting "
"the test. This results in a consistent file system layout. For a worldstone "
"test this would apply to <filename>/usr/obj</filename> (just reinitialize "
"with <command>newfs</command> and mount). To get 100% reproducibility, "
"populate the file system from a <citerefentry><refentrytitle>dd</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry> file (i.e.: "
"<command>dd if=myimage of=/dev/ad0s1h bs=1m</command>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4143
msgid ""
"Use malloc backed or preloaded <citerefentry><refentrytitle>md</"
"refentrytitle><manvolnum>4</manvolnum></citerefentry> partitions."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4148
msgid ""
"Reboot between individual iterations of the test, this gives a more "
"consistent state."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4153
msgid ""
"Remove all non-essential device drivers from the kernel. For instance if USB "
"is not needed for the test, do not put USB in the kernel. Drivers which "
"attach often have timeouts ticking away."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4160
msgid ""
"Unconfigure hardware that are not in use. Detach disks with "
"<citerefentry><refentrytitle>atacontrol</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>camcontrol</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> if the disks are not "
"used for the test."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4166
msgid ""
"Do not configure the network unless it is being tested, or wait until after "
"the test has been performed to ship the results off to another computer."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4170
msgid ""
"If the system must be connected to a public network, watch out for spikes of "
"broadcast traffic. Even though it is hardly noticeable, it will take up CPU "
"cycles. Multicast has similar caveats."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4177
msgid ""
"Put each file system on its own disk. This minimizes jitter from head-seek "
"optimizations."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4182
msgid ""
"Minimize output to serial or VGA consoles. Running output into files gives "
"less jitter. (Serial consoles easily become a bottleneck.) Do not touch "
"keyboard while the test is running, even <keycap>space</keycap> or "
"<keycap>back-space</keycap> shows up in the numbers."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4190
msgid ""
"Make sure the test is long enough, but not too long. If the test is too "
"short, timestamping is a problem. If it is too long temperature changes and "
"drift will affect the frequency of the quartz crystals in the computer. Rule "
"of thumb: more than a minute, less than an hour."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4198
msgid ""
"Try to keep the temperature as stable as possible around the machine. This "
"affects both quartz crystals and disk drive algorithms. To get real stable "
"clock, consider stabilized clock injection. E.g., get a OCXO + PLL, inject "
"output into clock circuits instead of motherboard xtal. Contact Poul-Henning "
"Kamp <email>phk@FreeBSD.org</email> for more information about this."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4208
msgid ""
"Run the test at least 3 times but it is better to run more than 20 times "
"both for <quote>before</quote> and <quote>after</quote> code. Try to "
"interleave if possible (i.e.: do not run 20 times before then 20 times "
"after), this makes it possible to spot environmental effects. Do not "
"interleave 1:1, but 3:3, this makes it possible to spot interaction effects."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4216
msgid ""
"A good pattern is: <literal>bababa{bbbaaa}*</literal>. This gives hint after "
"the first 1+1 runs (so it is possible to stop the test if it goes entirely "
"the wrong way), a standard deviation after the first 3+3 (gives a good "
"indication if it is going to be worth a long run) and trending and "
"interaction numbers later on."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4225
msgid ""
"Use <citerefentry><refentrytitle>ministat</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry> to see if the numbers are significant. Consider "
"buying <quote>Cartoon guide to statistics</quote> ISBN: 0062731025, highly "
"recommended, if you have forgotten or never learned about standard deviation "
"and Student's T."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4234
msgid ""
"Do not use background <citerefentry><refentrytitle>fsck</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> unless the test is a "
"benchmark of background <command>fsck</command>. Also, disable "
"<varname>background_fsck</varname> in <filename>/etc/rc.conf</filename> "
"unless the benchmark is not started at least 60+<quote><command>fsck</"
"command> runtime</quote> seconds after the boot, as "
"<citerefentry><refentrytitle>rc</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> wakes up and checks if <command>fsck</command> needs to run on "
"any file systems when background <command>fsck</command> is enabled. "
"Likewise, make sure there are no snapshots lying around unless the benchmark "
"is a test with snapshots."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4248
msgid ""
"If the benchmark show unexpected bad performance, check for things like high "
"interrupt volume from an unexpected source. Some versions of <acronym>ACPI</"
"acronym> have been reported to <quote>misbehave</quote> and generate excess "
"interrupts. To help diagnose odd test results, take a few snapshots of "
"<command>vmstat -i</command> and look for anything unusual."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4258
msgid ""
"Make sure to be careful about optimization parameters for kernel and "
"userspace, likewise debugging. It is easy to let something slip through and "
"realize later the test was not comparing the same thing."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4265
msgid ""
"Do not ever benchmark with the <literal>WITNESS</literal> and "
"<literal>INVARIANTS</literal> kernel options enabled unless the test is "
"interested to benchmarking those features. <literal>WITNESS</literal> can "
"cause 400%+ drops in performance. Likewise, userspace "
"<citerefentry><refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum></"
"citerefentry> parameters default differently in -CURRENT from the way they "
"ship in production releases."
msgstr ""

#. (itstool) path: section/title
#: book.translate.xml:4277
msgid "The FreeBSD Source Tinderbox"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4279
msgid "The source Tinderbox consists of:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4283
msgid ""
"A build script, <filename>tinderbox</filename>, that automates checking out "
"a specific version of the FreeBSD source tree and building it."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4288
msgid ""
"A supervisor script, <filename>tbmaster</filename>, that monitors individual "
"Tinderbox instances, logs their output, and emails failure notices."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4293
msgid ""
"A <acronym>CGI</acronym> script named <filename>index.cgi</filename> that "
"reads a set of tbmaster logs and presents an easy-to-read <acronym>HTML</"
"acronym> summary of them."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4299
msgid ""
"A set of build servers that continually test the tip of the most important "
"FreeBSD code branches."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4303
msgid ""
"A webserver that keeps a complete set of Tinderbox logs and displays an up-"
"to-date summary."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4308
msgid ""
"The scripts are maintained and were developed by Dag-Erling Smørgrav "
"<email>des@FreeBSD.org</email>, and are now written in Perl, a move on from "
"their original incarnation as shell scripts. All scripts and configuration "
"files are kept in <link xlink:href=\"https://www.freebsd.org/cgi/cvsweb.cgi/"
"projects/tinderbox/\">/projects/tinderbox/</link>."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4313
msgid ""
"For more information about the tinderbox and tbmaster scripts at this stage, "
"see their respective man pages: tinderbox(1) and tbmaster(1)."
msgstr ""

#. (itstool) path: section/title
#: book.translate.xml:4318
msgid "The <filename>index.cgi</filename> Script"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4320
msgid ""
"The <filename>index.cgi</filename> script generates the <acronym>HTML</"
"acronym> summary of tinderbox and tbmaster logs. Although originally "
"intended to be used as a <acronym>CGI</acronym> script, as indicated by its "
"name, this script can also be run from the command line or from a "
"<citerefentry><refentrytitle>cron</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> job, in which case it will look for logs in the directory "
"where the script is located. It will automatically detect context, "
"generating <acronym>HTTP</acronym> headers when it is run as a <acronym>CGI</"
"acronym> script. It conforms to <acronym>XHTML</acronym> standards and is "
"styled using <acronym>CSS</acronym>."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4332
msgid ""
"The script starts in the <function>main()</function> block by attempting to "
"verify that it is running on the official Tinderbox website. If it is not, a "
"page indicating it is not an official website is produced, and a "
"<acronym>URL</acronym> to the official site is provided."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4338
msgid ""
"Next, it scans the log directory to get an inventory of configurations, "
"branches and architectures for which log files exist, to avoid hard-coding a "
"list into the script and potentially ending up with blank rows or columns. "
"This information is derived from the names of the log files matching the "
"following pattern:"
msgstr ""

#. (itstool) path: section/programlisting
#: book.translate.xml:4345
#, no-wrap
msgid "tinderbox-$config-$branch-$arch-$machine.{brief,full}"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4347
msgid ""
"The configurations used on the official Tinderbox build servers are named "
"for the branches they build. For example, the <literal>releng_8</literal> "
"configuration is used to build <literal>RELENG_8</literal> as well as all "
"still-supported release branches."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4353
msgid ""
"Once all of this startup procedure has been successfully completed, "
"<function>do_config()</function> is called for each configuration."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4357
msgid ""
"The <function>do_config()</function> function generates <acronym>HTML</"
"acronym> for a single Tinderbox configuration."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4361
msgid ""
"It works by first generating a header row, then iterating over each branch "
"build with the specified configuration, producing a single row of results "
"for each in the following manner:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4368
msgid "For each item:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4371
msgid "For each machine within that architecture:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4374
msgid "If a brief log file exists, then:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4377
msgid ""
"Call <function>success()</function> to determine the outcome of the build."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4381
msgid "Output the modification size."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4384
msgid ""
"Output the size of the brief log file with a link to the log file itself."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4388
msgid "If a full log file also exists, then:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4392
msgid ""
"Output the size of the full log file with a link to the log file itself."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4400
msgid "Otherwise:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4403
msgid "No output."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4413
msgid ""
"The <function>success()</function> function mentioned above scans a brief "
"log file for the string <quote>tinderbox run completed</quote> in order to "
"determine whether the build was successful."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4418
msgid ""
"Configurations and branches are sorted according to their branch rank. This "
"is computed as follows:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4423
msgid "<literal>HEAD</literal> and <literal>CURRENT</literal> have rank 9999."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4427
msgid ""
"<literal>RELENG_<replaceable>x</replaceable></literal> has rank "
"<replaceable>xx</replaceable>99."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4431
msgid ""
"<literal>RELENG_<replaceable>x</replaceable>_<replaceable>y</replaceable></"
"literal> has rank <replaceable>xxyy</replaceable>."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4436
msgid ""
"This means that <literal>HEAD</literal> always ranks highest, and "
"<literal>RELENG</literal> branches are ranked in numerical order, with each "
"<literal>STABLE</literal> branch ranking higher than the release branches "
"forked off of it. For instance, for FreeBSD 8, the order from highest to "
"lowest would be:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4445
msgid "<literal>RELENG_8</literal> (branch rank 899)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4448
msgid "<literal>RELENG_8_3</literal> (branch rank 803)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4452
msgid "<literal>RELENG_8_2</literal> (branch rank 802)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4456
msgid "<literal>RELENG_8_1</literal> (branch rank 801)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4460
msgid "<literal>RELENG_8_0</literal> (branch rank 800)."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4465
msgid ""
"The colors that Tinderbox uses for each cell in the table are defined by "
"<acronym>CSS</acronym>. Successful builds are displayed with green text; "
"unsuccessful builds are displayed with red text. The color fades as time "
"passes since the corresponding build, with every half an hour bringing the "
"color closer to grey."
msgstr ""

#. (itstool) path: section/title
#: book.translate.xml:4474
msgid "Official Build Servers"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4476
msgid ""
"The official Tinderbox build servers are hosted by <link xlink:href=\"http://"
"www.sentex.ca\">Sentex Data Communications</link>, who also host the <link "
"xlink:href=\"https://www.freebsd.org/projects/netperf/cluster.html\">FreeBSD "
"Netperf Cluster</link>."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4480
msgid "Three build servers currently exist:"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4482
msgid "<emphasis>freebsd-current.sentex.ca</emphasis> builds:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4487
msgid ""
"<literal>HEAD</literal> for amd64, arm, i386, i386/pc98, ia64, mips, "
"powerpc, powerpc64, and sparc64."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4492
msgid ""
"<literal>RELENG_9</literal> and supported 9.<replaceable>X</replaceable> "
"branches for amd64, arm, i386, i386/pc98, ia64, mips, powerpc, powerpc64, "
"and sparc64."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4499
msgid "<emphasis>freebsd-stable.sentex.ca</emphasis> builds:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4504
msgid ""
"<literal>RELENG_8</literal> and supported 8.<replaceable>X</replaceable> "
"branches for amd64, i386, i386/pc98, ia64, mips, powerpc and sparc64."
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4510
msgid "<emphasis>freebsd-legacy.sentex.ca</emphasis> builds:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4515
msgid ""
"<literal>RELENG_7</literal> and supported 7.<replaceable>X</replaceable> "
"branches for amd64, i386, i386/pc98, ia64, powerpc, and sparc64."
msgstr ""

#. (itstool) path: section/title
#: book.translate.xml:4523
msgid "Official Summary Site"
msgstr ""

#. (itstool) path: section/para
#: book.translate.xml:4525
msgid ""
"Summaries and logs from the official build servers are available online at "
"<link xlink:href=\"http://tinderbox.FreeBSD.org\">http://tinderbox.FreeBSD."
"org</link>, hosted by Dag-Erling Smørgrav <email>des@FreeBSD.org</email> and "
"set up as follows:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4531
msgid ""
"A <citerefentry><refentrytitle>cron</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> job checks the build servers at regular intervals and "
"downloads any new log files using <citerefentry vendor="
"\"ports\"><refentrytitle>rsync</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:4536
msgid ""
"Apache is set up to use <filename>index.cgi</filename> as "
"<literal>DirectoryIndex</literal>."
msgstr ""

#. (itstool) path: part/title
#: book.translate.xml:4547
msgid "Interprocess Communication"
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:4557
msgid "Sockets"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:4560
msgid ""
"<personname> <firstname>G. Adam</firstname> <surname>Stanislav</surname> </"
"personname> <contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4573
msgid ""
"<acronym>BSD</acronym> sockets take interprocess communications to a new "
"level. It is no longer necessary for the communicating processes to run on "
"the same machine. They still <emphasis>can</emphasis>, but they do not have "
"to."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4578
msgid ""
"Not only do these processes not have to run on the same machine, they do not "
"have to run under the same operating system. Thanks to <acronym>BSD</"
"acronym> sockets, your FreeBSD software can smoothly cooperate with a "
"program running on a <trademark class=\"registered\">Macintosh</trademark>, "
"another one running on a <trademark>Sun</trademark> workstation, yet another "
"one running under <trademark class=\"registered\">Windows</trademark> 2000, "
"all connected with an Ethernet-based local area network."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4586
msgid ""
"But your software can equally well cooperate with processes running in "
"another building, or on another continent, inside a submarine, or a space "
"shuttle."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4590
msgid ""
"It can also cooperate with processes that are not part of a computer (at "
"least not in the strict sense of the word), but of such devices as printers, "
"digital cameras, medical equipment. Just about anything capable of digital "
"communications."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:4598
msgid "Networking and Diversity"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4600
msgid ""
"We have already hinted on the <emphasis>diversity</emphasis> of networking. "
"Many different systems have to talk to each other. And they have to speak "
"the same language. They also have to <emphasis>understand</emphasis> the "
"same language the same way."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4606
msgid ""
"People often think that <emphasis>body language</emphasis> is universal. But "
"it is not. Back in my early teens, my father took me to Bulgaria. We were "
"sitting at a table in a park in Sofia, when a vendor approached us trying to "
"sell us some roasted almonds."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4612
msgid ""
"I had not learned much Bulgarian by then, so, instead of saying no, I shook "
"my head from side to side, the <quote>universal</quote> body language for "
"<emphasis>no</emphasis>. The vendor quickly started serving us some almonds."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4618
msgid ""
"I then remembered I had been told that in Bulgaria shaking your head "
"sideways meant <emphasis>yes</emphasis>. Quickly, I started nodding my head "
"up and down. The vendor noticed, took his almonds, and walked away. To an "
"uninformed observer, I did not change the body language: I continued using "
"the language of shaking and nodding my head. What changed was the "
"<emphasis>meaning</emphasis> of the body language. At first, the vendor and "
"I interpreted the same language as having completely different meaning. I "
"had to adjust my own interpretation of that language so the vendor would "
"understand."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4630
msgid ""
"It is the same with computers: The same symbols may have different, even "
"outright opposite meaning. Therefore, for two computers to understand each "
"other, they must not only agree on the same <emphasis>language</emphasis>, "
"but on the same <emphasis>interpretation</emphasis> of the language."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:4638
msgid "Protocols"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4640
msgid ""
"While various programming languages tend to have complex syntax and use a "
"number of multi-letter reserved words (which makes them easy for the human "
"programmer to understand), the languages of data communications tend to be "
"very terse. Instead of multi-byte words, they often use individual "
"<emphasis>bits</emphasis>. There is a very convincing reason for it: While "
"data travels <emphasis>inside</emphasis> your computer at speeds approaching "
"the speed of light, it often travels considerably slower between two "
"computers."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4650
msgid ""
"Because the languages used in data communications are so terse, we usually "
"refer to them as <emphasis>protocols</emphasis> rather than languages."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4654
msgid ""
"As data travels from one computer to another, it always uses more than one "
"protocol. These protocols are <emphasis>layered</emphasis>. The data can be "
"compared to the inside of an onion: You have to peel off several layers of "
"<quote>skin</quote> to get to the data. This is best illustrated with a "
"picture:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:4663
msgctxt "_"
msgid "external ref='sockets/layers' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:4667
#, no-wrap
msgid ""
"+----------------+\n"
"|    Ethernet    |\n"
"|+--------------+|\n"
"||      IP      ||\n"
"||+------------+||\n"
"|||     TCP    |||\n"
"|||+----------+|||\n"
"||||   HTTP   ||||\n"
"||||+--------+||||\n"
"|||||   PNG  |||||\n"
"|||||+------+|||||\n"
"|||||| Data ||||||\n"
"|||||+------+|||||\n"
"||||+--------+||||\n"
"|||+----------+|||\n"
"||+------------+||\n"
"|+--------------+|\n"
"+----------------+"
msgstr ""

#. (itstool) path: sect1/mediaobject
#: book.translate.xml:4661
msgid ""
"<imageobject> <imagedata fileref=\"sockets/layers\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>Protocol Layers</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4692
msgid ""
"In this example, we are trying to get an image from a web page we are "
"connected to via an Ethernet."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4695
msgid ""
"The image consists of raw data, which is simply a sequence of <acronym>RGB</"
"acronym> values that our software can process, i.e., convert into an image "
"and display on our monitor."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4699
msgid ""
"Alas, our software has no way of knowing how the raw data is organized: Is "
"it a sequence of <acronym>RGB</acronym> values, or a sequence of grayscale "
"intensities, or perhaps of <acronym>CMYK</acronym> encoded colors? Is the "
"data represented by 8-bit quanta, or are they 16 bits in size, or perhaps 4 "
"bits? How many rows and columns does the image consist of? Should certain "
"pixels be transparent?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4707
msgid "I think you get the picture..."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4709
msgid ""
"To inform our software how to handle the raw data, it is encoded as a "
"<acronym>PNG</acronym> file. It could be a <acronym>GIF</acronym>, or a "
"<acronym>JPEG</acronym>, but it is a <acronym>PNG</acronym>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4714
msgid "And <acronym>PNG</acronym> is a protocol."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4716
msgid ""
"At this point, I can hear some of you yelling, <emphasis><quote>No, it is "
"not! It is a file format!</quote></emphasis>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4720
msgid ""
"Well, of course it is a file format. But from the perspective of data "
"communications, a file format is a protocol: The file structure is a "
"<emphasis>language</emphasis>, a terse one at that, communicating to our "
"<emphasis>process</emphasis> how the data is organized. Ergo, it is a "
"<emphasis>protocol</emphasis>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4727
msgid ""
"Alas, if all we received was the <acronym>PNG</acronym> file, our software "
"would be facing a serious problem: How is it supposed to know the data is "
"representing an image, as opposed to some text, or perhaps a sound, or what "
"not? Secondly, how is it supposed to know the image is in the <acronym>PNG</"
"acronym> format as opposed to <acronym>GIF</acronym>, or <acronym>JPEG</"
"acronym>, or some other image format?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4735
msgid ""
"To obtain that information, we are using another protocol: <acronym>HTTP</"
"acronym>. This protocol can tell us exactly that the data represents an "
"image, and that it uses the <acronym>PNG</acronym> protocol. It can also "
"tell us some other things, but let us stay focused on protocol layers here."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4741
msgid ""
"So, now we have some data wrapped in the <acronym>PNG</acronym> protocol, "
"wrapped in the <acronym>HTTP</acronym> protocol. How did we get it from the "
"server?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4746
msgid ""
"By using <acronym>TCP/IP</acronym> over Ethernet, that is how. Indeed, that "
"is three more protocols. Instead of continuing inside out, I am now going to "
"talk about Ethernet, simply because it is easier to explain the rest that "
"way."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4751
msgid ""
"Ethernet is an interesting system of connecting computers in a "
"<emphasis>local area network</emphasis> (<acronym>LAN</acronym>). Each "
"computer has a <emphasis>network interface card</emphasis> (<acronym>NIC</"
"acronym>), which has a unique 48-bit <acronym>ID</acronym> called its "
"<emphasis>address</emphasis>. No two Ethernet <acronym>NIC</acronym>s in the "
"world have the same address."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4760
msgid ""
"These <acronym>NIC</acronym>s are all connected with each other. Whenever "
"one computer wants to communicate with another in the same Ethernet "
"<acronym>LAN</acronym>, it sends a message over the network. Every "
"<acronym>NIC</acronym> sees the message. But as part of the Ethernet "
"<emphasis>protocol</emphasis>, the data contains the address of the "
"destination <acronym>NIC</acronym> (among other things). So, only one of all "
"the network interface cards will pay attention to it, the rest will ignore "
"it."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4770
msgid ""
"But not all computers are connected to the same network. Just because we "
"have received the data over our Ethernet does not mean it originated in our "
"own local area network. It could have come to us from some other network "
"(which may not even be Ethernet based) connected with our own network via "
"the Internet."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4777
msgid ""
"All data is transferred over the Internet using <acronym>IP</acronym>, which "
"stands for <emphasis>Internet Protocol</emphasis>. Its basic role is to let "
"us know where in the world the data has arrived from, and where it is "
"supposed to go to. It does not <emphasis>guarantee</emphasis> we will "
"receive the data, only that we will know where it came from <emphasis>if</"
"emphasis> we do receive it."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4785
msgid ""
"Even if we do receive the data, <acronym>IP</acronym> does not guarantee we "
"will receive various chunks of data in the same order the other computer has "
"sent it to us. So, we can receive the center of our image before we receive "
"the upper left corner and after the lower right, for example."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4791
msgid ""
"It is <acronym>TCP</acronym> (<emphasis>Transmission Control Protocol</"
"emphasis>) that asks the sender to resend any lost data and that places it "
"all into the proper order."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4795
msgid ""
"All in all, it took <emphasis>five</emphasis> different protocols for one "
"computer to communicate to another what an image looks like. We received the "
"data wrapped into the <acronym>PNG</acronym> protocol, which was wrapped "
"into the <acronym>HTTP</acronym> protocol, which was wrapped into the "
"<acronym>TCP</acronym> protocol, which was wrapped into the <acronym>IP</"
"acronym> protocol, which was wrapped into the <acronym>Ethernet</acronym> "
"protocol."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4804
msgid ""
"Oh, and by the way, there probably were several other protocols involved "
"somewhere on the way. For example, if our <acronym>LAN</acronym> was "
"connected to the Internet through a dial-up call, it used the <acronym>PPP</"
"acronym> protocol over the modem which used one (or several) of the various "
"modem protocols, et cetera, et cetera, et cetera..."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4811
msgid ""
"As a developer you should be asking by now, <emphasis><quote>How am I "
"supposed to handle it all?</quote></emphasis>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4815
msgid ""
"Luckily for you, you are <emphasis>not</emphasis> supposed to handle it all. "
"You <emphasis>are</emphasis> supposed to handle some of it, but not all of "
"it. Specifically, you need not worry about the physical connection (in our "
"case Ethernet and possibly <acronym>PPP</acronym>, etc). Nor do you need to "
"handle the Internet Protocol, or the Transmission Control Protocol."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4823
msgid ""
"In other words, you do not have to do anything to receive the data from the "
"other computer. Well, you do have to <emphasis>ask</emphasis> for it, but "
"that is almost as simple as opening a file."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4828
msgid ""
"Once you have received the data, it is up to you to figure out what to do "
"with it. In our case, you would need to understand the <acronym>HTTP</"
"acronym> protocol and the <acronym>PNG</acronym> file structure."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4833
msgid ""
"To use an analogy, all the internetworking protocols become a gray area: Not "
"so much because we do not understand how it works, but because we are no "
"longer concerned about it. The sockets interface takes care of this gray "
"area for us:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:4840
msgctxt "_"
msgid "external ref='sockets/slayers' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:4844
#, no-wrap
msgid ""
"+----------------+\n"
"|xxxxEthernetxxxx|\n"
"|+--------------+|\n"
"||xxxxxxIPxxxxxx||\n"
"||+------------+||\n"
"|||xxxxxTCPxxxx|||\n"
"|||+----------+|||\n"
"||||   HTTP   ||||\n"
"||||+--------+||||\n"
"|||||   PNG  |||||\n"
"|||||+------+|||||\n"
"|||||| Data ||||||\n"
"|||||+------+|||||\n"
"||||+--------+||||\n"
"|||+----------+|||\n"
"||+------------+||\n"
"|+--------------+|\n"
"+----------------+"
msgstr ""

#. (itstool) path: sect1/mediaobject
#: book.translate.xml:4838
msgid ""
"<imageobject> <imagedata fileref=\"sockets/slayers\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>Sockets "
"Covered Protocol Layers</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4869
msgid ""
"We only need to understand any protocols that tell us how to "
"<emphasis>interpret the data</emphasis>, not how to <emphasis>receive</"
"emphasis> it from another process, nor how to <emphasis>send</emphasis> it "
"to another process."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:4877
msgid "The Sockets Model"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4879
msgid ""
"<acronym>BSD</acronym> sockets are built on the basic <trademark class="
"\"registered\">UNIX</trademark> model: <emphasis>Everything is a file.</"
"emphasis> In our example, then, sockets would let us receive an "
"<emphasis>HTTP file</emphasis>, so to speak. It would then be up to us to "
"extract the <emphasis><acronym>PNG</acronym> file</emphasis> from it."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4886
msgid ""
"Because of the complexity of internetworking, we cannot just use the "
"<function role=\"syscall\">open</function> system call, or the "
"<function>open()</function> C function. Instead, we need to take several "
"steps to <quote>opening</quote> a socket."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4891
msgid ""
"Once we do, however, we can start treating the <emphasis>socket</emphasis> "
"the same way we treat any <emphasis>file descriptor</emphasis>: We can "
"<function>read</function> from it, <function>write</function> to it, "
"<function>pipe</function> it, and, eventually, <function>close</function> it."
""
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:4901
msgid "Essential Socket Functions"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:4903
msgid ""
"While FreeBSD offers different functions to work with sockets, we only "
"<emphasis>need</emphasis> four to <quote>open</quote> a socket. And in some "
"cases we only need two."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:4909
msgid "The Client-Server Difference"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:4911
msgid ""
"Typically, one of the ends of a socket-based data communication is a "
"<emphasis>server</emphasis>, the other is a <emphasis>client</emphasis>."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:4916
msgid "The Common Elements"
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:4919
msgid "<function>socket</function>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4921
msgid ""
"The one function used by both, clients and servers, is "
"<citerefentry><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></"
"citerefentry>. It is declared this way:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:4924
#, no-wrap
msgid "int socket(int domain, int type, int protocol);"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4926
msgid ""
"The return value is of the same type as that of <function>open</function>, "
"an integer. FreeBSD allocates its value from the same pool as that of file "
"handles. That is what allows sockets to be treated the same way as files."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4932
msgid ""
"The <varname>domain</varname> argument tells the system what "
"<emphasis>protocol family</emphasis> you want it to use. Many of them exist, "
"some are vendor specific, others are very common. They are declared in "
"<filename>sys/socket.h</filename>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4938
msgid ""
"Use <constant>PF_INET</constant> for <acronym>UDP</acronym>, <acronym>TCP</"
"acronym> and other Internet protocols (<acronym>IP</acronym>v4)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4942
msgid ""
"Five values are defined for the <varname>type</varname> argument, again, in "
"<filename>sys/socket.h</filename>. All of them start with "
"<quote><constant>SOCK_</constant></quote>. The most common one is "
"<constant>SOCK_STREAM</constant>, which tells the system you are asking for "
"a <emphasis>reliable stream delivery service</emphasis> (which is "
"<acronym>TCP</acronym> when used with <constant>PF_INET</constant>)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4952
msgid ""
"If you asked for <constant>SOCK_DGRAM</constant>, you would be requesting a "
"<emphasis>connectionless datagram delivery service</emphasis> (in our case, "
"<acronym>UDP</acronym>)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4957
msgid ""
"If you wanted to be in charge of the low-level protocols (such as "
"<acronym>IP</acronym>), or even network interfaces (e.g., the Ethernet), you "
"would need to specify <constant>SOCK_RAW</constant>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4962
msgid ""
"Finally, the <varname>protocol</varname> argument depends on the previous "
"two arguments, and is not always meaningful. In that case, use <constant>0</"
"constant> for its value."
msgstr ""

#. (itstool) path: note/title
#: book.translate.xml:4968
msgid "The Unconnected Socket"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:4970
msgid ""
"Nowhere, in the <function>socket</function> function have we specified to "
"what other system we should be connected. Our newly created socket remains "
"<emphasis>unconnected</emphasis>."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:4975
msgid ""
"This is on purpose: To use a telephone analogy, we have just attached a "
"modem to the phone line. We have neither told the modem to make a call, nor "
"to answer if the phone rings."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:4984
msgid "<varname>sockaddr</varname>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:4986
msgid ""
"Various functions of the sockets family expect the address of (or pointer "
"to, to use C terminology) a small area of the memory. The various C "
"declarations in the <filename>sys/socket.h</filename> refer to it as "
"<varname>struct sockaddr</varname>. This structure is declared in the same "
"file:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:4993
#, no-wrap
msgid ""
"/*\n"
" * Structure used by kernel to store most\n"
" * addresses.\n"
" */\n"
"struct sockaddr {\n"
"	unsigned char	sa_len;		/* total length */\n"
"	sa_family_t	sa_family;	/* address family */\n"
"	char		sa_data[14];	/* actually longer; address value */\n"
"};\n"
"#define	SOCK_MAXADDRLEN	255		/* longest possible addresses */"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5004
msgid ""
"Please note the <emphasis>vagueness</emphasis> with which the "
"<varname>sa_data</varname> field is declared, just as an array of "
"<constant>14</constant> bytes, with the comment hinting there can be more "
"than <constant>14</constant> of them."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5010
msgid ""
"This vagueness is quite deliberate. Sockets is a very powerful interface. "
"While most people perhaps think of it as nothing more than the Internet "
"interface—and most applications probably use it for that nowadays—sockets "
"can be used for just about <emphasis>any</emphasis> kind of interprocess "
"communications, of which the Internet (or, more precisely, <acronym>IP</"
"acronym>) is only one."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5019
msgid ""
"The <filename>sys/socket.h</filename> refers to the various types of "
"protocols sockets will handle as <emphasis>address families</emphasis>, and "
"lists them right before the definition of <varname>sockaddr</varname>:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5025
#, no-wrap
msgid ""
"/*\n"
" * Address families.\n"
" */\n"
"#define	AF_UNSPEC	0		/* unspecified */\n"
"#define	AF_LOCAL	1		/* local to host (pipes, portals) */\n"
"#define	AF_UNIX		AF_LOCAL	/* backward compatibility */\n"
"#define	AF_INET		2		/* internetwork: UDP, TCP, etc. */\n"
"#define	AF_IMPLINK	3		/* arpanet imp addresses */\n"
"#define	AF_PUP		4		/* pup protocols: e.g. BSP */\n"
"#define	AF_CHAOS	5		/* mit CHAOS protocols */\n"
"#define	AF_NS		6		/* XEROX NS protocols */\n"
"#define	AF_ISO		7		/* ISO protocols */\n"
"#define	AF_OSI		AF_ISO\n"
"#define	AF_ECMA		8		/* European computer manufacturers */\n"
"#define	AF_DATAKIT	9		/* datakit protocols */\n"
"#define	AF_CCITT	10		/* CCITT protocols, X.25 etc */\n"
"#define	AF_SNA		11		/* IBM SNA */\n"
"#define AF_DECnet	12		/* DECnet */\n"
"#define AF_DLI		13		/* DEC Direct data link interface */\n"
"#define AF_LAT		14		/* LAT */\n"
"#define	AF_HYLINK	15		/* NSC Hyperchannel */\n"
"#define	AF_APPLETALK	16		/* Apple Talk */\n"
"#define	AF_ROUTE	17		/* Internal Routing Protocol */\n"
"#define	AF_LINK		18		/* Link layer interface */\n"
"#define	pseudo_AF_XTP	19		/* eXpress Transfer Protocol (no AF) */\n"
"#define	AF_COIP		20		/* connection-oriented IP, aka ST II */\n"
"#define	AF_CNT		21		/* Computer Network Technology */\n"
"#define pseudo_AF_RTIP	22		/* Help Identify RTIP packets */\n"
"#define	AF_IPX		23		/* Novell Internet Protocol */\n"
"#define	AF_SIP		24		/* Simple Internet Protocol */\n"
"#define	pseudo_AF_PIP	25		/* Help Identify PIP packets */\n"
"#define	AF_ISDN		26		/* Integrated Services Digital Network*/\n"
"#define	AF_E164		AF_ISDN		/* CCITT E.164 recommendation */\n"
"#define	pseudo_AF_KEY	27		/* Internal key-management function */\n"
"#define	AF_INET6	28		/* IPv6 */\n"
"#define	AF_NATM		29		/* native ATM access */\n"
"#define	AF_ATM		30		/* ATM */\n"
"#define pseudo_AF_HDRCMPLT 31		/* Used by BPF to not rewrite headers\n"
"					 * in interface output routine\n"
"					 */\n"
"#define	AF_NETGRAPH	32		/* Netgraph sockets */\n"
"#define	AF_SLOW		33		/* 802.3ad slow protocol */\n"
"#define	AF_SCLUSTER	34		/* Sitara cluster protocol */\n"
"#define	AF_ARP		35\n"
"#define	AF_BLUETOOTH	36		/* Bluetooth sockets */\n"
"#define	AF_MAX		37"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5072
msgid ""
"The one used for <acronym>IP</acronym> is <symbol>AF_INET</symbol>. It is a "
"symbol for the constant <constant>2</constant>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5076
msgid ""
"It is the <emphasis>address family</emphasis> listed in the "
"<varname>sa_family</varname> field of <varname>sockaddr</varname> that "
"decides how exactly the vaguely named bytes of <varname>sa_data</varname> "
"will be used."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5082
msgid ""
"Specifically, whenever the <emphasis>address family</emphasis> is "
"<symbol>AF_INET</symbol>, we can use <varname>struct sockaddr_in</varname> "
"found in <filename>netinet/in.h</filename>, wherever <varname>sockaddr</"
"varname> is expected:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5088
#, no-wrap
msgid ""
"/*\n"
" * Socket address, internet style.\n"
" */\n"
"struct sockaddr_in {\n"
"	uint8_t		sin_len;\n"
"	sa_family_t	sin_family;\n"
"	in_port_t	sin_port;\n"
"	struct	in_addr sin_addr;\n"
"	char	sin_zero[8];\n"
"};"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5099
msgid "We can visualize its organization this way:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:5103
msgctxt "_"
msgid "external ref='sockets/sain' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:5107
#, no-wrap
msgid ""
"        0        1        2       3\n"
"   +--------+--------+-----------------+\n"
" 0 |    0   | Family |       Port      |\n"
"   +--------+--------+-----------------+\n"
" 4 |             IP Address            |\n"
"   +-----------------------------------+\n"
" 8 |                 0                 |\n"
"   +-----------------------------------+\n"
"12 |                 0                 |\n"
"   +-----------------------------------+"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5101
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sain\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>sockaddr_in</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5124
msgid ""
"The three important fields are <varname>sin_family</varname>, which is byte "
"1 of the structure, <varname>sin_port</varname>, a 16-bit value found in "
"bytes 2 and 3, and <varname>sin_addr</varname>, a 32-bit integer "
"representation of the <acronym>IP</acronym> address, stored in bytes 4-7."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5131
msgid ""
"Now, let us try to fill it out. Let us assume we are trying to write a "
"client for the <emphasis>daytime</emphasis> protocol, which simply states "
"that its server will write a text string representing the current date and "
"time to port 13. We want to use <acronym>TCP/IP</acronym>, so we need to "
"specify <constant>AF_INET</constant> in the address family field. "
"<constant>AF_INET</constant> is defined as <constant>2</constant>. Let us "
"use the <acronym>IP</acronym> address of <systemitem class=\"ipaddress\">192."
"43.244.18</systemitem>, which is the time server of US federal government "
"(<systemitem class=\"fqdomainname\">time.nist.gov</systemitem>)."
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:5145
msgctxt "_"
msgid "external ref='sockets/sainfill' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:5149
#, no-wrap
msgid ""
"        0        1        2       3\n"
"   +--------+--------+-----------------+\n"
" 0 |    0   |   2    |        13       |\n"
"   +-----------------+-----------------+\n"
" 4 |           192.43.244.18           |\n"
"   +-----------------------------------+\n"
" 8 |                 0                 |\n"
"   +-----------------------------------+\n"
"12 |                 0                 |\n"
"   +-----------------------------------+"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5143
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sainfill\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>Specific example of sockaddr_in</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5166
msgid ""
"By the way the <varname>sin_addr</varname> field is declared as being of the "
"<varname>struct in_addr</varname> type, which is defined in "
"<filename>netinet/in.h</filename>:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5171
#, no-wrap
msgid ""
"/*\n"
" * Internet address (a structure for historical reasons)\n"
" */\n"
"struct in_addr {\n"
"	in_addr_t s_addr;\n"
"};"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5178
msgid "In addition, <varname>in_addr_t</varname> is a 32-bit integer."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5181
msgid ""
"The <systemitem class=\"ipaddress\">192.43.244.18</systemitem> is just a "
"convenient notation of expressing a 32-bit integer by listing all of its 8-"
"bit bytes, starting with the <emphasis>most significant</emphasis> one."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5186
msgid ""
"So far, we have viewed <varname>sockaddr</varname> as an abstraction. Our "
"computer does not store <varname>short</varname> integers as a single 16-bit "
"entity, but as a sequence of 2 bytes. Similarly, it stores 32-bit integers "
"as a sequence of 4 bytes."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5192
msgid "Suppose we coded something like this:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5194
#, no-wrap
msgid ""
"sa.sin_family      = AF_INET;\n"
"sa.sin_port        = 13;\n"
"sa.sin_addr.s_addr = (((((192 &lt;&lt; 8) | 43) &lt;&lt; 8) | 244) &lt;&lt; "
"8) | 18;"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5198
msgid "What would the result look like?"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5200
msgid ""
"Well, that depends, of course. On a <trademark class=\"registered\">Pentium</"
"trademark>, or other x86, based computer, it would look like this:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:5205 book.translate.xml:5325
msgctxt "_"
msgid "external ref='sockets/sainlsb' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:5209 book.translate.xml:5329
#, no-wrap
msgid ""
"        0        1        2       3\n"
"   +--------+--------+--------+--------+\n"
" 0 |    0   |   2    |   13   |   0    |\n"
"   +--------+--------+--------+--------+\n"
" 4 |   18   |  244   |   43   |  192   |\n"
"   +-----------------------------------+\n"
" 8 |                 0                 |\n"
"   +-----------------------------------+\n"
"12 |                 0                 |\n"
"   +-----------------------------------+"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5203
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sainlsb\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>sockaddr_in on an Intel system</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5226
msgid "On a different system, it might look like this:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:5230 book.translate.xml:5352
msgctxt "_"
msgid "external ref='sockets/sainmsb' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:5234 book.translate.xml:5356
#, no-wrap
msgid ""
"        0        1        2       3\n"
"   +--------+--------+--------+--------+\n"
" 0 |    0   |   2    |    0   |   13   |\n"
"   +--------+--------+--------+--------+\n"
" 4 |   192  |   43   |   244  |   18   |\n"
"   +-----------------------------------+\n"
" 8 |                 0                 |\n"
"   +-----------------------------------+\n"
"12 |                 0                 |\n"
"   +-----------------------------------+"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5228
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sainmsb\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>sockaddr_in on an MSB system</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5251
msgid ""
"And on a PDP it might look different yet. But the above two are the most "
"common ways in use today."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5254
msgid ""
"Ordinarily, wanting to write portable code, programmers pretend that these "
"differences do not exist. And they get away with it (except when they code "
"in assembly language). Alas, you cannot get away with it that easily when "
"coding for sockets."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5260
msgid "Why?"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5262
msgid ""
"Because when communicating with another computer, you usually do not know "
"whether it stores data <emphasis>most significant byte</emphasis> "
"(<acronym>MSB</acronym>) or <emphasis>least significant byte</emphasis> "
"(<acronym>LSB</acronym>) first."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5268
msgid ""
"You might be wondering, <emphasis><quote>So, will sockets not handle it for "
"me?</quote></emphasis>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5272
msgid "It will not."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5274
msgid ""
"While that answer may surprise you at first, remember that the general "
"sockets interface only understands the <varname>sa_len</varname> and "
"<varname>sa_family</varname> fields of the <varname>sockaddr</varname> "
"structure. You do not have to worry about the byte order there (of course, "
"on FreeBSD <varname>sa_family</varname> is only 1 byte anyway, but many "
"other <trademark class=\"registered\">UNIX</trademark> systems do not have "
"<varname>sa_len</varname> and use 2 bytes for <varname>sa_family</varname>, "
"and expect the data in whatever order is native to the computer)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5285
msgid ""
"But the rest of the data is just <varname>sa_data[14]</varname> as far as "
"sockets goes. Depending on the <emphasis>address family</emphasis>, sockets "
"just forwards that data to its destination."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5290
msgid ""
"Indeed, when we enter a port number, it is because we want the other "
"computer to know what service we are asking for. And, when we are the "
"server, we read the port number so we know what service the other computer "
"is expecting from us. Either way, sockets only has to forward the port "
"number as data. It does not interpret it in any way."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5298
msgid ""
"Similarly, we enter the <acronym>IP</acronym> address to tell everyone on "
"the way where to send our data to. Sockets, again, only forwards it as data."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5302
msgid ""
"That is why, we (the <emphasis>programmers</emphasis>, not the "
"<emphasis>sockets</emphasis>) have to distinguish between the byte order "
"used by our computer and a conventional byte order to send the data in to "
"the other computer."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5308
msgid ""
"We will call the byte order our computer uses the <emphasis>host byte order</"
"emphasis>, or just the <emphasis>host order</emphasis>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5312
msgid ""
"There is a convention of sending the multi-byte data over <acronym>IP</"
"acronym> <emphasis><acronym>MSB</acronym> first</emphasis>. This, we will "
"refer to as the <emphasis>network byte order</emphasis>, or simply the "
"<emphasis>network order</emphasis>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5319
msgid ""
"Now, if we compiled the above code for an Intel based computer, our "
"<emphasis>host byte order</emphasis> would produce:"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5323
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sainlsb\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>Host "
"byte order on an Intel system</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5346
msgid ""
"But the <emphasis>network byte order</emphasis> requires that we store the "
"data <acronym>MSB</acronym> first:"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5350
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sainmsb\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>Network "
"byte order</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5373
msgid ""
"Unfortunately, our <emphasis>host order</emphasis> is the exact opposite of "
"the <emphasis>network order</emphasis>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5377
msgid ""
"We have several ways of dealing with it. One would be to <emphasis>reverse</"
"emphasis> the values in our code:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5381
#, no-wrap
msgid ""
"sa.sin_family      = AF_INET;\n"
"sa.sin_port        = 13 &lt;&lt; 8;\n"
"sa.sin_addr.s_addr = (((((18 &lt;&lt; 8) | 244) &lt;&lt; 8) | 43) &lt;&lt; "
"8) | 192;"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5385
msgid ""
"This will <emphasis>trick</emphasis> our compiler into storing the data in "
"the <emphasis>network byte order</emphasis>. In some cases, this is exactly "
"the way to do it (e.g., when programming in assembly language). In most "
"cases, however, it can cause a problem."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5392
msgid ""
"Suppose, you wrote a sockets-based program in C. You know it is going to run "
"on a <trademark class=\"registered\">Pentium</trademark>, so you enter all "
"your constants in reverse and force them to the <emphasis>network byte "
"order</emphasis>. It works well."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5398
msgid ""
"Then, some day, your trusted old <trademark class=\"registered\">Pentium</"
"trademark> becomes a rusty old <trademark class=\"registered\">Pentium</"
"trademark>. You replace it with a system whose <emphasis>host order</"
"emphasis> is the same as the <emphasis>network order</emphasis>. You need to "
"recompile all your software. All of your software continues to perform well, "
"except the one program you wrote."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5405
msgid ""
"You have since forgotten that you had forced all of your constants to the "
"opposite of the <emphasis>host order</emphasis>. You spend some quality time "
"tearing out your hair, calling the names of all gods you ever heard of (and "
"some you made up), hitting your monitor with a nerf bat, and performing all "
"the other traditional ceremonies of trying to figure out why something that "
"has worked so well is suddenly not working at all."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5414
msgid ""
"Eventually, you figure it out, say a couple of swear words, and start "
"rewriting your code."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5417
msgid ""
"Luckily, you are not the first one to face the problem. Someone else has "
"created the <citerefentry><refentrytitle>htons</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>htonl</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> C functions to convert "
"a <varname>short</varname> and <varname>long</varname> respectively from the "
"<emphasis>host byte order</emphasis> to the <emphasis>network byte order</"
"emphasis>, and the <citerefentry><refentrytitle>ntohs</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> and "
"<citerefentry><refentrytitle>ntohl</refentrytitle><manvolnum>3</manvolnum></"
"citerefentry> C functions to go the other way."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5426
msgid ""
"On <emphasis><acronym>MSB</acronym>-first</emphasis> systems these functions "
"do nothing. On <emphasis><acronym>LSB</acronym>-first</emphasis> systems "
"they convert values to the proper order."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5431
msgid ""
"So, regardless of what system your software is compiled on, your data will "
"end up in the correct order if you use these functions."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:5438
msgid "Client Functions"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:5440
msgid ""
"Typically, the client initiates the connection to the server. The client "
"knows which server it is about to call: It knows its <acronym>IP</acronym> "
"address, and it knows the <emphasis>port</emphasis> the server resides at. "
"It is akin to you picking up the phone and dialing the number (the "
"<emphasis>address</emphasis>), then, after someone answers, asking for the "
"person in charge of wingdings (the <emphasis>port</emphasis>)."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:5450
msgid "<function>connect</function>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5452
msgid ""
"Once a client has created a socket, it needs to connect it to a specific "
"port on a remote system. It uses <citerefentry><refentrytitle>connect</"
"refentrytitle><manvolnum>2</manvolnum></citerefentry>:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5456
#, no-wrap
msgid "int connect(int s, const struct sockaddr *name, socklen_t namelen);"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5458
msgid ""
"The <varname>s</varname> argument is the socket, i.e., the value returned by "
"the <function>socket</function> function. The <varname>name</varname> is a "
"pointer to <varname>sockaddr</varname>, the structure we have talked about "
"extensively. Finally, <varname>namelen</varname> informs the system how many "
"bytes are in our <varname>sockaddr</varname> structure."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5466
msgid ""
"If <function>connect</function> is successful, it returns <constant>0</"
"constant>. Otherwise it returns <constant>-1</constant> and stores the error "
"code in <varname>errno</varname>."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5471
msgid ""
"There are many reasons why <function>connect</function> may fail. For "
"example, with an attempt to an Internet connection, the <acronym>IP</"
"acronym> address may not exist, or it may be down, or just too busy, or it "
"may not have a server listening at the specified port. Or it may outright "
"<emphasis>refuse</emphasis> any request for specific code."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:5482
msgid "Our First Client"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5484
msgid ""
"We now know enough to write a very simple client, one that will get current "
"time from <systemitem class=\"ipaddress\">192.43.244.18</systemitem> and "
"print it to <filename>stdout</filename>."
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5488
#, no-wrap
msgid ""
"/*\n"
" * daytime.c\n"
" *\n"
" * Programmed by G. Adam Stanislav\n"
" */\n"
"#include &lt;stdio.h&gt;\n"
"#include &lt;string.h&gt;\n"
"#include &lt;sys/types.h&gt;\n"
"#include &lt;sys/socket.h&gt;\n"
"#include &lt;netinet/in.h&gt;\n"
"\n"
"int main() {\n"
"  register int s;\n"
"  register int bytes;\n"
"  struct sockaddr_in sa;\n"
"  char buffer[BUFSIZ+1];\n"
"\n"
"  if ((s = socket(PF_INET, SOCK_STREAM, 0)) &lt; 0) {\n"
"    perror(\"socket\");\n"
"    return 1;\n"
"  }\n"
"\n"
"  bzero(&amp;sa, sizeof sa);\n"
"\n"
"  sa.sin_family = AF_INET;\n"
"  sa.sin_port = htons(13);\n"
"  sa.sin_addr.s_addr = htonl((((((192 &lt;&lt; 8) | 43) &lt;&lt; 8) | 244) "
"&lt;&lt; 8) | 18);\n"
"  if (connect(s, (struct sockaddr *)&amp;sa, sizeof sa) &lt; 0) {\n"
"    perror(\"connect\");\n"
"    close(s);\n"
"    return 2;\n"
"  }\n"
"\n"
"  while ((bytes = read(s, buffer, BUFSIZ)) &gt; 0)\n"
"    write(1, buffer, bytes);\n"
"\n"
"  close(s);\n"
"  return 0;\n"
"}"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5528
msgid ""
"Go ahead, enter it in your editor, save it as <filename>daytime.c</"
"filename>, then compile and run it:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:5532
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>cc -O3 -o daytime daytime.c</userinput>\n"
"<prompt>%</prompt> <userinput>./daytime</userinput>\n"
"\n"
"52079 01-06-19 02:29:25 50 0 1 543.9 UTC(NIST) *\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5538
msgid ""
"In this case, the date was June 19, 2001, the time was 02:29:25 "
"<acronym>UTC</acronym>. Naturally, your results will vary."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:5545
msgid "Server Functions"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:5547
msgid ""
"The typical server does not initiate the connection. Instead, it waits for a "
"client to call it and request services. It does not know when the client "
"will call, nor how many clients will call. It may be just sitting there, "
"waiting patiently, one moment, The next moment, it can find itself swamped "
"with requests from a number of clients, all calling in at the same time."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:5555
msgid "The sockets interface offers three basic functions to handle this."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:5559
msgid "<function>bind</function>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5561
msgid ""
"Ports are like extensions to a phone line: After you dial a number, you dial "
"the extension to get to a specific person or department."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5565
msgid ""
"There are 65535 <acronym>IP</acronym> ports, but a server usually processes "
"requests that come in on only one of them. It is like telling the phone room "
"operator that we are now at work and available to answer the phone at a "
"specific extension. We use <citerefentry><refentrytitle>bind</"
"refentrytitle><manvolnum>2</manvolnum></citerefentry> to tell sockets which "
"port we want to serve."
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5572
#, no-wrap
msgid "int bind(int s, const struct sockaddr *addr, socklen_t addrlen);"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5574
msgid ""
"Beside specifying the port in <varname>addr</varname>, the server may "
"include its <acronym>IP</acronym> address. However, it can just use the "
"symbolic constant <symbol>INADDR_ANY</symbol> to indicate it will serve all "
"requests to the specified port regardless of what its <acronym>IP</acronym> "
"address is. This symbol, along with several similar ones, is declared in "
"<filename>netinet/in.h</filename>"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5583
#, no-wrap
msgid "#define	INADDR_ANY		(u_int32_t)0x00000000"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5585
msgid ""
"Suppose we were writing a server for the <emphasis>daytime</emphasis> "
"protocol over <acronym>TCP</acronym>/<acronym>IP</acronym>. Recall that it "
"uses port 13. Our <varname>sockaddr_in</varname> structure would look like "
"this:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:5593
msgctxt "_"
msgid "external ref='sockets/sainserv' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:5597
#, no-wrap
msgid ""
"        0        1        2       3\n"
"   +--------+--------+--------+--------+\n"
" 0 |    0   |   2    |    0   |   13   |\n"
"   +--------+--------+--------+--------+\n"
" 4 |                 0                 |\n"
"   +-----------------------------------+\n"
" 8 |                 0                 |\n"
"   +-----------------------------------+\n"
"12 |                 0                 |\n"
"   +-----------------------------------+"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5591
msgid ""
"<imageobject> <imagedata fileref=\"sockets/sainserv\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>Example "
"Server sockaddr_in</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:5616
msgid "<function>listen</function>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5618
msgid ""
"To continue our office phone analogy, after you have told the phone central "
"operator what extension you will be at, you now walk into your office, and "
"make sure your own phone is plugged in and the ringer is turned on. Plus, "
"you make sure your call waiting is activated, so you can hear the phone ring "
"even while you are talking to someone."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5626
msgid ""
"The server ensures all of that with the <citerefentry><refentrytitle>listen</"
"refentrytitle><manvolnum>2</manvolnum></citerefentry> function."
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5629
#, no-wrap
msgid "int listen(int s, int backlog);"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5631
msgid ""
"In here, the <varname>backlog</varname> variable tells sockets how many "
"incoming requests to accept while you are busy processing the last request. "
"In other words, it determines the maximum size of the queue of pending "
"connections."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:5639
msgid "<function>accept</function>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5641
msgid ""
"After you hear the phone ringing, you accept the call by answering the call. "
"You have now established a connection with your client. This connection "
"remains active until either you or your client hang up."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5646
msgid ""
"The server accepts the connection by using the "
"<citerefentry><refentrytitle>accept</refentrytitle><manvolnum>2</manvolnum></"
"citerefentry> function."
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5649
#, no-wrap
msgid "int accept(int s, struct sockaddr *addr, socklen_t *addrlen);"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5651
msgid ""
"Note that this time <varname>addrlen</varname> is a pointer. This is "
"necessary because in this case it is the socket that fills out "
"<varname>addr</varname>, the <varname>sockaddr_in</varname> structure."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5656
msgid ""
"The return value is an integer. Indeed, the <function>accept</function> "
"returns a <emphasis>new socket</emphasis>. You will use this new socket to "
"communicate with the client."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5661
msgid ""
"What happens to the old socket? It continues to listen for more requests "
"(remember the <varname>backlog</varname> variable we passed to "
"<function>listen</function>?) until we <function>close</function> it."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5666
msgid ""
"Now, the new socket is meant only for communications. It is fully connected. "
"We cannot pass it to <function>listen</function> again, trying to accept "
"additional connections."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:5673
msgid "Our First Server"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5675
msgid ""
"Our first server will be somewhat more complex than our first client was: "
"Not only do we have more sockets functions to use, but we need to write it "
"as a daemon."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5680
msgid ""
"This is best achieved by creating a <emphasis>child process</emphasis> after "
"binding the port. The main process then exits and returns control to the "
"<application>shell</application> (or whatever program invoked it)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5686
msgid ""
"The child calls <function>listen</function>, then starts an endless loop, "
"which accepts a connection, serves it, and eventually closes its socket."
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5690
#, no-wrap
msgid ""
"/*\n"
" * daytimed - a port 13 server\n"
" *\n"
" * Programmed by G. Adam Stanislav\n"
" * June 19, 2001\n"
" */\n"
"#include &lt;stdio.h&gt;\n"
"#include &lt;string.h&gt;\n"
"#include &lt;time.h&gt;\n"
"#include &lt;unistd.h&gt;\n"
"#include &lt;sys/types.h&gt;\n"
"#include &lt;sys/socket.h&gt;\n"
"#include &lt;netinet/in.h&gt;\n"
"\n"
"#define BACKLOG 4\n"
"\n"
"int main() {\n"
"    register int s, c;\n"
"    int b;\n"
"    struct sockaddr_in sa;\n"
"    time_t t;\n"
"    struct tm *tm;\n"
"    FILE *client;\n"
"\n"
"    if ((s = socket(PF_INET, SOCK_STREAM, 0)) &lt; 0) {\n"
"        perror(\"socket\");\n"
"        return 1;\n"
"    }\n"
"\n"
"    bzero(&amp;sa, sizeof sa);\n"
"\n"
"    sa.sin_family = AF_INET;\n"
"    sa.sin_port   = htons(13);\n"
"\n"
"    if (INADDR_ANY)\n"
"        sa.sin_addr.s_addr = htonl(INADDR_ANY);\n"
"\n"
"    if (bind(s, (struct sockaddr *)&amp;sa, sizeof sa) &lt; 0) {\n"
"        perror(\"bind\");\n"
"        return 2;\n"
"    }\n"
"\n"
"    switch (fork()) {\n"
"        case -1:\n"
"            perror(\"fork\");\n"
"            return 3;\n"
"            break;\n"
"        default:\n"
"            close(s);\n"
"            return 0;\n"
"            break;\n"
"        case 0:\n"
"            break;\n"
"    }\n"
"\n"
"    listen(s, BACKLOG);\n"
"\n"
"    for (;;) {\n"
"        b = sizeof sa;\n"
"\n"
"        if ((c = accept(s, (struct sockaddr *)&amp;sa, &amp;b)) &lt; 0) {\n"
"            perror(\"daytimed accept\");\n"
"            return 4;\n"
"        }\n"
"\n"
"        if ((client = fdopen(c, \"w\")) == NULL) {\n"
"            perror(\"daytimed fdopen\");\n"
"            return 5;\n"
"        }\n"
"\n"
"        if ((t = time(NULL)) &lt; 0) {\n"
"            perror(\"daytimed time\");\n"
"\n"
"            return 6;\n"
"        }\n"
"\n"
"        tm = gmtime(&amp;t);\n"
"        fprintf(client, \"%.4i-%.2i-%.2iT%.2i:%.2i:%.2iZ\\n\",\n"
"            tm-&gt;tm_year + 1900,\n"
"            tm-&gt;tm_mon + 1,\n"
"            tm-&gt;tm_mday,\n"
"            tm-&gt;tm_hour,\n"
"            tm-&gt;tm_min,\n"
"            tm-&gt;tm_sec);\n"
"\n"
"        fclose(client);\n"
"    }\n"
"}"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5779
msgid ""
"We start by creating a socket. Then we fill out the <varname>sockaddr_in</"
"varname> structure in <varname>sa</varname>. Note the conditional use of "
"<symbol>INADDR_ANY</symbol>:"
msgstr ""

#. (itstool) path: sect4/programlisting
#: book.translate.xml:5784
#, no-wrap
msgid "if (INADDR_ANY)\n"
"        sa.sin_addr.s_addr = htonl(INADDR_ANY);"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5787
msgid ""
"Its value is <constant>0</constant>. Since we have just used "
"<function>bzero</function> on the entire structure, it would be redundant to "
"set it to <constant>0</constant> again. But if we port our code to some "
"other system where <symbol>INADDR_ANY</symbol> is perhaps not a zero, we "
"need to assign it to <varname>sa.sin_addr.s_addr</varname>. Most modern C "
"compilers are clever enough to notice that <symbol>INADDR_ANY</symbol> is a "
"constant. As long as it is a zero, they will optimize the entire conditional "
"statement out of the code."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5799
msgid ""
"After we have called <function>bind</function> successfully, we are ready to "
"become a <emphasis>daemon</emphasis>: We use <function>fork</function> to "
"create a child process. In both, the parent and the child, the <varname>s</"
"varname> variable is our socket. The parent process will not need it, so it "
"calls <function>close</function>, then it returns <constant>0</constant> to "
"inform its own parent it had terminated successfully."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5809
msgid ""
"Meanwhile, the child process continues working in the background. It calls "
"<function>listen</function> and sets its backlog to <constant>4</constant>. "
"It does not need a large value here because <emphasis>daytime</emphasis> is "
"not a protocol many clients request all the time, and because it can process "
"each request instantly anyway."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5817
msgid ""
"Finally, the daemon starts an endless loop, which performs the following "
"steps:"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:5822
msgid ""
"Call <function>accept</function>. It waits here until a client contacts it. "
"At that point, it receives a new socket, <varname>c</varname>, which it can "
"use to communicate with this particular client."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:5830
msgid ""
"It uses the C function <function>fdopen</function> to turn the socket from a "
"low-level <emphasis>file descriptor</emphasis> to a C-style <varname>FILE</"
"varname> pointer. This will allow the use of <function>fprintf</function> "
"later on."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:5839
msgid ""
"It checks the time, and prints it in the <emphasis><acronym>ISO</acronym> "
"8601</emphasis> format to the <varname>client</varname> <quote>file</quote>. "
"It then uses <function>fclose</function> to close the file. That will "
"automatically close the socket as well."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5849
msgid ""
"We can <emphasis>generalize</emphasis> this, and use it as a model for many "
"other servers:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:5854
msgctxt "_"
msgid "external ref='sockets/serv' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:5858
#, no-wrap
msgid ""
"+-----------------+\n"
"|  Create Socket  |\n"
"+-----------------+\n"
"          |\n"
"+-----------------+\n"
"|    Bind Port    |       Daemon Process\n"
"+-----------------+\n"
"          |                 +--------+\n"
"          +-------------+--&gt;|  Init  |\n"
"          |             |   +--------+\n"
"+-----------------+     |         |\n"
"|        Exit     |     |   +--------+\n"
"+-----------------+     |   | Listen |\n"
"                        |   +--------+\n"
"                        |         |\n"
"                        |   +--------+\n"
"                        |   | Accept |\n"
"                        |   +--------+\n"
"                        |         |\n"
"                        |   +--------+\n"
"                        |   | Serve  |\n"
"                        |   +--------+\n"
"                        |         |\n"
"                        |   +--------+\n"
"                        |   | Close  |\n"
"                        |&lt;--------+"
msgstr ""

#. (itstool) path: sect4/mediaobject
#: book.translate.xml:5852
msgid ""
"<imageobject> <imagedata fileref=\"sockets/serv\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>Sequential Server</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5891
msgid ""
"This flowchart is good for <emphasis>sequential servers</emphasis>, i.e., "
"servers that can serve one client at a time, just as we were able to with "
"our <emphasis>daytime</emphasis> server. This is only possible whenever "
"there is no real <quote>conversation</quote> going on between the client and "
"the server: As soon as the server detects a connection to the client, it "
"sends out some data and closes the connection. The entire operation may take "
"nanoseconds, and it is finished."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5902
msgid ""
"The advantage of this flowchart is that, except for the brief moment after "
"the parent <function>fork</function>s and before it exits, there is always "
"only one <emphasis>process</emphasis> active: Our server does not take up "
"much memory and other system resources."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5909
msgid ""
"Note that we have added <emphasis>initialize daemon</emphasis> in our "
"flowchart. We did not need to initialize our own daemon, but this is a good "
"place in the flow of the program to set up any <function>signal</function> "
"handlers, open any files we may need, etc."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5916
msgid ""
"Just about everything in the flow chart can be used literally on many "
"different servers. The <emphasis>serve</emphasis> entry is the exception. We "
"think of it as a <emphasis><quote>black box</quote></emphasis>, i.e., "
"something you design specifically for your own server, and just <quote>plug "
"it into the rest.</quote>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5924
msgid ""
"Not all protocols are that simple. Many receive a request from the client, "
"reply to it, then receive another request from the same client. Because of "
"that, they do not know in advance how long they will be serving the client. "
"Such servers usually start a new process for each client. While the new "
"process is serving its client, the daemon can continue listening for more "
"connections."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5932
msgid ""
"Now, go ahead, save the above source code as <filename>daytimed.c</filename> "
"(it is customary to end the names of daemons with the letter <constant>d</"
"constant>). After you have compiled it, try running it:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:5938
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>./daytimed</userinput>\n"
"bind: Permission denied\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5942
msgid ""
"What happened here? As you will recall, the <emphasis>daytime</emphasis> "
"protocol uses port 13. But all ports below 1024 are reserved to the "
"superuser (otherwise, anyone could start a daemon pretending to serve a "
"commonly used port, while causing a security breach)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5949
msgid "Try again, this time as the superuser:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:5951
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>./daytimed</userinput>\n"
"<prompt>#</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5954
msgid "What... Nothing? Let us try again:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:5956
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>./daytimed</userinput>\n"
"\n"
"bind: Address already in use\n"
"<prompt>#</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5961
msgid ""
"Every port can only be bound by one program at a time. Our first attempt was "
"indeed successful: It started the child daemon and returned quietly. It is "
"still running and will continue to run until you either kill it, or any of "
"its system calls fail, or you reboot the system."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5967
msgid ""
"Fine, we know it is running in the background. But is it working? How do we "
"know it is a proper <emphasis>daytime</emphasis> server? Simple:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:5971
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>telnet localhost 13</userinput>\n"
"\n"
"Trying ::1...\n"
"telnet: connect to address ::1: Connection refused\n"
"Trying 127.0.0.1...\n"
"Connected to localhost.\n"
"Escape character is '^]'.\n"
"2001-06-19T21:04:42Z\n"
"Connection closed by foreign host.\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5982
msgid ""
"<application>telnet</application> tried the new <acronym>IP</acronym>v6, and "
"failed. It retried with <acronym>IP</acronym>v4 and succeeded. The daemon "
"works."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:5987
msgid ""
"If you have access to another <trademark class=\"registered\">UNIX</"
"trademark> system via <application>telnet</application>, you can use it to "
"test accessing the server remotely. My computer does not have a static "
"<acronym>IP</acronym> address, so this is what I did:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:5993
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>who</userinput>\n"
"\n"
"whizkid          ttyp0   Jun 19 16:59   (216.127.220.143)\n"
"xxx              ttyp1   Jun 19 16:06   (xx.xx.xx.xx)\n"
"<prompt>%</prompt> <userinput>telnet 216.127.220.143 13</userinput>\n"
"\n"
"Trying 216.127.220.143...\n"
"Connected to r47.bfm.org.\n"
"Escape character is '^]'.\n"
"2001-06-19T21:31:11Z\n"
"Connection closed by foreign host.\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6006
msgid "Again, it worked. Will it work using the domain name?"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:6009
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>telnet r47.bfm.org 13</userinput>\n"
"\n"
"Trying 216.127.220.143...\n"
"Connected to r47.bfm.org.\n"
"Escape character is '^]'.\n"
"2001-06-19T21:31:40Z\n"
"Connection closed by foreign host.\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6018
msgid ""
"By the way, <application>telnet</application> prints the "
"<emphasis>Connection closed by foreign host</emphasis> message after our "
"daemon has closed the socket. This shows us that, indeed, using "
"<function>fclose(client);</function> in our code works as advertised."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:6030
msgid "Helper Functions"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6032
msgid ""
"FreeBSD C library contains many helper functions for sockets programming. "
"For example, in our sample client we hard coded the <systemitem class="
"\"fqdomainname\">time.nist.gov</systemitem> <acronym>IP</acronym> address. "
"But we do not always know the <acronym>IP</acronym> address. Even if we do, "
"our software is more flexible if it allows the user to enter the "
"<acronym>IP</acronym> address, or even the domain name."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:6041
msgid "<function>gethostbyname</function>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6043
msgid ""
"While there is no way to pass the domain name directly to any of the sockets "
"functions, the FreeBSD C library comes with the "
"<citerefentry><refentrytitle>gethostbyname</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>gethostbyname2</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> functions, declared in "
"<filename>netdb.h</filename>."
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:6048
#, no-wrap
msgid ""
"struct hostent * gethostbyname(const char *name);\n"
"struct hostent * gethostbyname2(const char *name, int af);"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6051
msgid ""
"Both return a pointer to the <varname>hostent</varname> structure, with much "
"information about the domain. For our purposes, the <varname>h_addr_list[0]</"
"varname> field of the structure points at <varname>h_length</varname> bytes "
"of the correct address, already stored in the <emphasis>network byte order</"
"emphasis>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6058
msgid ""
"This allows us to create a much more flexible—and much more useful—version "
"of our <application>daytime</application> program:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:6062
#, no-wrap
msgid ""
"/*\n"
" * daytime.c\n"
" *\n"
" * Programmed by G. Adam Stanislav\n"
" * 19 June 2001\n"
" */\n"
"#include &lt;stdio.h&gt;\n"
"#include &lt;string.h&gt;\n"
"#include &lt;sys/types.h&gt;\n"
"#include &lt;sys/socket.h&gt;\n"
"#include &lt;netinet/in.h&gt;\n"
"#include &lt;netdb.h&gt;\n"
"\n"
"int main(int argc, char *argv[]) {\n"
"  register int s;\n"
"  register int bytes;\n"
"  struct sockaddr_in sa;\n"
"  struct hostent *he;\n"
"  char buf[BUFSIZ+1];\n"
"  char *host;\n"
"\n"
"  if ((s = socket(PF_INET, SOCK_STREAM, 0)) &lt; 0) {\n"
"    perror(\"socket\");\n"
"    return 1;\n"
"  }\n"
"\n"
"  bzero(&amp;sa, sizeof sa);\n"
"\n"
"  sa.sin_family = AF_INET;\n"
"  sa.sin_port = htons(13);\n"
"\n"
"  host = (argc &gt; 1) ? (char *)argv[1] : \"time.nist.gov\";\n"
"\n"
"  if ((he = gethostbyname(host)) == NULL) {\n"
"    herror(host);\n"
"    return 2;\n"
"  }\n"
"\n"
"  bcopy(he-&gt;h_addr_list[0],&amp;sa.sin_addr, he-&gt;h_length);\n"
"\n"
"  if (connect(s, (struct sockaddr *)&amp;sa, sizeof sa) &lt; 0) {\n"
"    perror(\"connect\");\n"
"    return 3;\n"
"  }\n"
"\n"
"  while ((bytes = read(s, buf, BUFSIZ)) &gt; 0)\n"
"    write(1, buf, bytes);\n"
"\n"
"  close(s);\n"
"  return 0;\n"
"}"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6114
msgid ""
"We now can type a domain name (or an <acronym>IP</acronym> address, it works "
"both ways) on the command line, and the program will try to connect to its "
"<emphasis>daytime</emphasis> server. Otherwise, it will still default to "
"<systemitem class=\"fqdomainname\">time.nist.gov</systemitem>. However, even "
"in this case we will use <function>gethostbyname</function> rather than hard "
"coding <systemitem class=\"ipaddress\">192.43.244.18</systemitem>. That way, "
"even if its <acronym>IP</acronym> address changes in the future, we will "
"still find it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6125
msgid ""
"Since it takes virtually no time to get the time from your local server, you "
"could run <application>daytime</application> twice in a row: First to get "
"the time from <systemitem class=\"fqdomainname\">time.nist.gov</systemitem>, "
"the second time from your own system. You can then compare the results and "
"see how exact your system clock is:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:6131
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>daytime ; daytime localhost</userinput>\n"
"\n"
"\n"
"52080 01-06-20 04:02:33 50 0 0 390.2 UTC(NIST) *\n"
"2001-06-20T04:02:35Z\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6138
msgid ""
"As you can see, my system was two seconds ahead of the <acronym>NIST</"
"acronym> time."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:6143
msgid "<function>getservbyname</function>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6145
msgid ""
"Sometimes you may not be sure what port a certain service uses. The "
"<citerefentry><refentrytitle>getservbyname</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> function, also declared in <filename>netdb.h</"
"filename> comes in very handy in those cases:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:6150
#, no-wrap
msgid "struct servent * getservbyname(const char *name, const char *proto);"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6152
msgid ""
"The <varname>servent</varname> structure contains the <varname>s_port</"
"varname>, which contains the proper port, already in <emphasis>network byte "
"order</emphasis>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6156
msgid ""
"Had we not known the correct port for the <emphasis>daytime</emphasis> "
"service, we could have found it this way:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:6160
#, no-wrap
msgid ""
"struct servent *se;\n"
"  ...\n"
"  if ((se = getservbyname(\"daytime\", \"tcp\")) == NULL {\n"
"    fprintf(stderr, \"Cannot determine which port to use.\\n\");\n"
"    return 7;\n"
"  }\n"
"  sa.sin_port = se-&gt;s_port;"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:6168
msgid ""
"You usually do know the port. But if you are developing a new protocol, you "
"may be testing it on an unofficial port. Some day, you will register the "
"protocol and its port (if nowhere else, at least in your <filename>/etc/"
"services</filename>, which is where <function>getservbyname</function> "
"looks). Instead of returning an error in the above code, you just use the "
"temporary port number. Once you have listed the protocol in <filename>/etc/"
"services</filename>, your software will find its port without you having to "
"rewrite the code."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:6182
msgid "Concurrent Servers"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6184
msgid ""
"Unlike a sequential server, a <emphasis>concurrent server</emphasis> has to "
"be able to serve more than one client at a time. For example, a "
"<emphasis>chat server</emphasis> may be serving a specific client for "
"hours—it cannot wait till it stops serving a client before it serves the "
"next one."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6190
msgid "This requires a significant change in our flowchart:"
msgstr ""

#. (itstool) path: imageobject/imagedata
#. This is a reference to an external file such as an image or video. When
#. the file changes, the md5 hash will change to let you know you need to
#. update your localized copy. The msgstr is not used at all. Set it to
#. whatever you like once you have updated your copy of the file.
#: book.translate.xml:6194
msgctxt "_"
msgid "external ref='sockets/serv2' md5='__failed__'"
msgstr ""

#. (itstool) path: textobject/literallayout
#: book.translate.xml:6198
#, no-wrap
msgid ""
"+-----------------+\n"
"|  Create Socket  |\n"
"+-----------------+\n"
"          |\n"
"+-----------------+\n"
"|    Bind Port    |       Daemon Process\n"
"+-----------------+\n"
"          |                 +--------+\n"
"          +-------------+--&gt;|  Init  |\n"
"          |             |   +--------+\n"
"+-----------------+     |         |\n"
"|        Exit     |     |   +--------+\n"
"+-----------------+     |   | Listen |\n"
"                        |   +--------+\n"
"                        |         |\n"
"                        |   +--------+\n"
"                        |   | Accept |\n"
"                        |   +--------+\n"
"                        |         |       +------------------+\n"
"                        |         +------&gt;| Close Top Socket |\n"
"                        |         |       +------------------+\n"
"                        |   +--------+             |\n"
"                        |   | Close  |    +------------------+\n"
"                        |   +--------+    |     Serve        |\n"
"                        |         |       +------------------+\n"
"                        |&lt;--------+                |\n"
"                                          +------------------+\n"
"                                          | Close Acc Socket |\n"
"                            +--------+    +------------------+\n"
"                            | Signal |             |\n"
"                            +--------+    +------------------+\n"
"                                          |      Exit        |\n"
"                                          +------------------+"
msgstr ""

#. (itstool) path: sect1/mediaobject
#: book.translate.xml:6192
msgid ""
"<imageobject> <imagedata fileref=\"sockets/serv2\"/> </imageobject> "
"<textobject> <_:literallayout-1/> </textobject> <textobject> "
"<phrase>Concurrent Server</phrase> </textobject>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6238
msgid ""
"We moved the <emphasis>serve</emphasis> from the <emphasis>daemon process</"
"emphasis> to its own <emphasis>server process</emphasis>. However, because "
"each child process inherits all open files (and a socket is treated just "
"like a file), the new process inherits not only the "
"<emphasis><quote>accepted handle,</quote></emphasis> i.e., the socket "
"returned by the <function>accept</function> call, but also the <emphasis>top "
"socket</emphasis>, i.e., the one opened by the top process right at the "
"beginning."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6248
msgid ""
"However, the <emphasis>server process</emphasis> does not need this socket "
"and should <function>close</function> it immediately. Similarly, the "
"<emphasis>daemon process</emphasis> no longer needs the <emphasis>accepted "
"socket</emphasis>, and not only should, but <emphasis>must</emphasis> "
"<function>close</function> it—otherwise, it will run out of available "
"<emphasis>file descriptors</emphasis> sooner or later."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6257
msgid ""
"After the <emphasis>server process</emphasis> is done serving, it should "
"close the <emphasis>accepted socket</emphasis>. Instead of returning to "
"<function>accept</function>, it now exits."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6262
msgid ""
"Under <trademark class=\"registered\">UNIX</trademark>, a process does not "
"really <emphasis>exit</emphasis>. Instead, it <emphasis>returns</emphasis> "
"to its parent. Typically, a parent process <function>wait</function>s for "
"its child process, and obtains a return value. However, our <emphasis>daemon "
"process</emphasis> cannot simply stop and wait. That would defeat the whole "
"purpose of creating additional processes. But if it never does "
"<function>wait</function>, its children will become <emphasis>zombies</"
"emphasis>—no longer functional but still roaming around."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6273
msgid ""
"For that reason, the <emphasis>daemon process</emphasis> needs to set "
"<emphasis>signal handlers</emphasis> in its <emphasis>initialize daemon</"
"emphasis> phase. At least a <symbol>SIGCHLD</symbol> signal has to be "
"processed, so the daemon can remove the zombie return values from the system "
"and release the system resources they are taking up."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6280
msgid ""
"That is why our flowchart now contains a <emphasis>process signals</"
"emphasis> box, which is not connected to any other box. By the way, many "
"servers also process <symbol>SIGHUP</symbol>, and typically interpret as the "
"signal from the superuser that they should reread their configuration files. "
"This allows us to change settings without having to kill and restart these "
"servers."
msgstr ""

#. (itstool) path: chapter/title
#: book.translate.xml:6297
msgid "IPv6 Internals"
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:6301
msgid "IPv6/IPsec Implementation"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:6304
msgid ""
"<personname> <firstname>Yoshinobu</firstname> <surname>Inoue</surname> </"
"personname> <contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:6314
msgid ""
"This section should explain IPv6 and IPsec related implementation internals. "
"These functionalities are derived from <link xlink:href=\"http://www.kame."
"net/\">KAME project</link>"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:6320
msgid "IPv6"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6323
msgid "Conformance"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6325
msgid ""
"The IPv6 related functions conforms, or tries to conform to the latest set "
"of IPv6 specifications. For future reference we list some of the relevant "
"documents below (<emphasis>NOTE</emphasis>: this is not a complete list - "
"this is too hard to maintain...)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6331
msgid ""
"For details please refer to specific chapter in the document, RFCs, manual "
"pages, or comments in the source code."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6335
msgid ""
"Conformance tests have been performed on the KAME STABLE kit at TAHI project."
" Results can be viewed at <uri xlink:href=\"http://www.tahi.org/report/KAME/"
"\">http://www.tahi.org/report/KAME/</uri>. We also attended University of "
"New Hampshire IOL tests (<uri xlink:href=\"http://www.iol.unh.edu/\">http://"
"www.iol.unh.edu/</uri>) in the past, with our past snapshots."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6342
msgid "RFC1639: FTP Operation Over Big Address Records (FOOBAR)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6346 book.translate.xml:6447
msgid ""
"RFC2428 is preferred over RFC1639. FTP clients will first try RFC2428, then "
"RFC1639 if failed."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6354
msgid "RFC1886: DNS Extensions to support IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6358
msgid "RFC1933: Transition Mechanisms for IPv6 Hosts and Routers"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6362
msgid "IPv4 compatible address is not supported."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6365
msgid "automatic tunneling (described in 4.3 of this RFC) is not supported."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6369
msgid ""
"<citerefentry><refentrytitle>gif</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> interface implements IPv[46]-over-IPv[46] tunnel in a generic "
"way, and it covers \"configured tunnel\" described in the spec. See <link "
"linkend=\"gif\">23.5.1.5</link> in this document for details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6379
msgid "RFC1981: Path MTU Discovery for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6383
msgid "RFC2080: RIPng for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6386
msgid "usr.sbin/route6d support this."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6392
msgid "RFC2292: Advanced Sockets API for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6395
msgid ""
"For supported library functions/kernel APIs, see <filename>sys/netinet6/"
"ADVAPI</filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6402
msgid "RFC2362: Protocol Independent Multicast-Sparse Mode (PIM-SM)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6406
msgid ""
"RFC2362 defines packet formats for PIM-SM. <filename>draft-ietf-pim-ipv6-01."
"txt</filename> is written based on this."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6414
msgid "RFC2373: IPv6 Addressing Architecture"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6417
msgid ""
"supports node required addresses, and conforms to the scope requirement."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6424
msgid "RFC2374: An IPv6 Aggregatable Global Unicast Address Format"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6428
msgid "supports 64-bit length of Interface ID."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6434
msgid "RFC2375: IPv6 Multicast Address Assignments"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6437
msgid ""
"Userland applications use the well-known addresses assigned in the RFC."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6444
msgid "RFC2428: FTP Extensions for IPv6 and NATs"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6455
msgid "RFC2460: IPv6 specification"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6459
msgid "RFC2461: Neighbor discovery for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6462
msgid ""
"See <link linkend=\"neighbor-discovery\">23.5.1.2</link> in this document "
"for details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6469
msgid "RFC2462: IPv6 Stateless Address Autoconfiguration"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6473
msgid ""
"See <link linkend=\"ipv6-pnp\">23.5.1.4</link> in this document for details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6480
msgid "RFC2463: ICMPv6 for IPv6 specification"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6483
msgid ""
"See <link linkend=\"icmpv6\">23.5.1.9</link> in this document for details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6490
msgid "RFC2464: Transmission of IPv6 Packets over Ethernet Networks"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6495
msgid "RFC2465: MIB for IPv6: Textual Conventions and General Group"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6499
msgid ""
"Necessary statistics are gathered by the kernel. Actual IPv6 MIB support is "
"provided as a patchkit for ucd-snmp."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6507
msgid "RFC2466: MIB for IPv6: ICMPv6 group"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6510
msgid ""
"Necessary statistics are gathered by the kernel. Actual IPv6 MIB support is "
"provided as patchkit for ucd-snmp."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6518
msgid "RFC2467: Transmission of IPv6 Packets over FDDI Networks"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6523
msgid "RFC2497: Transmission of IPv6 packet over ARCnet Networks"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6528
msgid "RFC2553: Basic Socket Interface Extensions for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6532
msgid ""
"IPv4 mapped address (3.7) and special behavior of IPv6 wildcard bind socket "
"(3.8) are supported. See <link linkend=\"ipv6-wildcard-socket\">23.5.1.12</"
"link> in this document for details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6541
msgid "RFC2675: IPv6 Jumbograms"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6544
msgid ""
"See <link linkend=\"ipv6-jumbo\">23.5.1.7</link> in this document for "
"details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6551
msgid "RFC2710: Multicast Listener Discovery for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6556
msgid "RFC2711: IPv6 router alert option"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6560
msgid ""
"<filename>draft-ietf-ipngwg-router-renum-08</filename>: Router renumbering "
"for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6565
msgid ""
"<filename>draft-ietf-ipngwg-icmp-namelookups-02</filename>: IPv6 Name "
"Lookups Through ICMP"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6570
msgid ""
"<filename>draft-ietf-ipngwg-icmp-name-lookups-03</filename>: IPv6 Name "
"Lookups Through ICMP"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6575
msgid "<filename>draft-ietf-pim-ipv6-01.txt</filename>: PIM for IPv6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6579
msgid ""
"<citerefentry><refentrytitle>pim6dd</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> implements dense mode. <citerefentry><refentrytitle>pim6sd</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> implements sparse mode."
""
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6586
msgid ""
"<filename>draft-itojun-ipv6-tcp-to-anycast-00</filename>: Disconnecting TCP "
"connection toward IPv6 anycast address"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6592
msgid "<filename>draft-yamamoto-wideipv6-comm-model-00</filename>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6595
msgid ""
"See <link linkend=\"ipv6-sas\">23.5.1.6</link> in this document for details."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6602
msgid ""
"<filename>draft-ietf-ipngwg-scopedaddr-format-00.txt</filename>: An "
"Extension of Format for IPv6 Scoped Addresses"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6609
msgid "Neighbor Discovery"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6611
msgid ""
"Neighbor Discovery is fairly stable. Currently Address Resolution, "
"Duplicated Address Detection, and Neighbor Unreachability Detection are "
"supported. In the near future we will be adding Proxy Neighbor Advertisement "
"support in the kernel and Unsolicited Neighbor Advertisement transmission "
"command as admin tool."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6618
msgid ""
"If DAD fails, the address will be marked \"duplicated\" and message will be "
"generated to syslog (and usually to console). The \"duplicated\" mark can be "
"checked with <citerefentry><refentrytitle>ifconfig</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry>. It is administrators' "
"responsibility to check for and recover from DAD failures. The behavior "
"should be improved in the near future."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6625
msgid ""
"Some of the network driver loops multicast packets back to itself, even if "
"instructed not to do so (especially in promiscuous mode). In such cases DAD "
"may fail, because DAD engine sees inbound NS packet (actually from the node "
"itself) and considers it as a sign of duplicate. You may want to look at #if "
"condition marked \"heuristics\" in sys/netinet6/nd6_nbr.c:nd6_dad_timer() as "
"workaround (note that the code fragment in \"heuristics\" section is not "
"spec conformant)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6635
msgid ""
"Neighbor Discovery specification (RFC2461) does not talk about neighbor "
"cache handling in the following cases:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6640
msgid ""
"when there was no neighbor cache entry, node received unsolicited RS/NS/NA/"
"redirect packet without link-layer address"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6645
msgid ""
"neighbor cache handling on medium without link-layer address (we need a "
"neighbor cache entry for IsRouter bit)"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6651
msgid ""
"For first case, we implemented workaround based on discussions on IETF "
"ipngwg mailing list. For more details, see the comments in the source code "
"and email thread started from (IPng 7155), dated Feb 6 1999."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6656
msgid ""
"IPv6 on-link determination rule (RFC2461) is quite different from "
"assumptions in BSD network code. At this moment, no on-link determination "
"rule is supported where default router list is empty (RFC2461, section 5.2, "
"last sentence in 2nd paragraph - note that the spec misuse the word \"host\" "
"and \"node\" in several places in the section)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6664
msgid ""
"To avoid possible DoS attacks and infinite loops, only 10 options on ND "
"packet is accepted now. Therefore, if you have 20 prefix options attached to "
"RA, only the first 10 prefixes will be recognized. If this troubles you, "
"please ask it on FREEBSD-CURRENT mailing list and/or modify nd6_maxndopt in "
"<filename>sys/netinet6/nd6.c</filename>. If there are high demands we may "
"provide sysctl knob for the variable."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6675
msgid "Scope Index"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6677
msgid ""
"IPv6 uses scoped addresses. Therefore, it is very important to specify scope "
"index (interface index for link-local address, or site index for site-local "
"address) with an IPv6 address. Without scope index, scoped IPv6 address is "
"ambiguous to the kernel, and kernel will not be able to determine the "
"outbound interface for a packet."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6685
msgid ""
"Ordinary userland applications should use advanced API (RFC2292) to specify "
"scope index, or interface index. For similar purpose, sin6_scope_id member "
"in sockaddr_in6 structure is defined in RFC2553. However, the semantics for "
"sin6_scope_id is rather vague. If you care about portability of your "
"application, we suggest you to use advanced API rather than sin6_scope_id."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6693
msgid ""
"In the kernel, an interface index for link-local scoped address is embedded "
"into 2nd 16bit-word (3rd and 4th byte) in IPv6 address. For example, you may "
"see something like:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:6698
#, no-wrap
msgid "	fe80:1::200:f8ff:fe01:6317"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6700
msgid ""
"in the routing table and interface address structure (struct in6_ifaddr). "
"The address above is a link-local unicast address which belongs to a network "
"interface whose interface identifier is 1. The embedded index enables us to "
"identify IPv6 link local addresses over multiple interfaces effectively and "
"with only a little code change."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6707
msgid ""
"Routing daemons and configuration programs, like "
"<citerefentry><refentrytitle>route6d</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>ifconfig</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry>, will need to "
"manipulate the \"embedded\" scope index. These programs use routing sockets "
"and ioctls (like SIOCGIFADDR_IN6) and the kernel API will return IPv6 "
"addresses with 2nd 16bit-word filled in. The APIs are for manipulating "
"kernel internal structure. Programs that use these APIs have to be prepared "
"about differences in kernels anyway."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6716
msgid ""
"When you specify scoped address to the command line, NEVER write the "
"embedded form (such as ff02:1::1 or fe80:2::fedc). This is not supposed to "
"work. Always use standard form, like ff02::1 or fe80::fedc, with command "
"line option for specifying interface (like <command>ping6 -I ne0 ff02::1</"
"command>). In general, if a command does not have command line option to "
"specify outgoing interface, that command is not ready to accept scoped "
"address. This may seem to be opposite from IPv6's premise to support "
"\"dentist office\" situation. We believe that specifications need some "
"improvements for this."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6728
msgid ""
"Some of the userland tools support extended numeric IPv6 syntax, as "
"documented in <filename>draft-ietf-ipngwg-scopedaddr-format-00.txt</"
"filename>. You can specify outgoing link, by using name of the outgoing "
"interface like \"fe80::1%ne0\". This way you will be able to specify link-"
"local scoped address without much trouble."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6736
msgid ""
"To use this extension in your program, you will need to use "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry>, and <citerefentry><refentrytitle>getnameinfo</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> with NI_WITHSCOPEID. "
"The implementation currently assumes 1-to-1 relationship between a link and "
"an interface, which is stronger than what specs say."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6744
msgid "Plug and Play"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6746
msgid ""
"Most of the IPv6 stateless address autoconfiguration is implemented in the "
"kernel. Neighbor Discovery functions are implemented in the kernel as a "
"whole. Router Advertisement (RA) input for hosts is implemented in the "
"kernel. Router Solicitation (RS) output for endhosts, RS input for routers, "
"and RA output for routers are implemented in the userland."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:6755
msgid "Assignment of link-local, and special addresses"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6758
msgid ""
"IPv6 link-local address is generated from IEEE802 address (Ethernet MAC "
"address). Each of interface is assigned an IPv6 link-local address "
"automatically, when the interface becomes up (IFF_UP). Also, direct route "
"for the link-local address is added to routing table."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6764
msgid "Here is an output of netstat command:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:6766
#, no-wrap
msgid ""
"Internet6:\n"
"Destination                   Gateway                   Flags      Netif "
"Expire\n"
"fe80:1::%ed0/64               link#1                    UC          ed0\n"
"fe80:2::%ep0/64               link#2                    UC          ep0"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6771
msgid ""
"Interfaces that has no IEEE802 address (pseudo interfaces like tunnel "
"interfaces, or ppp interfaces) will borrow IEEE802 address from other "
"interfaces, such as Ethernet interfaces, whenever possible. If there is no "
"IEEE802 hardware attached, a last resort pseudo-random value, MD5(hostname), "
"will be used as source of link-local address. If it is not suitable for your "
"usage, you will need to configure the link-local address manually."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6780
msgid ""
"If an interface is not capable of handling IPv6 (such as lack of multicast "
"support), link-local address will not be assigned to that interface. See "
"section 2 for details."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6785
msgid ""
"Each interface joins the solicited multicast address and the link-local all-"
"nodes multicast addresses (e.g., fe80::1:ff01:6317 and ff02::1, "
"respectively, on the link the interface is attached). In addition to a link-"
"local address, the loopback address (::1) will be assigned to the loopback "
"interface. Also, ::1/128 and ff01::/32 are automatically added to routing "
"table, and loopback interface joins node-local multicast group ff01::1."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:6796
msgid "Stateless address autoconfiguration on Hosts"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6798
msgid ""
"In IPv6 specification, nodes are separated into two categories: "
"<emphasis>routers</emphasis> and <emphasis>hosts</emphasis>. Routers forward "
"packets addressed to others, hosts does not forward the packets. net.inet6."
"ip6.forwarding defines whether this node is router or host (router if it is "
"1, host if it is 0)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6806
msgid ""
"When a host hears Router Advertisement from the router, a host may "
"autoconfigure itself by stateless address autoconfiguration. This behavior "
"can be controlled by net.inet6.ip6.accept_rtadv (host autoconfigures itself "
"if it is set to 1). By autoconfiguration, network address prefix for the "
"receiving interface (usually global address prefix) is added. Default route "
"is also configured. Routers periodically generate Router Advertisement "
"packets. To request an adjacent router to generate RA packet, a host can "
"transmit Router Solicitation. To generate a RS packet at any time, use the "
"<emphasis>rtsol</emphasis> command. <citerefentry><refentrytitle>rtsold</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> daemon is also "
"available. <citerefentry><refentrytitle>rtsold</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> generates Router Solicitation whenever necessary, "
"and it works great for nomadic usage (notebooks/laptops). If one wishes to "
"ignore Router Advertisements, use sysctl to set net.inet6.ip6.accept_rtadv "
"to 0."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6824
msgid ""
"To generate Router Advertisement from a router, use the "
"<citerefentry><refentrytitle>rtadvd</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> daemon."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6827
msgid ""
"Note that, IPv6 specification assumes the following items, and nonconforming "
"cases are left unspecified:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6833
msgid "Only hosts will listen to router advertisements"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6837
msgid "Hosts have single network interface (except loopback)"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6842
msgid ""
"Therefore, this is unwise to enable net.inet6.ip6.accept_rtadv on routers, "
"or multi-interface host. A misconfigured node can behave strange "
"(nonconforming configuration allowed for those who would like to do some "
"experiments)."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6848
msgid "To summarize the sysctl knob:"
msgstr ""

#. (itstool) path: sect4/screen
#: book.translate.xml:6850
#, no-wrap
msgid ""
"	accept_rtadv	forwarding	role of the node\n"
"	---		---		---\n"
"	0		0		host (to be manually configured)\n"
"	0		1		router\n"
"	1		0		autoconfigured host\n"
"					(spec assumes that host has single\n"
"					interface only, autoconfigured host\n"
"					with multiple interface is\n"
"					out-of-scope)\n"
"	1		1		invalid, or experimental\n"
"					(out-of-scope of spec)"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6862
msgid ""
"RFC2462 has validation rule against incoming RA prefix information option, "
"in 5.5.3 (e). This is to protect hosts from malicious (or misconfigured) "
"routers that advertise very short prefix lifetime. There was an update from "
"Jim Bound to ipngwg mailing list (look for \"(ipng 6712)\" in the archive) "
"and it is implemented Jim's update."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:6870
msgid ""
"See <link linkend=\"neighbor-discovery\">23.5.1.2</link> in the document for "
"relationship between DAD and autoconfiguration."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6877
msgid "Generic Tunnel Interface"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6879
msgid ""
"GIF (Generic InterFace) is a pseudo interface for configured tunnel. Details "
"are described in <citerefentry><refentrytitle>gif</"
"refentrytitle><manvolnum>4</manvolnum></citerefentry>. Currently"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6885
msgid "v6 in v6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6888
msgid "v6 in v4"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6891
msgid "v4 in v6"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6894
msgid "v4 in v4"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6898
msgid ""
"are available. Use <citerefentry><refentrytitle>gifconfig</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> to assign physical "
"(outer) source and destination address to gif interfaces. Configuration that "
"uses same address family for inner and outer IP header (v4 in v4, or v6 in "
"v6) is dangerous. It is very easy to configure interfaces and routing tables "
"to perform infinite level of tunneling. <emphasis>Please be warned</"
"emphasis>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6906
msgid ""
"gif can be configured to be ECN-friendly. See <link linkend=\"ipsec-ecn\">23."
"5.4.5</link> for ECN-friendliness of tunnels, and "
"<citerefentry><refentrytitle>gif</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> for how to configure."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6909
msgid ""
"If you would like to configure an IPv4-in-IPv6 tunnel with gif interface, "
"read <citerefentry><refentrytitle>gif</refentrytitle><manvolnum>4</"
"manvolnum></citerefentry> carefully. You will need to remove IPv6 link-local "
"address automatically assigned to the gif interface."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6916
msgid "Source Address Selection"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6918
msgid ""
"Current source selection rule is scope oriented (there are some exceptions - "
"see below). For a given destination, a source IPv6 address is selected by "
"the following rule:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6925
msgid ""
"If the source address is explicitly specified by the user (e.g., via the "
"advanced API), the specified address is used."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6931
msgid ""
"If there is an address assigned to the outgoing interface (which is usually "
"determined by looking up the routing table) that has the same scope as the "
"destination address, the address is used."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6936
msgid "This is the most typical case."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6940
msgid ""
"If there is no address that satisfies the above condition, choose a global "
"address assigned to one of the interfaces on the sending node."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6946
msgid ""
"If there is no address that satisfies the above condition, and destination "
"address is site local scope, choose a site local address assigned to one of "
"the interfaces on the sending node."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:6953
msgid ""
"If there is no address that satisfies the above condition, choose the "
"address associated with the routing table entry for the destination. This is "
"the last resort, which may cause scope violation."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6960
msgid ""
"For instance, ::1 is selected for ff01::1, fe80:1::200:f8ff:fe01:6317 for "
"fe80:1::2a0:24ff:feab:839b (note that embedded interface index - described "
"in <link linkend=\"ipv6-scope-index\">23.5.1.3</link> - helps us choose the "
"right source address. Those embedded indices will not be on the wire). If "
"the outgoing interface has multiple address for the scope, a source is "
"selected longest match basis (rule 3). Suppose 2001:0DB8:808:1:200:f8ff:fe01:"
"6317 and 2001:0DB8:9:124:200:f8ff:fe01:6317 are given to the outgoing "
"interface. 2001:0DB8:808:1:200:f8ff:fe01:6317 is chosen as the source for "
"the destination 2001:0DB8:800::1."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6972
msgid ""
"Note that the above rule is not documented in the IPv6 spec. It is "
"considered \"up to implementation\" item. There are some cases where we do "
"not use the above rule. One example is connected TCP session, and we use the "
"address kept in tcb as the source. Another example is source address for "
"Neighbor Advertisement. Under the spec (RFC2461 7.2.2) NA's source should be "
"the target address of the corresponding NS's target. In this case we follow "
"the spec rather than the above longest-match rule."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6982
msgid ""
"For new connections (when rule 1 does not apply), deprecated addresses "
"(addresses with preferred lifetime = 0) will not be chosen as source address "
"if other choices are available. If no other choices are available, "
"deprecated address will be used as a last resort. If there are multiple "
"choice of deprecated addresses, the above scope rule will be used to choose "
"from those deprecated addresses. If you would like to prohibit the use of "
"deprecated address for some reason, configure net.inet6.ip6.use_deprecated "
"to 0. The issue related to deprecated address is described in RFC2462 5.5.4 "
"(NOTE: there is some debate underway in IETF ipngwg on how to use "
"\"deprecated\" address)."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:6997
msgid "Jumbo Payload"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:6999
msgid ""
"The Jumbo Payload hop-by-hop option is implemented and can be used to send "
"IPv6 packets with payloads longer than 65,535 octets. But currently no "
"physical interface whose MTU is more than 65,535 is supported, so such "
"payloads can be seen only on the loopback interface (i.e., lo0)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7005
msgid ""
"If you want to try jumbo payloads, you first have to reconfigure the kernel "
"so that the MTU of the loopback interface is more than 65,535 bytes; add the "
"following to the kernel configuration file:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7010
msgid "<literal>options \"LARGE_LOMTU\" #To test jumbo payload</literal>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7013
msgid "and recompile the new kernel."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7015
msgid ""
"Then you can test jumbo payloads by the <citerefentry><refentrytitle>ping6</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> command with -b and -s "
"options. The -b option must be specified to enlarge the size of the socket "
"buffer and the -s option specifies the length of the packet, which should be "
"more than 65,535. For example, type as follows:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:7021
#, no-wrap
msgid "<prompt>%</prompt> <userinput>ping6 -b 70000 -s 68000 ::1</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7023
msgid ""
"The IPv6 specification requires that the Jumbo Payload option must not be "
"used in a packet that carries a fragment header. If this condition is "
"broken, an ICMPv6 Parameter Problem message must be sent to the sender. "
"specification is followed, but you cannot usually see an ICMPv6 error caused "
"by this requirement."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7030
msgid ""
"When an IPv6 packet is received, the frame length is checked and compared to "
"the length specified in the payload length field of the IPv6 header or in "
"the value of the Jumbo Payload option, if any. If the former is shorter than "
"the latter, the packet is discarded and statistics are incremented. You can "
"see the statistics as output of <citerefentry><refentrytitle>netstat</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> command with `-s -p "
"ip6' option:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:7038
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>netstat -s -p ip6</userinput>\n"
"	  ip6:\n"
"		(snip)\n"
"		1 with data size &lt; data length"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7043
msgid ""
"So, kernel does not send an ICMPv6 error unless the erroneous packet is an "
"actual Jumbo Payload, that is, its packet size is more than 65,535 bytes. As "
"described above, currently no physical interface with such a huge MTU is "
"supported, so it rarely returns an ICMPv6 error."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7049
msgid ""
"TCP/UDP over jumbogram is not supported at this moment. This is because we "
"have no medium (other than loopback) to test this. Contact us if you need "
"this."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7053
msgid ""
"IPsec does not work on jumbograms. This is due to some specification twists "
"in supporting AH with jumbograms (AH header size influences payload length, "
"and this makes it real hard to authenticate inbound packet with jumbo "
"payload option as well as AH)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7059
msgid ""
"There are fundamental issues in *BSD support for jumbograms. We would like "
"to address those, but we need more time to finalize these. To name a few:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7065
msgid ""
"mbuf pkthdr.len field is typed as \"int\" in 4.4BSD, so it will not hold "
"jumbogram with len &gt; 2G on 32bit architecture CPUs. If we would like to "
"support jumbogram properly, the field must be expanded to hold 4G + IPv6 "
"header + link-layer header. Therefore, it must be expanded to at least "
"int64_t (u_int32_t is NOT enough)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7075
msgid ""
"We mistakingly use \"int\" to hold packet length in many places. We need to "
"convert them into larger integral type. It needs a great care, as we may "
"experience overflow during packet length computation."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7083
msgid ""
"We mistakingly check for ip6_plen field of IPv6 header for packet payload "
"length in various places. We should be checking mbuf pkthdr.len instead. "
"ip6_input() will perform sanity check on jumbo payload option on input, and "
"we can safely use mbuf pkthdr.len afterwards."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7092
msgid "TCP code needs a careful update in bunch of places, of course."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7099
msgid "Loop Prevention in Header Processing"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7101
msgid ""
"IPv6 specification allows arbitrary number of extension headers to be placed "
"onto packets. If we implement IPv6 packet processing code in the way BSD "
"IPv4 code is implemented, kernel stack may overflow due to long function "
"call chain. sys/netinet6 code is carefully designed to avoid kernel stack "
"overflow. Because of this, sys/netinet6 code defines its own protocol switch "
"structure, as \"struct ip6protosw\" (see <filename>netinet6/ip6protosw.h</"
"filename>). There is no such update to IPv4 part (sys/netinet) for "
"compatibility, but small change is added to its pr_input() prototype. So "
"\"struct ipprotosw\" is also defined. Because of this, if you receive IPsec-"
"over-IPv4 packet with massive number of IPsec headers, kernel stack may blow "
"up. IPsec-over-IPv6 is okay. (Off-course, for those all IPsec headers to be "
"processed, each such IPsec header must pass each IPsec check. So an "
"anonymous attacker will not be able to do such an attack.)"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7122
msgid "ICMPv6"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7124
msgid ""
"After RFC2463 was published, IETF ipngwg has decided to disallow ICMPv6 "
"error packet against ICMPv6 redirect, to prevent ICMPv6 storm on a network "
"medium. This is already implemented into the kernel."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7131
msgid "Applications"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7133
msgid ""
"For userland programming, we support IPv6 socket API as specified in "
"RFC2553, RFC2292 and upcoming Internet drafts."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7137
msgid ""
"TCP/UDP over IPv6 is available and quite stable. You can enjoy "
"<citerefentry><refentrytitle>telnet</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry>, <citerefentry><refentrytitle>ftp</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry>, <citerefentry><refentrytitle>rlogin</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry>, "
"<citerefentry><refentrytitle>rsh</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry>, <citerefentry><refentrytitle>ssh</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry>, etc. These applications are protocol independent. "
"That is, they automatically chooses IPv4 or IPv6 according to DNS."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7145
msgid "Kernel Internals"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7147
msgid ""
"While ip_forward() calls ip_output(), ip6_forward() directly calls "
"if_output() since routers must not divide IPv6 packets into fragments."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7151
msgid ""
"ICMPv6 should contain the original packet as long as possible up to 1280. "
"UDP6/IP6 port unreach, for instance, should contain all extension headers "
"and the *unchanged* UDP6 and IP6 headers. So, all IP6 functions except TCP "
"never convert network byte order into host byte order, to save the original "
"packet."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7158
msgid ""
"tcp_input(), udp6_input() and icmp6_input() can not assume that IP6 header "
"is preceding the transport headers due to extension headers. So, in6_cksum() "
"was implemented to handle packets whose IP6 header and transport header is "
"not continuous. TCP/IP6 nor UDP6/IP6 header structures do not exist for "
"checksum calculation."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7165
msgid ""
"To process IP6 header, extension headers and transport headers easily, "
"network drivers are now required to store packets in one internal mbuf or "
"one or more external mbufs. A typical old driver prepares two internal mbufs "
"for 96 - 204 bytes data, however, now such packet data is stored in one "
"external mbuf."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7172
msgid ""
"<command>netstat -s -p ip6</command> tells you whether or not your driver "
"conforms such requirement. In the following example, \"cce0\" violates the "
"requirement. (For more information, refer to Section 2.)"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:7177
#, no-wrap
msgid ""
"Mbuf statistics:\n"
"                317 one mbuf\n"
"                two or more mbuf::\n"
"                        lo0 = 8\n"
"			cce0 = 10\n"
"                3282 one ext mbuf\n"
"                0 two or more ext mbuf"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7185
msgid ""
"Each input function calls IP6_EXTHDR_CHECK in the beginning to check if the "
"region between IP6 and its header is continuous. IP6_EXTHDR_CHECK calls "
"m_pullup() only if the mbuf has M_LOOP flag, that is, the packet comes from "
"the loopback interface. m_pullup() is never called for packets coming from "
"physical network interfaces."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7192
msgid "Both IP and IP6 reassemble functions never call m_pullup()."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7197
msgid "IPv4 Mapped Address and IPv6 Wildcard Socket"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7199
msgid ""
"RFC2553 describes IPv4 mapped address (3.7) and special behavior of IPv6 "
"wildcard bind socket (3.8). The spec allows you to:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7204
msgid "Accept IPv4 connections by AF_INET6 wildcard bind socket."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7208
msgid ""
"Transmit IPv4 packet over AF_INET6 socket by using special form of the "
"address like ::ffff:10.1.1.1."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7213
msgid ""
"but the spec itself is very complicated and does not specify how the socket "
"layer should behave. Here we call the former one \"listening side\" and the "
"latter one \"initiating side\", for reference purposes."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7218
msgid ""
"You can perform wildcard bind on both of the address families, on the same "
"port."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7221
msgid "The following table show the behavior of FreeBSD 4.x."
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:7224
#, no-wrap
msgid ""
"listening side          initiating side\n"
"                (AF_INET6 wildcard      (connection to ::ffff:10.1.1.1)\n"
"                socket gets IPv4 conn.)\n"
"                ---                     ---\n"
"FreeBSD 4.x     configurable            supported\n"
"                default: enabled"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7231
msgid ""
"The following sections will give you more details, and how you can configure "
"the behavior."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7234
msgid "Comments on listening side:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7236
msgid ""
"It looks that RFC2553 talks too little on wildcard bind issue, especially on "
"the port space issue, failure mode and relationship between AF_INET/INET6 "
"wildcard bind. There can be several separate interpretation for this RFC "
"which conform to it but behaves differently. So, to implement portable "
"application you should assume nothing about the behavior in the kernel. "
"Using <citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> is the safest way. Port number space and wildcard "
"bind issues were discussed in detail on ipv6imp mailing list, in mid March "
"1999 and it looks that there is no concrete consensus (means, up to "
"implementers). You may want to check the mailing list archives."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7249
msgid ""
"If a server application would like to accept IPv4 and IPv6 connections, "
"there will be two alternatives."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7252
msgid ""
"One is using AF_INET and AF_INET6 socket (you will need two sockets). Use "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> with AI_PASSIVE into ai_flags, and "
"<citerefentry><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></"
"citerefentry> and <citerefentry><refentrytitle>bind</"
"refentrytitle><manvolnum>2</manvolnum></citerefentry> to all the addresses "
"returned. By opening multiple sockets, you can accept connections onto the "
"socket with proper address family. IPv4 connections will be accepted by "
"AF_INET socket, and IPv6 connections will be accepted by AF_INET6 socket."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7261
msgid ""
"Another way is using one AF_INET6 wildcard bind socket. Use "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> with AI_PASSIVE into ai_flags and with AF_INET6 "
"into ai_family, and set the 1st argument hostname to NULL. And "
"<citerefentry><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></"
"citerefentry> and <citerefentry><refentrytitle>bind</"
"refentrytitle><manvolnum>2</manvolnum></citerefentry> to the address "
"returned. (should be IPv6 unspecified addr). You can accept either of IPv4 "
"and IPv6 packet via this one socket."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7269
msgid ""
"To support only IPv6 traffic on AF_INET6 wildcard binded socket portably, "
"always check the peer address when a connection is made toward AF_INET6 "
"listening socket. If the address is IPv4 mapped address, you may want to "
"reject the connection. You can check the condition by using "
"IN6_IS_ADDR_V4MAPPED() macro."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7276
msgid ""
"To resolve this issue more easily, there is system dependent "
"<citerefentry><refentrytitle>setsockopt</refentrytitle><manvolnum>2</"
"manvolnum></citerefentry> option, IPV6_BINDV6ONLY, used like below."
msgstr ""

#. (itstool) path: sect3/programlisting
#. (itstool) path: sect5/programlisting
#: book.translate.xml:7280 book.translate.xml:7379
#, no-wrap
msgid ""
"	int on;\n"
"\n"
"	setsockopt(s, IPPROTO_IPV6, IPV6_BINDV6ONLY,\n"
"		   (char *)&amp;on, sizeof (on)) &lt; 0));"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7285
msgid "When this call succeed, then this socket only receive IPv6 packets."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7288
msgid "Comments on initiating side:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7290
msgid ""
"Advise to application implementers: to implement a portable IPv6 application "
"(which works on multiple IPv6 kernels), we believe that the following is the "
"key to the success:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7297
msgid "NEVER hardcode AF_INET nor AF_INET6."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7301
msgid ""
"Use <citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>getnameinfo</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry> throughout the system. "
"Never use gethostby*(), getaddrby*(), inet_*() or getipnodeby*(). (To update "
"existing applications to be IPv6 aware easily, sometime getipnodeby*() will "
"be useful. But if possible, try to rewrite the code to use "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> and <citerefentry><refentrytitle>getnameinfo</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry>.)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7311
msgid ""
"If you would like to connect to destination, use "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> and try all the destination returned, like "
"<citerefentry><refentrytitle>telnet</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry> does."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7317
msgid ""
"Some of the IPv6 stack is shipped with buggy "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry>. Ship a minimal working version with your "
"application and use that as last resort."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7324
msgid ""
"If you would like to use AF_INET6 socket for both IPv4 and IPv6 outgoing "
"connection, you will need to use "
"<citerefentry><refentrytitle>getipnodebyname</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry>. When you would like to update your existing "
"application to be IPv6 aware with minimal effort, this approach might be "
"chosen. But please note that it is a temporal solution, because "
"<citerefentry><refentrytitle>getipnodebyname</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> itself is not recommended as it does not handle "
"scoped IPv6 addresses at all. For IPv6 name resolution, "
"<citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</"
"manvolnum></citerefentry> is the preferred API. So you should rewrite your "
"application to use <citerefentry><refentrytitle>getaddrinfo</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry>, when you get the time "
"to do it."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7336
msgid ""
"When writing applications that make outgoing connections, story goes much "
"simpler if you treat AF_INET and AF_INET6 as totally separate address family."
" {set,get}sockopt issue goes simpler, DNS issue will be made simpler. We do "
"not recommend you to rely upon IPv4 mapped address."
msgstr ""

#. (itstool) path: sect4/title
#: book.translate.xml:7344
msgid "unified tcp and inpcb code"
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:7346
msgid ""
"FreeBSD 4.x uses shared tcp code between IPv4 and IPv6 (from sys/netinet/"
"tcp*) and separate udp4/6 code. It uses unified inpcb structure."
msgstr ""

#. (itstool) path: sect4/para
#: book.translate.xml:7350
msgid ""
"The platform can be configured to support IPv4 mapped address. Kernel "
"configuration is summarized as follows:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7356
msgid ""
"By default, AF_INET6 socket will grab IPv4 connections in certain condition, "
"and can initiate connection to IPv4 destination embedded in IPv4 mapped IPv6 "
"address."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7363
msgid "You can disable it on entire system with sysctl like below."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7366
msgid "<command>sysctl net.inet6.ip6.mapped_addr=0</command>"
msgstr ""

#. (itstool) path: sect5/title
#: book.translate.xml:7372
msgid "Listening Side"
msgstr ""

#. (itstool) path: sect5/para
#: book.translate.xml:7374
msgid ""
"Each socket can be configured to support special AF_INET6 wildcard bind "
"(enabled by default). You can disable it on each socket basis with "
"<citerefentry><refentrytitle>setsockopt</refentrytitle><manvolnum>2</"
"manvolnum></citerefentry> like below."
msgstr ""

#. (itstool) path: sect5/para
#: book.translate.xml:7384
msgid ""
"Wildcard AF_INET6 socket grabs IPv4 connection if and only if the following "
"conditions are satisfied:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7390
msgid "there is no AF_INET socket that matches the IPv4 connection"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7395
msgid ""
"the AF_INET6 socket is configured to accept IPv4 traffic, i.e., "
"getsockopt(IPV6_BINDV6ONLY) returns 0."
msgstr ""

#. (itstool) path: sect5/para
#: book.translate.xml:7401
msgid "There is no problem with open/close ordering."
msgstr ""

#. (itstool) path: sect5/title
#: book.translate.xml:7405
msgid "Initiating Side"
msgstr ""

#. (itstool) path: sect5/para
#: book.translate.xml:7407
msgid ""
"FreeBSD 4.x supports outgoing connection to IPv4 mapped address (::ffff:10.1."
"1.1), if the node is configured to support IPv4 mapped address."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7415
msgid "sockaddr_storage"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7417
msgid ""
"When RFC2553 was about to be finalized, there was discussion on how struct "
"sockaddr_storage members are named. One proposal is to prepend \"__\" to the "
"members (like \"__ss_len\") as they should not be touched. The other "
"proposal was not to prepend it (like \"ss_len\") as we need to touch those "
"members directly. There was no clear consensus on it."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7425
msgid "As a result, RFC2553 defines struct sockaddr_storage as follows:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:7428
#, no-wrap
msgid ""
"	struct sockaddr_storage {\n"
"		u_char	__ss_len;	/* address length */\n"
"		u_char	__ss_family;	/* address family */\n"
"		/* and bunch of padding */\n"
"	};"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7434
msgid "On the contrary, XNET draft defines as follows:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:7436
#, no-wrap
msgid ""
"	struct sockaddr_storage {\n"
"		u_char	ss_len;		/* address length */\n"
"		u_char	ss_family;	/* address family */\n"
"		/* and bunch of padding */\n"
"	};"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7442
msgid ""
"In December 1999, it was agreed that RFC2553bis should pick the latter "
"(XNET) definition."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7445
msgid ""
"Current implementation conforms to XNET definition, based on RFC2553bis "
"discussion."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7448
msgid ""
"If you look at multiple IPv6 implementations, you will be able to see both "
"definitions. As an userland programmer, the most portable way of dealing "
"with it is to:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7454
msgid ""
"ensure ss_family and/or ss_len are available on the platform, by using GNU "
"autoconf,"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7459
msgid ""
"have -Dss_family=__ss_family to unify all occurrences (including header "
"file) into __ss_family, or"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7465
msgid "never touch __ss_family. cast to sockaddr * and use sa_family like:"
msgstr ""

#. (itstool) path: listitem/programlisting
#: book.translate.xml:7468
#, no-wrap
msgid ""
"	struct sockaddr_storage ss;\n"
"	family = ((struct sockaddr *)&amp;ss)-&gt;sa_family"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:7477
msgid "Network Drivers"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:7479
msgid ""
"Now following two items are required to be supported by standard drivers:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7484
msgid ""
"mbuf clustering requirement. In this stable release, we changed MINCLSIZE "
"into MHLEN+1 for all the operating systems in order to make all the drivers "
"behave as we expect."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7491
msgid ""
"multicast. If <citerefentry><refentrytitle>ifmcstat</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> yields no multicast "
"group for a interface, that interface has to be patched."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:7497
msgid ""
"If any of the drivers do not support the requirements, then the drivers "
"cannot be used for IPv6 and/or IPsec communication. If you find any problem "
"with your card using IPv6/IPsec, then, please report it to the <link xlink:"
"href=\"http://lists.FreeBSD.org/mailman/listinfo/freebsd-bugs\">FreeBSD "
"problem reports mailing list</link>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:7502
msgid ""
"(NOTE: In the past we required all PCMCIA drivers to have a call to "
"in6_ifattach(). We have no such requirement any more)"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:7508
msgid "Translator"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:7510
msgid "We categorize IPv4/IPv6 translator into 4 types:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7514
msgid ""
"<emphasis>Translator A</emphasis> --- It is used in the early stage of "
"transition to make it possible to establish a connection from an IPv6 host "
"in an IPv6 island to an IPv4 host in the IPv4 ocean."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7521
msgid ""
"<emphasis>Translator B</emphasis> --- It is used in the early stage of "
"transition to make it possible to establish a connection from an IPv4 host "
"in the IPv4 ocean to an IPv6 host in an IPv6 island."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7528
msgid ""
"<emphasis>Translator C</emphasis> --- It is used in the late stage of "
"transition to make it possible to establish a connection from an IPv4 host "
"in an IPv4 island to an IPv6 host in the IPv6 ocean."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7535
msgid ""
"<emphasis>Translator D</emphasis> --- It is used in the late stage of "
"transition to make it possible to establish a connection from an IPv6 host "
"in the IPv6 ocean to an IPv4 host in an IPv4 island."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:7542
msgid ""
"TCP relay translator for category A is supported. This is called \"FAITH\". "
"We also provide IP header translator for category A. (The latter is not yet "
"put into FreeBSD 4.x yet.)"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7548
msgid "FAITH TCP Relay Translator"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7550
msgid ""
"FAITH system uses TCP relay daemon called "
"<citerefentry><refentrytitle>faithd</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> helped by the kernel. FAITH will reserve an IPv6 address "
"prefix, and relay TCP connection toward that prefix to IPv4 destination."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7555
msgid ""
"For example, if the reserved IPv6 prefix is 2001:0DB8:0200:ffff::, and the "
"IPv6 destination for TCP connection is 2001:0DB8:0200:ffff::163.221.202.12, "
"the connection will be relayed toward IPv4 destination 163.221.202.12."
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:7561
#, no-wrap
msgid ""
"	destination IPv4 node (163.221.202.12)\n"
"	  ^\n"
"	  | IPv4 tcp toward 163.221.202.12\n"
"	FAITH-relay dual stack node\n"
"	  ^\n"
"	  | IPv6 TCP toward 2001:0DB8:0200:ffff::163.221.202.12\n"
"	source IPv6 node"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7569
msgid ""
"<citerefentry><refentrytitle>faithd</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry> must be invoked on FAITH-relay dual stack node."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7572
msgid ""
"For more details, consult <filename>src/usr.sbin/faithd/README</filename>"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:7578
msgid "IPsec"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:7580
msgid "IPsec is mainly organized by three components."
msgstr ""

#. (itstool) path: listitem/para
#. (itstool) path: sect3/title
#: book.translate.xml:7584 book.translate.xml:7597
msgid "Policy Management"
msgstr ""

#. (itstool) path: listitem/para
#. (itstool) path: sect3/title
#: book.translate.xml:7588 book.translate.xml:7612
msgid "Key Management"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7592
msgid "AH and ESP handling"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7599
msgid ""
"The kernel implements experimental policy management code. There are two way "
"to manage security policy. One is to configure per-socket policy using "
"<citerefentry><refentrytitle>setsockopt</refentrytitle><manvolnum>2</"
"manvolnum></citerefentry>. In this cases, policy configuration is described "
"in <citerefentry><refentrytitle>ipsec_set_policy</"
"refentrytitle><manvolnum>3</manvolnum></citerefentry>. The other is to "
"configure kernel packet filter-based policy using PF_KEY interface, via "
"<citerefentry><refentrytitle>setkey</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7607
msgid ""
"The policy entry is not re-ordered with its indexes, so the order of entry "
"when you add is very significant."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7614
msgid ""
"The key management code implemented in this kit (sys/netkey) is a home-brew "
"PFKEY v2 implementation. This conforms to RFC2367."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7618
msgid ""
"The home-brew IKE daemon, \"racoon\" is included in the kit (kame/kame/"
"racoon). Basically you will need to run racoon as daemon, then set up a "
"policy to require keys (like <command>ping -P 'out ipsec esp/transport//"
"use'</command>). The kernel will contact racoon daemon as necessary to "
"exchange keys."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7627
msgid "AH and ESP Handling"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7629
msgid ""
"IPsec module is implemented as \"hooks\" to the standard IPv4/IPv6 "
"processing. When sending a packet, ip{,6}_output() checks if ESP/AH "
"processing is required by checking if a matching SPD (Security Policy "
"Database) is found. If ESP/AH is needed, {esp,ah}{4,6}_output() will be "
"called and mbuf will be updated accordingly. When a packet is received, "
"{esp,ah}4_input() will be called based on protocol number, i.e., "
"(*inetsw[proto])(). {esp,ah}4_input() will decrypt/check authenticity of the "
"packet, and strips off daisy-chained header and padding for ESP/AH. It is "
"safe to strip off the ESP/AH header on packet reception, since we will never "
"use the received packet in \"as is\" form."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7643
msgid ""
"By using ESP/AH, TCP4/6 effective data segment size will be affected by "
"extra daisy-chained headers inserted by ESP/AH. Our code takes care of the "
"case."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7647
msgid ""
"Basic crypto functions can be found in directory \"sys/crypto\". ESP/AH "
"transform are listed in {esp,ah}_core.c with wrapper functions. If you wish "
"to add some algorithm, add wrapper function in {esp,ah}_core.c, and add your "
"crypto algorithm code into sys/crypto."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7653
msgid ""
"Tunnel mode is partially supported in this release, with the following "
"restrictions:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7658
msgid ""
"IPsec tunnel is not combined with GIF generic tunneling interface. It needs "
"a great care because we may create an infinite loop between ip_output() and "
"tunnelifp-&gt;if_output(). Opinion varies if it is better to unify them, or "
"not."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7666
msgid ""
"MTU and Don't Fragment bit (IPv4) considerations need more checking, but "
"basically works fine."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7671
msgid ""
"Authentication model for AH tunnel must be revisited. We will need to "
"improve the policy management engine, eventually."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7679
msgid "Conformance to RFCs and IDs"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7681
msgid ""
"The IPsec code in the kernel conforms (or, tries to conform) to the "
"following standards:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7684
msgid ""
"\"old IPsec\" specification documented in <filename>rfc182[5-9].txt</"
"filename>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7687
msgid ""
"\"new IPsec\" specification documented in <filename>rfc240[1-6].txt</"
"filename>, <filename>rfc241[01].txt</filename>, <filename>rfc2451.txt</"
"filename> and <filename>draft-mcdonald-simple-ipsec-api-01.txt</filename> "
"(draft expired, but you can take from <link xlink:href=\"ftp://ftp.kame.net/"
"pub/internet-drafts/\"> ftp://ftp.kame.net/pub/internet-drafts/</link>). "
"(NOTE: IKE specifications, <filename>rfc241[7-9].txt</filename> are "
"implemented in userland, as \"racoon\" IKE daemon)"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7697
msgid "Currently supported algorithms are:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7700 book.translate.xml:7818
msgid "old IPsec AH"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7703 book.translate.xml:7743
msgid "null crypto checksum (no document, just for debugging)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7707
msgid ""
"keyed MD5 with 128bit crypto checksum (<filename>rfc1828.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7711
msgid "keyed SHA1 with 128bit crypto checksum (no document)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7715
msgid ""
"HMAC MD5 with 128bit crypto checksum (<filename>rfc2085.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7719
msgid "HMAC SHA1 with 128bit crypto checksum (no document)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7726
msgid "old IPsec ESP"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7729
msgid ""
"null encryption (no document, similar to <filename>rfc2410.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7733
msgid "DES-CBC mode (<filename>rfc1829.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7740
msgid "new IPsec AH"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7747
msgid "keyed MD5 with 96bit crypto checksum (no document)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7751
msgid "keyed SHA1 with 96bit crypto checksum (no document)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7755
msgid "HMAC MD5 with 96bit crypto checksum (<filename>rfc2403.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7759
msgid ""
"HMAC SHA1 with 96bit crypto checksum (<filename>rfc2404.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7766
msgid "new IPsec ESP"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7769
msgid "null encryption (<filename>rfc2410.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7773
msgid ""
"DES-CBC with derived IV (<filename>draft-ietf-ipsec-ciph-des-derived-01.txt</"
"filename>, draft expired)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7778
msgid "DES-CBC with explicit IV (<filename>rfc2405.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7782
msgid "3DES-CBC with explicit IV (<filename>rfc2451.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7786
msgid "BLOWFISH CBC (<filename>rfc2451.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7790
msgid "CAST128 CBC (<filename>rfc2451.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7794
msgid "RC5 CBC (<filename>rfc2451.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7798
msgid "each of the above can be combined with:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7801
msgid "ESP authentication with HMAC-MD5(96bit)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7805
msgid "ESP authentication with HMAC-SHA1(96bit)"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7814
msgid "The following algorithms are NOT supported:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7822
msgid ""
"HMAC MD5 with 128bit crypto checksum + 64bit replay prevention "
"(<filename>rfc2085.txt</filename>)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7827
msgid ""
"keyed SHA1 with 160bit crypto checksum + 32bit padding (<filename>rfc1852."
"txt</filename>)"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7834
msgid ""
"IPsec (in kernel) and IKE (in userland as \"racoon\") has been tested at "
"several interoperability test events, and it is known to interoperate with "
"many other implementations well. Also, current IPsec implementation as quite "
"wide coverage for IPsec crypto algorithms documented in RFC (we cover "
"algorithms without intellectual property issues only)."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7844
msgid "ECN Consideration on IPsec Tunnels"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7846
msgid ""
"ECN-friendly IPsec tunnel is supported as described in <filename>draft-ipsec-"
"ecn-00.txt</filename>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7849
msgid ""
"Normal IPsec tunnel is described in RFC2401. On encapsulation, IPv4 TOS "
"field (or, IPv6 traffic class field) will be copied from inner IP header to "
"outer IP header. On decapsulation outer IP header will be simply dropped. "
"The decapsulation rule is not compatible with ECN, since ECN bit on the "
"outer IP TOS/traffic class field will be lost."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7856
msgid ""
"To make IPsec tunnel ECN-friendly, we should modify encapsulation and "
"decapsulation procedure. This is described in <link xlink:href=\"http://www."
"aciri.org/floyd/papers/draft-ipsec-ecn-00.txt\"> http://www.aciri.org/floyd/"
"papers/draft-ipsec-ecn-00.txt</link>, chapter 3."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7862
msgid ""
"IPsec tunnel implementation can give you three behaviors, by setting net."
"inet.ipsec.ecn (or net.inet6.ipsec6.ecn) to some value:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7868
msgid "RFC2401: no consideration for ECN (sysctl value -1)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7872
msgid "ECN forbidden (sysctl value 0)"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7875
msgid "ECN allowed (sysctl value 1)"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7879
msgid ""
"Note that the behavior is configurable in per-node manner, not per-SA manner "
"(draft-ipsec-ecn-00 wants per-SA configuration, but it looks too much for "
"me)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7883
msgid ""
"The behavior is summarized as follows (see source code for more detail):"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:7886
#, no-wrap
msgid ""
"encapsulate                     decapsulate\n"
"                ---                             ---\n"
"RFC2401         copy all TOS bits               drop TOS bits on outer\n"
"                from inner to outer.            (use inner TOS bits as is)\n"
"\n"
"ECN forbidden   copy TOS bits except for ECN    drop TOS bits on outer\n"
"                (masked with 0xfc) from inner   (use inner TOS bits as is)\n"
"                to outer.  set ECN bits to 0.\n"
"\n"
"ECN allowed     copy TOS bits except for ECN    use inner TOS bits with some\n"
"                CE (masked with 0xfe) from      change.  if outer ECN CE bit\n"
"                inner to outer.                 is 1, enable ECN CE bit on\n"
"                set ECN CE bit to 0.            the inner."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7900
msgid "General strategy for configuration is as follows:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7903
msgid ""
"if both IPsec tunnel endpoint are capable of ECN-friendly behavior, you "
"should better configure both end to <quote>ECN allowed</quote> (sysctl value "
"1)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7909
msgid ""
"if the other end is very strict about TOS bit, use \"RFC2401\" (sysctl value "
"-1)."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:7913
msgid "in other cases, use \"ECN forbidden\" (sysctl value 0)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7918
msgid "The default behavior is \"ECN forbidden\" (sysctl value 0)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7921
msgid "For more information, please refer to:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7923
msgid ""
"<link xlink:href=\"http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00."
"txt\"> http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt</link>, "
"RFC2481 (Explicit Congestion Notification), src/sys/netinet6/{ah,esp}_input."
"c"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7928
msgid ""
"(Thanks goes to Kenjiro Cho <email>kjc@csl.sony.co.jp</email> for detailed "
"analysis)"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:7934
msgid "Interoperability"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7936
msgid ""
"Here are (some of) platforms that KAME code have tested IPsec/IKE "
"interoperability in the past. Note that both ends may have modified their "
"implementation, so use the following list just for reference purposes."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:7941
msgid ""
"Altiga, Ashley-laurent (vpcom.com), Data Fellows (F-Secure), Ericsson ACC, "
"FreeS/WAN, HITACHI, IBM <trademark class=\"registered\">AIX</trademark>, "
"IIJ, Intel, <trademark class=\"registered\">Microsoft</trademark> <trademark "
"class=\"registered\">Windows NT</trademark>, NIST (linux IPsec + plutoplus), "
"Netscreen, OpenBSD, RedCreek, Routerware, SSH, Secure Computing, Soliton, "
"Toshiba, VPNet, Yamaha RT100i"
msgstr ""

#. (itstool) path: part/title
#: book.translate.xml:7956
msgid "Kernel"
msgstr ""

#. (itstool) path: chapter/title
#: book.translate.xml:7965
msgid "Building and Installing a FreeBSD Kernel"
msgstr ""

#. (itstool) path: chapter/para
#: book.translate.xml:7967
msgid ""
"Being a kernel developer requires understanding of the kernel build process. "
"To debug the FreeBSD kernel it is required to be able to build one. There "
"are two known ways to do so:"
msgstr ""

#. (itstool) path: chapter/para
#: book.translate.xml:7971
msgid ""
"The supported procedure to build and install a kernel is documented in the "
"<link xlink:href=\"../handbook/kernelconfig-building.html\">Building and "
"Installing a Custom Kernel</link> chapter of the FreeBSD Handbook."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:7977
msgid ""
"It is supposed that the reader of this chapter is familiar with the "
"information described in the <link xlink:href=\"../handbook/kernelconfig-"
"building.html\">Building and Installing a Custom Kernel</link> chapter of "
"the FreeBSD Handbook. If this is not the case, please read through the above "
"mentioned chapter to understand how the build process works."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:7986
msgid "Building the Faster but Brittle Way"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:7988
msgid ""
"Building the kernel this way may be useful when working on the kernel code "
"and it may actually be faster than the documented procedure when only a "
"single option or two were tweaked in the kernel configuration file. On the "
"other hand, it might lead to unexpected kernel build breakage."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:7997
msgid ""
"Run <citerefentry><refentrytitle>config</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> to generate the kernel source code:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:8000
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>/usr/sbin/config <replaceable>MYKERNEL</"
"replaceable></userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:8004
msgid ""
"Change into the build directory. <citerefentry><refentrytitle>config</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> will print the name of "
"this directory after being run as above."
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:8008
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>cd ../compile/<replaceable>MYKERNEL</"
"replaceable></userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:8012
msgid "Compile the kernel:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:8014
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>make depend</userinput>\n"
"<prompt>#</prompt> <userinput>make</userinput>"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:8019
msgid "Install the new kernel:"
msgstr ""

#. (itstool) path: step/screen
#: book.translate.xml:8021
#, no-wrap
msgid "<prompt>#</prompt> <userinput>make install</userinput>"
msgstr ""

#. (itstool) path: info/title
#: book.translate.xml:8035
msgid "Kernel Debugging"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:8037
msgid ""
"<personname><firstname>Paul</firstname><surname>Richards</surname></"
"personname><contrib>Contributed by </contrib>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:8038
msgid ""
"<personname><firstname>Jörg</firstname><surname>Wunsch</surname></"
"personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:8039
msgid ""
"<personname><firstname>Robert</firstname><surname>Watson</surname></"
"personname>"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8046
msgid "Obtaining a Kernel Crash Dump"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8048
msgid ""
"When running a development kernel (e.g., FreeBSD-CURRENT), such as a kernel "
"under extreme conditions (e.g., very high load averages, tens of thousands "
"of connections, exceedingly high number of concurrent users, hundreds of "
"<citerefentry><refentrytitle>jail</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry>s, etc.), or using a new feature or device driver on FreeBSD-"
"STABLE (e.g., <acronym>PAE</acronym>), sometimes a kernel will panic. In the "
"event that it does, this chapter will demonstrate how to extract useful "
"information out of a crash."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8057
msgid ""
"A system reboot is inevitable once a kernel panics. Once a system is "
"rebooted, the contents of a system's physical memory (<acronym>RAM</"
"acronym>) is lost, as well as any bits that are on the swap device before "
"the panic. To preserve the bits in physical memory, the kernel makes use of "
"the swap device as a temporary place to store the bits that are in RAM "
"across a reboot after a crash. In doing this, when FreeBSD boots after a "
"crash, a kernel image can now be extracted and debugging can take place."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:8067
msgid ""
"A swap device that has been configured as a dump device still acts as a swap "
"device. Dumps to non-swap devices (such as tapes or CDRWs, for example) are "
"not supported at this time. A <quote>swap device</quote> is synonymous with "
"a <quote>swap partition.</quote>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8073
msgid "Several types of kernel crash dumps are available:"
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:8076
msgid "Full memory dumps"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8079
msgid "Hold the complete contents of physical memory."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:8085
msgid "Minidumps"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8088
msgid "Hold only memory pages in use by the kernel (FreeBSD 6.2 and higher)."
msgstr ""

#. (itstool) path: varlistentry/term
#: book.translate.xml:8094
msgid "Textdumps"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8097
msgid ""
"Hold captured, scripted, or interactive debugger output (FreeBSD 7.1 and "
"higher)."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8103
msgid ""
"Minidumps are the default dump type as of FreeBSD 7.0, and in most cases "
"will capture all necessary information present in a full memory dump, as "
"most problems can be isolated only using kernel state."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:8109
msgid "Configuring the Dump Device"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8111
msgid ""
"Before the kernel will dump the contents of its physical memory to a dump "
"device, a dump device must be configured. A dump device is specified by "
"using the <citerefentry><refentrytitle>dumpon</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> command to tell the kernel where to save kernel "
"crash dumps. The <citerefentry><refentrytitle>dumpon</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> program must be called "
"after the swap partition has been configured with "
"<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></"
"citerefentry>. This is normally handled by setting the <varname>dumpdev</"
"varname> variable in <citerefentry><refentrytitle>rc.conf</"
"refentrytitle><manvolnum>5</manvolnum></citerefentry> to the path of the "
"swap device (the recommended way to extract a kernel dump) or <literal>AUTO</"
"literal> to use the first configured swap device. The default for "
"<varname>dumpdev</varname> is <literal>AUTO</literal> in HEAD, and changed "
"to <literal>NO</literal> on RELENG_* branches (except for RELENG_7, which "
"was left set to <literal>AUTO</literal>). On FreeBSD 9.0-RELEASE and later "
"versions, <application>bsdinstall</application> will ask whether crash dumps "
"should be enabled on the target system during the install process."
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:8129
msgid ""
"Check <filename>/etc/fstab</filename> or "
"<citerefentry><refentrytitle>swapinfo</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> for a list of swap devices."
msgstr ""

#. (itstool) path: important/para
#: book.translate.xml:8132
msgid ""
"Make sure the <varname>dumpdir</varname> specified in "
"<citerefentry><refentrytitle>rc.conf</refentrytitle><manvolnum>5</"
"manvolnum></citerefentry> exists before a kernel crash!"
msgstr ""

#. (itstool) path: important/screen
#: book.translate.xml:8136
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>mkdir /var/crash</userinput>\n"
"<prompt>#</prompt> <userinput>chmod 700 /var/crash</userinput>"
msgstr ""

#. (itstool) path: important/para
#: book.translate.xml:8139
msgid ""
"Also, remember that the contents of <filename>/var/crash</filename> is "
"sensitive and very likely contains confidential information such as "
"passwords."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:8146
msgid "Extracting a Kernel Dump"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8148
msgid ""
"Once a dump has been written to a dump device, the dump must be extracted "
"before the swap device is mounted. To extract a dump from a dump device, use "
"the <citerefentry><refentrytitle>savecore</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> program. If <varname>dumpdev</varname> has been "
"set in <citerefentry><refentrytitle>rc.conf</refentrytitle><manvolnum>5</"
"manvolnum></citerefentry>, <citerefentry><refentrytitle>savecore</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> will be called "
"automatically on the first multi-user boot after the crash and before the "
"swap device is mounted. The location of the extracted core is placed in the "
"<citerefentry><refentrytitle>rc.conf</refentrytitle><manvolnum>5</"
"manvolnum></citerefentry> value <varname>dumpdir</varname>, by default "
"<filename>/var/crash</filename> and will be named <filename>vmcore.0</"
"filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8160
msgid ""
"In the event that there is already a file called <filename>vmcore.0</"
"filename> in <filename>/var/crash</filename> (or whatever <varname>dumpdir</"
"varname> is set to), the kernel will increment the trailing number for every "
"crash to avoid overwriting an existing <filename>vmcore</filename> (e.g., "
"<filename>vmcore.1</filename>). <citerefentry><refentrytitle>savecore</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> will always create a "
"symbolic link to named <filename>vmcore.last</filename> in <filename>/var/"
"crash</filename> after a dump is saved. This symbolic link can be used to "
"locate the name of the most recent dump."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8172
msgid ""
"The <citerefentry><refentrytitle>crashinfo</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> utility generates a text file containing a summary "
"of information from a full memory dump or minidump. If <varname>dumpdev</"
"varname> has been set in <citerefentry><refentrytitle>rc.conf</"
"refentrytitle><manvolnum>5</manvolnum></citerefentry>, "
"<citerefentry><refentrytitle>crashinfo</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> will be invoked automatically after "
"<citerefentry><refentrytitle>savecore</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry>. The output is saved to a file in "
"<varname>dumpdir</varname> named <filename>core.txt.<replaceable>N</"
"replaceable></filename>."
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:8181
msgid ""
"If you are testing a new kernel but need to boot a different one in order to "
"get your system up and running again, boot it only into single user mode "
"using the <option>-s</option> flag at the boot prompt, and then perform the "
"following steps:"
msgstr ""

#. (itstool) path: tip/screen
#: book.translate.xml:8186
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>fsck -p</userinput>\n"
"<prompt>#</prompt> <userinput>mount -a -t ufs</userinput>       # make sure /"
"var/crash is writable\n"
"<prompt>#</prompt> <userinput>savecore /var/crash /dev/ad0s1b</userinput>\n"
"<prompt>#</prompt> <userinput>exit</userinput>                  # exit to "
"multi-user"
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:8191
msgid ""
"This instructs <citerefentry><refentrytitle>savecore</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> to extract a kernel "
"dump from <filename>/dev/ad0s1b</filename> and place the contents in "
"<filename>/var/crash</filename>. Do not forget to make sure the destination "
"directory <filename>/var/crash</filename> has enough space for the dump. "
"Also, do not forget to specify the correct path to your swap device as it is "
"likely different than <filename>/dev/ad0s1b</filename>!"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:8201
msgid "Testing Kernel Dump Configuration"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8203
msgid ""
"The kernel includes a <citerefentry><refentrytitle>sysctl</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry> node that requests a "
"kernel panic. This can be used to verify that your system is properly "
"configured to save kernel crash dumps. You may wish to remount existing file "
"systems as read-only in single user mode before triggering the crash to "
"avoid data loss."
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:8209
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>shutdown now</userinput>\n"
"...\n"
"Enter full pathname of shell or RETURN for /bin/sh:\n"
"<prompt>#</prompt> <userinput>mount -a -u -r</userinput>\n"
"<prompt>#</prompt> <userinput>sysctl debug.kdb.panic=1</userinput>\n"
"debug.kdb.panic:panic: kdb_sysctl_panic\n"
"..."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8217
msgid ""
"After rebooting, your system should save a dump in <filename>/var/crash</"
"filename> along with a matching summary from "
"<citerefentry><refentrytitle>crashinfo</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8224
msgid "Debugging a Kernel Crash Dump with <command>kgdb</command>"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:8227
msgid ""
"This section covers <citerefentry><refentrytitle>kgdb</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry>. The latest version is "
"included in the <package>devel/gdb</package>. An older version is also "
"present in FreeBSD 11 and earlier."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8232
msgid ""
"To enter into the debugger and begin getting information from the dump, "
"start kgdb:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8235
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>kgdb -n <replaceable>N</replaceable></"
"userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8237
msgid ""
"Where <replaceable>N</replaceable> is the suffix of the <filename>vmcore."
"<replaceable>N</replaceable></filename> to examine. To open the most recent "
"dump use:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8241
#, no-wrap
msgid "<prompt>#</prompt> <userinput>kgdb -n last</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8243
msgid ""
"Normally, <citerefentry><refentrytitle>kgdb</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry> should be able to locate the kernel running at the "
"time the dump was generated. If it is not able to locate the correct kernel, "
"pass the pathname of the kernel and dump as two arguments to kgdb:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8248
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>kgdb /boot/kernel/kernel /var/crash/vmcore.0</"
"userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8250
msgid ""
"You can debug the crash dump using the kernel sources just like you can for "
"any other program."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8253
msgid ""
"This dump is from a 5.2-BETA kernel and the crash comes from deep within the "
"kernel. The output below has been modified to include line numbers on the "
"left. This first trace inspects the instruction pointer and obtains a back "
"trace. The address that is used on line 41 for the <command>list</command> "
"command is the instruction pointer and can be found on line 17. Most "
"developers will request having at least this information sent to them if you "
"are unable to debug the problem yourself. If, however, you do solve the "
"problem, make sure that your patch winds its way into the source tree via a "
"problem report, mailing lists, or by being able to commit it!"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8265
#, no-wrap
msgid ""
" 1:<prompt>#</prompt> <userinput>cd /usr/obj/usr/src/sys/"
"<replaceable>KERNCONF</replaceable></userinput>\n"
" 2:<prompt>#</prompt> <userinput>kgdb kernel.debug /var/crash/vmcore.0</"
"userinput>\n"
" 3:GNU gdb 5.2.1 (FreeBSD)\n"
" 4:Copyright 2002 Free Software Foundation, Inc.\n"
" 5:GDB is free software, covered by the GNU General Public License, and you "
"are\n"
" 6:welcome to change it and/or distribute copies of it under certain "
"conditions.\n"
" 7:Type \"show copying\" to see the conditions.\n"
" 8:There is absolutely no warranty for GDB.  Type \"show warranty\" for "
"details.\n"
" 9:This GDB was configured as \"i386-undermydesk-freebsd\"...\n"
"10:panic: page fault\n"
"11:panic messages:\n"
"12:---\n"
"13:Fatal trap 12: page fault while in kernel mode\n"
"14:cpuid = 0; apic id = 00\n"
"15:fault virtual address   = 0x300\n"
"16:fault code:             = supervisor read, page not present\n"
"17:instruction pointer     = 0x8:0xc0713860\n"
"18:stack pointer           = 0x10:0xdc1d0b70\n"
"19:frame pointer           = 0x10:0xdc1d0b7c\n"
"20:code segment            = base 0x0, limit 0xfffff, type 0x1b\n"
"21:                        = DPL 0, pres 1, def32 1, gran 1\n"
"22:processor eflags        = resume, IOPL = 0\n"
"23:current process         = 14394 (uname)\n"
"24:trap number             = 12\n"
"25:panic: page fault\n"
"26      cpuid = 0;\n"
"27:Stack backtrace:\n"
"28\n"
"29:syncing disks, buffers remaining... 2199 2199 panic: mi_switch: switch in "
"a critical section\n"
"30:cpuid = 0;\n"
"31:Uptime: 2h43m19s\n"
"32:Dumping 255 MB\n"
"33: 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240\n"
"34:---\n"
"35:Reading symbols from /boot/kernel/snd_maestro3.ko...done.\n"
"36:Loaded symbols for /boot/kernel/snd_maestro3.ko\n"
"37:Reading symbols from /boot/kernel/snd_pcm.ko...done.\n"
"38:Loaded symbols for /boot/kernel/snd_pcm.ko\n"
"39:#0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240\n"
"40:240             dumping++;\n"
"41:<prompt>(kgdb)</prompt> <userinput>list *0xc0713860</userinput>\n"
"42:0xc0713860 is in lapic_ipi_wait (/usr/src/sys/i386/i386/local_apic.c:663)."
"\n"
"43:658                     incr = 0;\n"
"44:659                     delay = 1;\n"
"45:660             } else\n"
"46:661                     incr = 1;\n"
"47:662             for (x = 0; x &lt; delay; x += incr) {\n"
"48:663                     if ((lapic-&gt;icr_lo &amp; APIC_DELSTAT_MASK) == "
"APIC_DELSTAT_IDLE)\n"
"49:664                             return (1);\n"
"50:665                     ia32_pause();\n"
"51:666             }\n"
"52:667             return (0);\n"
"53:<prompt>(kgdb)</prompt> <userinput>backtrace</userinput>\n"
"54:#0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240\n"
"55:#1  0xc055fd9b in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:"
"372\n"
"56:#2  0xc056019d in panic () at /usr/src/sys/kern/kern_shutdown.c:550\n"
"57:#3  0xc0567ef5 in mi_switch () at /usr/src/sys/kern/kern_synch.c:470\n"
"58:#4  0xc055fa87 in boot (howto=256) at /usr/src/sys/kern/kern_shutdown.c:"
"312\n"
"59:#5  0xc056019d in panic () at /usr/src/sys/kern/kern_shutdown.c:550\n"
"60:#6  0xc0720c66 in trap_fatal (frame=0xdc1d0b30, eva=0)\n"
"61:    at /usr/src/sys/i386/i386/trap.c:821\n"
"62:#7  0xc07202b3 in trap (frame=\n"
"63:      {tf_fs = -1065484264, tf_es = -1065484272, tf_ds = -1065484272, "
"tf_edi = 1, tf_esi = 0, tf_ebp = -602076292, tf_isp = -602076324, tf_ebx = "
"0, tf_edx = 0, tf_ecx = 1000000, tf_eax = 243, tf_trapno = 12, tf_err = 0, "
"tf_eip = -1066321824, tf_cs = 8, tf_eflags = 65671, tf_esp = 243, tf_ss = "
"0})\n"
"64:    at /usr/src/sys/i386/i386/trap.c:250\n"
"65:#8  0xc070c9f8 in calltrap () at {standard input}:94\n"
"66:#9  0xc07139f3 in lapic_ipi_vectored (vector=0, dest=0)\n"
"67:    at /usr/src/sys/i386/i386/local_apic.c:733\n"
"68:#10 0xc0718b23 in ipi_selected (cpus=1, ipi=1)\n"
"69:    at /usr/src/sys/i386/i386/mp_machdep.c:1115\n"
"70:#11 0xc057473e in kseq_notify (ke=0xcc05e360, cpu=0)\n"
"71:    at /usr/src/sys/kern/sched_ule.c:520\n"
"72:#12 0xc0575cad in sched_add (td=0xcbcf5c80)\n"
"73:    at /usr/src/sys/kern/sched_ule.c:1366\n"
"74:#13 0xc05666c6 in setrunqueue (td=0xcc05e360)\n"
"75:    at /usr/src/sys/kern/kern_switch.c:422\n"
"76:#14 0xc05752f4 in sched_wakeup (td=0xcbcf5c80)\n"
"77:    at /usr/src/sys/kern/sched_ule.c:999\n"
"78:#15 0xc056816c in setrunnable (td=0xcbcf5c80)\n"
"79:    at /usr/src/sys/kern/kern_synch.c:570\n"
"80:#16 0xc0567d53 in wakeup (ident=0xcbcf5c80)\n"
"81:    at /usr/src/sys/kern/kern_synch.c:411\n"
"82:#17 0xc05490a8 in exit1 (td=0xcbcf5b40, rv=0)\n"
"83:    at /usr/src/sys/kern/kern_exit.c:509\n"
"84:#18 0xc0548011 in sys_exit () at /usr/src/sys/kern/kern_exit.c:102\n"
"85:#19 0xc0720fd0 in syscall (frame=\n"
"86:      {tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = 0, tf_esi = -1, "
"tf_ebp = -1077940712, tf_isp = -602075788, tf_ebx = 672411944, tf_edx = 10, "
"tf_ecx = 672411600, tf_eax = 1, tf_trapno = 12, tf_err = 2, tf_eip = "
"671899563, tf_cs = 31, tf_eflags = 642, tf_esp = -1077940740, tf_ss = 47})\n"
"87:    at /usr/src/sys/i386/i386/trap.c:1010\n"
"88:#20 0xc070ca4d in Xint0x80_syscall () at {standard input}:136\n"
"89:---Can't read userspace from dump, or kernel process---\n"
"90:<prompt>(kgdb)</prompt> <userinput>quit</userinput>"
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:8355
msgid ""
"If your system is crashing regularly and you are running out of disk space, "
"deleting old <filename>vmcore</filename> files in <filename>/var/crash</"
"filename> could save a considerable amount of disk space!"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8362
msgid "On-Line Kernel Debugging Using DDB"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8364
msgid ""
"While <command>kgdb</command> as an off-line debugger provides a very high "
"level of user interface, there are some things it cannot do. The most "
"important ones being breakpointing and single-stepping kernel code."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8369
msgid ""
"If you need to do low-level debugging on your kernel, there is an on-line "
"debugger available called DDB. It allows setting of breakpoints, single-"
"stepping kernel functions, examining and changing kernel variables, etc. "
"However, it cannot access kernel source files, and only has access to the "
"global and static symbols, not to the full debug information like "
"<command>kgdb</command> does."
msgstr ""

#. (itstool) path: para/programlisting
#: book.translate.xml:8378
#, no-wrap
msgid "options KDB"
msgstr ""

#. (itstool) path: para/programlisting
#: book.translate.xml:8379
#, no-wrap
msgid "options DDB"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8376
msgid ""
"To configure your kernel to include DDB, add the options <_:programlisting-1/"
"> <_:programlisting-2/> to your config file, and rebuild. (See <link xlink:"
"href=\"@@URL_RELPREFIX@@/doc/en_US.ISO8859-1/books/handbook/index.html\">The "
"FreeBSD Handbook</link> for details on configuring the FreeBSD kernel)."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8384
msgid ""
"Once your DDB kernel is running, there are several ways to enter DDB. The "
"first, and earliest way is to use the boot flag <option>-d</option>. The "
"kernel will start up in debug mode and enter DDB prior to any device probing."
" Hence you can even debug the device probe/attach functions. To use this, "
"exit the loader's boot menu and enter <command>boot -d</command> at the "
"loader prompt."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8392
msgid ""
"The second scenario is to drop to the debugger once the system has booted. "
"There are two simple ways to accomplish this. If you would like to break to "
"the debugger from the command prompt, simply type the command:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8397
#, no-wrap
msgid "<prompt>#</prompt> <userinput>sysctl debug.kdb.enter=1</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8399
msgid ""
"Alternatively, if you are at the system console, you may use a hot-key on "
"the keyboard. The default break-to-debugger sequence is <keycombo action="
"\"simul\"><keycap>Ctrl</keycap> <keycap>Alt</keycap><keycap>ESC</keycap></"
"keycombo>. For syscons, this sequence can be remapped and some of the "
"distributed maps out there do this, so check to make sure you know the right "
"sequence to use. There is an option available for serial consoles that "
"allows the use of a serial line BREAK on the console line to enter DDB "
"(<literal>options BREAK_TO_DEBUGGER</literal> in the kernel config file). It "
"is not the default since there are a lot of serial adapters around that "
"gratuitously generate a BREAK condition, for example when pulling the cable."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8412
msgid ""
"The third way is that any panic condition will branch to DDB if the kernel "
"is configured to use it. For this reason, it is not wise to configure a "
"kernel with DDB for a machine running unattended."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8416
msgid "To obtain the unattended functionality, add:"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:8418
#, no-wrap
msgid "options	KDB_UNATTENDED"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8420
msgid "to the kernel configuration file and rebuild/reinstall."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8422
msgid ""
"The DDB commands roughly resemble some <command>gdb</command> commands. The "
"first thing you probably need to do is to set a breakpoint:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8426
#, no-wrap
msgid "<userinput>break function-name address</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8428
msgid ""
"Numbers are taken hexadecimal by default, but to make them distinct from "
"symbol names; hexadecimal numbers starting with the letters <literal>a-f</"
"literal> need to be preceded with <literal>0x</literal> (this is optional "
"for other numbers). Simple expressions are allowed, for example: "
"<literal>function-name + 0x103</literal>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8434
msgid "To exit the debugger and continue execution, type:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8437
#, no-wrap
msgid "<userinput>continue</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8439
msgid "To get a stack trace of the current thread, use:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8441
#, no-wrap
msgid "<userinput>trace</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8443
msgid ""
"To get a stack trace of an arbitrary thread, specify a process ID or thread "
"ID as a second argument to <command>trace</command>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8447
msgid "If you want to remove a breakpoint, use"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8449
#, no-wrap
msgid ""
"<userinput>del</userinput>\n"
"<userinput>del address-expression</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8452
msgid ""
"The first form will be accepted immediately after a breakpoint hit, and "
"deletes the current breakpoint. The second form can remove any breakpoint, "
"but you need to specify the exact address; this can be obtained from:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8457
#, no-wrap
msgid "<userinput>show b</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8459
msgid "or:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8461
#, no-wrap
msgid "<userinput>show break</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8463
msgid "To single-step the kernel, try:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8465
#, no-wrap
msgid "<userinput>s</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8467
msgid ""
"This will step into functions, but you can make DDB trace them until the "
"matching return statement is reached by:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8470
#, no-wrap
msgid "<userinput>n</userinput>"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:8473
msgid ""
"This is different from <command>gdb</command>'s <command>next</command> "
"statement; it is like <command>gdb</command>'s <command>finish</command>. "
"Pressing <keycap>n</keycap> more than once will cause a continue."
msgstr ""

#. (itstool) path: para/screen
#: book.translate.xml:8481
#, no-wrap
msgid ""
"<userinput>x/wx 0xf0133fe0,40</userinput>\n"
"<userinput>x/hd db_symtab_space</userinput>\n"
"<userinput>x/bc termbuf,10</userinput>\n"
"<userinput>x/s stringbuf</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8479
msgid ""
"To examine data from memory, use (for example): <_:screen-1/> for word/"
"halfword/byte access, and hexadecimal/decimal/character/ string display. The "
"number after the comma is the object count. To display the next 0x10 items, "
"simply use:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8490
#, no-wrap
msgid "<userinput>x ,10</userinput>"
msgstr ""

#. (itstool) path: para/screen
#: book.translate.xml:8494
#, no-wrap
msgid "<userinput>x/ia foofunc,10</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8492
msgid ""
"Similarly, use <_:screen-1/> to disassemble the first 0x10 instructions of "
"<function>foofunc</function>, and display them along with their offset from "
"the beginning of <function>foofunc</function>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8500
msgid "To modify memory, use the write command:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8502
#, no-wrap
msgid ""
"<userinput>w/b termbuf 0xa 0xb 0</userinput>\n"
"<userinput>w/w 0xf0010030 0 0</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8505
msgid ""
"The command modifier (<literal>b</literal>/<literal>h</literal>/<literal>w</"
"literal>) specifies the size of the data to be written, the first following "
"expression is the address to write to and the remainder is interpreted as "
"data to write to successive memory locations."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8511
msgid "If you need to know the current registers, use:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8513
#, no-wrap
msgid "<userinput>show reg</userinput>"
msgstr ""

#. (itstool) path: para/screen
#: book.translate.xml:8517
#, no-wrap
msgid "<userinput>p $eax</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8515
msgid ""
"Alternatively, you can display a single register value by e.g. <_:screen-1/> "
"and modify it by:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8521
#, no-wrap
msgid "<userinput>set $eax new-value</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8523
msgid "Should you need to call some kernel functions from DDB, simply say:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8526
#, no-wrap
msgid "<userinput>call func(arg1, arg2, ...)</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8528
msgid "The return value will be printed."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8530
msgid ""
"For a <citerefentry><refentrytitle>ps</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry> style summary of all running processes, use:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8532
#, no-wrap
msgid "<userinput>ps</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8534
msgid ""
"Now you have examined why your kernel failed, and you wish to reboot. "
"Remember that, depending on the severity of previous malfunctioning, not all "
"parts of the kernel might still be working as expected. Perform one of the "
"following actions to shut down and reboot your system:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8540
#, no-wrap
msgid "<userinput>panic</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8542
msgid ""
"This will cause your kernel to dump core and reboot, so you can later "
"analyze the core on a higher level with <citerefentry><refentrytitle>kgdb</"
"refentrytitle><manvolnum>1</manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8545
#, no-wrap
msgid "<userinput>call boot(0)</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8547
msgid ""
"Might be a good way to cleanly shut down the running system, "
"<function>sync()</function> all disks, and finally, in some cases, reboot. "
"As long as the disk and filesystem interfaces of the kernel are not damaged, "
"this could be a good way for an almost clean shutdown."
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8553
#, no-wrap
msgid "<userinput>reset</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8555
msgid ""
"This is the final way out of disaster and almost the same as hitting the Big "
"Red Button."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8558
msgid "If you need a short command summary, simply type:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8560
#, no-wrap
msgid "<userinput>help</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8562
msgid ""
"It is highly recommended to have a printed copy of the "
"<citerefentry><refentrytitle>ddb</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> manual page ready for a debugging session. Remember that it is "
"hard to read the on-line manual while single-stepping the kernel."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8569
msgid "On-Line Kernel Debugging Using Remote GDB"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8571
msgid ""
"This feature has been supported since FreeBSD 2.2, and it is actually a very "
"neat one."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8574
msgid ""
"GDB has already supported <emphasis>remote debugging</emphasis> for a long "
"time. This is done using a very simple protocol along a serial line. Unlike "
"the other methods described above, you will need two machines for doing this."
" One is the host providing the debugging environment, including all the "
"sources, and a copy of the kernel binary with all the symbols in it, and the "
"other one is the target machine that simply runs a similar copy of the very "
"same kernel (but stripped of the debugging information)."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8583
msgid ""
"You should configure the kernel in question with <command>config -g</"
"command> if building the <quote>traditional</quote> way. If building the "
"<quote>new</quote> way, make sure that <literal>makeoptions DEBUG=-g</"
"literal> is in the configuration. In both cases, include <option>DDB</"
"option> in the configuration, and compile it as usual. This gives a large "
"binary, due to the debugging information. Copy this kernel to the target "
"machine, strip the debugging symbols off with <command>strip -x</command>, "
"and boot it using the <option>-d</option> boot option. Connect the serial "
"line of the target machine that has \"flags 080\" set on its uart device to "
"any serial line of the debugging host. See "
"<citerefentry><refentrytitle>uart</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> for information on how to set the flags on an uart device. "
"Now, on the debugging machine, go to the compile directory of the target "
"kernel, and start <command>gdb</command>:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8598
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>kgdb kernel</userinput>\n"
"GDB is free software and you are welcome to distribute copies of it\n"
" under certain conditions; type \"show copying\" to see the conditions.\n"
"There is absolutely no warranty for GDB; type \"show warranty\" for details.\n"
"GDB 4.16 (i386-unknown-freebsd),\n"
"Copyright 1996 Free Software Foundation, Inc...\n"
"<prompt>(kgdb)</prompt> "
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8606
msgid ""
"Initialize the remote debugging session (assuming the first serial port is "
"being used) by:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8609
#, no-wrap
msgid ""
"<prompt>(kgdb)</prompt> <userinput>target remote /dev/cuau0</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8611
msgid ""
"Now, on the target host (the one that entered DDB right before even starting "
"the device probe), type:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8614
#, no-wrap
msgid ""
"Debugger(\"Boot flags requested debugger\")\n"
"Stopped at Debugger+0x35: movb	$0, edata+0x51bc\n"
"<prompt>db&gt;</prompt> <userinput>gdb</userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8618
msgid "DDB will respond with:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8620
#, no-wrap
msgid "Next trap will enter GDB remote protocol mode"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8622
msgid ""
"Every time you type <command>gdb</command>, the mode will be toggled between "
"remote GDB and local DDB. In order to force a next trap immediately, simply "
"type <command>s</command> (step). Your hosting GDB will now gain control "
"over the target kernel:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:8627
#, no-wrap
msgid ""
"Remote debugging using /dev/cuau0\n"
"Debugger (msg=0xf01b0383 \"Boot flags requested debugger\")\n"
"    at ../../i386/i386/db_interface.c:257\n"
"<prompt>(kgdb)</prompt>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8632
msgid ""
"You can use this session almost as any other GDB session, including full "
"access to the source, running it in gud-mode inside an Emacs window (which "
"gives you an automatic source code display in another Emacs window), etc."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8639
msgid "Debugging a Console Driver"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8641
msgid ""
"Since you need a console driver to run DDB on, things are more complicated "
"if the console driver itself is failing. You might remember the use of a "
"serial console (either with modified boot blocks, or by specifying <option>-"
"h</option> at the <prompt>Boot:</prompt> prompt), and hook up a standard "
"terminal onto your first serial port. DDB works on any configured console "
"driver, including a serial console."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8651
msgid "Debugging Deadlocks"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8653
msgid ""
"You may experience so called deadlocks, a situation where a system stops "
"doing useful work. To provide a helpful bug report in this situation, use "
"<citerefentry><refentrytitle>ddb</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> as described in the previous section. Include the output of "
"<command>ps</command> and <command>trace</command> for suspected processes "
"in the report."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8660
msgid ""
"If possible, consider doing further investigation. The recipe below is "
"especially useful if you suspect that a deadlock occurs in the VFS layer. "
"Add these options to the kernel configuration file."
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:8665
#, no-wrap
msgid ""
"makeoptions 	DEBUG=-g\n"
"options 	INVARIANTS\n"
"options 	INVARIANT_SUPPORT\n"
"options 	WITNESS\n"
"options 	WITNESS_SKIPSPIN\n"
"options 	DEBUG_LOCKS\n"
"options 	DEBUG_VFS_LOCKS\n"
"options 	DIAGNOSTIC"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8674
msgid ""
"When a deadlock occurs, in addition to the output of the <command>ps</"
"command> command, provide information from the <command>show pcpu</command>, "
"<command>show allpcpu</command>, <command>show locks</command>, "
"<command>show alllocks</command>, <command>show lockedvnods</command> and "
"<command>alltrace</command>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8681
msgid ""
"To obtain meaningful backtraces for threaded processes, use <command>thread "
"thread-id</command> to switch to the thread stack, and do a backtrace with "
"<command>where</command>."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8687
msgid "Kernel debugging with Dcons"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8689
msgid ""
"<citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> is a very simple console driver that is not directly connected "
"with any physical devices. It just reads and writes characters from and to a "
"buffer in a kernel or loader. Due to its simple nature, it is very useful "
"for kernel debugging, especially with a <trademark class="
"\"registered\">FireWire</trademark> device. Currently, FreeBSD provides two "
"ways to interact with the buffer from outside of the kernel using "
"<citerefentry><refentrytitle>dconschat</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:8698
msgid "Dcons over <trademark class=\"registered\">FireWire</trademark>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8700
msgid ""
"Most <trademark class=\"registered\">FireWire</trademark> (IEEE1394) host "
"controllers are based on the <acronym>OHCI</acronym> specification that "
"supports physical access to the host memory. This means that once the host "
"controller is initialized, we can access the host memory without the help of "
"software (kernel). We can exploit this facility for interaction with "
"<citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry>. <citerefentry><refentrytitle>dcons</"
"refentrytitle><manvolnum>4</manvolnum></citerefentry> provides similar "
"functionality as a serial console. It emulates two serial ports, one for the "
"console and <acronym>DDB</acronym>, the other for <acronym>GDB</acronym>. "
"Because remote memory access is fully handled by the hardware, the "
"<citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</manvolnum></"
"citerefentry> buffer is accessible even when the system crashes."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8713
msgid ""
"<trademark class=\"registered\">FireWire</trademark> devices are not limited "
"to those integrated into motherboards. <acronym>PCI</acronym> cards exist "
"for desktops, and a cardbus interface can be purchased for laptops."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:8719
msgid ""
"Enabling <trademark class=\"registered\">FireWire</trademark> and Dcons "
"support on the target machine"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8722
msgid ""
"To enable <trademark class=\"registered\">FireWire</trademark> and Dcons "
"support in the kernel of the <emphasis>target machine</emphasis>:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8727
msgid ""
"Make sure your kernel supports <literal>dcons</literal>, "
"<literal>dcons_crom</literal> and <literal>firewire</literal>. "
"<literal>Dcons</literal> should be statically linked with the kernel. For "
"<literal>dcons_crom</literal> and <literal>firewire</literal>, modules "
"should be OK."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8736
msgid ""
"Make sure physical <acronym>DMA</acronym> is enabled. You may need to add "
"<literal>hw.firewire.phydma_enable=1</literal> to <filename>/boot/loader."
"conf</filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8742
msgid "Add options for debugging."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8745
msgid ""
"Add <literal>dcons_gdb=1</literal> in <filename>/boot/loader.conf</filename> "
"if you use GDB over <trademark class=\"registered\">FireWire</trademark>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8750
msgid "Enable <literal>dcons</literal> in <filename>/etc/ttys</filename>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8754
msgid ""
"Optionally, to force <literal>dcons</literal> to be the high-level console, "
"add <literal>hw.firewire.dcons_crom.force_console=1</literal> to "
"<filename>loader.conf</filename>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8761
msgid ""
"To enable <trademark class=\"registered\">FireWire</trademark> and Dcons "
"support in <citerefentry><refentrytitle>loader</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> on i386 or amd64:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8764
msgid ""
"Add <literal>LOADER_FIREWIRE_SUPPORT=YES</literal> in <filename>/etc/make."
"conf</filename> and rebuild <citerefentry><refentrytitle>loader</"
"refentrytitle><manvolnum>8</manvolnum></citerefentry>:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8769
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>cd /sys/boot/i386 &amp;&amp; make clean "
"&amp;&amp; make &amp;&amp; make install</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8771
msgid ""
"To enable <citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</"
"manvolnum></citerefentry> as an active low-level console, add "
"<literal>boot_multicons=\"YES\"</literal> to <filename>/boot/loader.conf</"
"filename>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8775
msgid ""
"Here are a few configuration examples. A sample kernel configuration file "
"would contain:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8778
#, no-wrap
msgid ""
"device dcons\n"
"device dcons_crom\n"
"options KDB\n"
"options DDB\n"
"options GDB\n"
"options ALT_BREAK_TO_DEBUGGER"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8785
msgid "And a sample <filename>/boot/loader.conf</filename> would contain:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8788
#, no-wrap
msgid ""
"dcons_crom_load=\"YES\"\n"
"dcons_gdb=1\n"
"boot_multicons=\"YES\"\n"
"hw.firewire.phydma_enable=1\n"
"hw.firewire.dcons_crom.force_console=1"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:8797
msgid ""
"Enabling <trademark class=\"registered\">FireWire</trademark> and Dcons "
"support on the host machine"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8800
msgid ""
"To enable <trademark class=\"registered\">FireWire</trademark> support in "
"the kernel on the <emphasis>host machine</emphasis>:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8803
#, no-wrap
msgid "<prompt>#</prompt> <userinput>kldload firewire</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8805
msgid ""
"Find out the <acronym>EUI64</acronym> (the unique 64 bit identifier) of the "
"<trademark class=\"registered\">FireWire</trademark> host controller, and "
"use <citerefentry><refentrytitle>fwcontrol</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> or <command>dmesg</command> to find the "
"<acronym>EUI64</acronym> of the target machine."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8810
msgid ""
"Run <citerefentry><refentrytitle>dconschat</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry>, with:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8812
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>dconschat -e \\# -br -G 12345 -t "
"<replaceable>00-11-22-33-44-55-66-77</replaceable></userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8814
msgid ""
"The following key combinations can be used once "
"<citerefentry><refentrytitle>dconschat</refentrytitle><manvolnum>8</"
"manvolnum></citerefentry> is running:"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8821
msgid ""
"<keycombo action=\"seq\"> <keycap>~</keycap> <keycap>.</keycap> </keycombo>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8827
msgid "Disconnect"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8830
msgid ""
"<keycombo action=\"seq\"> <keycap>~</keycap> <keycombo action=\"simul\"> "
"<keycap>Ctrl</keycap> <keycap>B</keycap> </keycombo> </keycombo>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8839
msgid "ALT BREAK"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8842
msgid ""
"<keycombo action=\"seq\"> <keycap>~</keycap> <keycombo action=\"simul\"> "
"<keycap>Ctrl</keycap> <keycap>R</keycap> </keycombo> </keycombo>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8851
msgid "RESET target"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8854
msgid ""
"<keycombo action=\"seq\"> <keycap>~</keycap> <keycombo action=\"simul\"> "
"<keycap>Ctrl</keycap> <keycap>Z</keycap> </keycombo> </keycombo>"
msgstr ""

#. (itstool) path: row/entry
#: book.translate.xml:8863
msgid "Suspend dconschat"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8869
msgid ""
"Attach remote <acronym>GDB</acronym> by starting "
"<citerefentry><refentrytitle>kgdb</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry> with a remote debugging session:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8872
#, no-wrap
msgid "<userinput>kgdb -r :12345 kernel</userinput>"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:8876
msgid "Some general tips"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8878
msgid "Here are some general tips:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8880
msgid ""
"To take full advantage of the speed of <trademark class="
"\"registered\">FireWire</trademark>, disable other slow console drivers:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8883
#, no-wrap
msgid ""
"<prompt>#</prompt> conscontrol delete ttyd0	     # serial console\n"
"<prompt>#</prompt> conscontrol delete consolectl	# video/keyboard"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8886
msgid ""
"There exists a <acronym>GDB</acronym> mode for <citerefentry vendor="
"\"ports\"><refentrytitle>emacs</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry>; this is what you will need to add to your <filename>.emacs</"
"filename>:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8890
#, no-wrap
msgid ""
"<userinput>(setq gud-gdba-command-name \"kgdb -a -a -a -r :12345\")\n"
"(setq gdb-many-windows t)\n"
"(xterm-mouse-mode 1)\n"
"M-x gdba</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8895
msgid "And for <acronym>DDD</acronym> (<filename>devel/ddd</filename>):"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8897
#, no-wrap
msgid ""
"# remote serial protocol\n"
"LANG=C ddd --debugger kgdb -r :12345 kernel\n"
"# live core debug\n"
"LANG=C ddd --debugger kgdb kernel /dev/fwmem0.2"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:8905
msgid "Dcons with KVM"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:8907
msgid ""
"We can directly read the <citerefentry><refentrytitle>dcons</"
"refentrytitle><manvolnum>4</manvolnum></citerefentry> buffer via <filename>/"
"dev/mem</filename> for live systems, and in the core dump for crashed "
"systems. These give you similar output to <command>dmesg -a</command>, but "
"the <citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</"
"manvolnum></citerefentry> buffer includes more information."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:8914
msgid "Using Dcons with KVM"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8916
msgid ""
"To use <citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</"
"manvolnum></citerefentry> with <acronym>KVM</acronym>:"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8918
msgid ""
"Dump a <citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</"
"manvolnum></citerefentry> buffer of a live system:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8920
#, no-wrap
msgid "<prompt>#</prompt> <userinput>dconschat -1</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8922
msgid ""
"Dump a <citerefentry><refentrytitle>dcons</refentrytitle><manvolnum>4</"
"manvolnum></citerefentry> buffer of a crash dump:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8924
#, no-wrap
msgid "<prompt>#</prompt> <userinput>dconschat -1 -M vmcore.XX</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:8926
msgid "Live core debugging can be done via:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:8928
#, no-wrap
msgid ""
"<prompt>#</prompt> <userinput>fwcontrol -m target_eui64</userinput>\n"
"<prompt>#</prompt> <userinput>kgdb kernel /dev/fwmem0.2</userinput>"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:8935
msgid "Glossary of Kernel Options for Debugging"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:8937
msgid ""
"This section provides a brief glossary of compile-time kernel options used "
"for debugging:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8942
msgid ""
"<literal>options KDB</literal>: compiles in the kernel debugger framework. "
"Required for <literal>options DDB</literal> and <literal>options GDB</"
"literal>. Little or no performance overhead. By default, the debugger will "
"be entered on panic instead of an automatic reboot."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8950
msgid ""
"<literal>options KDB_UNATTENDED</literal>: change the default value of the "
"<literal>debug.debugger_on_panic</literal> sysctl to 0, which controls "
"whether the debugger is entered on panic. When <literal>options KDB</"
"literal> is not compiled into the kernel, the behavior is to automatically "
"reboot on panic; when it is compiled into the kernel, the default behavior "
"is to drop into the debugger unless <literal>options KDB_UNATTENDED</"
"literal> is compiled in. If you want to leave the kernel debugger compiled "
"into the kernel but want the system to come back up unless you're on-hand to "
"use the debugger for diagnostics, use this option."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8963
msgid ""
"<literal>options KDB_TRACE</literal>: change the default value of the "
"<literal>debug.trace_on_panic</literal> sysctl to 1, which controls whether "
"the debugger automatically prints a stack trace on panic. Especially if "
"running with <literal>options KDB_UNATTENDED</literal>, this can be helpful "
"to gather basic debugging information on the serial or firewire console "
"while still rebooting to recover."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8973
msgid ""
"<literal>options DDB</literal>: compile in support for the console debugger, "
"DDB. This interactive debugger runs on whatever the active low-level console "
"of the system is, which includes the video console, serial console, or "
"firewire console. It provides basic integrated debugging facilities, such as "
"stack tracing, process and thread listing, dumping of lock state, VM state, "
"file system state, and kernel memory management. DDB does not require "
"software running on a second machine or being able to generate a core dump "
"or full debugging kernel symbols, and provides detailed diagnostics of the "
"kernel at run-time. Many bugs can be fully diagnosed using only DDB output. "
"This option depends on <literal>options KDB</literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:8988
msgid ""
"<literal>options GDB</literal>: compile in support for the remote debugger, "
"GDB, which can operate over serial cable or firewire. When the debugger is "
"entered, GDB may be attached to inspect structure contents, generate stack "
"traces, etc. Some kernel state is more awkward to access than in DDB, which "
"is able to generate useful summaries of kernel state automatically, such as "
"automatically walking lock debugging or kernel memory management structures, "
"and a second machine running the debugger is required. On the other hand, "
"GDB combines information from the kernel source and full debugging symbols, "
"and is aware of full data structure definitions, local variables, and is "
"scriptable. This option is not required to run GDB on a kernel core dump. "
"This option depends on <literal>options KDB</literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9005
msgid ""
"<literal>options BREAK_TO_DEBUGGER</literal>, <literal>options "
"ALT_BREAK_TO_DEBUGGER</literal>: allow a break signal or alternative signal "
"on the console to enter the debugger. If the system hangs without a panic, "
"this is a useful way to reach the debugger. Due to the current kernel "
"locking, a break signal generated on a serial console is significantly more "
"reliable at getting into the debugger, and is generally recommended. This "
"option has little or no performance impact."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9016
msgid ""
"<literal>options INVARIANTS</literal>: compile into the kernel a large "
"number of run-time assertion checks and tests, which constantly test the "
"integrity of kernel data structures and the invariants of kernel algorithms. "
"These tests can be expensive, so are not compiled in by default, but help "
"provide useful \"fail stop\" behavior, in which certain classes of undesired "
"behavior enter the debugger before kernel data corruption occurs, making "
"them easier to debug. Tests include memory scrubbing and use-after-free "
"testing, which is one of the more significant sources of overhead. This "
"option depends on <literal>options INVARIANT_SUPPORT</literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9030
msgid ""
"<literal>options INVARIANT_SUPPORT</literal>: many of the tests present in "
"<literal>options INVARIANTS</literal> require modified data structures or "
"additional kernel symbols to be defined."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9036
msgid ""
"<literal>options WITNESS</literal>: this option enables run-time lock order "
"tracking and verification, and is an invaluable tool for deadlock diagnosis. "
"WITNESS maintains a graph of acquired lock orders by lock type, and checks "
"the graph at each acquire for cycles (implicit or explicit). If a cycle is "
"detected, a warning and stack trace are generated to the console, indicating "
"that a potential deadlock might have occurred. WITNESS is required in order "
"to use the <command>show locks</command>, <command>show witness</command> "
"and <command>show alllocks</command> DDB commands. This debug option has "
"significant performance overhead, which may be somewhat mitigated through "
"the use of <literal>options WITNESS_SKIPSPIN</literal>. Detailed "
"documentation may be found in <citerefentry><refentrytitle>witness</"
"refentrytitle><manvolnum>4</manvolnum></citerefentry>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9052
msgid ""
"<literal>options WITNESS_SKIPSPIN</literal>: disable run-time checking of "
"spinlock lock order with WITNESS. As spin locks are acquired most frequently "
"in the scheduler, and scheduler events occur often, this option can "
"significantly speed up systems running with WITNESS. This option depends on "
"<literal>options WITNESS</literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9061
msgid ""
"<literal>options WITNESS_KDB</literal>: change the default value of the "
"<literal>debug.witness.kdb</literal> sysctl to 1, which causes WITNESS to "
"enter the debugger when a lock order violation is detected, rather than "
"simply printing a warning. This option depends on <literal>options WITNESS</"
"literal>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9069
msgid ""
"<literal>options SOCKBUF_DEBUG</literal>: perform extensive run-time "
"consistency checking on socket buffers, which can be useful for debugging "
"both socket bugs and race conditions in protocols and device drivers that "
"interact with sockets. This option significantly impacts network "
"performance, and may change the timing in device driver races."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9078
msgid ""
"<literal>options DEBUG_VFS_LOCKS</literal>: track lock acquisition points "
"for lockmgr/vnode locks, expanding the amount of information displayed by "
"<command>show lockedvnods</command> in DDB. This option has a measurable "
"performance impact."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9085
msgid ""
"<literal>options DEBUG_MEMGUARD</literal>: a replacement for the "
"<citerefentry><refentrytitle>malloc</refentrytitle><manvolnum>9</manvolnum></"
"citerefentry> kernel memory allocator that uses the VM system to detect "
"reads or writes from allocated memory after free. Details may be found in "
"<citerefentry><refentrytitle>memguard</refentrytitle><manvolnum>9</"
"manvolnum></citerefentry>. This option has a significant performance impact, "
"but can be very helpful in debugging kernel memory corruption bugs."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:9094
msgid ""
"<literal>options DIAGNOSTIC</literal>: enable additional, more expensive "
"diagnostic tests along the lines of <literal>options INVARIANTS</literal>."
msgstr ""

#. (itstool) path: part/title
#: book.translate.xml:9108
msgid "Architectures"
msgstr ""

#. (itstool) path: chapter/title
#: book.translate.xml:9132
msgid "x86 Assembly Language Programming"
msgstr ""

#. (itstool) path: chapter/para
#: book.translate.xml:9134
msgid ""
"<emphasis>This chapter was written by G. Adam Stanislav "
"<email>adam@redprince.net</email>.</emphasis>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9140
msgid ""
"Assembly language programming under <trademark class=\"registered\">UNIX</"
"trademark> is highly undocumented. It is generally assumed that no one would "
"ever want to use it because various <trademark class=\"registered\">UNIX</"
"trademark> systems run on different microprocessors, so everything should be "
"written in C for portability."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9146
msgid ""
"In reality, C portability is quite a myth. Even C programs need to be "
"modified when ported from one <trademark class=\"registered\">UNIX</"
"trademark> to another, regardless of what processor each runs on. Typically, "
"such a program is full of conditional statements depending on the system it "
"is compiled for."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9152
msgid ""
"Even if we believe that all of <trademark class=\"registered\">UNIX</"
"trademark> software should be written in C, or some other high-level "
"language, we still need assembly language programmers: Who else would write "
"the section of C library that accesses the kernel?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9157
msgid ""
"In this chapter I will attempt to show you how you can use assembly language "
"writing <trademark class=\"registered\">UNIX</trademark> programs, "
"specifically under FreeBSD."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9161
msgid ""
"This chapter does not explain the basics of assembly language. There are "
"enough resources about that (for a complete online course in assembly "
"language, see Randall Hyde's <link xlink:href=\"http://webster.cs.ucr.edu/"
"\">Art of Assembly Language</link>; or if you prefer a printed book, take a "
"look at Jeff Duntemann's Assembly Language Step-by-Step (ISBN: 0471375233). "
"However, once the chapter is finished, any assembly language programmer will "
"be able to write programs for FreeBSD quickly and efficiently."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9170 book.translate.xml:15396
msgid "Copyright © 2000-2001 G. Adam Stanislav. All rights reserved."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:9175
msgid "The Tools"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9178
msgid "The Assembler"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9180
msgid ""
"The most important tool for assembly language programming is the assembler, "
"the software that converts assembly language code into machine language."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9184
msgid ""
"Two very different assemblers are available for FreeBSD. One is "
"<citerefentry><refentrytitle>as</refentrytitle><manvolnum>1</manvolnum></"
"citerefentry>, which uses the traditional <trademark class="
"\"registered\">UNIX</trademark> assembly language syntax. It comes with the "
"system."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9190
msgid ""
"The other is <application>/usr/ports/devel/nasm</application>. It uses the "
"Intel syntax. Its main advantage is that it can assemble code for many "
"operating systems. It needs to be installed separately, but is completely "
"free."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9196
msgid ""
"This chapter uses <application>nasm</application> syntax because most "
"assembly language programmers coming to FreeBSD from other operating systems "
"will find it easier to understand. And, because, quite frankly, that is what "
"I am used to."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9204
msgid "The Linker"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9206
msgid ""
"The output of the assembler, like that of any compiler, needs to be linked "
"to form an executable file."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9209
msgid ""
"The standard <citerefentry><refentrytitle>ld</refentrytitle><manvolnum>1</"
"manvolnum></citerefentry> linker comes with FreeBSD. It works with the code "
"assembled with either assembler."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:9217
msgid "System Calls"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9220
msgid "Default Calling Convention"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9222
msgid ""
"By default, the FreeBSD kernel uses the C calling convention. Further, "
"although the kernel is accessed using <function role=\"opcode\">int 80h</"
"function>, it is assumed the program will call a function that issues "
"<function role=\"opcode\">int 80h</function>, rather than issuing <function "
"role=\"opcode\">int 80h</function> directly."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9228
msgid ""
"This convention is very convenient, and quite superior to the <trademark "
"class=\"registered\">Microsoft</trademark> convention used by "
"<acronym><trademark class=\"registered\">MS-DOS</trademark></acronym>. Why? "
"Because the <trademark class=\"registered\">UNIX</trademark> convention "
"allows any program written in any language to access the kernel."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9234
msgid ""
"An assembly language program can do that as well. For example, we could open "
"a file:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9237
#, no-wrap
msgid ""
"kernel:\n"
"	int	80h	; Call kernel\n"
"	ret\n"
"\n"
"open:\n"
"	push	dword mode\n"
"	push	dword flags\n"
"	push	dword path\n"
"	mov	eax, 5\n"
"	call	kernel\n"
"	add	esp, byte 12\n"
"	ret"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9250
msgid ""
"This is a very clean and portable way of coding. If you need to port the "
"code to a <trademark class=\"registered\">UNIX</trademark> system which uses "
"a different interrupt, or a different way of passing parameters, all you "
"need to change is the kernel procedure."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9255
msgid ""
"But assembly language programmers like to shave off cycles. The above "
"example requires a <function role=\"opcode\">call/ret</function> combination."
" We can eliminate it by <function role=\"opcode\">push</function>ing an "
"extra dword:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9260
#, no-wrap
msgid ""
"open:\n"
"	push	dword mode\n"
"	push	dword flags\n"
"	push	dword path\n"
"	mov	eax, 5\n"
"	push	eax		; Or any other dword\n"
"	int	80h\n"
"	add	esp, byte 16"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9269
msgid ""
"The <constant>5</constant> that we have placed in <varname role="
"\"register\">EAX</varname> identifies the kernel function, in this case "
"<function role=\"syscall\">open</function>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9274
msgid "Alternate Calling Convention"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9276
msgid ""
"FreeBSD is an extremely flexible system. It offers other ways of calling the "
"kernel. For it to work, however, the system must have Linux emulation "
"installed."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9280
msgid ""
"Linux is a <trademark class=\"registered\">UNIX</trademark> like system. "
"However, its kernel uses the same system-call convention of passing "
"parameters in registers <acronym><trademark class=\"registered\">MS-DOS</"
"trademark></acronym> does. As with the <trademark class=\"registered\">UNIX</"
"trademark> convention, the function number is placed in <varname role="
"\"register\">EAX</varname>. The parameters, however, are not passed on the "
"stack but in <varname role=\"register\">EBX, ECX, EDX, ESI, EDI, EBP</"
"varname>:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9287
#, no-wrap
msgid ""
"open:\n"
"	mov	eax, 5\n"
"	mov	ebx, path\n"
"	mov	ecx, flags\n"
"	mov	edx, mode\n"
"	int	80h"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9294
msgid ""
"This convention has a great disadvantage over the <trademark class="
"\"registered\">UNIX</trademark> way, at least as far as assembly language "
"programming is concerned: Every time you make a kernel call you must "
"<function role=\"opcode\">push</function> the registers, then <function role="
"\"opcode\">pop</function> them later. This makes your code bulkier and "
"slower. Nevertheless, FreeBSD gives you a choice."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9302
msgid ""
"If you do choose the Linux convention, you must let the system know about it."
" After your program is assembled and linked, you need to brand the "
"executable:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:9306
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>brandelf -t Linux <replaceable>filename</"
"replaceable></userinput>"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9310
msgid "Which Convention Should You Use?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9312
msgid ""
"If you are coding specifically for FreeBSD, you should always use the "
"<trademark class=\"registered\">UNIX</trademark> convention: It is faster, "
"you can store global variables in registers, you do not have to brand the "
"executable, and you do not impose the installation of the Linux emulation "
"package on the target system."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9318
msgid ""
"If you want to create portable code that can also run on Linux, you will "
"probably still want to give the FreeBSD users as efficient a code as "
"possible. I will show you how you can accomplish that after I have explained "
"the basics."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9325
msgid "Call Numbers"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9327
msgid ""
"To tell the kernel which system service you are calling, place its number in "
"<varname role=\"register\">EAX</varname>. Of course, you need to know what "
"the number is."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:9332
msgid "The <filename>syscalls</filename> File"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9334
msgid ""
"The numbers are listed in <filename>syscalls</filename>. <command>locate "
"syscalls</command> finds this file in several different formats, all "
"produced automatically from <filename>syscalls.master</filename>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9339
msgid ""
"You can find the master file for the default <trademark class="
"\"registered\">UNIX</trademark> calling convention in <filename>/usr/src/sys/"
"kern/syscalls.master</filename>. If you need to use the other convention "
"implemented in the Linux emulation mode, read <filename>/usr/src/sys/i386/"
"linux/syscalls.master</filename>."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9347
msgid ""
"Not only do FreeBSD and Linux use different calling conventions, they "
"sometimes use different numbers for the same functions."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9352
msgid ""
"<filename>syscalls.master</filename> describes how the call is to be made:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:9355
#, no-wrap
msgid ""
"0	STD	NOHIDE	{ int nosys(void); } syscall nosys_args int\n"
"1	STD	NOHIDE	{ void exit(int rval); } exit rexit_args void\n"
"2	STD	POSIX	{ int fork(void); }\n"
"3	STD	POSIX	{ ssize_t read(int fd, void *buf, size_t nbyte); }\n"
"4	STD	POSIX	{ ssize_t write(int fd, const void *buf, size_t nbyte); }\n"
"5	STD	POSIX	{ int open(char *path, int flags, int mode); }\n"
"6	STD	POSIX	{ int close(int fd); }\n"
"etc..."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9364
msgid ""
"It is the leftmost column that tells us the number to place in <varname role="
"\"register\">EAX</varname>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9367
msgid ""
"The rightmost column tells us what parameters to <function role="
"\"opcode\">push</function>. They are <function role=\"opcode\">push</"
"function>ed <emphasis>from right to left</emphasis>."
msgstr ""

#. (itstool) path: informalexample/para
#: book.translate.xml:9371
msgid ""
"For example, to <function>open</function> a file, we need to <function role="
"\"opcode\">push</function> the <varname>mode</varname> first, then "
"<varname>flags</varname>, then the address at which the <varname>path</"
"varname> is stored."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:9382
msgid "Return Values"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9384
msgid ""
"A system call would not be useful most of the time if it did not return some "
"kind of a value: The file descriptor of an open file, the number of bytes "
"read to a buffer, the system time, etc."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9389
msgid ""
"Additionally, the system needs to inform us if an error occurs: A file does "
"not exist, system resources are exhausted, we passed an invalid parameter, "
"etc."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9394
msgid "Man Pages"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9396
msgid ""
"The traditional place to look for information about various system calls "
"under <trademark class=\"registered\">UNIX</trademark> systems are the "
"manual pages. FreeBSD describes its system calls in section 2, sometimes in "
"section 3."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9401
msgid ""
"For example, <citerefentry><refentrytitle>open</refentrytitle><manvolnum>2</"
"manvolnum></citerefentry> says:"
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:9406
msgid ""
"If successful, <function>open()</function> returns a non-negative integer, "
"termed a file descriptor. It returns <varname>-1</varname> on failure, and "
"sets <varname>errno</varname> to indicate the error."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9412
msgid ""
"The assembly language programmer new to <trademark class="
"\"registered\">UNIX</trademark> and FreeBSD will immediately ask the "
"puzzling question: Where is <varname>errno</varname> and how do I get to it?"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9417
msgid ""
"The information presented in the manual pages applies to C programs. The "
"assembly language programmer needs additional information."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9424
msgid "Where Are the Return Values?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9426
msgid ""
"Unfortunately, it depends... For most system calls it is in <varname role="
"\"register\">EAX</varname>, but not for all. A good rule of thumb, when "
"working with a system call for the first time, is to look for the return "
"value in <varname role=\"register\">EAX</varname>. If it is not there, you "
"need further research."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9433
msgid ""
"I am aware of one system call that returns the value in <varname role="
"\"register\">EDX</varname>: <function role=\"syscall\">SYS_fork</function>. "
"All others I have worked with use <varname role=\"register\">EAX</varname>. "
"But I have not worked with them all yet."
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:9440
msgid ""
"If you cannot find the answer here or anywhere else, study "
"<application>libc</application> source code and see how it interfaces with "
"the kernel."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9447
msgid "Where Is <varname>errno</varname>?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9449
msgid "Actually, nowhere..."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9451
msgid ""
"<varname>errno</varname> is part of the C language, not the <trademark class="
"\"registered\">UNIX</trademark> kernel. When accessing kernel services "
"directly, the error code is returned in <varname role=\"register\">EAX</"
"varname>, the same register the proper return value generally ends up in."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9456
msgid ""
"This makes perfect sense. If there is no error, there is no error code. If "
"there is an error, there is no return value. One register can contain either."
""
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9462
msgid "Determining an Error Occurred"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9464
msgid ""
"When using the standard FreeBSD calling convention, the <varname role="
"\"register\">carry flag</varname> is cleared upon success, set upon failure."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9468
msgid ""
"When using the Linux emulation mode, the signed value in <varname role="
"\"register\">EAX</varname> is non-negative upon success, and contains the "
"return value. In case of an error, the value is negative, i.e., <varname>-"
"errno</varname>."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:9476
msgid "Creating Portable Code"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9478
msgid ""
"Portability is generally not one of the strengths of assembly language. Yet, "
"writing assembly language programs for different platforms is possible, "
"especially with <application>nasm</application>. I have written assembly "
"language libraries that can be assembled for such different operating "
"systems as <trademark class=\"registered\">Windows</trademark> and FreeBSD."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9485
msgid ""
"It is all the more possible when you want your code to run on two platforms "
"which, while different, are based on similar architectures."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9489
msgid ""
"For example, FreeBSD is <trademark class=\"registered\">UNIX</trademark>, "
"Linux is <trademark class=\"registered\">UNIX</trademark> like. I only "
"mentioned three differences between them (from an assembly language "
"programmer's perspective): The calling convention, the function numbers, and "
"the way of returning values."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9495
msgid "Dealing with Function Numbers"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9497
msgid ""
"In many cases the function numbers are the same. However, even when they are "
"not, the problem is easy to deal with: Instead of using numbers in your "
"code, use constants which you have declared differently depending on the "
"target architecture:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9503
#, no-wrap
msgid "%ifdef	LINUX\n"
"%define	SYS_execve	11\n"
"%else\n"
"%define	SYS_execve	59\n"
"%endif"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9511
msgid "Dealing with Conventions"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9513
msgid ""
"Both, the calling convention, and the return value (the <varname>errno</"
"varname> problem) can be resolved with macros:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9517
#, no-wrap
msgid ""
"%ifdef	LINUX\n"
"\n"
"%macro	system	0\n"
"	call	kernel\n"
"%endmacro\n"
"\n"
"align 4\n"
"kernel:\n"
"	push	ebx\n"
"	push	ecx\n"
"	push	edx\n"
"	push	esi\n"
"	push	edi\n"
"	push	ebp\n"
"\n"
"	mov	ebx, [esp+32]\n"
"	mov	ecx, [esp+36]\n"
"	mov	edx, [esp+40]\n"
"	mov	esi, [esp+44]\n"
"	mov	ebp, [esp+48]\n"
"	int	80h\n"
"\n"
"	pop	ebp\n"
"	pop	edi\n"
"	pop	esi\n"
"	pop	edx\n"
"	pop	ecx\n"
"	pop	ebx\n"
"\n"
"	or	eax, eax\n"
"	js	.errno\n"
"	clc\n"
"	ret\n"
"\n"
".errno:\n"
"	neg	eax\n"
"	stc\n"
"	ret\n"
"\n"
"%else\n"
"\n"
"%macro	system	0\n"
"	int	80h\n"
"%endmacro\n"
"\n"
"%endif"
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9566
msgid "Dealing with Other Portability Issues"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9568
msgid ""
"The above solutions can handle most cases of writing code portable between "
"FreeBSD and Linux. Nevertheless, with some kernel services the differences "
"are deeper."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9572
msgid ""
"In that case, you need to write two different handlers for those particular "
"system calls, and use conditional assembly. Luckily, most of your code does "
"something other than calling the kernel, so usually you will only need a few "
"such conditional sections in your code."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9580
msgid "Using a Library"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9582
msgid ""
"You can avoid portability issues in your main code altogether by writing a "
"library of system calls. Create a separate library for FreeBSD, a different "
"one for Linux, and yet other libraries for more operating systems."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9587
msgid ""
"In your library, write a separate function (or procedure, if you prefer the "
"traditional assembly language terminology) for each system call. Use the C "
"calling convention of passing parameters. But still use <varname role="
"\"register\">EAX</varname> to pass the call number in. In that case, your "
"FreeBSD library can be very simple, as many seemingly different functions "
"can be just labels to the same code:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9595
#, no-wrap
msgid "sys.open:\n"
"sys.close:\n"
"[etc...]\n"
"	int	80h\n"
"	ret"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9601
msgid ""
"Your Linux library will require more different functions. But even here you "
"can group system calls using the same number of parameters:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9605
#, no-wrap
msgid ""
"sys.exit:\n"
"sys.close:\n"
"[etc... one-parameter functions]\n"
"	push	ebx\n"
"	mov	ebx, [esp+12]\n"
"	int	80h\n"
"	pop	ebx\n"
"	jmp	sys.return\n"
"\n"
"...\n"
"\n"
"sys.return:\n"
"	or	eax, eax\n"
"	js	sys.err\n"
"	clc\n"
"	ret\n"
"\n"
"sys.err:\n"
"	neg	eax\n"
"	stc\n"
"	ret"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9627
msgid ""
"The library approach may seem inconvenient at first because it requires you "
"to produce a separate file your code depends on. But it has many advantages: "
"For one, you only need to write it once and can use it for all your programs."
" You can even let other assembly language programmers use it, or perhaps use "
"one written by someone else. But perhaps the greatest advantage of the "
"library is that your code can be ported to other systems, even by other "
"programmers, by simply writing a new library without any changes to your "
"code."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9637
msgid ""
"If you do not like the idea of having a library, you can at least place all "
"your system calls in a separate assembly language file and link it with your "
"main program. Here, again, all porters have to do is create a new object "
"file to link with your main program."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9645
msgid "Using an Include File"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9647
msgid ""
"If you are releasing your software as (or with) source code, you can use "
"macros and place them in a separate file, which you include in your code."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9651
msgid ""
"Porters of your software will simply write a new include file. No library or "
"external object file is necessary, yet your code is portable without any "
"need to edit the code."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9656
msgid ""
"This is the approach we will use throughout this chapter. We will name our "
"include file <filename>system.inc</filename>, and add to it whenever we deal "
"with a new system call."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9661
msgid ""
"We can start our <filename>system.inc</filename> by declaring the standard "
"file descriptors:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9664
#, no-wrap
msgid "%define	stdin	0\n"
"%define	stdout	1\n"
"%define	stderr	2"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9668
msgid "Next, we create a symbolic name for each system call:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9670
#, no-wrap
msgid ""
"%define	SYS_nosys	0\n"
"%define	SYS_exit	1\n"
"%define	SYS_fork	2\n"
"%define	SYS_read	3\n"
"%define	SYS_write	4\n"
"; [etc...]"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9677
msgid ""
"We add a short, non-global procedure with a long name, so we do not "
"accidentally reuse the name in our code:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9680
#, no-wrap
msgid "section	.text\n"
"align 4\n"
"access.the.bsd.kernel:\n"
"	int	80h\n"
"	ret"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9686
msgid "We create a macro which takes one argument, the syscall number:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9689
#, no-wrap
msgid "%macro	system	1\n"
"	mov	eax, %1\n"
"	call	access.the.bsd.kernel\n"
"%endmacro"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9694
msgid ""
"Finally, we create macros for each syscall. These macros take no arguments."
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:9697
#, no-wrap
msgid ""
"%macro	sys.exit	0\n"
"	system	SYS_exit\n"
"%endmacro\n"
"\n"
"%macro	sys.fork	0\n"
"	system	SYS_fork\n"
"%endmacro\n"
"\n"
"%macro	sys.read	0\n"
"	system	SYS_read\n"
"%endmacro\n"
"\n"
"%macro	sys.write	0\n"
"	system	SYS_write\n"
"%endmacro\n"
"\n"
"; [etc...]"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9715
msgid ""
"Go ahead, enter it into your editor and save it as <filename>system.inc</"
"filename>. We will add more to it as we discuss more syscalls."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:9722
msgid "Our First Program"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9724
msgid ""
"We are now ready for our first program, the mandatory <application>Hello, "
"World!</application>"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:9727
#, no-wrap
msgid ""
"1:	%include	'system.inc'\n"
" 2:\n"
" 3:	section	.data\n"
" 4:	hello	db	'Hello, World!', 0Ah\n"
" 5:	hbytes	equ	$-hello\n"
" 6:\n"
" 7:	section	.text\n"
" 8:	global	_start\n"
" 9:	_start:\n"
"10:	push	dword hbytes\n"
"11:	push	dword hello\n"
"12:	push	dword stdout\n"
"13:	sys.write\n"
"14:\n"
"15:	push	dword 0\n"
"16:	sys.exit"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9744
msgid ""
"Here is what it does: Line 1 includes the defines, the macros, and the code "
"from <filename>system.inc</filename>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9747
msgid ""
"Lines 3-5 are the data: Line 3 starts the data section/segment. Line 4 "
"contains the string \"Hello, World!\" followed by a new line (<constant>0Ah</"
"constant>). Line 5 creates a constant that contains the length of the string "
"from line 4 in bytes."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9753
msgid ""
"Lines 7-16 contain the code. Note that FreeBSD uses the <emphasis>elf</"
"emphasis> file format for its executables, which requires every program to "
"start at the point labeled <varname>_start</varname> (or, more precisely, "
"the linker expects that). This label has to be global."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9759
msgid ""
"Lines 10-13 ask the system to write <varname>hbytes</varname> bytes of the "
"<varname>hello</varname> string to <varname>stdout</varname>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9763
msgid ""
"Lines 15-16 ask the system to end the program with the return value of "
"<constant>0</constant>. The <function role=\"syscall\">SYS_exit</function> "
"syscall never returns, so the code ends there."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9768
msgid ""
"If you have come to <trademark class=\"registered\">UNIX</trademark> from "
"<acronym><trademark class=\"registered\">MS-DOS</trademark></acronym> "
"assembly language background, you may be used to writing directly to the "
"video hardware. You will never have to worry about this in FreeBSD, or any "
"other flavor of <trademark class=\"registered\">UNIX</trademark>. As far as "
"you are concerned, you are writing to a file known as <filename>stdout</"
"filename>. This can be the video screen, or a <application>telnet</"
"application> terminal, or an actual file, or even the input of another "
"program. Which one it is, is for the system to figure out."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:9779
msgid "Assembling the Code"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:9781
msgid ""
"Type the code (except the line numbers) in an editor, and save it in a file "
"named <filename>hello.asm</filename>. You need <application>nasm</"
"application> to assemble it."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:9785
msgid "Installing <application>nasm</application>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9787
msgid "If you do not have <application>nasm</application>, type:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:9790
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>su</userinput>\n"
"Password:<userinput><replaceable>your root password</replaceable></"
"userinput>\n"
"<prompt>#</prompt> <userinput>cd /usr/ports/devel/nasm</userinput>\n"
"<prompt>#</prompt> <userinput>make install</userinput>\n"
"<prompt>#</prompt> <userinput>exit</userinput>\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9797
msgid ""
"You may type <userinput>make install clean</userinput> instead of just "
"<userinput>make install</userinput> if you do not want to keep "
"<application>nasm</application> source code."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9803
msgid ""
"Either way, FreeBSD will automatically download <application>nasm</"
"application> from the Internet, compile it, and install it on your system."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9810
msgid ""
"If your system is not FreeBSD, you need to get <application>nasm</"
"application> from its <link xlink:href=\"https://sourceforge.net/projects/"
"nasm\">home page</link>. You can still use it to assemble FreeBSD code."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:9818
msgid "Now you can assemble, link, and run the code:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:9822
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>nasm -f elf hello.asm</userinput>\n"
"<prompt>%</prompt> <userinput>ld -s -o hello hello.o</userinput>\n"
"<prompt>%</prompt> <userinput>./hello</userinput>\n"
"Hello, World!\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:9835
msgid "Writing <trademark class=\"registered\">UNIX</trademark> Filters"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9837
msgid ""
"A common type of <trademark class=\"registered\">UNIX</trademark> "
"application is a filter—a program that reads data from the <filename>stdin</"
"filename>, processes it somehow, then writes the result to <filename>stdout</"
"filename>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9843
msgid ""
"In this chapter, we shall develop a simple filter, and learn how to read "
"from <filename>stdin</filename> and write to <filename>stdout</filename>. "
"This filter will convert each byte of its input into a hexadecimal number "
"followed by a blank space."
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:9851
#, no-wrap
msgid ""
"\n"
"%include	'system.inc'\n"
"\n"
"section	.data\n"
"hex	db	'0123456789ABCDEF'\n"
"buffer	db	0, 0, ' '\n"
"\n"
"section	.text\n"
"global	_start\n"
"_start:\n"
"	; read a byte from stdin\n"
"	push	dword 1\n"
"	push	dword buffer\n"
"	push	dword stdin\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	or	eax, eax\n"
"	je	.done\n"
"\n"
"	; convert it to hex\n"
"	movzx	eax, byte [buffer]\n"
"	mov	edx, eax\n"
"	shr	dl, 4\n"
"	mov	dl, [hex+edx]\n"
"	mov	[buffer], dl\n"
"	and	al, 0Fh\n"
"	mov	al, [hex+eax]\n"
"	mov	[buffer+1], al\n"
"\n"
"	; print it\n"
"	push	dword 3\n"
"	push	dword buffer\n"
"	push	dword stdout\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	jmp	short _start\n"
"\n"
".done:\n"
"	push	dword 0\n"
"	sys.exit\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9892
msgid ""
"In the data section we create an array called <varname>hex</varname>. It "
"contains the 16 hexadecimal digits in ascending order. The array is followed "
"by a buffer which we will use for both input and output. The first two bytes "
"of the buffer are initially set to <constant>0</constant>. This is where we "
"will write the two hexadecimal digits (the first byte also is where we will "
"read the input). The third byte is a space."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9903
msgid ""
"The code section consists of four parts: Reading the byte, converting it to "
"a hexadecimal number, writing the result, and eventually exiting the program."
""
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9909
msgid ""
"To read the byte, we ask the system to read one byte from <filename>stdin</"
"filename>, and store it in the first byte of the <varname>buffer</varname>. "
"The system returns the number of bytes read in <varname role="
"\"register\">EAX</varname>. This will be <constant>1</constant> while data "
"is coming, or <constant>0</constant>, when no more input data is available. "
"Therefore, we check the value of <varname role=\"register\">EAX</varname>. "
"If it is <constant>0</constant>, we jump to <varname>.done</varname>, "
"otherwise we continue."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9921
msgid ""
"For simplicity sake, we are ignoring the possibility of an error condition "
"at this time."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9927
msgid ""
"The hexadecimal conversion reads the byte from the <varname>buffer</varname> "
"into <varname role=\"register\">EAX</varname>, or actually just <varname "
"role=\"register\">AL</varname>, while clearing the remaining bits of "
"<varname role=\"register\">EAX</varname> to zeros. We also copy the byte to "
"<varname role=\"register\">EDX</varname> because we need to convert the "
"upper four bits (nibble) separately from the lower four bits. We store the "
"result in the first two bytes of the buffer."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9938
msgid ""
"Next, we ask the system to write the three bytes of the buffer, i.e., the "
"two hexadecimal digits and the blank space, to <filename>stdout</filename>. "
"We then jump back to the beginning of the program and process the next byte."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9946
msgid ""
"Once there is no more input left, we ask the system to exit our program, "
"returning a zero, which is the traditional value meaning the program was "
"successful."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9953
msgid ""
"Go ahead, and save the code in a file named <filename>hex.asm</filename>, "
"then type the following (the <userinput>^D</userinput> means press the "
"control key and type <userinput>D</userinput> while holding the control key "
"down):"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:9960
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>nasm -f elf hex.asm</userinput>\n"
"<prompt>%</prompt> <userinput>ld -s -o hex hex.o</userinput>\n"
"<prompt>%</prompt> <userinput>./hex</userinput>\n"
"<userinput>Hello, World!</userinput>\n"
"48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A <userinput>Here I come!</"
"userinput>\n"
"48 65 72 65 20 49 20 63 6F 6D 65 21 0A <userinput>^D</userinput> <prompt>%</"
"prompt>"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:9968
msgid ""
"If you are migrating to <trademark class=\"registered\">UNIX</trademark> "
"from <acronym><trademark class=\"registered\">MS-DOS</trademark></acronym>, "
"you may be wondering why each line ends with <constant>0A</constant> instead "
"of <constant>0D 0A</constant>. This is because <trademark class="
"\"registered\">UNIX</trademark> does not use the cr/lf convention, but a "
"\"new line\" convention, which is <constant>0A</constant> in hexadecimal."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:9977
msgid ""
"Can we improve this? Well, for one, it is a bit confusing because once we "
"have converted a line of text, our input no longer starts at the beginning "
"of the line. We can modify it to print a new line instead of a space after "
"each <constant>0A</constant>:"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:9984
#, no-wrap
msgid ""
"\n"
"%include	'system.inc'\n"
"\n"
"section	.data\n"
"hex	db	'0123456789ABCDEF'\n"
"buffer	db	0, 0, ' '\n"
"\n"
"section	.text\n"
"global	_start\n"
"_start:\n"
"	mov	cl, ' '\n"
"\n"
".loop:\n"
"	; read a byte from stdin\n"
"	push	dword 1\n"
"	push	dword buffer\n"
"	push	dword stdin\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	or	eax, eax\n"
"	je	.done\n"
"\n"
"	; convert it to hex\n"
"	movzx	eax, byte [buffer]\n"
"	mov	[buffer+2], cl\n"
"	cmp	al, 0Ah\n"
"	jne	.hex\n"
"	mov	[buffer+2], al\n"
"\n"
".hex:\n"
"	mov	edx, eax\n"
"	shr	dl, 4\n"
"	mov	dl, [hex+edx]\n"
"	mov	[buffer], dl\n"
"	and	al, 0Fh\n"
"	mov	al, [hex+eax]\n"
"	mov	[buffer+1], al\n"
"\n"
"	; print it\n"
"	push	dword 3\n"
"	push	dword buffer\n"
"	push	dword stdout\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	jmp	short .loop\n"
"\n"
".done:\n"
"	push	dword 0\n"
"	sys.exit\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10034
msgid ""
"We have stored the space in the <varname role=\"register\">CL</varname> "
"register. We can do this safely because, unlike <trademark class="
"\"registered\">Microsoft</trademark> <trademark class="
"\"registered\">Windows</trademark>, <trademark class=\"registered\">UNIX</"
"trademark> system calls do not modify the value of any register they do not "
"use to return a value in."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10041
msgid ""
"That means we only need to set <varname role=\"register\">CL</varname> once. "
"We have, therefore, added a new label <varname>.loop</varname> and jump to "
"it for the next byte instead of jumping at <varname>_start</varname>. We "
"have also added the <varname>.hex</varname> label so we can either have a "
"blank space or a new line as the third byte of the <varname>buffer</varname>."
""
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10049
msgid ""
"Once you have changed <filename>hex.asm</filename> to reflect these changes, "
"type:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:10054 book.translate.xml:10342
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>nasm -f elf hex.asm</userinput>\n"
"<prompt>%</prompt> <userinput>ld -s -o hex hex.o</userinput>\n"
"<prompt>%</prompt> <userinput>./hex</userinput>\n"
"<userinput>Hello, World!</userinput>\n"
"48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A\n"
"<userinput>Here I come!</userinput>\n"
"48 65 72 65 20 49 20 63 6F 6D 65 21 0A\n"
"<userinput>^D</userinput> <prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10063
msgid ""
"That looks better. But this code is quite inefficient! We are making a "
"system call for every single byte twice (once to read it, another time to "
"write the output)."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:10072
msgid "Buffered Input and Output"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10074
msgid ""
"We can improve the efficiency of our code by buffering our input and output. "
"We create an input buffer and read a whole sequence of bytes at one time. "
"Then we fetch them one by one from the buffer."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10081
msgid ""
"We also create an output buffer. We store our output in it until it is full. "
"At that time we ask the kernel to write the contents of the buffer to "
"<filename>stdout</filename>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10087
msgid ""
"The program ends when there is no more input. But we still need to ask the "
"kernel to write the contents of our output buffer to <filename>stdout</"
"filename> one last time, otherwise some of our output would make it to the "
"output buffer, but never be sent out. Do not forget that, or you will be "
"wondering why some of your output is missing."
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:10096
#, no-wrap
msgid ""
"\n"
"%include	'system.inc'\n"
"\n"
"%define	BUFSIZE	2048\n"
"\n"
"section	.data\n"
"hex	db	'0123456789ABCDEF'\n"
"\n"
"section .bss\n"
"ibuffer	resb	BUFSIZE\n"
"obuffer	resb	BUFSIZE\n"
"\n"
"section	.text\n"
"global	_start\n"
"_start:\n"
"	sub	eax, eax\n"
"	sub	ebx, ebx\n"
"	sub	ecx, ecx\n"
"	mov	edi, obuffer\n"
"\n"
".loop:\n"
"	; read a byte from stdin\n"
"	call	getchar\n"
"\n"
"	; convert it to hex\n"
"	mov	dl, al\n"
"	shr	al, 4\n"
"	mov	al, [hex+eax]\n"
"	call	putchar\n"
"\n"
"	mov	al, dl\n"
"	and	al, 0Fh\n"
"	mov	al, [hex+eax]\n"
"	call	putchar\n"
"\n"
"	mov	al, ' '\n"
"	cmp	dl, 0Ah\n"
"	jne	.put\n"
"	mov	al, dl\n"
"\n"
".put:\n"
"	call	putchar\n"
"	jmp	short .loop\n"
"\n"
"align 4\n"
"getchar:\n"
"	or	ebx, ebx\n"
"	jne	.fetch\n"
"\n"
"	call	read\n"
"\n"
".fetch:\n"
"	lodsb\n"
"	dec	ebx\n"
"	ret\n"
"\n"
"read:\n"
"	push	dword BUFSIZE\n"
"	mov	esi, ibuffer\n"
"	push	esi\n"
"	push	dword stdin\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	mov	ebx, eax\n"
"	or	eax, eax\n"
"	je	.done\n"
"	sub	eax, eax\n"
"	ret\n"
"\n"
"align 4\n"
".done:\n"
"	call	write		; flush output buffer\n"
"	push	dword 0\n"
"	sys.exit\n"
"\n"
"align 4\n"
"putchar:\n"
"	stosb\n"
"	inc	ecx\n"
"	cmp	ecx, BUFSIZE\n"
"	je	write\n"
"	ret\n"
"\n"
"align 4\n"
"write:\n"
"	sub	edi, ecx	; start of buffer\n"
"	push	ecx\n"
"	push	edi\n"
"	push	dword stdout\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	sub	eax, eax\n"
"	sub	ecx, ecx	; buffer is empty now\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10191
msgid ""
"We now have a third section in the source code, named <varname>.bss</"
"varname>. This section is not included in our executable file, and, "
"therefore, cannot be initialized. We use <function role=\"opcode\">resb</"
"function> instead of <function role=\"opcode\">db</function>. It simply "
"reserves the requested size of uninitialized memory for our use."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10200
msgid ""
"We take advantage of the fact that the system does not modify the registers: "
"We use registers for what, otherwise, would have to be global variables "
"stored in the <varname>.data</varname> section. This is also why the "
"<trademark class=\"registered\">UNIX</trademark> convention of passing "
"parameters to system calls on the stack is superior to the Microsoft "
"convention of passing them in the registers: We can keep the registers for "
"our own use."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10209
msgid ""
"We use <varname role=\"register\">EDI</varname> and <varname role="
"\"register\">ESI</varname> as pointers to the next byte to be read from or "
"written to. We use <varname role=\"register\">EBX</varname> and <varname "
"role=\"register\">ECX</varname> to keep count of the number of bytes in the "
"two buffers, so we know when to dump the output to, or read more input from, "
"the system."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10217
msgid "Let us see how it works now:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:10221
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>nasm -f elf hex.asm</userinput>\n"
"<prompt>%</prompt> <userinput>ld -s -o hex hex.o</userinput>\n"
"<prompt>%</prompt> <userinput>./hex</userinput>\n"
"<userinput>Hello, World!</userinput>\n"
"<userinput>Here I come!</userinput>\n"
"48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A\n"
"48 65 72 65 20 49 20 63 6F 6D 65 21 0A\n"
"<userinput>^D</userinput> <prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10230
msgid ""
"Not what you expected? The program did not print the output until we pressed "
"<userinput>^D</userinput>. That is easy to fix by inserting three lines of "
"code to write the output every time we have converted a new line to "
"<constant>0A</constant>. I have marked the three lines with &gt; (do not "
"copy the &gt; in your <filename>hex.asm</filename>)."
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:10239
#, no-wrap
msgid ""
"\n"
"%include	'system.inc'\n"
"\n"
"%define	BUFSIZE	2048\n"
"\n"
"section	.data\n"
"hex	db	'0123456789ABCDEF'\n"
"\n"
"section .bss\n"
"ibuffer	resb	BUFSIZE\n"
"obuffer	resb	BUFSIZE\n"
"\n"
"section	.text\n"
"global	_start\n"
"_start:\n"
"	sub	eax, eax\n"
"	sub	ebx, ebx\n"
"	sub	ecx, ecx\n"
"	mov	edi, obuffer\n"
"\n"
".loop:\n"
"	; read a byte from stdin\n"
"	call	getchar\n"
"\n"
"	; convert it to hex\n"
"	mov	dl, al\n"
"	shr	al, 4\n"
"	mov	al, [hex+eax]\n"
"	call	putchar\n"
"\n"
"	mov	al, dl\n"
"	and	al, 0Fh\n"
"	mov	al, [hex+eax]\n"
"	call	putchar\n"
"\n"
"	mov	al, ' '\n"
"	cmp	dl, 0Ah\n"
"	jne	.put\n"
"	mov	al, dl\n"
"\n"
".put:\n"
"	call	putchar\n"
"&gt;	cmp	al, 0Ah\n"
"&gt;	jne	.loop\n"
"&gt;	call	write\n"
"	jmp	short .loop\n"
"\n"
"align 4\n"
"getchar:\n"
"	or	ebx, ebx\n"
"	jne	.fetch\n"
"\n"
"	call	read\n"
"\n"
".fetch:\n"
"	lodsb\n"
"	dec	ebx\n"
"	ret\n"
"\n"
"read:\n"
"	push	dword BUFSIZE\n"
"	mov	esi, ibuffer\n"
"	push	esi\n"
"	push	dword stdin\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	mov	ebx, eax\n"
"	or	eax, eax\n"
"	je	.done\n"
"	sub	eax, eax\n"
"	ret\n"
"\n"
"align 4\n"
".done:\n"
"	call	write		; flush output buffer\n"
"	push	dword 0\n"
"	sys.exit\n"
"\n"
"align 4\n"
"putchar:\n"
"	stosb\n"
"	inc	ecx\n"
"	cmp	ecx, BUFSIZE\n"
"	je	write\n"
"	ret\n"
"\n"
"align 4\n"
"write:\n"
"	sub	edi, ecx	; start of buffer\n"
"	push	ecx\n"
"	push	edi\n"
"	push	dword stdout\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	sub	eax, eax\n"
"	sub	ecx, ecx	; buffer is empty now\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10338
msgid "Now, let us see how it works:"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10351
msgid "Not bad for a 644-byte executable, is it!"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:10356
msgid ""
"This approach to buffered input/output still contains a hidden danger. I "
"will discuss—and fix—it later, when I talk about the <link linkend=\"x86-"
"buffered-dark-side\">dark side of buffering</link>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:10365
msgid "How to Unread a Character"
msgstr ""

#. (itstool) path: warning/para
#: book.translate.xml:10367
msgid ""
"This may be a somewhat advanced topic, mostly of interest to programmers "
"familiar with the theory of compilers. If you wish, you may <link linkend="
"\"x86-command-line\">skip to the next section</link>, and perhaps read this "
"later."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10374
msgid ""
"While our sample program does not require it, more sophisticated filters "
"often need to look ahead. In other words, they may need to see what the next "
"character is (or even several characters). If the next character is of a "
"certain value, it is part of the token currently being processed. Otherwise, "
"it is not."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10382
msgid ""
"For example, you may be parsing the input stream for a textual string (e.g., "
"when implementing a language compiler): If a character is followed by "
"another character, or perhaps a digit, it is part of the token you are "
"processing. If it is followed by white space, or some other value, then it "
"is not part of the current token."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10391
msgid ""
"This presents an interesting problem: How to return the next character back "
"to the input stream, so it can be read again later?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10397
msgid ""
"One possible solution is to store it in a character variable, then set a "
"flag. We can modify <function>getchar</function> to check the flag, and if "
"it is set, fetch the byte from that variable instead of the input buffer, "
"and reset the flag. But, of course, that slows us down."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10405
msgid ""
"The C language has an <function>ungetc()</function> function, just for that "
"purpose. Is there a quick way to implement it in our code? I would like you "
"to scroll back up and take a look at the <function>getchar</function> "
"procedure and see if you can find a nice and fast solution before reading "
"the next paragraph. Then come back here and see my own solution."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10414
msgid ""
"The key to returning a character back to the stream is in how we are getting "
"the characters to start with:"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10419
msgid ""
"First we check if the buffer is empty by testing the value of <varname role="
"\"register\">EBX</varname>. If it is zero, we call the <function>read</"
"function> procedure."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10425
msgid ""
"If we do have a character available, we use <function role=\"opcode\">lodsb</"
"function>, then decrease the value of <varname role=\"register\">EBX</"
"varname>. The <function role=\"opcode\">lodsb</function> instruction is "
"effectively identical to:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:10431
#, no-wrap
msgid "\n"
"	mov	al, [esi]\n"
"	inc	esi\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10436
msgid ""
"The byte we have fetched remains in the buffer until the next time "
"<function>read</function> is called. We do not know when that happens, but "
"we do know it will not happen until the next call to <function>getchar</"
"function>. Hence, to \"return\" the last-read byte back to the stream, all "
"we have to do is decrease the value of <varname role=\"register\">ESI</"
"varname> and increase the value of <varname role=\"register\">EBX</varname>:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:10445
#, no-wrap
msgid "\n"
"ungetc:\n"
"	dec	esi\n"
"	inc	ebx\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10452
msgid ""
"But, be careful! We are perfectly safe doing this if our look-ahead is at "
"most one character at a time. If we are examining more than one upcoming "
"character and call <function>ungetc</function> several times in a row, it "
"will work most of the time, but not all the time (and will be tough to "
"debug). Why?"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10460
msgid ""
"Because as long as <function>getchar</function> does not have to call "
"<function>read</function>, all of the pre-read bytes are still in the "
"buffer, and our <function>ungetc</function> works without a glitch. But the "
"moment <function>getchar</function> calls <function>read</function>, the "
"contents of the buffer change."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10468
msgid ""
"We can always rely on <function>ungetc</function> working properly on the "
"last character we have read with <function>getchar</function>, but not on "
"anything we have read before that."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10474
msgid ""
"If your program reads more than one byte ahead, you have at least two "
"choices:"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10479
msgid ""
"If possible, modify the program so it only reads one byte ahead. This is the "
"simplest solution."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10484
msgid ""
"If that option is not available, first of all determine the maximum number "
"of characters your program needs to return to the input stream at one time. "
"Increase that number slightly, just to be sure, preferably to a multiple of "
"16—so it aligns nicely. Then modify the <varname>.bss</varname> section of "
"your code, and create a small \"spare\" buffer right before your input "
"buffer, something like this:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:10494
#, no-wrap
msgid ""
"\n"
"section	.bss\n"
"	resb	16	; or whatever the value you came up with\n"
"ibuffer	resb	BUFSIZE\n"
"obuffer	resb	BUFSIZE\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10501
msgid ""
"You also need to modify your <function>ungetc</function> to pass the value "
"of the byte to unget in <varname role=\"register\">AL</varname>:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:10506
#, no-wrap
msgid "\n"
"ungetc:\n"
"	dec	esi\n"
"	inc	ebx\n"
"	mov	[esi], al\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10514
msgid ""
"With this modification, you can call <function>ungetc</function> up to 17 "
"times in a row safely (the first call will still be within the buffer, the "
"remaining 16 may be either within the buffer or within the \"spare\")."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:10525
msgid "Command Line Arguments"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10527
msgid ""
"Our <application>hex</application> program will be more useful if it can "
"read the names of an input and output file from its command line, i.e., if "
"it can process the command line arguments. But... Where are they?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10534
msgid ""
"Before a <trademark class=\"registered\">UNIX</trademark> system starts a "
"program, it <function role=\"opcode\">push</function>es some data on the "
"stack, then jumps at the <varname>_start</varname> label of the program. "
"Yes, I said jumps, not calls. That means the data can be accessed by reading "
"<varname>[esp+offset]</varname>, or by simply <function role=\"opcode\">pop</"
"function>ping it."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10542
msgid ""
"The value at the top of the stack contains the number of command line "
"arguments. It is traditionally called <varname>argc</varname>, for "
"\"argument count.\""
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10548
msgid ""
"Command line arguments follow next, all <varname>argc</varname> of them. "
"These are typically referred to as <varname>argv</varname>, for \"argument "
"value(s).\" That is, we get <varname>argv[0]</varname>, <varname>argv[1]</"
"varname>, <varname>...</varname>, <varname>argv[argc-1]</varname>. These are "
"not the actual arguments, but pointers to arguments, i.e., memory addresses "
"of the actual arguments. The arguments themselves are NUL-terminated "
"character strings."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10559
msgid ""
"The <varname>argv</varname> list is followed by a NULL pointer, which is "
"simply a <constant>0</constant>. There is more, but this is enough for our "
"purposes right now."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:10566
msgid ""
"If you have come from the <acronym><trademark class=\"registered\">MS-DOS</"
"trademark></acronym> programming environment, the main difference is that "
"each argument is in a separate string. The second difference is that there "
"is no practical limit on how many arguments there can be."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10574
msgid ""
"Armed with this knowledge, we are almost ready for the next version of "
"<filename>hex.asm</filename>. First, however, we need to add a few lines to "
"<filename>system.inc</filename>:"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10580
msgid ""
"First, we need to add two new entries to our list of system call numbers:"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:10585
#, no-wrap
msgid "\n"
"%define	SYS_open	5\n"
"%define	SYS_close	6\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10590
msgid "Then we add two new macros at the end of the file:"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:10594
#, no-wrap
msgid ""
"\n"
"%macro	sys.open	0\n"
"	system	SYS_open\n"
"%endmacro\n"
"\n"
"%macro	sys.close	0\n"
"	system	SYS_close\n"
"%endmacro\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10604
msgid "Here, then, is our modified source code:"
msgstr ""

#. (itstool) path: sect1/programlisting
#: book.translate.xml:10608
#, no-wrap
msgid ""
"\n"
"%include	'system.inc'\n"
"\n"
"%define	BUFSIZE	2048\n"
"\n"
"section	.data\n"
"fd.in	dd	stdin\n"
"fd.out	dd	stdout\n"
"hex	db	'0123456789ABCDEF'\n"
"\n"
"section .bss\n"
"ibuffer	resb	BUFSIZE\n"
"obuffer	resb	BUFSIZE\n"
"\n"
"section	.text\n"
"align 4\n"
"err:\n"
"	push	dword 1		; return failure\n"
"	sys.exit\n"
"\n"
"align 4\n"
"global	_start\n"
"_start:\n"
"	add	esp, byte 8	; discard argc and argv[0]\n"
"\n"
"	pop	ecx\n"
"	jecxz	.init		; no more arguments\n"
"\n"
"	; ECX contains the path to input file\n"
"	push	dword 0		; O_RDONLY\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	err		; open failed\n"
"\n"
"	add	esp, byte 8\n"
"	mov	[fd.in], eax\n"
"\n"
"	pop	ecx\n"
"	jecxz	.init		; no more arguments\n"
"\n"
"	; ECX contains the path to output file\n"
"	push	dword 420	; file mode (644 octal)\n"
"	push	dword 0200h | 0400h | 01h\n"
"	; O_CREAT | O_TRUNC | O_WRONLY\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	err\n"
"\n"
"	add	esp, byte 12\n"
"	mov	[fd.out], eax\n"
"\n"
".init:\n"
"	sub	eax, eax\n"
"	sub	ebx, ebx\n"
"	sub	ecx, ecx\n"
"	mov	edi, obuffer\n"
"\n"
".loop:\n"
"	; read a byte from input file or stdin\n"
"	call	getchar\n"
"\n"
"	; convert it to hex\n"
"	mov	dl, al\n"
"	shr	al, 4\n"
"	mov	al, [hex+eax]\n"
"	call	putchar\n"
"\n"
"	mov	al, dl\n"
"	and	al, 0Fh\n"
"	mov	al, [hex+eax]\n"
"	call	putchar\n"
"\n"
"	mov	al, ' '\n"
"	cmp	dl, 0Ah\n"
"	jne	.put\n"
"	mov	al, dl\n"
"\n"
".put:\n"
"	call	putchar\n"
"	cmp	al, dl\n"
"	jne	.loop\n"
"	call	write\n"
"	jmp	short .loop\n"
"\n"
"align 4\n"
"getchar:\n"
"	or	ebx, ebx\n"
"	jne	.fetch\n"
"\n"
"	call	read\n"
"\n"
".fetch:\n"
"	lodsb\n"
"	dec	ebx\n"
"	ret\n"
"\n"
"read:\n"
"	push	dword BUFSIZE\n"
"	mov	esi, ibuffer\n"
"	push	esi\n"
"	push	dword [fd.in]\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	mov	ebx, eax\n"
"	or	eax, eax\n"
"	je	.done\n"
"	sub	eax, eax\n"
"	ret\n"
"\n"
"align 4\n"
".done:\n"
"	call	write		; flush output buffer\n"
"\n"
"	; close files\n"
"	push	dword [fd.in]\n"
"	sys.close\n"
"\n"
"	push	dword [fd.out]\n"
"	sys.close\n"
"\n"
"	; return success\n"
"	push	dword 0\n"
"	sys.exit\n"
"\n"
"align 4\n"
"putchar:\n"
"	stosb\n"
"	inc	ecx\n"
"	cmp	ecx, BUFSIZE\n"
"	je	write\n"
"	ret\n"
"\n"
"align 4\n"
"write:\n"
"	sub	edi, ecx	; start of buffer\n"
"	push	ecx\n"
"	push	edi\n"
"	push	dword [fd.out]\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	sub	eax, eax\n"
"	sub	ecx, ecx	; buffer is empty now\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10753
msgid ""
"In our <varname>.data</varname> section we now have two new variables, "
"<varname>fd.in</varname> and <varname>fd.out</varname>. We store the input "
"and output file descriptors here."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10759
msgid ""
"In the <varname>.text</varname> section we have replaced the references to "
"<varname>stdin</varname> and <varname>stdout</varname> with <varname>[fd."
"in]</varname> and <varname>[fd.out]</varname>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10765
msgid ""
"The <varname>.text</varname> section now starts with a simple error handler, "
"which does nothing but exit the program with a return value of <constant>1</"
"constant>. The error handler is before <varname>_start</varname> so we are "
"within a short distance from where the errors occur."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10773
msgid ""
"Naturally, the program execution still begins at <varname>_start</varname>. "
"First, we remove <varname>argc</varname> and <varname>argv[0]</varname> from "
"the stack: They are of no interest to us (in this program, that is)."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10779
msgid ""
"We pop <varname>argv[1]</varname> to <varname role=\"register\">ECX</"
"varname>. This register is particularly suited for pointers, as we can "
"handle NULL pointers with <function role=\"opcode\">jecxz</function>. If "
"<varname>argv[1]</varname> is not NULL, we try to open the file named in the "
"first argument. Otherwise, we continue the program as before: Reading from "
"<varname>stdin</varname>, writing to <varname>stdout</varname>. If we fail "
"to open the input file (e.g., it does not exist), we jump to the error "
"handler and quit."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10790
msgid ""
"If all went well, we now check for the second argument. If it is there, we "
"open the output file. Otherwise, we send the output to <varname>stdout</"
"varname>. If we fail to open the output file (e.g., it exists and we do not "
"have the write permission), we, again, jump to the error handler."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10798
msgid ""
"The rest of the code is the same as before, except we close the input and "
"output files before exiting, and, as mentioned, we use <varname>[fd.in]</"
"varname> and <varname>[fd.out]</varname>."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10804
msgid "Our executable is now a whopping 768 bytes long."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10808
msgid ""
"Can we still improve it? Of course! Every program can be improved. Here are "
"a few ideas of what we could do:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10815
msgid "Have our error handler print a message to <varname>stderr</varname>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10822
msgid ""
"Add error handlers to the <function>read</function> and <function>write</"
"function> functions."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10829
msgid ""
"Close <varname>stdin</varname> when we open an input file, <varname>stdout</"
"varname> when we open an output file."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10836
msgid ""
"Add command line switches, such as <parameter>-i</parameter> and <parameter>-"
"o</parameter>, so we can list the input and output files in any order, or "
"perhaps read from <varname>stdin</varname> and write to a file."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10845
msgid "Print a usage message if command line arguments are incorrect."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10851
msgid ""
"I shall leave these enhancements as an exercise to the reader: You already "
"know everything you need to know to implement them."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:10859
msgid "<trademark class=\"registered\">UNIX</trademark> Environment"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:10861
msgid ""
"An important <trademark class=\"registered\">UNIX</trademark> concept is the "
"environment, which is defined by <emphasis>environment variables</emphasis>. "
"Some are set by the system, others by you, yet others by the "
"<application>shell</application>, or any program that loads another program."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:10869
msgid "How to Find Environment Variables"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10871
msgid ""
"I said earlier that when a program starts executing, the stack contains "
"<varname>argc</varname> followed by the NULL-terminated <varname>argv</"
"varname> array, followed by something else. The \"something else\" is the "
"<emphasis>environment</emphasis>, or, to be more precise, a NULL-terminated "
"array of pointers to <emphasis>environment variables</emphasis>. This is "
"often referred to as <varname>env</varname>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10881
msgid ""
"The structure of <varname>env</varname> is the same as that of "
"<varname>argv</varname>, a list of memory addresses followed by a NULL "
"(<constant>0</constant>). In this case, there is no <varname>\"envc\"</"
"varname>—we figure out where the array ends by searching for the final NULL."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10889
msgid ""
"The variables usually come in the <varname>name=value</varname> format, but "
"sometimes the <varname>=value</varname> part may be missing. We need to "
"account for that possibility."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:10898
msgid "webvars"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:10900
msgid ""
"I could just show you some code that prints the environment the same way the "
"<trademark class=\"registered\">UNIX</trademark> <application>env</"
"application> command does. But I thought it would be more interesting to "
"write a simple assembly language CGI utility."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:10908
msgid "CGI: A Quick Overview"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:10910
msgid ""
"I have a <link xlink:href=\"http://www.whizkidtech.redprince.net/cgi-bin/"
"tutorial\">detailed <acronym>CGI</acronym> tutorial</link> on my web site, "
"but here is a very quick overview of <acronym>CGI</acronym>:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10919
msgid ""
"The web server communicates with the <acronym>CGI</acronym> program by "
"setting <emphasis>environment variables</emphasis>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10926
msgid ""
"The <acronym>CGI</acronym> program sends its output to <filename>stdout</"
"filename>. The web server reads it from there."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10934
msgid ""
"It must start with an <acronym>HTTP</acronym> header followed by two blank "
"lines."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:10941
msgid ""
"It then prints the <acronym>HTML</acronym> code, or whatever other type of "
"data it is producing."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:10949
msgid ""
"While certain <emphasis>environment variables</emphasis> use standard names, "
"others vary, depending on the web server. That makes <application>webvars</"
"application> quite a useful diagnostic tool."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:10960
msgid "The Code"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:10962
msgid ""
"Our <application>webvars</application> program, then, must send out the "
"<acronym>HTTP</acronym> header followed by some <acronym>HTML</acronym> mark-"
"up. It then must read the <emphasis>environment variables</emphasis> one by "
"one and send them out as part of the <acronym>HTML</acronym> page."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:10971
msgid ""
"The code follows. I placed comments and explanations right inside the code:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:10976
#, no-wrap
msgid ""
"\n"
";;;;;;; webvars.asm "
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
";\n"
"; Copyright (c) 2000 G. Adam Stanislav\n"
"; All rights reserved.\n"
";\n"
"; Redistribution and use in source and binary forms, with or without\n"
"; modification, are permitted provided that the following conditions\n"
"; are met:\n"
"; 1. Redistributions of source code must retain the above copyright\n"
";    notice, this list of conditions and the following disclaimer.\n"
"; 2. Redistributions in binary form must reproduce the above copyright\n"
";    notice, this list of conditions and the following disclaimer in the\n"
";    documentation and/or other materials provided with the distribution.\n"
";\n"
"; THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND\n"
"; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE\n"
"; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE\n"
"; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE\n"
"; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL\n"
"; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS\n"
"; OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)\n"
"; HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT\n"
"; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY\n"
"; OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF\n"
"; SUCH DAMAGE.\n"
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
";\n"
"; Version 1.0\n"
";\n"
"; Started:	 8-Dec-2000\n"
"; Updated:	 8-Dec-2000\n"
";\n"
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
"%include	'system.inc'\n"
"\n"
"section	.data\n"
"http	db	'Content-type: text/html', 0Ah, 0Ah\n"
"	db	'&lt;?xml version=\"1.0\" encoding=\"utf-8\"?&gt;', 0Ah\n"
"	db	'&lt;!DOCTYPE html PUBLIC \"-//W3C/DTD XHTML Strict//EN\" '\n"
"	db	'\"DTD/xhtml1-strict.dtd\"&gt;', 0Ah\n"
"	db	'&lt;html xmlns=\"http://www.w3.org/1999/xhtml\" '\n"
"	db	'xml.lang=\"en\" lang=\"en\"&gt;', 0Ah\n"
"	db	'&lt;head&gt;', 0Ah\n"
"	db	'&lt;title&gt;Web Environment&lt;/title&gt;', 0Ah\n"
"	db	'&lt;meta name=\"author\" content=\"G. Adam Stanislav\" /&gt;', 0Ah\n"
"	db	'&lt;/head&gt;', 0Ah, 0Ah\n"
"	db	'&lt;body bgcolor=\"#ffffff\" text=\"#000000\" link=\"#0000ff\" '\n"
"	db	'vlink=\"#840084\" alink=\"#0000ff\"&gt;', 0Ah\n"
"	db	'&lt;div class=\"webvars\"&gt;', 0Ah\n"
"	db	'&lt;h1&gt;Web Environment&lt;/h1&gt;', 0Ah\n"
"	db	'&lt;p&gt;The following &lt;b&gt;environment variables&lt;/b&gt; are "
"defined '\n"
"	db	'on this web server:&lt;/p&gt;', 0Ah, 0Ah\n"
"	db	'&lt;table align=\"center\" width=\"80\" border=\"0\" cellpadding=\"10\" "
"'\n"
"	db	'cellspacing=\"0\" class=\"webvars\"&gt;', 0Ah\n"
"httplen	equ	$-http\n"
"left	db	'&lt;tr&gt;', 0Ah\n"
"	db	'&lt;td class=\"name\"&gt;&lt;tt&gt;'\n"
"leftlen	equ	$-left\n"
"middle	db	'&lt;/tt&gt;&lt;/td&gt;', 0Ah\n"
"	db	'&lt;td class=\"value\"&gt;&lt;tt&gt;&lt;b&gt;'\n"
"midlen	equ	$-middle\n"
"undef	db	'&lt;i&gt;(undefined)&lt;/i&gt;'\n"
"undeflen	equ	$-undef\n"
"right	db	'&lt;/b&gt;&lt;/tt&gt;&lt;/td&gt;', 0Ah\n"
"	db	'&lt;/tr&gt;', 0Ah\n"
"rightlen	equ	$-right\n"
"wrap	db	'&lt;/table&gt;', 0Ah\n"
"	db	'&lt;/div&gt;', 0Ah\n"
"	db	'&lt;/body&gt;', 0Ah\n"
"	db	'&lt;/html&gt;', 0Ah, 0Ah\n"
"wraplen	equ	$-wrap\n"
"\n"
"section	.text\n"
"global	_start\n"
"_start:\n"
"	; First, send out all the http and xhtml stuff that is\n"
"	; needed before we start showing the environment\n"
"	push	dword httplen\n"
"	push	dword http\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; Now find how far on the stack the environment pointers\n"
"	; are. We have 12 bytes we have pushed before \"argc\"\n"
"	mov	eax, [esp+12]\n"
"\n"
"	; We need to remove the following from the stack:\n"
"	;\n"
"	;	The 12 bytes we pushed for sys.write\n"
"	;	The  4 bytes of argc\n"
"	;	The EAX*4 bytes of argv\n"
"	;	The  4 bytes of the NULL after argv\n"
"	;\n"
"	; Total:\n"
"	;	20 + eax * 4\n"
"	;\n"
"	; Because stack grows down, we need to ADD that many bytes\n"
"	; to ESP.\n"
"	lea	esp, [esp+20+eax*4]\n"
"	cld		; This should already be the case, but let's be sure.\n"
"\n"
"	; Loop through the environment, printing it out\n"
".loop:\n"
"	pop	edi\n"
"	or	edi, edi	; Done yet?\n"
"	je	near .wrap\n"
"\n"
"	; Print the left part of HTML\n"
"	push	dword leftlen\n"
"	push	dword left\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; It may be tempting to search for the '=' in the env string next.\n"
"	; But it is possible there is no '=', so we search for the\n"
"	; terminating NUL first.\n"
"	mov	esi, edi	; Save start of string\n"
"	sub	ecx, ecx\n"
"	not	ecx		; ECX = FFFFFFFF\n"
"	sub	eax, eax\n"
"repne	scasb\n"
"	not	ecx		; ECX = string length + 1\n"
"	mov	ebx, ecx	; Save it in EBX\n"
"\n"
"	; Now is the time to find '='\n"
"	mov	edi, esi	; Start of string\n"
"	mov	al, '='\n"
"repne	scasb\n"
"	not	ecx\n"
"	add	ecx, ebx	; Length of name\n"
"\n"
"	push	ecx\n"
"	push	esi\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; Print the middle part of HTML table code\n"
"	push	dword midlen\n"
"	push	dword middle\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; Find the length of the value\n"
"	not	ecx\n"
"	lea	ebx, [ebx+ecx-1]\n"
"\n"
"	; Print \"undefined\" if 0\n"
"	or	ebx, ebx\n"
"	jne	.value\n"
"\n"
"	mov	ebx, undeflen\n"
"	mov	edi, undef\n"
"\n"
".value:\n"
"	push	ebx\n"
"	push	edi\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; Print the right part of the table row\n"
"	push	dword rightlen\n"
"	push	dword right\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; Get rid of the 60 bytes we have pushed\n"
"	add	esp, byte 60\n"
"\n"
"	; Get the next variable\n"
"	jmp	.loop\n"
"\n"
".wrap:\n"
"	; Print the rest of HTML\n"
"	push	dword wraplen\n"
"	push	dword wrap\n"
"	push	dword stdout\n"
"	sys.write\n"
"\n"
"	; Return success\n"
"	push	dword 0\n"
"	sys.exit\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11160
msgid ""
"This code produces a 1,396-byte executable. Most of it is data, i.e., the "
"<acronym>HTML</acronym> mark-up we need to send out."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11165
msgid "Assemble and link it as usual:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:11169
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>nasm -f elf webvars.asm</userinput>\n"
"<prompt>%</prompt> <userinput>ld -s -o webvars webvars.o</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11172
msgid ""
"To use it, you need to upload <filename>webvars</filename> to your web "
"server. Depending on how your web server is set up, you may have to store it "
"in a special <filename>cgi-bin</filename> directory, or perhaps rename it "
"with a <filename>.cgi</filename> extension."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11179
msgid ""
"Then you need to use your browser to view its output. To see its output on "
"my web server, please go to <link xlink:href=\"http://www.int80h.org/webvars/"
"\"><filename>http://www.int80h.org/webvars/</filename></link>. If curious "
"about the additional environment variables present in a password protected "
"web directory, go to <link xlink:href=\"http://www.int80h.org/private/"
"\"><filename>http://www.int80h.org/private/</filename></link>, using the "
"name <userinput>asm</userinput> and password <userinput>programmer</"
"userinput>."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:11197
msgid "Working with Files"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11199
msgid ""
"We have already done some basic file work: We know how to open and close "
"them, how to read and write them using buffers. But <trademark class="
"\"registered\">UNIX</trademark> offers much more functionality when it comes "
"to files. We will examine some of it in this section, and end up with a nice "
"file conversion utility."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11207
msgid ""
"Indeed, let us start at the end, that is, with the file conversion utility. "
"It always makes programming easier when we know from the start what the end "
"product is supposed to do."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11214
msgid ""
"One of the first programs I wrote for <trademark class=\"registered\">UNIX</"
"trademark> was <link xlink:href=\"ftp://ftp.int80h.org/unix/tuc/"
"\"><application>tuc</application></link>, a text-to-<trademark class="
"\"registered\">UNIX</trademark> file converter. It converts a text file from "
"other operating systems to a <trademark class=\"registered\">UNIX</"
"trademark> text file. In other words, it changes from different kind of line "
"endings to the newline convention of <trademark class=\"registered\">UNIX</"
"trademark>. It saves the output in a different file. Optionally, it converts "
"a <trademark class=\"registered\">UNIX</trademark> text file to a "
"<acronym>DOS</acronym> text file."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11225
msgid ""
"I have used <application>tuc</application> extensively, but always only to "
"convert from some other <acronym>OS</acronym> to <trademark class="
"\"registered\">UNIX</trademark>, never the other way. I have always wished "
"it would just overwrite the file instead of me having to send the output to "
"a different file. Most of the time, I end up using it like this:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:11234
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>tuc <replaceable>myfile tempfile</"
"replaceable></userinput>\n"
"<prompt>%</prompt> <userinput>mv <replaceable>tempfile myfile</replaceable></"
"userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11237
msgid ""
"It would be nice to have a <application>ftuc</application>, i.e., "
"<emphasis>fast tuc</emphasis>, and use it like this:"
msgstr ""

#. (itstool) path: sect1/screen
#: book.translate.xml:11242
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>ftuc <replaceable>myfile</replaceable></"
"userinput>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11244
msgid ""
"In this chapter, then, we will write <application>ftuc</application> in "
"assembly language (the original <application>tuc</application> is in C), and "
"study various file-oriented kernel services in the process."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11252
msgid ""
"At first sight, such a file conversion is very simple: All you have to do is "
"strip the carriage returns, right?"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11258
msgid ""
"If you answered yes, think again: That approach will work most of the time "
"(at least with <acronym>MS DOS</acronym> text files), but will fail "
"occasionally."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11264
msgid ""
"The problem is that not all non <trademark class=\"registered\">UNIX</"
"trademark> text files end their line with the carriage return / line feed "
"sequence. Some use carriage returns without line feeds. Others combine "
"several blank lines into a single carriage return followed by several line "
"feeds. And so on."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11272
msgid ""
"A text file converter, then, must be able to handle any possible line "
"endings:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11279
msgid "carriage return / line feed"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11285
msgid "carriage return"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11291
msgid "line feed / carriage return"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11297
msgid "line feed"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:11303
msgid ""
"It should also handle files that use some kind of a combination of the above "
"(e.g., carriage return followed by several line feeds)."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:11310
msgid "Finite State Machine"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11312
msgid ""
"The problem is easily solved by the use of a technique called "
"<emphasis>finite state machine</emphasis>, originally developed by the "
"designers of digital electronic circuits. A <emphasis>finite state machine</"
"emphasis> is a digital circuit whose output is dependent not only on its "
"input but on its previous input, i.e., on its state. The microprocessor is "
"an example of a <emphasis>finite state machine</emphasis>: Our assembly "
"language code is assembled to machine language in which some assembly "
"language code produces a single byte of machine language, while others "
"produce several bytes. As the microprocessor fetches the bytes from the "
"memory one by one, some of them simply change its state rather than produce "
"some output. When all the bytes of the op code are fetched, the "
"microprocessor produces some output, or changes the value of a register, etc."
""
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11330
msgid ""
"Because of that, all software is essentially a sequence of state "
"instructions for the microprocessor. Nevertheless, the concept of "
"<emphasis>finite state machine</emphasis> is useful in software design as "
"well."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11336
msgid ""
"Our text file converter can be designed as a <emphasis>finite state machine</"
"emphasis> with three possible states. We could call them states 0-2, but it "
"will make our life easier if we give them symbolic names:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11344
msgid "<symbol>ordinary </symbol>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11350
msgid "<symbol>cr </symbol>"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11356
msgid "<symbol>lf </symbol>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11362
msgid ""
"Our program will start in the <symbol>ordinary</symbol> state. During this "
"state, the program action depends on its input as follows:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11370
msgid ""
"If the input is anything other than a carriage return or line feed, the "
"input is simply passed on to the output. The state remains unchanged."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11378
msgid ""
"If the input is a carriage return, the state is changed to <symbol>cr</"
"symbol>. The input is then discarded, i.e., no output is made."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11386
msgid ""
"If the input is a line feed, the state is changed to <symbol>lf</symbol>. "
"The input is then discarded."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11393
msgid ""
"Whenever we are in the <symbol>cr</symbol> state, it is because the last "
"input was a carriage return, which was unprocessed. What our software does "
"in this state again depends on the current input:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11402
msgid ""
"If the input is anything other than a carriage return or line feed, output a "
"line feed, then output the input, then change the state to <symbol>ordinary</"
"symbol>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11410
msgid ""
"If the input is a carriage return, we have received two (or more) carriage "
"returns in a row. We discard the input, we output a line feed, and leave the "
"state unchanged."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11418
msgid ""
"If the input is a line feed, we output the line feed and change the state to "
"<symbol>ordinary</symbol>. Note that this is not the same as the first case "
"above – if we tried to combine them, we would be outputting two line feeds "
"instead of one."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11428
msgid ""
"Finally, we are in the <symbol>lf</symbol> state after we have received a "
"line feed that was not preceded by a carriage return. This will happen when "
"our file already is in <trademark class=\"registered\">UNIX</trademark> "
"format, or whenever several lines in a row are expressed by a single "
"carriage return followed by several line feeds, or when line ends with a "
"line feed / carriage return sequence. Here is how we need to handle our "
"input in this state:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11441
msgid ""
"If the input is anything other than a carriage return or line feed, we "
"output a line feed, then output the input, then change the state to "
"<symbol>ordinary</symbol>. This is exactly the same action as in the "
"<symbol>cr</symbol> state upon receiving the same kind of input."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11451
msgid ""
"If the input is a carriage return, we discard the input, we output a line "
"feed, then change the state to <symbol>ordinary</symbol>."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:11458
msgid ""
"If the input is a line feed, we output the line feed, and leave the state "
"unchanged."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:11466
msgid "The Final State"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11468
msgid ""
"The above <emphasis>finite state machine</emphasis> works for the entire "
"file, but leaves the possibility that the final line end will be ignored. "
"That will happen whenever the file ends with a single carriage return or a "
"single line feed. I did not think of it when I wrote <application>tuc</"
"application>, just to discover that occasionally it strips the last line "
"ending."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11477
msgid ""
"This problem is easily fixed by checking the state after the entire file was "
"processed. If the state is not <symbol>ordinary</symbol>, we simply need to "
"output one last line feed."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:11485
msgid ""
"Now that we have expressed our algorithm as a <emphasis>finite state "
"machine</emphasis>, we could easily design a dedicated digital electronic "
"circuit (a \"chip\") to do the conversion for us. Of course, doing so would "
"be considerably more expensive than writing an assembly language program."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:11497
msgid "The Output Counter"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:11499
msgid ""
"Because our file conversion program may be combining two characters into "
"one, we need to use an output counter. We initialize it to <constant>0</"
"constant>, and increase it every time we send a character to the output. At "
"the end of the program, the counter will tell us what size we need to set "
"the file to."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:11513
msgid "Implementing FSM in Software"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11515
msgid ""
"The hardest part of working with a <emphasis>finite state machine</emphasis> "
"is analyzing the problem and expressing it as a <emphasis>finite state "
"machine</emphasis>. That accomplished, the software almost writes itself."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11522
msgid ""
"In a high-level language, such as C, there are several main approaches. One "
"is to use a <function role=\"statement\">switch</function> statement which "
"chooses what function should be run. For example,"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11528
#, no-wrap
msgid ""
"\n"
"	switch (state) {\n"
"	default:\n"
"	case REGULAR:\n"
"		regular(inputchar);\n"
"		break;\n"
"	case CR:\n"
"		cr(inputchar);\n"
"		break;\n"
"	case LF:\n"
"		lf(inputchar);\n"
"		break;\n"
"	}\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11543
msgid ""
"Another approach is by using an array of function pointers, something like "
"this:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11548
#, no-wrap
msgid "\n"
"	(output[state])(inputchar);\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11552
msgid ""
"Yet another is to have <varname>state</varname> be a function pointer, set "
"to point at the appropriate function:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11557
#, no-wrap
msgid "\n"
"	(*state)(inputchar);\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11560
msgid ""
"This is the approach we will use in our program because it is very easy to "
"do in assembly language, and very fast, too. We will simply keep the address "
"of the right procedure in <varname role=\"register\">EBX</varname>, and then "
"just issue:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11563
#, no-wrap
msgid "\n"
"	call	ebx\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11567
msgid ""
"This is possibly faster than hardcoding the address in the code because the "
"microprocessor does not have to fetch the address from the memory—it is "
"already stored in one of its registers. I said <emphasis>possibly</emphasis> "
"because with the caching modern microprocessors do, either way may be "
"equally fast."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:11578
msgid "Memory Mapped Files"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11580
msgid ""
"Because our program works on a single file, we cannot use the approach that "
"worked for us before, i.e., to read from an input file and to write to an "
"output file."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11586
msgid ""
"<trademark class=\"registered\">UNIX</trademark> allows us to map a file, or "
"a section of a file, into memory. To do that, we first need to open the file "
"with the appropriate read/write flags. Then we use the <function role="
"\"syscall\">mmap</function> system call to map it into the memory. One nice "
"thing about <function role=\"syscall\">mmap</function> is that it "
"automatically works with virtual memory: We can map more of the file into "
"the memory than we have physical memory available, yet still access it "
"through regular memory op codes, such as <function role=\"opcode\">mov</"
"function>, <function role=\"opcode\">lods</function>, and <function role="
"\"opcode\">stos</function>. Whatever changes we make to the memory image of "
"the file will be written to the file by the system. We do not even have to "
"keep the file open: As long as it stays mapped, we can read from it and "
"write to it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11602
msgid ""
"The 32-bit Intel microprocessors can access up to four gigabytes of memory – "
"physical or virtual. The FreeBSD system allows us to use up to a half of it "
"for file mapping."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11608
msgid ""
"For simplicity sake, in this tutorial we will only convert files that can be "
"mapped into the memory in their entirety. There are probably not too many "
"text files that exceed two gigabytes in size. If our program encounters one, "
"it will simply display a message suggesting we use the original "
"<application>tuc</application> instead."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11617
msgid ""
"If you examine your copy of <filename>syscalls.master</filename>, you will "
"find two separate syscalls named <function role=\"syscall\">mmap</function>. "
"This is because of evolution of <trademark class=\"registered\">UNIX</"
"trademark>: There was the traditional <acronym>BSD</acronym> <function role="
"\"syscall\">mmap</function>, syscall 71. That one was superseded by the "
"<acronym><trademark class=\"registered\">POSIX</trademark></acronym> "
"<function role=\"syscall\">mmap</function>, syscall 197. The FreeBSD system "
"supports both because older programs were written by using the original "
"<acronym>BSD</acronym> version. But new software uses the "
"<acronym><trademark class=\"registered\">POSIX</trademark></acronym> "
"version, which is what we will use."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11629
msgid ""
"The <filename>syscalls.master</filename> file lists the <acronym><trademark "
"class=\"registered\">POSIX</trademark></acronym> version like this:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11634
#, no-wrap
msgid ""
"\n"
"197	STD	BSD	{ caddr_t mmap(caddr_t addr, size_t len, int prot, \\\n"
"			    int flags, int fd, long pad, off_t pos); }\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11639
msgid ""
"This differs slightly from what <citerefentry><refentrytitle>mmap</"
"refentrytitle><manvolnum>2</manvolnum></citerefentry> says. That is because "
"<citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></"
"citerefentry> describes the C version."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11647
msgid ""
"The difference is in the <varname>long pad</varname> argument, which is not "
"present in the C version. However, the FreeBSD syscalls add a 32-bit pad "
"after <function role=\"opcode\">push</function>ing a 64-bit argument. In "
"this case, <varname>off_t</varname> is a 64-bit value."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11650
msgid ""
"When we are finished working with a memory-mapped file, we unmap it with the "
"<function role=\"syscall\">munmap</function> syscall:"
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:11656
msgid ""
"For an in-depth treatment of <function role=\"syscall\">mmap</function>, see "
"W. Richard Stevens' <link xlink:href=\"http://www.int80h.org/cgi-bin/"
"isbn?isbn=0130810819\">Unix Network Programming, Volume 2, Chapter 12</link>."
""
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:11667
msgid "Determining File Size"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11669
msgid ""
"Because we need to tell <function role=\"syscall\">mmap</function> how many "
"bytes of the file to map into the memory, and because we want to map the "
"entire file, we need to determine the size of the file."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11675
msgid ""
"We can use the <function role=\"syscall\">fstat</function> syscall to get "
"all the information about an open file that the system can give us. That "
"includes the file size."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11681
msgid ""
"Again, <filename>syscalls.master</filename> lists two versions of <function "
"role=\"syscall\">fstat</function>, a traditional one (syscall 62), and a "
"<acronym><trademark class=\"registered\">POSIX</trademark></acronym> one "
"(syscall 189). Naturally, we will use the <acronym><trademark class="
"\"registered\">POSIX</trademark></acronym> version:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11689
#, no-wrap
msgid "\n"
"189	STD	POSIX	{ int fstat(int fd, struct stat *sb); }\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11693
msgid ""
"This is a very straightforward call: We pass to it the address of a <varname "
"remap=\"structname\">stat</varname> structure and the descriptor of an open "
"file. It will fill out the contents of the <varname remap="
"\"structname\">stat</varname> structure."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11700
msgid ""
"I do, however, have to say that I tried to declare the <varname remap="
"\"structname\">stat</varname> structure in the <varname>.bss</varname> "
"section, and <function role=\"syscall\">fstat</function> did not like it: It "
"set the carry flag indicating an error. After I changed the code to allocate "
"the structure on the stack, everything was working fine."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:11712
msgid "Changing the File Size"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11714
msgid ""
"Because our program may combine carriage return / line feed sequences into "
"straight line feeds, our output may be smaller than our input. However, "
"since we are placing our output into the same file we read the input from, "
"we may have to change the size of the file."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11722
msgid ""
"The <function role=\"syscall\">ftruncate</function> system call allows us to "
"do just that. Despite its somewhat misleading name, the <function role="
"\"syscall\">ftruncate</function> system call can be used to both truncate "
"the file (make it smaller) and to grow it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11729
msgid ""
"And yes, we will find two versions of <function role=\"syscall\">ftruncate</"
"function> in <filename>syscalls.master</filename>, an older one (130), and a "
"newer one (201). We will use the newer one:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11736
#, no-wrap
msgid "\n"
"201	STD	BSD	{ int ftruncate(int fd, int pad, off_t length); }\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11740
msgid "Please note that this one contains a <varname>int pad</varname> again."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:11747
msgid "ftuc"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11749
msgid ""
"We now know everything we need to write <application>ftuc</application>. We "
"start by adding some new lines in <filename>system.inc</filename>. First, we "
"define some constants and structures, somewhere at or near the beginning of "
"the file:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11756
#, no-wrap
msgid ""
"\n"
";;;;;;; open flags\n"
"%define	O_RDONLY	0\n"
"%define	O_WRONLY	1\n"
"%define	O_RDWR	2\n"
"\n"
";;;;;;; mmap flags\n"
"%define	PROT_NONE	0\n"
"%define	PROT_READ	1\n"
"%define	PROT_WRITE	2\n"
"%define	PROT_EXEC	4\n"
";;\n"
"%define	MAP_SHARED	0001h\n"
"%define	MAP_PRIVATE	0002h\n"
"\n"
";;;;;;; stat structure\n"
"struc	stat\n"
"st_dev		resd	1	; = 0\n"
"st_ino		resd	1	; = 4\n"
"st_mode		resw	1	; = 8, size is 16 bits\n"
"st_nlink	resw	1	; = 10, ditto\n"
"st_uid		resd	1	; = 12\n"
"st_gid		resd	1	; = 16\n"
"st_rdev		resd	1	; = 20\n"
"st_atime	resd	1	; = 24\n"
"st_atimensec	resd	1	; = 28\n"
"st_mtime	resd	1	; = 32\n"
"st_mtimensec	resd	1	; = 36\n"
"st_ctime	resd	1	; = 40\n"
"st_ctimensec	resd	1	; = 44\n"
"st_size		resd	2	; = 48, size is 64 bits\n"
"st_blocks	resd	2	; = 56, ditto\n"
"st_blksize	resd	1	; = 64\n"
"st_flags	resd	1	; = 68\n"
"st_gen		resd	1	; = 72\n"
"st_lspare	resd	1	; = 76\n"
"st_qspare	resd	4	; = 80\n"
"endstruc\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11796
msgid "We define the new syscalls:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11800
#, no-wrap
msgid ""
"\n"
"%define	SYS_mmap	197\n"
"%define	SYS_munmap	73\n"
"%define	SYS_fstat	189\n"
"%define	SYS_ftruncate	201\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11807
msgid "We add the macros for their use:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11811
#, no-wrap
msgid ""
"\n"
"%macro	sys.mmap	0\n"
"	system	SYS_mmap\n"
"%endmacro\n"
"\n"
"%macro	sys.munmap	0\n"
"	system	SYS_munmap\n"
"%endmacro\n"
"\n"
"%macro	sys.ftruncate	0\n"
"	system	SYS_ftruncate\n"
"%endmacro\n"
"\n"
"%macro	sys.fstat	0\n"
"	system	SYS_fstat\n"
"%endmacro\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:11829
msgid "And here is our code:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:11833
#, no-wrap
msgid ""
"\n"
";;;;;;; Fast Text-to-Unix Conversion (ftuc.asm) "
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
";;\n"
";; Started:	21-Dec-2000\n"
";; Updated:	22-Dec-2000\n"
";;\n"
";; Copyright 2000 G. Adam Stanislav.\n"
";; All rights reserved.\n"
";;\n"
";;;;;;; v.1 "
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
"%include	'system.inc'\n"
"\n"
"section	.data\n"
"	db	'Copyright 2000 G. Adam Stanislav.', 0Ah\n"
"	db	'All rights reserved.', 0Ah\n"
"usg	db	'Usage: ftuc filename', 0Ah\n"
"usglen	equ	$-usg\n"
"co	db	\"ftuc: Can't open file.\", 0Ah\n"
"colen	equ	$-co\n"
"fae	db	'ftuc: File access error.', 0Ah\n"
"faelen	equ	$-fae\n"
"ftl	db	'ftuc: File too long, use regular tuc instead.', 0Ah\n"
"ftllen	equ	$-ftl\n"
"mae	db	'ftuc: Memory allocation error.', 0Ah\n"
"maelen	equ	$-mae\n"
"\n"
"section	.text\n"
"\n"
"align 4\n"
"memerr:\n"
"	push	dword maelen\n"
"	push	dword mae\n"
"	jmp	short error\n"
"\n"
"align 4\n"
"toolong:\n"
"	push	dword ftllen\n"
"	push	dword ftl\n"
"	jmp	short error\n"
"\n"
"align 4\n"
"facerr:\n"
"	push	dword faelen\n"
"	push	dword fae\n"
"	jmp	short error\n"
"\n"
"align 4\n"
"cantopen:\n"
"	push	dword colen\n"
"	push	dword co\n"
"	jmp	short error\n"
"\n"
"align 4\n"
"usage:\n"
"	push	dword usglen\n"
"	push	dword usg\n"
"\n"
"error:\n"
"	push	dword stderr\n"
"	sys.write\n"
"\n"
"	push	dword 1\n"
"	sys.exit\n"
"\n"
"align 4\n"
"global	_start\n"
"_start:\n"
"	pop	eax		; argc\n"
"	pop	eax		; program name\n"
"	pop	ecx		; file to convert\n"
"	jecxz	usage\n"
"\n"
"	pop	eax\n"
"	or	eax, eax	; Too many arguments?\n"
"	jne	usage\n"
"\n"
"	; Open the file\n"
"	push	dword O_RDWR\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	cantopen\n"
"\n"
"	mov	ebp, eax	; Save fd\n"
"\n"
"	sub	esp, byte stat_size\n"
"	mov	ebx, esp\n"
"\n"
"	; Find file size\n"
"	push	ebx\n"
"	push	ebp		; fd\n"
"	sys.fstat\n"
"	jc	facerr\n"
"\n"
"	mov	edx, [ebx + st_size + 4]\n"
"\n"
"	; File is too long if EDX != 0 ...\n"
"	or	edx, edx\n"
"	jne	near toolong\n"
"	mov	ecx, [ebx + st_size]\n"
"	; ... or if it is above 2 GB\n"
"	or	ecx, ecx\n"
"	js	near toolong\n"
"\n"
"	; Do nothing if the file is 0 bytes in size\n"
"	jecxz	.quit\n"
"\n"
"	; Map the entire file in memory\n"
"	push	edx\n"
"	push	edx		; starting at offset 0\n"
"	push	edx		; pad\n"
"	push	ebp		; fd\n"
"	push	dword MAP_SHARED\n"
"	push	dword PROT_READ | PROT_WRITE\n"
"	push	ecx		; entire file size\n"
"	push	edx		; let system decide on the address\n"
"	sys.mmap\n"
"	jc	near memerr\n"
"\n"
"	mov	edi, eax\n"
"	mov	esi, eax\n"
"	push	ecx		; for SYS_munmap\n"
"	push	edi\n"
"\n"
"	; Use EBX for state machine\n"
"	mov	ebx, ordinary\n"
"	mov	ah, 0Ah\n"
"	cld\n"
"\n"
".loop:\n"
"	lodsb\n"
"	call	ebx\n"
"	loop	.loop\n"
"\n"
"	cmp	ebx, ordinary\n"
"	je	.filesize\n"
"\n"
"	; Output final lf\n"
"	mov	al, ah\n"
"	stosb\n"
"	inc	edx\n"
"\n"
".filesize:\n"
"	; truncate file to new size\n"
"	push	dword 0		; high dword\n"
"	push	edx		; low dword\n"
"	push	eax		; pad\n"
"	push	ebp\n"
"	sys.ftruncate\n"
"\n"
"	; close it (ebp still pushed)\n"
"	sys.close\n"
"\n"
"	add	esp, byte 16\n"
"	sys.munmap\n"
"\n"
".quit:\n"
"	push	dword 0\n"
"	sys.exit\n"
"\n"
"align 4\n"
"ordinary:\n"
"	cmp	al, 0Dh\n"
"	je	.cr\n"
"\n"
"	cmp	al, ah\n"
"	je	.lf\n"
"\n"
"	stosb\n"
"	inc	edx\n"
"	ret\n"
"\n"
"align 4\n"
".cr:\n"
"	mov	ebx, cr\n"
"	ret\n"
"\n"
"align 4\n"
".lf:\n"
"	mov	ebx, lf\n"
"	ret\n"
"\n"
"align 4\n"
"cr:\n"
"	cmp	al, 0Dh\n"
"	je	.cr\n"
"\n"
"	cmp	al, ah\n"
"	je	.lf\n"
"\n"
"	xchg	al, ah\n"
"	stosb\n"
"	inc	edx\n"
"\n"
"	xchg	al, ah\n"
"	; fall through\n"
"\n"
".lf:\n"
"	stosb\n"
"	inc	edx\n"
"	mov	ebx, ordinary\n"
"	ret\n"
"\n"
"align 4\n"
".cr:\n"
"	mov	al, ah\n"
"	stosb\n"
"	inc	edx\n"
"	ret\n"
"\n"
"align 4\n"
"lf:\n"
"	cmp	al, ah\n"
"	je	.lf\n"
"\n"
"	cmp	al, 0Dh\n"
"	je	.cr\n"
"\n"
"	xchg	al, ah\n"
"	stosb\n"
"	inc	edx\n"
"\n"
"	xchg	al, ah\n"
"	stosb\n"
"	inc	edx\n"
"	mov	ebx, ordinary\n"
"	ret\n"
"\n"
"align 4\n"
".cr:\n"
"	mov	ebx, ordinary\n"
"	mov	al, ah\n"
"	; fall through\n"
"\n"
".lf:\n"
"	stosb\n"
"	inc	edx\n"
"	ret\n"
msgstr ""

#. (itstool) path: warning/para
#: book.translate.xml:12072
msgid ""
"Do not use this program on files stored on a disk formatted by "
"<acronym><trademark class=\"registered\">MS-DOS</trademark></acronym> or "
"<trademark class=\"registered\">Windows</trademark>. There seems to be a "
"subtle bug in the FreeBSD code when using <function role=\"syscall\">mmap</"
"function> on these drives mounted under FreeBSD: If the file is over a "
"certain size, <function role=\"syscall\">mmap</function> will just fill the "
"memory with zeros, and then copy them to the file overwriting its contents."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:12087
msgid "One-Pointed Mind"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:12089
msgid ""
"As a student of Zen, I like the idea of a one-pointed mind: Do one thing at "
"a time, and do it well."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:12094
msgid ""
"This, indeed, is very much how <trademark class=\"registered\">UNIX</"
"trademark> works as well. While a typical <trademark class="
"\"registered\">Windows</trademark> application is attempting to do "
"everything imaginable (and is, therefore, riddled with bugs), a typical "
"<trademark class=\"registered\">UNIX</trademark> program does only one "
"thing, and it does it well."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:12102
msgid ""
"The typical <trademark class=\"registered\">UNIX</trademark> user then "
"essentially assembles his own applications by writing a shell script which "
"combines the various existing programs by piping the output of one program "
"to the input of another."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:12109
msgid ""
"When writing your own <trademark class=\"registered\">UNIX</trademark> "
"software, it is generally a good idea to see what parts of the problem you "
"need to solve can be handled by existing programs, and only write your own "
"programs for that part of the problem that you do not have an existing "
"solution for."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:12117
msgid "CSV"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12119
msgid ""
"I will illustrate this principle with a specific real-life example I was "
"faced with recently:"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12124
msgid ""
"I needed to extract the 11th field of each record from a database I "
"downloaded from a web site. The database was a <acronym>CSV</acronym> file, "
"i.e., a list of <emphasis>comma-separated values</emphasis>. That is quite a "
"standard format for sharing data among people who may be using different "
"database software."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12133
msgid ""
"The first line of the file contains the list of various fields separated by "
"commas. The rest of the file contains the data listed line by line, with "
"values separated by commas."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12139
msgid ""
"I tried <application>awk</application>, using the comma as a separator. But "
"because several lines contained a quoted comma, <application>awk</"
"application> was extracting the wrong field from those lines."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12146
msgid ""
"Therefore, I needed to write my own software to extract the 11th field from "
"the <acronym>CSV</acronym> file. However, going with the <trademark class="
"\"registered\">UNIX</trademark> spirit, I only needed to write a simple "
"filter that would do the following:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:12155
msgid "Remove the first line from the file;"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:12161
msgid "Change all unquoted commas to a different character;"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:12167
msgid "Remove all quotation marks."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12173
msgid ""
"Strictly speaking, I could use <application>sed</application> to remove the "
"first line from the file, but doing so in my own program was very easy, so I "
"decided to do it and reduce the size of the pipeline."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12180
msgid ""
"At any rate, writing a program like this took me about 20 minutes. Writing a "
"program that extracts the 11th field from the <acronym>CSV</acronym> file "
"would take a lot longer, and I could not reuse it to extract some other "
"field from some other database."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12188
msgid ""
"This time I decided to let it do a little more work than a typical tutorial "
"program would:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:12195
msgid "It parses its command line for options;"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:12201
msgid "It displays proper usage if it finds wrong arguments;"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:12207
msgid "It produces meaningful error messages."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12213
msgid "Here is its usage message:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:12217
#, no-wrap
msgid ""
"Usage: csv [-t&lt;delim&gt;] [-c&lt;comma&gt;] [-p] [-o &lt;outfile&gt;] [-i "
"&lt;infile&gt;]"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12219
msgid "All parameters are optional, and can appear in any order."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12223
msgid ""
"The <parameter>-t</parameter> parameter declares what to replace the commas "
"with. The <constant>tab</constant> is the default here. For example, "
"<parameter>-t;</parameter> will replace all unquoted commas with semicolons."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12230
msgid ""
"I did not need the <parameter>-c</parameter> option, but it may come in "
"handy in the future. It lets me declare that I want a character other than a "
"comma replaced with something else. For example, <parameter>-c@</parameter> "
"will replace all at signs (useful if you want to split a list of email "
"addresses to their user names and domains)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12239
msgid ""
"The <parameter>-p</parameter> option preserves the first line, i.e., it does "
"not delete it. By default, we delete the first line because in a "
"<acronym>CSV</acronym> file it contains the field names rather than data."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12246
msgid ""
"The <parameter>-i</parameter> and <parameter>-o</parameter> options let me "
"specify the input and the output files. Defaults are <filename>stdin</"
"filename> and <filename>stdout</filename>, so this is a regular <trademark "
"class=\"registered\">UNIX</trademark> filter."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12253
msgid ""
"I made sure that both <parameter>-i filename</parameter> and <parameter>-"
"ifilename</parameter> are accepted. I also made sure that only one input and "
"one output files may be specified."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12260
msgid "To get the 11th field of each record, I can now do:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:12264
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>csv '-t;' <replaceable>data.csv</replaceable> "
"| awk '-F;' '{print $11}'</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12266
msgid ""
"The code stores the options (except for the file descriptors) in <varname "
"role=\"register\">EDX</varname>: The comma in <varname role=\"register\">DH</"
"varname>, the new separator in <varname role=\"register\">DL</varname>, and "
"the flag for the <parameter>-p</parameter> option in the highest bit of "
"<varname role=\"register\">EDX</varname>, so a check for its sign will give "
"us a quick decision what to do."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12275
msgid "Here is the code:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:12279
#, no-wrap
msgid ""
"\n"
";;;;;;; csv.asm "
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
";\n"
"; Convert a comma-separated file to a something-else separated file.\n"
";\n"
"; Started:	31-May-2001\n"
"; Updated:	 1-Jun-2001\n"
";\n"
"; Copyright (c) 2001 G. Adam Stanislav\n"
"; All rights reserved.\n"
";\n"
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
"\n"
"%include	'system.inc'\n"
"\n"
"%define	BUFSIZE	2048\n"
"\n"
"section	.data\n"
"fd.in	dd	stdin\n"
"fd.out	dd	stdout\n"
"usg	db	'Usage: csv [-t&lt;delim&gt;] [-c&lt;comma&gt;] [-p] [-o "
"&lt;outfile&gt;] [-i &lt;infile&gt;]', 0Ah\n"
"usglen	equ	$-usg\n"
"iemsg	db	\"csv: Can't open input file\", 0Ah\n"
"iemlen	equ	$-iemsg\n"
"oemsg	db	\"csv: Can't create output file\", 0Ah\n"
"oemlen	equ	$-oemsg\n"
"\n"
"section .bss\n"
"ibuffer	resb	BUFSIZE\n"
"obuffer	resb	BUFSIZE\n"
"\n"
"section	.text\n"
"align 4\n"
"ierr:\n"
"	push	dword iemlen\n"
"	push	dword iemsg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 1		; return failure\n"
"	sys.exit\n"
"\n"
"align 4\n"
"oerr:\n"
"	push	dword oemlen\n"
"	push	dword oemsg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 2\n"
"	sys.exit\n"
"\n"
"align 4\n"
"usage:\n"
"	push	dword usglen\n"
"	push	dword usg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 3\n"
"	sys.exit\n"
"\n"
"align 4\n"
"global	_start\n"
"_start:\n"
"	add	esp, byte 8	; discard argc and argv[0]\n"
"	mov	edx, (',' &lt;&lt; 8) | 9\n"
"\n"
".arg:\n"
"	pop	ecx\n"
"	or	ecx, ecx\n"
"	je	near .init		; no more arguments\n"
"\n"
"	; ECX contains the pointer to an argument\n"
"	cmp	byte [ecx], '-'\n"
"	jne	usage\n"
"\n"
"	inc	ecx\n"
"	mov	ax, [ecx]\n"
"\n"
".o:\n"
"	cmp	al, 'o'\n"
"	jne	.i\n"
"\n"
"	; Make sure we are not asked for the output file twice\n"
"	cmp	dword [fd.out], stdout\n"
"	jne	usage\n"
"\n"
"	; Find the path to output file - it is either at [ECX+1],\n"
"	; i.e., -ofile --\n"
"	; or in the next argument,\n"
"	; i.e., -o file\n"
"\n"
"	inc	ecx\n"
"	or	ah, ah\n"
"	jne	.openoutput\n"
"	pop	ecx\n"
"	jecxz	usage\n"
"\n"
".openoutput:\n"
"	push	dword 420	; file mode (644 octal)\n"
"	push	dword 0200h | 0400h | 01h\n"
"	; O_CREAT | O_TRUNC | O_WRONLY\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	near oerr\n"
"\n"
"	add	esp, byte 12\n"
"	mov	[fd.out], eax\n"
"	jmp	short .arg\n"
"\n"
".i:\n"
"	cmp	al, 'i'\n"
"	jne	.p\n"
"\n"
"	; Make sure we are not asked twice\n"
"	cmp	dword [fd.in], stdin\n"
"	jne	near usage\n"
"\n"
"	; Find the path to the input file\n"
"	inc	ecx\n"
"	or	ah, ah\n"
"	jne	.openinput\n"
"	pop	ecx\n"
"	or	ecx, ecx\n"
"	je near usage\n"
"\n"
".openinput:\n"
"	push	dword 0		; O_RDONLY\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	near ierr		; open failed\n"
"\n"
"	add	esp, byte 8\n"
"	mov	[fd.in], eax\n"
"	jmp	.arg\n"
"\n"
".p:\n"
"	cmp	al, 'p'\n"
"	jne	.t\n"
"	or	ah, ah\n"
"	jne	near usage\n"
"	or	edx, 1 &lt;&lt; 31\n"
"	jmp	.arg\n"
"\n"
".t:\n"
"	cmp	al, 't'		; redefine output delimiter\n"
"	jne	.c\n"
"	or	ah, ah\n"
"	je	near usage\n"
"	mov	dl, ah\n"
"	jmp	.arg\n"
"\n"
".c:\n"
"	cmp	al, 'c'\n"
"	jne	near usage\n"
"	or	ah, ah\n"
"	je	near usage\n"
"	mov	dh, ah\n"
"	jmp	.arg\n"
"\n"
"align 4\n"
".init:\n"
"	sub	eax, eax\n"
"	sub	ebx, ebx\n"
"	sub	ecx, ecx\n"
"	mov	edi, obuffer\n"
"\n"
"	; See if we are to preserve the first line\n"
"	or	edx, edx\n"
"	js	.loop\n"
"\n"
".firstline:\n"
"	; get rid of the first line\n"
"	call	getchar\n"
"	cmp	al, 0Ah\n"
"	jne	.firstline\n"
"\n"
".loop:\n"
"	; read a byte from stdin\n"
"	call	getchar\n"
"\n"
"	; is it a comma (or whatever the user asked for)?\n"
"	cmp	al, dh\n"
"	jne	.quote\n"
"\n"
"	; Replace the comma with a tab (or whatever the user wants)\n"
"	mov	al, dl\n"
"\n"
".put:\n"
"	call	putchar\n"
"	jmp	short .loop\n"
"\n"
".quote:\n"
"	cmp	al, '\"'\n"
"	jne	.put\n"
"\n"
"	; Print everything until you get another quote or EOL. If it\n"
"	; is a quote, skip it. If it is EOL, print it.\n"
".qloop:\n"
"	call	getchar\n"
"	cmp	al, '\"'\n"
"	je	.loop\n"
"\n"
"	cmp	al, 0Ah\n"
"	je	.put\n"
"\n"
"	call	putchar\n"
"	jmp	short .qloop\n"
"\n"
"align 4\n"
"getchar:\n"
"	or	ebx, ebx\n"
"	jne	.fetch\n"
"\n"
"	call	read\n"
"\n"
".fetch:\n"
"	lodsb\n"
"	dec	ebx\n"
"	ret\n"
"\n"
"read:\n"
"	jecxz	.read\n"
"	call	write\n"
"\n"
".read:\n"
"	push	dword BUFSIZE\n"
"	mov	esi, ibuffer\n"
"	push	esi\n"
"	push	dword [fd.in]\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	mov	ebx, eax\n"
"	or	eax, eax\n"
"	je	.done\n"
"	sub	eax, eax\n"
"	ret\n"
"\n"
"align 4\n"
".done:\n"
"	call	write		; flush output buffer\n"
"\n"
"	; close files\n"
"	push	dword [fd.in]\n"
"	sys.close\n"
"\n"
"	push	dword [fd.out]\n"
"	sys.close\n"
"\n"
"	; return success\n"
"	push	dword 0\n"
"	sys.exit\n"
"\n"
"align 4\n"
"putchar:\n"
"	stosb\n"
"	inc	ecx\n"
"	cmp	ecx, BUFSIZE\n"
"	je	write\n"
"	ret\n"
"\n"
"align 4\n"
"write:\n"
"	jecxz	.ret	; nothing to write\n"
"	sub	edi, ecx	; start of buffer\n"
"	push	ecx\n"
"	push	edi\n"
"	push	dword [fd.out]\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	sub	eax, eax\n"
"	sub	ecx, ecx	; buffer is empty now\n"
".ret:\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12553
msgid ""
"Much of it is taken from <filename>hex.asm</filename> above. But there is "
"one important difference: I no longer call <function>write</function> "
"whenever I am outputting a line feed. Yet, the code can be used "
"interactively."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12560
msgid ""
"I have found a better solution for the interactive problem since I first "
"started writing this chapter. I wanted to make sure each line is printed out "
"separately only when needed. After all, there is no need to flush out every "
"line when used non-interactively."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12568
msgid ""
"The new solution I use now is to call <function>write</function> every time "
"I find the input buffer empty. That way, when running in the interactive "
"mode, the program reads one line from the user's keyboard, processes it, and "
"sees its input buffer is empty. It flushes its output and reads the next "
"line."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:12577
msgid "The Dark Side of Buffering"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12578
msgid ""
"This change prevents a mysterious lockup in a very specific case. I refer to "
"it as the <emphasis>dark side of buffering</emphasis>, mostly because it "
"presents a danger that is not quite obvious."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12586
msgid ""
"It is unlikely to happen with a program like the <application>csv</"
"application> above, so let us consider yet another filter: In this case we "
"expect our input to be raw data representing color values, such as the "
"<emphasis>red</emphasis>, <emphasis>green</emphasis>, and <emphasis>blue</"
"emphasis> intensities of a pixel. Our output will be the negative of our "
"input."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12596
msgid ""
"Such a filter would be very simple to write. Most of it would look just like "
"all the other filters we have written so far, so I am only going to show you "
"its inner loop:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:12603
#, no-wrap
msgid ""
"\n"
".loop:\n"
"	call	getchar\n"
"	not	al		; Create a negative\n"
"	call	putchar\n"
"	jmp	short .loop\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12610
msgid ""
"Because this filter works with raw data, it is unlikely to be used "
"interactively."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12615
msgid ""
"But it could be called by image manipulation software. And, unless it calls "
"<function>write</function> before each call to <function>read</function>, "
"chances are it will lock up."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12621
msgid "Here is what might happen:"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12625
msgid ""
"The image editor will load our filter using the C function "
"<function>popen()</function>."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12630
msgid "It will read the first row of pixels from a bitmap or pixmap."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12635
msgid ""
"It will write the first row of pixels to the <emphasis>pipe</emphasis> "
"leading to the <varname>fd.in</varname> of our filter."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12641
msgid ""
"Our filter will read each pixel from its input, turn it to a negative, and "
"write it to its output buffer."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12647
msgid ""
"Our filter will call <function>getchar</function> to fetch the next pixel."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12652
msgid ""
"<function>getchar</function> will find an empty input buffer, so it will "
"call <function>read</function>."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12658
msgid ""
"<function>read</function> will call the <function role=\"syscall\">SYS_read</"
"function> system call."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12663
msgid ""
"The <emphasis>kernel</emphasis> will suspend our filter until the image "
"editor sends more data to the pipe."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12669
msgid ""
"The image editor will read from the other pipe, connected to the <varname>fd."
"out</varname> of our filter so it can set the first row of the output image "
"<emphasis>before</emphasis> it sends us the second row of the input."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:12677
msgid ""
"The <emphasis>kernel</emphasis> suspends the image editor until it receives "
"some output from our filter, so it can pass it on to the image editor."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12685
msgid ""
"At this point our filter waits for the image editor to send it more data to "
"process, while the image editor is waiting for our filter to send it the "
"result of the processing of the first row. But the result sits in our output "
"buffer."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12694
msgid ""
"The filter and the image editor will continue waiting for each other forever "
"(or, at least, until they are killed). Our software has just entered a <link "
"linkend=\"secure-race-conditions\">race condition</link>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12702
msgid ""
"This problem does not exist if our filter flushes its output buffer "
"<emphasis>before</emphasis> asking the <emphasis>kernel</emphasis> for more "
"input data."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:12715
msgid "Using the <acronym>FPU</acronym>"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:12716
msgid ""
"Strangely enough, most of assembly language literature does not even mention "
"the existence of the <acronym>FPU</acronym>, or <emphasis>floating point "
"unit</emphasis>, let alone discuss programming it."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:12723
msgid ""
"Yet, never does assembly language shine more than when we create highly "
"optimized <acronym>FPU</acronym> code by doing things that can be done "
"<emphasis>only</emphasis> in assembly language."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:12728
msgid "Organization of the <acronym>FPU</acronym>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12729
msgid ""
"The <acronym>FPU</acronym> consists of 8 80–bit floating–point registers. "
"These are organized in a stack fashion—you can <function>push</function> a "
"value on <acronym>TOS</acronym> (<emphasis>top of stack</emphasis>) and you "
"can <function>pop</function> it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12737
msgid ""
"That said, the assembly language op codes are not <function role="
"\"opcode\">push</function> and <function role=\"opcode\">pop</function> "
"because those are already taken."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12741
msgid ""
"You can <function>push</function> a value on <acronym>TOS</acronym> by using "
"<function role=\"opcode\">fld</function>, <function role=\"opcode\">fild</"
"function>, and <function role=\"opcode\">fbld</function>. Several other op "
"codes let you <function>push</function> many common <emphasis>constants</"
"emphasis>—such as <emphasis>pi</emphasis>—on the <acronym>TOS</acronym>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12750
msgid ""
"Similarly, you can <function>pop</function> a value by using <function role="
"\"opcode\">fst</function>, <function role=\"opcode\">fstp</function>, "
"<function role=\"opcode\">fist</function>, <function role=\"opcode\">fistp</"
"function>, and <function role=\"opcode\">fbstp</function>. Actually, only "
"the op codes that end with a <emphasis>p</emphasis> will literally "
"<function>pop</function> the value, the rest will <function>store</function> "
"it somewhere else without removing it from the <acronym>TOS</acronym>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12762
msgid ""
"We can transfer the data between the <acronym>TOS</acronym> and the computer "
"memory either as a 32–bit, 64–bit, or 80–bit <emphasis>real</emphasis>, a "
"16–bit, 32–bit, or 64–bit <emphasis>integer</emphasis>, or an 80–bit "
"<emphasis>packed decimal</emphasis>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12770
msgid ""
"The 80–bit <emphasis>packed decimal</emphasis> is a special case of "
"<emphasis>binary coded decimal</emphasis> which is very convenient when "
"converting between the <acronym>ASCII</acronym> representation of data and "
"the internal data of the <acronym>FPU</acronym>. It allows us to use 18 "
"significant digits."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12780
msgid ""
"No matter how we represent data in the memory, the <acronym>FPU</acronym> "
"always stores it in the 80–bit <emphasis>real</emphasis> format in its "
"registers."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12786
msgid ""
"Its internal precision is at least 19 decimal digits, so even if we choose "
"to display results as <acronym>ASCII</acronym> in the full 18–digit "
"precision, we are still showing correct results."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12794
msgid ""
"We can perform mathematical operations on the <acronym>TOS</acronym>: We can "
"calculate its <emphasis>sine</emphasis>, we can <emphasis>scale</emphasis> "
"it (i.e., we can multiply or divide it by a power of 2), we can calculate "
"its base–2 <emphasis>logarithm</emphasis>, and many other things."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12803
msgid ""
"We can also <emphasis>multiply</emphasis> or <emphasis>divide</emphasis> it "
"by, <emphasis>add</emphasis> it to, or <emphasis>subtract</emphasis> it "
"from, any of the <acronym>FPU</acronym> registers (including itself)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12811
msgid ""
"The official Intel op code for the <acronym>TOS</acronym> is <varname role="
"\"register\">st</varname>, and for the <emphasis>registers</emphasis> "
"<varname role=\"register\">st(0)</varname>–<varname role=\"register\">st(7)</"
"varname>. <varname role=\"register\">st</varname> and <varname role="
"\"register\">st(0)</varname>, then, refer to the same register."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12820
msgid ""
"For whatever reasons, the original author of <application>nasm</application> "
"has decided to use different op codes, namely <varname role="
"\"register\">st0</varname>–<varname role=\"register\">st7</varname>. In "
"other words, there are no parentheses, and the <acronym>TOS</acronym> is "
"always <varname role=\"register\">st0</varname>, never just <function role="
"\"opcode\">st</function>."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:12831
msgid "The Packed Decimal Format"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12832
msgid ""
"The <emphasis>packed decimal</emphasis> format uses 10 bytes (80 bits) of "
"memory to represent 18 digits. The number represented there is always an "
"<emphasis>integer</emphasis>."
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:12841
msgid ""
"You can use it to get decimal places by multiplying the <acronym>TOS</"
"acronym> by a power of 10 first."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12848
msgid ""
"The highest bit of the highest byte (byte 9) is the <emphasis>sign bit</"
"emphasis>: If it is set, the number is <emphasis>negative</emphasis>, "
"otherwise, it is <emphasis>positive</emphasis>. The rest of the bits of this "
"byte are unused/ignored."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12856
msgid ""
"The remaining 9 bytes store the 18 digits of the number: 2 digits per byte."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12860
msgid ""
"The <emphasis>more significant digit</emphasis> is stored in the high "
"<emphasis>nibble</emphasis> (4 bits), the <emphasis>less significant digit</"
"emphasis> in the low <emphasis>nibble</emphasis>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12867
msgid ""
"That said, you might think that <constant>-1234567</constant> would be "
"stored in the memory like this (using hexadecimal notation):"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:12873
#, no-wrap
msgid "\n"
"80 00 00 00 00 00 01 23 45 67\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12876
msgid ""
"Alas it is not! As with everything else of Intel make, even the "
"<emphasis>packed decimal</emphasis> is <emphasis>little–endian</emphasis>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12881
msgid "That means our <constant>-1234567</constant> is stored like this:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:12886
#, no-wrap
msgid "\n"
"67 45 23 01 00 00 00 00 00 80\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12889
msgid "Remember that, or you will be pulling your hair out in desperation!"
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:12895
msgid ""
"The book to read—if you can find it—is Richard Startz' <link xlink:href="
"\"http://www.amazon.com/exec/obidos/ASIN/013246604X/whizkidtechnomag\">8087/"
"80287/80387 for the IBM PC &amp; Compatibles</link>. Though it does seem to "
"take the fact about the little–endian storage of the <emphasis>packed "
"decimal</emphasis> for granted. I kid you not about the desperation of "
"trying to figure out what was wrong with the filter I show below "
"<emphasis>before</emphasis> it occurred to me I should try the little–endian "
"order even for this type of data."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:12914
msgid "Excursion to Pinhole Photography"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12915
msgid ""
"To write meaningful software, we must not only understand our programming "
"tools, but also the field we are creating software for."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:12921
msgid ""
"Our next filter will help us whenever we want to build a <emphasis>pinhole "
"camera</emphasis>, so, we need some background in <emphasis>pinhole "
"photography</emphasis> before we can continue."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:12929
msgid "The Camera"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12930
msgid ""
"The easiest way to describe any camera ever built is as some empty space "
"enclosed in some lightproof material, with a small hole in the enclosure."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12937
msgid ""
"The enclosure is usually sturdy (e.g., a box), though sometimes it is "
"flexible (the bellows). It is quite dark inside the camera. However, the "
"hole lets light rays in through a single point (though in some cases there "
"may be several). These light rays form an image, a representation of "
"whatever is outside the camera, in front of the hole."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12948
msgid ""
"If some light sensitive material (such as film) is placed inside the camera, "
"it can capture the image."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12953
msgid ""
"The hole often contains a <emphasis>lens</emphasis>, or a lens assembly, "
"often called the <emphasis>objective</emphasis>."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:12961
msgid "The Pinhole"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12962
msgid ""
"But, strictly speaking, the lens is not necessary: The original cameras did "
"not use a lens but a <emphasis>pinhole</emphasis>. Even today, "
"<emphasis>pinholes</emphasis> are used, both as a tool to study how cameras "
"work, and to achieve a special kind of image."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12970
msgid ""
"The image produced by the <emphasis>pinhole</emphasis> is all equally sharp. "
"Or <emphasis>blurred</emphasis>. There is an ideal size for a pinhole: If it "
"is either larger or smaller, the image loses its sharpness."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:12980
msgid "Focal Length"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12981
msgid ""
"This ideal pinhole diameter is a function of the square root of "
"<emphasis>focal length</emphasis>, which is the distance of the pinhole from "
"the film."
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:12988
#, no-wrap
msgid "\n"
"	D = PC * sqrt(FL)\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:12991
msgid ""
"In here, <varname>D</varname> is the ideal diameter of the pinhole, "
"<varname>FL</varname> is the focal length, and <constant>PC</constant> is a "
"pinhole constant. According to Jay Bender, its value is <constant>0.04</"
"constant>, while Kenneth Connors has determined it to be <constant>0.037</"
"constant>. Others have proposed other values. Plus, this value is for the "
"daylight only: Other types of light will require a different constant, whose "
"value can only be determined by experimentation."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:13010
msgid "The F–Number"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13011
msgid ""
"The f–number is a very useful measure of how much light reaches the film. A "
"light meter can determine that, for example, to expose a film of specific "
"sensitivity with f5.6 may require the exposure to last 1/1000 sec."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13019
msgid ""
"It does not matter whether it is a 35–mm camera, or a 6x9cm camera, etc. As "
"long as we know the f–number, we can determine the proper exposure."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13026
msgid "The f–number is easy to calculate:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:13030
#, no-wrap
msgid "\n"
"	F = FL / D\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13033
msgid ""
"In other words, the f–number equals the focal length divided by the diameter "
"of the pinhole. It also means a higher f–number either implies a smaller "
"pinhole or a larger focal distance, or both. That, in turn, implies, the "
"higher the f–number, the longer the exposure has to be."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13042
msgid ""
"Furthermore, while pinhole diameter and focal distance are one–dimensional "
"measurements, both, the film and the pinhole, are two–dimensional. That "
"means that if you have measured the exposure at f–number <varname>A</"
"varname> as <varname>t</varname>, then the exposure at f–number <varname>B</"
"varname> is:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:13051
#, no-wrap
msgid "\n"
"	t * (B / A)²\n"
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:13057
msgid "Normalized F–Number"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13058
msgid ""
"While many modern cameras can change the diameter of their pinhole, and thus "
"their f–number, quite smoothly and gradually, such was not always the case."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13064
msgid ""
"To allow for different f–numbers, cameras typically contained a metal plate "
"with several holes of different sizes drilled to them."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13070
msgid ""
"Their sizes were chosen according to the above formula in such a way that "
"the resultant f–number was one of standard f–numbers used on all cameras "
"everywhere. For example, a very old Kodak Duaflex IV camera in my possession "
"has three such holes for f–numbers 8, 11, and 16."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13079
msgid ""
"A more recently made camera may offer f–numbers of 2.8, 4, 5.6, 8, 11, 16, "
"22, and 32 (as well as others). These numbers were not chosen arbitrarily: "
"They all are powers of the square root of 2, though they may be rounded "
"somewhat."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:13091
msgid "The F–Stop"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13092
msgid ""
"A typical camera is designed in such a way that setting any of the "
"normalized f–numbers changes the feel of the dial. It will naturally "
"<emphasis>stop</emphasis> in that position. Because of that, these positions "
"of the dial are called f–stops."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13099
msgid ""
"Since the f–numbers at each stop are powers of the square root of 2, moving "
"the dial by 1 stop will double the amount of light required for proper "
"exposure. Moving it by 2 stops will quadruple the required exposure. Moving "
"the dial by 3 stops will require the increase in exposure 8 times, etc."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:13114
msgid "Designing the Pinhole Software"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:13115
msgid ""
"We are now ready to decide what exactly we want our pinhole software to do."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:13121
msgid "Processing Program Input"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13122
msgid ""
"Since its main purpose is to help us design a working pinhole camera, we "
"will use the <emphasis>focal length</emphasis> as the input to the program. "
"This is something we can determine without software: Proper focal length is "
"determined by the size of the film and by the need to shoot \"regular\" "
"pictures, wide angle pictures, or telephoto pictures."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13132
msgid ""
"Most of the programs we have written so far worked with individual "
"characters, or bytes, as their input: The <application>hex</application> "
"program converted individual bytes into a hexadecimal number, the "
"<application>csv</application> program either let a character through, or "
"deleted it, or changed it to a different character, etc."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13141
msgid ""
"One program, <application>ftuc</application> used the state machine to "
"consider at most two input bytes at a time."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13146
msgid ""
"But our <application>pinhole</application> program cannot just work with "
"individual characters, it has to deal with larger syntactic units."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13152
msgid ""
"For example, if we want the program to calculate the pinhole diameter (and "
"other values we will discuss later) at the focal lengths of <constant>100 "
"mm</constant>, <constant>150 mm</constant>, and <constant>210 mm</constant>, "
"we may want to enter something like this:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13159
#, no-wrap
msgid "<userinput>100, 150, 210</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13160
msgid ""
"Our program needs to consider more than a single byte of input at a time. "
"When it sees the first <constant>1</constant>, it must understand it is "
"seeing the first digit of a decimal number. When it sees the <constant>0</"
"constant> and the other <constant>0</constant>, it must know it is seeing "
"more digits of the same number."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13169
msgid ""
"When it encounters the first comma, it must know it is no longer receiving "
"the digits of the first number. It must be able to convert the digits of the "
"first number into the value of <constant>100</constant>. And the digits of "
"the second number into the value of <constant>150</constant>. And, of "
"course, the digits of the third number into the numeric value of "
"<constant>210</constant>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13179
msgid ""
"We need to decide what delimiters to accept: Do the input numbers have to be "
"separated by a comma? If so, how do we treat two numbers separated by "
"something else?"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13185
msgid ""
"Personally, I like to keep it simple. Something either is a number, so I "
"process it. Or it is not a number, so I discard it. I do not like the "
"computer complaining about me typing in an extra character when it is "
"<emphasis>obvious</emphasis> that it is an extra character. Duh!"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13193
msgid ""
"Plus, it allows me to break up the monotony of computing and type in a query "
"instead of just a number:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13198
#, no-wrap
msgid ""
"<userinput>What is the best pinhole diameter for the focal length of 150?</"
"userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13199
msgid ""
"There is no reason for the computer to spit out a number of complaints:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13204
#, no-wrap
msgid ""
"Syntax error: What\n"
"Syntax error: is\n"
"Syntax error: the\n"
"Syntax error: best"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13208
msgid "Et cetera, et cetera, et cetera."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13211
msgid ""
"Secondly, I like the <constant>#</constant> character to denote the start of "
"a comment which extends to the end of the line. This does not take too much "
"effort to code, and lets me treat input files for my software as executable "
"scripts."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13219
msgid ""
"In our case, we also need to decide what units the input should come in: We "
"choose <emphasis>millimeters</emphasis> because that is how most "
"photographers measure the focus length."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13226
msgid ""
"Finally, we need to decide whether to allow the use of the decimal point (in "
"which case we must also consider the fact that much of the world uses a "
"decimal <emphasis>comma</emphasis>)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13232
msgid ""
"In our case allowing for the decimal point/comma would offer a false sense "
"of precision: There is little if any noticeable difference between the focus "
"lengths of <constant>50</constant> and <constant>51</constant>, so allowing "
"the user to input something like <constant>50.5</constant> is not a good "
"idea. This is my opinion, mind you, but I am the one writing this program. "
"You can make other choices in yours, of course."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:13247
msgid "Offering Options"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13248
msgid ""
"The most important thing we need to know when building a pinhole camera is "
"the diameter of the pinhole. Since we want to shoot sharp images, we will "
"use the above formula to calculate the pinhole diameter from focal length. "
"As experts are offering several different values for the <constant>PC</"
"constant> constant, we will need to have the choice."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13257
msgid ""
"It is traditional in <trademark class=\"registered\">UNIX</trademark> "
"programming to have two main ways of choosing program parameters, plus to "
"have a default for the time the user does not make a choice."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13263
msgid "Why have two ways of choosing?"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13266
msgid ""
"One is to allow a (relatively) <emphasis>permanent</emphasis> choice that "
"applies automatically each time the software is run without us having to "
"tell it over and over what we want it to do."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13273
msgid ""
"The permanent choices may be stored in a configuration file, typically found "
"in the user's home directory. The file usually has the same name as the "
"application but is started with a dot. Often <emphasis>\"rc\"</emphasis> is "
"added to the file name. So, ours could be <filename>~/.pinhole</filename> or "
"<filename>~/.pinholerc</filename>. (The <filename>~/</filename> means "
"current user's home directory.)"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13284
msgid ""
"The configuration file is used mostly by programs that have many "
"configurable parameters. Those that have only one (or a few) often use a "
"different method: They expect to find the parameter in an "
"<emphasis>environment variable</emphasis>. In our case, we might look at an "
"environment variable named <varname>PINHOLE</varname>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13294
msgid ""
"Usually, a program uses one or the other of the above methods. Otherwise, if "
"a configuration file said one thing, but an environment variable another, "
"the program might get confused (or just too complicated)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13302
msgid ""
"Because we only need to choose <emphasis>one</emphasis> such parameter, we "
"will go with the second method and search the environment for a variable "
"named <varname>PINHOLE</varname>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13308
msgid ""
"The other way allows us to make <emphasis>ad hoc</emphasis> decisions: "
"<emphasis>\"Though I usually want you to use 0.039, this time I want 0.03872."
"\"</emphasis> In other words, it allows us to <emphasis>override</emphasis> "
"the permanent choice."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13316
msgid "This type of choice is usually done with command line parameters."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13321
msgid ""
"Finally, a program <emphasis>always</emphasis> needs a <emphasis>default</"
"emphasis>. The user may not make any choices. Perhaps he does not know what "
"to choose. Perhaps he is \"just browsing.\" Preferably, the default will be "
"the value most users would choose anyway. That way they do not need to "
"choose. Or, rather, they can choose the default without an additional effort."
""
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13333
msgid ""
"Given this system, the program may find conflicting options, and handle them "
"this way:"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13338
msgid ""
"If it finds an <emphasis>ad hoc</emphasis> choice (e.g., command line "
"parameter), it should accept that choice. It must ignore any permanent "
"choice and any default."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13345
msgid ""
"<emphasis>Otherwise</emphasis>, if it finds a permanent option (e.g., an "
"environment variable), it should accept it, and ignore the default."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13351
msgid "<emphasis>Otherwise</emphasis>, it should use the default."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13357
msgid ""
"We also need to decide what <emphasis>format</emphasis> our <constant>PC</"
"constant> option should have."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13362
msgid ""
"At first site, it seems obvious to use the <varname>PINHOLE=0.04</varname> "
"format for the environment variable, and <parameter>-p0.04</parameter> for "
"the command line."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13369
msgid ""
"Allowing that is actually a security risk. The <constant>PC</constant> "
"constant is a very small number. Naturally, we will test our software using "
"various small values of <constant>PC</constant>. But what will happen if "
"someone runs the program choosing a huge value?"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13378
msgid ""
"It may crash the program because we have not designed it to handle huge "
"numbers."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13383
msgid ""
"Or, we may spend more time on the program so it can handle huge numbers. We "
"might do that if we were writing commercial software for computer illiterate "
"audience."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13390
msgid ""
"Or, we might say, <emphasis>\"Tough! The user should know better.\"\"</"
"emphasis>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13395
msgid ""
"Or, we just may make it impossible for the user to enter a huge number. This "
"is the approach we will take: We will use an <emphasis>implied 0.</emphasis> "
"prefix."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13402
msgid ""
"In other words, if the user wants <constant>0.04</constant>, we will expect "
"him to type <parameter>-p04</parameter>, or set <varname>PINHOLE=04</"
"varname> in his environment. So, if he says <parameter>-p9999999</"
"parameter>, we will interpret it as <constant>0.9999999</constant>—still "
"ridiculous but at least safer."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13411
msgid ""
"Secondly, many users will just want to go with either Bender's constant or "
"Connors' constant. To make it easier on them, we will interpret <parameter>-"
"b</parameter> as identical to <parameter>-p04</parameter>, and <parameter>-"
"c</parameter> as identical to <parameter>-p037</parameter>."
msgstr ""

#. (itstool) path: sect3/title
#: book.translate.xml:13422
msgid "The Output"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13423
msgid ""
"We need to decide what we want our software to send to the output, and in "
"what format."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13428
msgid ""
"Since our input allows for an unspecified number of focal length entries, it "
"makes sense to use a traditional database–style output of showing the result "
"of the calculation for each focal length on a separate line, while "
"separating all values on one line by a <constant>tab</constant> character."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13438
msgid ""
"Optionally, we should also allow the user to specify the use of the "
"<acronym>CSV</acronym> format we have studied earlier. In this case, we will "
"print out a line of comma–separated names describing each field of every "
"line, then show our results as before, but substituting a <constant>comma</"
"constant> for the <constant>tab</constant>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13447
msgid ""
"We need a command line option for the <acronym>CSV</acronym> format. We "
"cannot use <parameter>-c</parameter> because that already means "
"<emphasis>use Connors' constant</emphasis>. For some strange reason, many "
"web sites refer to <acronym>CSV</acronym> files as <emphasis>\"Excel "
"spreadsheet\"</emphasis> (though the <acronym>CSV</acronym> format predates "
"Excel). We will, therefore, use the <parameter>-e</parameter> switch to "
"inform our software we want the output in the <acronym>CSV</acronym> format."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13459
msgid ""
"We will start each line of the output with the focal length. This may sound "
"repetitious at first, especially in the interactive mode: The user types in "
"the focal length, and we are repeating it."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13466
msgid ""
"But the user can type several focal lengths on one line. The input can also "
"come in from a file or from the output of another program. In that case the "
"user does not see the input at all."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13473
msgid ""
"By the same token, the output can go to a file which we will want to examine "
"later, or it could go to the printer, or become the input of another program."
""
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13480
msgid ""
"So, it makes perfect sense to start each line with the focal length as "
"entered by the user."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13485
msgid ""
"No, wait! Not as entered by the user. What if the user types in something "
"like this:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13489
#, no-wrap
msgid "<userinput>00000000150</userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13490
msgid "Clearly, we need to strip those leading zeros."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13493
msgid ""
"So, we might consider reading the user input as is, converting it to binary "
"inside the <acronym>FPU</acronym>, and printing it out from there."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13499 book.translate.xml:13921
msgid "But..."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13502
msgid "What if the user types something like this:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13506
#, no-wrap
msgid ""
"<userinput>17459765723452353453534535353530530534563507309676764423</"
"userinput>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13507
msgid ""
"Ha! The packed decimal <acronym>FPU</acronym> format lets us input 18–digit "
"numbers. But the user has entered more than 18 digits. How do we handle "
"that?"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13514
msgid ""
"Well, we <emphasis>could</emphasis> modify our code to read the first 18 "
"digits, enter it to the <acronym>FPU</acronym>, then read more, multiply "
"what we already have on the <acronym>TOS</acronym> by 10 raised to the "
"number of additional digits, then <function>add</function> to it."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13522
msgid ""
"Yes, we could do that. But in <emphasis>this</emphasis> program it would be "
"ridiculous (in a different one it may be just the thing to do): Even the "
"circumference of the Earth expressed in millimeters only takes 11 digits. "
"Clearly, we cannot build a camera that large (not yet, anyway)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13530
msgid ""
"So, if the user enters such a huge number, he is either bored, or testing "
"us, or trying to break into the system, or playing games—doing anything but "
"designing a pinhole camera."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13537
msgid "What will we do?"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13540
msgid "We will slap him in the face, in a manner of speaking:"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13543
#, no-wrap
msgid ""
"17459765723452353453534535353530530534563507309676764423	???	???	???	???	???"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13544
msgid ""
"To achieve that, we will simply ignore any leading zeros. Once we find a "
"non–zero digit, we will initialize a counter to <constant>0</constant> and "
"start taking three steps:"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13551
msgid "Send the digit to the output."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13555
msgid ""
"Append the digit to a buffer we will use later to produce the packed decimal "
"we can send to the <acronym>FPU</acronym>."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13561
msgid "Increase the counter."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13566
msgid ""
"Now, while we are taking these three steps, we also need to watch out for "
"one of two conditions:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:13573
msgid ""
"If the counter grows above 18, we stop appending to the buffer. We continue "
"reading the digits and sending them to the output."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:13582
msgid ""
"If, or rather <emphasis>when</emphasis>, the next input character is not a "
"digit, we are done inputting for now."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:13589
msgid ""
"Incidentally, we can simply discard the non–digit, unless it is a "
"<constant>#</constant>, which we must return to the input stream. It starts "
"a comment, so we must see it after we are done producing output and start "
"looking for more input."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13601
msgid ""
"That still leaves one possibility uncovered: If all the user enters is a "
"zero (or several zeros), we will never find a non–zero to display."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13608
msgid ""
"We can determine this has happened whenever our counter stays at "
"<constant>0</constant>. In that case we need to send <constant>0</constant> "
"to the output, and perform another \"slap in the face\":"
msgstr ""

#. (itstool) path: sect3/screen
#: book.translate.xml:13616
#, no-wrap
msgid "0	???	???	???	???	???"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13617
msgid ""
"Once we have displayed the focal length and determined it is valid (greater "
"than <constant>0</constant> but not exceeding 18 digits), we can calculate "
"the pinhole diameter."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13625
msgid ""
"It is not by coincidence that <emphasis>pinhole</emphasis> contains the word "
"<emphasis>pin</emphasis>. Indeed, many a pinhole literally is a "
"<emphasis>pin hole</emphasis>, a hole carefully punched with the tip of a "
"pin."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13633
msgid ""
"That is because a typical pinhole is very small. Our formula gets the result "
"in millimeters. We will multiply it by <constant>1000</constant>, so we can "
"output the result in <emphasis>microns</emphasis>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13640
msgid ""
"At this point we have yet another trap to face: <emphasis>Too much precision."
"</emphasis>"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13645
msgid ""
"Yes, the <acronym>FPU</acronym> was designed for high precision mathematics. "
"But we are not dealing with high precision mathematics. We are dealing with "
"physics (optics, specifically)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13653
msgid ""
"Suppose we want to convert a truck into a pinhole camera (we would not be "
"the first ones to do that!). Suppose its box is <constant>12</constant> "
"meters long, so we have the focal length of <constant>12000</constant>. "
"Well, using Bender's constant, it gives us square root of <constant>12000</"
"constant> multiplied by <constant>0.04</constant>, which is <constant>4."
"381780460</constant> millimeters, or <constant>4381.780460</constant> "
"microns."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13665
msgid ""
"Put either way, the result is absurdly precise. Our truck is not "
"<emphasis>exactly</emphasis> <constant>12000</constant> millimeters long. We "
"did not measure its length with such a precision, so stating we need a "
"pinhole with the diameter of <constant>4.381780460</constant> millimeters "
"is, well, deceiving. <constant>4.4</constant> millimeters would do just fine."
""
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:13676
msgid ""
"I \"only\" used ten digits in the above example. Imagine the absurdity of "
"going for all 18!"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13682
msgid ""
"We need to limit the number of significant digits of our result. One way of "
"doing it is by using an integer representing microns. So, our truck would "
"need a pinhole with the diameter of <constant>4382</constant> microns. "
"Looking at that number, we still decide that <constant>4400</constant> "
"microns, or <constant>4.4</constant> millimeters is close enough."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13691
msgid ""
"Additionally, we can decide that no matter how big a result we get, we only "
"want to display four significant digits (or any other number of them, of "
"course). Alas, the <acronym>FPU</acronym> does not offer rounding to a "
"specific number of digits (after all, it does not view the numbers as "
"decimal but as binary)."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13701
msgid ""
"We, therefore, must devise an algorithm to reduce the number of significant "
"digits."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13706
msgid ""
"Here is mine (I think it is awkward—if you know a better one, "
"<emphasis>please</emphasis>, let me know):"
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13711
msgid "Initialize a counter to <constant>0</constant>."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13715
msgid ""
"While the number is greater than or equal to <constant>10000</constant>, "
"divide it by <constant>10</constant> and increase the counter."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13721
msgid "Output the result."
msgstr ""

#. (itstool) path: step/para
#: book.translate.xml:13724
msgid ""
"While the counter is greater than <constant>0</constant>, output "
"<constant>0</constant> and decrease the counter."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:13731
msgid ""
"The <constant>10000</constant> is only good if you want <emphasis>four</"
"emphasis> significant digits. For any other number of significant digits, "
"replace <constant>10000</constant> with <constant>10</constant> raised to "
"the number of significant digits."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13740
msgid ""
"We will, then, output the pinhole diameter in microns, rounded off to four "
"significant digits."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13746
msgid ""
"At this point, we know the <emphasis>focal length</emphasis> and the "
"<emphasis>pinhole diameter</emphasis>. That means we have enough information "
"to also calculate the <emphasis>f–number</emphasis>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13754
msgid ""
"We will display the f–number, rounded to four significant digits. Chances "
"are the f–number will tell us very little. To make it more meaningful, we "
"can find the nearest <emphasis>normalized f–number</emphasis>, i.e., the "
"nearest power of the square root of 2."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13764
msgid ""
"We do that by multiplying the actual f–number by itself, which, of course, "
"will give us its <function>square</function>. We will then calculate its "
"base–2 logarithm, which is much easier to do than calculating the "
"base–square–root–of–2 logarithm! We will round the result to the nearest "
"integer. Next, we will raise 2 to the result. Actually, the <acronym>FPU</"
"acronym> gives us a good shortcut to do that: We can use the <function role="
"\"opcode\">fscale</function> op code to \"scale\" 1, which is analogous to "
"<function role=\"opcode\">shift</function>ing an integer left. Finally, we "
"calculate the square root of it all, and we have the nearest normalized "
"f–number."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13782
msgid ""
"If all that sounds overwhelming—or too much work, perhaps—it may become much "
"clearer if you see the code. It takes 9 op codes altogether:"
msgstr ""

#. (itstool) path: sect3/programlisting
#: book.translate.xml:13788
#, no-wrap
msgid ""
"\n"
"	fmul	st0, st0\n"
"	fld1\n"
"	fld	st1\n"
"	fyl2x\n"
"	frndint\n"
"	fld1\n"
"	fscale\n"
"	fsqrt\n"
"	fstp	st1\n"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13799
msgid ""
"The first line, <function role=\"opcode\">fmul st0, st0</function>, squares "
"the contents of the <acronym>TOS</acronym> (top of the stack, same as "
"<varname role=\"register\">st</varname>, called <varname role="
"\"register\">st0</varname> by <application>nasm</application>). The "
"<function role=\"opcode\">fld1</function> pushes <constant>1</constant> on "
"the <acronym>TOS</acronym>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13807
msgid ""
"The next line, <function role=\"opcode\">fld st1</function>, pushes the "
"square back to the <acronym>TOS</acronym>. At this point the square is both "
"in <varname role=\"register\">st</varname> and <varname role="
"\"register\">st(2)</varname> (it will become clear why we leave a second "
"copy on the stack in a moment). <varname role=\"register\">st(1)</varname> "
"contains <constant>1</constant>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13817
msgid ""
"Next, <function role=\"opcode\">fyl2x</function> calculates base–2 logarithm "
"of <varname role=\"register\">st</varname> multiplied by <varname role="
"\"register\">st(1)</varname>. That is why we placed <constant>1</constant> "
"on <varname role=\"register\">st(1)</varname> before."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13822
msgid ""
"At this point, <varname role=\"register\">st</varname> contains the "
"logarithm we have just calculated, <varname role=\"register\">st(1)</"
"varname> contains the square of the actual f–number we saved for later."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13829
msgid ""
"<function role=\"opcode\">frndint</function> rounds the <acronym>TOS</"
"acronym> to the nearest integer. <function role=\"opcode\">fld1</function> "
"pushes a <constant>1</constant>. <function role=\"opcode\">fscale</function> "
"shifts the <constant>1</constant> we have on the <acronym>TOS</acronym> by "
"the value in <varname role=\"register\">st(1)</varname>, effectively raising "
"2 to <varname role=\"register\">st(1)</varname>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13838
msgid ""
"Finally, <function role=\"opcode\">fsqrt</function> calculates the square "
"root of the result, i.e., the nearest normalized f–number."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13844
msgid ""
"We now have the nearest normalized f–number on the <acronym>TOS</acronym>, "
"the base–2 logarithm rounded to the nearest integer in <varname role="
"\"register\">st(1)</varname>, and the square of the actual f–number in "
"<varname role=\"register\">st(2)</varname>. We are saving the value in "
"<varname role=\"register\">st(2)</varname> for later."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13854
msgid ""
"But we do not need the contents of <varname role=\"register\">st(1)</"
"varname> anymore. The last line, <function role=\"opcode\">fstp st1</"
"function>, places the contents of <varname role=\"register\">st</varname> to "
"<varname role=\"register\">st(1)</varname>, and pops. As a result, what was "
"<varname role=\"register\">st(1)</varname> is now <varname role="
"\"register\">st</varname>, what was <varname role=\"register\">st(2)</"
"varname> is now <varname role=\"register\">st(1)</varname>, etc. The new "
"<varname role=\"register\">st</varname> contains the normalized f–number. "
"The new <varname role=\"register\">st(1)</varname> contains the square of "
"the actual f–number we have stored there for posterity."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13870
msgid ""
"At this point, we are ready to output the normalized f–number. Because it is "
"normalized, we will not round it off to four significant digits, but will "
"send it out in its full precision."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13878
msgid ""
"The normalized f-number is useful as long as it is reasonably small and can "
"be found on our light meter. Otherwise we need a different method of "
"determining proper exposure."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13886
msgid ""
"Earlier we have figured out the formula of calculating proper exposure at an "
"arbitrary f–number from that measured at a different f–number."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13893
msgid ""
"Every light meter I have ever seen can determine proper exposure at f5.6. We "
"will, therefore, calculate an <emphasis>\"f5.6 multiplier,\"</emphasis> i.e."
", by how much we need to multiply the exposure measured at f5.6 to determine "
"the proper exposure for our pinhole camera."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13902
msgid ""
"From the above formula we know this factor can be calculated by dividing our "
"f–number (the actual one, not the normalized one) by <constant>5.6</"
"constant>, and squaring the result."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13909
msgid ""
"Mathematically, dividing the square of our f–number by the square of "
"<constant>5.6</constant> will give us the same result."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13915
msgid ""
"Computationally, we do not want to square two numbers when we can only "
"square one. So, the first solution seems better at first."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13924
msgid ""
"<constant>5.6</constant> is a <emphasis>constant</emphasis>. We do not have "
"to have our <acronym>FPU</acronym> waste precious cycles. We can just tell "
"it to divide the square of the f–number by whatever <constant>5.6²</"
"constant> equals to. Or we can divide the f–number by <constant>5.6</"
"constant>, and then square the result. The two ways now seem equal."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13935
msgid "But, they are not!"
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13938
msgid ""
"Having studied the principles of photography above, we remember that the "
"<constant>5.6</constant> is actually square root of 2 raised to the fifth "
"power. An <emphasis>irrational</emphasis> number. The square of this number "
"is <emphasis>exactly</emphasis> <constant>32</constant>."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13947
msgid ""
"Not only is <constant>32</constant> an integer, it is a power of 2. We do "
"not need to divide the square of the f–number by <constant>32</constant>. We "
"only need to use <function role=\"opcode\">fscale</function> to shift it "
"right by five positions. In the <acronym>FPU</acronym> lingo it means we "
"will <function role=\"opcode\">fscale</function> it with <varname role="
"\"register\">st(1)</varname> equal to <constant>-5</constant>. That is "
"<emphasis>much faster</emphasis> than a division."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13960
msgid ""
"So, now it has become clear why we have saved the square of the f–number on "
"the top of the <acronym>FPU</acronym> stack. The calculation of the f5.6 "
"multiplier is the easiest calculation of this entire program! We will output "
"it rounded to four significant digits."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13970
msgid ""
"There is one more useful number we can calculate: The number of stops our "
"f–number is from f5.6. This may help us if our f–number is just outside the "
"range of our light meter, but we have a shutter which lets us set various "
"speeds, and this shutter uses stops."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13979
msgid ""
"Say, our f–number is 5 stops from f5.6, and the light meter says we should "
"use 1/1000 sec. Then we can set our shutter speed to 1/1000 first, then move "
"the dial by 5 stops."
msgstr ""

#. (itstool) path: sect3/para
#: book.translate.xml:13987
msgid ""
"This calculation is quite easy as well. All we have to do is to calculate "
"the base-2 logarithm of the f5.6 multiplier we had just calculated (though "
"we need its value from before we rounded it off). We then output the result "
"rounded to the nearest integer. We do not need to worry about having more "
"than four significant digits in this one: The result is most likely to have "
"only one or two digits anyway."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:14004
msgid "FPU Optimizations"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14005
msgid ""
"In assembly language we can optimize the <acronym>FPU</acronym> code in ways "
"impossible in high languages, including C."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14011
msgid ""
"Whenever a C function needs to calculate a floating–point value, it loads "
"all necessary variables and constants into <acronym>FPU</acronym> registers. "
"It then does whatever calculation is required to get the correct result. "
"Good C compilers can optimize that part of the code really well."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14021
msgid ""
"It \"returns\" the value by leaving the result on the <acronym>TOS</acronym>."
" However, before it returns, it cleans up. Any variables and constants it "
"used in its calculation are now gone from the <acronym>FPU</acronym>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14029
msgid ""
"It cannot do what we just did above: We calculated the square of the "
"f–number and kept it on the stack for later use by another function."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14035
msgid ""
"We <emphasis>knew</emphasis> we would need that value later on. We also knew "
"we had enough room on the stack (which only has room for 8 numbers) to store "
"it there."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14042
msgid ""
"A C compiler has no way of knowing that a value it has on the stack will be "
"required again in the very near future."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14048
msgid ""
"Of course, the C programmer may know it. But the only recourse he has is to "
"store the value in a memory variable."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14054
msgid ""
"That means, for one, the value will be changed from the 80-bit precision "
"used internally by the <acronym>FPU</acronym> to a C <emphasis>double</"
"emphasis> (64 bits) or even <emphasis>single</emphasis> (32 bits)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14062
msgid ""
"That also means that the value must be moved from the <acronym>TOS</acronym> "
"into the memory, and then back again. Alas, of all <acronym>FPU</acronym> "
"operations, the ones that access the computer memory are the slowest."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14070
msgid ""
"So, whenever programming the <acronym>FPU</acronym> in assembly language, "
"look for the ways of keeping intermediate results on the <acronym>FPU</"
"acronym> stack."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14077
msgid ""
"We can take that idea even further! In our program we are using a "
"<emphasis>constant</emphasis> (the one we named <constant>PC</constant>)."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14083
msgid ""
"It does not matter how many pinhole diameters we are calculating: 1, 10, 20, "
"1000, we are always using the same constant. Therefore, we can optimize our "
"program by keeping the constant on the stack all the time."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14091
msgid ""
"Early on in our program, we are calculating the value of the above constant. "
"We need to divide our input by <constant>10</constant> for every digit in "
"the constant."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14098
msgid ""
"It is much faster to multiply than to divide. So, at the start of our "
"program, we divide <constant>10</constant> into <constant>1</constant> to "
"obtain <constant>0.1</constant>, which we then keep on the stack: Instead of "
"dividing the input by <constant>10</constant> for every digit, we multiply "
"it by <constant>0.1</constant>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14107
msgid ""
"By the way, we do not input <constant>0.1</constant> directly, even though "
"we could. We have a reason for that: While <constant>0.1</constant> can be "
"expressed with just one decimal place, we do not know how many "
"<emphasis>binary</emphasis> places it takes. We, therefore, let the "
"<acronym>FPU</acronym> calculate its binary value to its own high precision."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14116
msgid ""
"We are using other constants: We multiply the pinhole diameter by "
"<constant>1000</constant> to convert it from millimeters to microns. We "
"compare numbers to <constant>10000</constant> when we are rounding them off "
"to four significant digits. So, we keep both, <constant>1000</constant> and "
"<constant>10000</constant>, on the stack. And, of course, we reuse the "
"<constant>0.1</constant> when rounding off numbers to four digits."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14127
msgid ""
"Last but not least, we keep <constant>-5</constant> on the stack. We need it "
"to scale the square of the f–number, instead of dividing it by <constant>32</"
"constant>. It is not by coincidence we load this constant last. That makes "
"it the top of the stack when only the constants are on it. So, when the "
"square of the f–number is being scaled, the <constant>-5</constant> is at "
"<varname role=\"register\">st(1)</varname>, precisely where <function role="
"\"opcode\">fscale</function> expects it to be."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14138
msgid ""
"It is common to create certain constants from scratch instead of loading "
"them from the memory. That is what we are doing with <constant>-5</constant>:"
""
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:14144
#, no-wrap
msgid ""
"\n"
"	fld1			; TOS =  1\n"
"	fadd	st0, st0	; TOS =  2\n"
"	fadd	st0, st0	; TOS =  4\n"
"	fld1			; TOS =  1\n"
"	faddp	st1, st0	; TOS =  5\n"
"	fchs			; TOS = -5\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14152
msgid ""
"We can generalize all these optimizations into one rule: <emphasis>Keep "
"repeat values on the stack!</emphasis>"
msgstr ""

#. (itstool) path: tip/para
#: book.translate.xml:14158
msgid ""
"<emphasis><trademark class=\"registered\">PostScript</trademark></emphasis> "
"is a stack–oriented programming language. There are many more books "
"available about <trademark class=\"registered\">PostScript</trademark> than "
"about the <acronym>FPU</acronym> assembly language: Mastering <trademark "
"class=\"registered\">PostScript</trademark> will help you master the "
"<acronym>FPU</acronym>."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:14170
msgid "<application>pinhole</application>—The Code"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:14171
#, no-wrap
msgid ""
"\n"
";;;;;;; pinhole.asm "
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
";\n"
"; Find various parameters of a pinhole camera construction and use\n"
";\n"
"; Started:	 9-Jun-2001\n"
"; Updated:	10-Jun-2001\n"
";\n"
"; Copyright (c) 2001 G. Adam Stanislav\n"
"; All rights reserved.\n"
";\n"
";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n"
"\n"
"%include	'system.inc'\n"
"\n"
"%define	BUFSIZE	2048\n"
"\n"
"section	.data\n"
"align 4\n"
"ten	dd	10\n"
"thousand	dd	1000\n"
"tthou	dd	10000\n"
"fd.in	dd	stdin\n"
"fd.out	dd	stdout\n"
"envar	db	'PINHOLE='	; Exactly 8 bytes, or 2 dwords long\n"
"pinhole	db	'04,', 		; Bender's constant (0.04)\n"
"connors	db	'037', 0Ah	; Connors' constant\n"
"usg	db	'Usage: pinhole [-b] [-c] [-e] [-p &lt;value&gt;] [-o "
"&lt;outfile&gt;] [-i &lt;infile&gt;]', 0Ah\n"
"usglen	equ	$-usg\n"
"iemsg	db	\"pinhole: Can't open input file\", 0Ah\n"
"iemlen	equ	$-iemsg\n"
"oemsg	db	\"pinhole: Can't create output file\", 0Ah\n"
"oemlen	equ	$-oemsg\n"
"pinmsg	db	\"pinhole: The PINHOLE constant must not be 0\", 0Ah\n"
"pinlen	equ	$-pinmsg\n"
"toobig	db	\"pinhole: The PINHOLE constant may not exceed 18 decimal "
"places\", 0Ah\n"
"biglen	equ	$-toobig\n"
"huhmsg	db	9, '???'\n"
"separ	db	9, '???'\n"
"sep2	db	9, '???'\n"
"sep3	db	9, '???'\n"
"sep4	db	9, '???', 0Ah\n"
"huhlen	equ	$-huhmsg\n"
"header	db	'focal length in millimeters,pinhole diameter in microns,'\n"
"	db	'F-number,normalized F-number,F-5.6 multiplier,stops '\n"
"	db	'from F-5.6', 0Ah\n"
"headlen	equ	$-header\n"
"\n"
"section .bss\n"
"ibuffer	resb	BUFSIZE\n"
"obuffer	resb	BUFSIZE\n"
"dbuffer	resb	20		; decimal input buffer\n"
"bbuffer	resb	10		; BCD buffer\n"
"\n"
"section	.text\n"
"align 4\n"
"huh:\n"
"	call	write\n"
"	push	dword huhlen\n"
"	push	dword huhmsg\n"
"	push	dword [fd.out]\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	ret\n"
"\n"
"align 4\n"
"perr:\n"
"	push	dword pinlen\n"
"	push	dword pinmsg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 4		; return failure\n"
"	sys.exit\n"
"\n"
"align 4\n"
"consttoobig:\n"
"	push	dword biglen\n"
"	push	dword toobig\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 5		; return failure\n"
"	sys.exit\n"
"\n"
"align 4\n"
"ierr:\n"
"	push	dword iemlen\n"
"	push	dword iemsg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 1		; return failure\n"
"	sys.exit\n"
"\n"
"align 4\n"
"oerr:\n"
"	push	dword oemlen\n"
"	push	dword oemsg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 2\n"
"	sys.exit\n"
"\n"
"align 4\n"
"usage:\n"
"	push	dword usglen\n"
"	push	dword usg\n"
"	push	dword stderr\n"
"	sys.write\n"
"	push	dword 3\n"
"	sys.exit\n"
"\n"
"align 4\n"
"global	_start\n"
"_start:\n"
"	add	esp, byte 8	; discard argc and argv[0]\n"
"	sub	esi, esi\n"
"\n"
".arg:\n"
"	pop	ecx\n"
"	or	ecx, ecx\n"
"	je	near .getenv		; no more arguments\n"
"\n"
"	; ECX contains the pointer to an argument\n"
"	cmp	byte [ecx], '-'\n"
"	jne	usage\n"
"\n"
"	inc	ecx\n"
"	mov	ax, [ecx]\n"
"	inc	ecx\n"
"\n"
".o:\n"
"	cmp	al, 'o'\n"
"	jne	.i\n"
"\n"
"	; Make sure we are not asked for the output file twice\n"
"	cmp	dword [fd.out], stdout\n"
"	jne	usage\n"
"\n"
"	; Find the path to output file - it is either at [ECX+1],\n"
"	; i.e., -ofile --\n"
"	; or in the next argument,\n"
"	; i.e., -o file\n"
"\n"
"	or	ah, ah\n"
"	jne	.openoutput\n"
"	pop	ecx\n"
"	jecxz	usage\n"
"\n"
".openoutput:\n"
"	push	dword 420	; file mode (644 octal)\n"
"	push	dword 0200h | 0400h | 01h\n"
"	; O_CREAT | O_TRUNC | O_WRONLY\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	near oerr\n"
"\n"
"	add	esp, byte 12\n"
"	mov	[fd.out], eax\n"
"	jmp	short .arg\n"
"\n"
".i:\n"
"	cmp	al, 'i'\n"
"	jne	.p\n"
"\n"
"	; Make sure we are not asked twice\n"
"	cmp	dword [fd.in], stdin\n"
"	jne	near usage\n"
"\n"
"	; Find the path to the input file\n"
"	or	ah, ah\n"
"	jne	.openinput\n"
"	pop	ecx\n"
"	or	ecx, ecx\n"
"	je near usage\n"
"\n"
".openinput:\n"
"	push	dword 0		; O_RDONLY\n"
"	push	ecx\n"
"	sys.open\n"
"	jc	near ierr		; open failed\n"
"\n"
"	add	esp, byte 8\n"
"	mov	[fd.in], eax\n"
"	jmp	.arg\n"
"\n"
".p:\n"
"	cmp	al, 'p'\n"
"	jne	.c\n"
"	or	ah, ah\n"
"	jne	.pcheck\n"
"\n"
"	pop	ecx\n"
"	or	ecx, ecx\n"
"	je	near usage\n"
"\n"
"	mov	ah, [ecx]\n"
"\n"
".pcheck:\n"
"	cmp	ah, '0'\n"
"	jl	near usage\n"
"	cmp	ah, '9'\n"
"	ja	near usage\n"
"	mov	esi, ecx\n"
"	jmp	.arg\n"
"\n"
".c:\n"
"	cmp	al, 'c'\n"
"	jne	.b\n"
"	or	ah, ah\n"
"	jne	near usage\n"
"	mov	esi, connors\n"
"	jmp	.arg\n"
"\n"
".b:\n"
"	cmp	al, 'b'\n"
"	jne	.e\n"
"	or	ah, ah\n"
"	jne	near usage\n"
"	mov	esi, pinhole\n"
"	jmp	.arg\n"
"\n"
".e:\n"
"	cmp	al, 'e'\n"
"	jne	near usage\n"
"	or	ah, ah\n"
"	jne	near usage\n"
"	mov	al, ','\n"
"	mov	[huhmsg], al\n"
"	mov	[separ], al\n"
"	mov	[sep2], al\n"
"	mov	[sep3], al\n"
"	mov	[sep4], al\n"
"	jmp	.arg\n"
"\n"
"align 4\n"
".getenv:\n"
"	; If ESI = 0, we did not have a -p argument,\n"
"	; and need to check the environment for \"PINHOLE=\"\n"
"	or	esi, esi\n"
"	jne	.init\n"
"\n"
"	sub	ecx, ecx\n"
"\n"
".nextenv:\n"
"	pop	esi\n"
"	or	esi, esi\n"
"	je	.default	; no PINHOLE envar found\n"
"\n"
"	; check if this envar starts with 'PINHOLE='\n"
"	mov	edi, envar\n"
"	mov	cl, 2		; 'PINHOLE=' is 2 dwords long\n"
"rep	cmpsd\n"
"	jne	.nextenv\n"
"\n"
"	; Check if it is followed by a digit\n"
"	mov	al, [esi]\n"
"	cmp	al, '0'\n"
"	jl	.default\n"
"	cmp	al, '9'\n"
"	jbe	.init\n"
"	; fall through\n"
"\n"
"align 4\n"
".default:\n"
"	; We got here because we had no -p argument,\n"
"	; and did not find the PINHOLE envar.\n"
"	mov	esi, pinhole\n"
"	; fall through\n"
"\n"
"align 4\n"
".init:\n"
"	sub	eax, eax\n"
"	sub	ebx, ebx\n"
"	sub	ecx, ecx\n"
"	sub	edx, edx\n"
"	mov	edi, dbuffer+1\n"
"	mov	byte [dbuffer], '0'\n"
"\n"
"	; Convert the pinhole constant to real\n"
".constloop:\n"
"	lodsb\n"
"	cmp	al, '9'\n"
"	ja	.setconst\n"
"	cmp	al, '0'\n"
"	je	.processconst\n"
"	jb	.setconst\n"
"\n"
"	inc	dl\n"
"\n"
".processconst:\n"
"	inc	cl\n"
"	cmp	cl, 18\n"
"	ja	near consttoobig\n"
"	stosb\n"
"	jmp	short .constloop\n"
"\n"
"align 4\n"
".setconst:\n"
"	or	dl, dl\n"
"	je	near perr\n"
"\n"
"	finit\n"
"	fild	dword [tthou]\n"
"\n"
"	fld1\n"
"	fild	dword [ten]\n"
"	fdivp	st1, st0\n"
"\n"
"	fild	dword [thousand]\n"
"	mov	edi, obuffer\n"
"\n"
"	mov	ebp, ecx\n"
"	call	bcdload\n"
"\n"
".constdiv:\n"
"	fmul	st0, st2\n"
"	loop	.constdiv\n"
"\n"
"	fld1\n"
"	fadd	st0, st0\n"
"	fadd	st0, st0\n"
"	fld1\n"
"	faddp	st1, st0\n"
"	fchs\n"
"\n"
"	; If we are creating a CSV file,\n"
"	; print header\n"
"	cmp	byte [separ], ','\n"
"	jne	.bigloop\n"
"\n"
"	push	dword headlen\n"
"	push	dword header\n"
"	push	dword [fd.out]\n"
"	sys.write\n"
"\n"
".bigloop:\n"
"	call	getchar\n"
"	jc	near done\n"
"\n"
"	; Skip to the end of the line if you got '#'\n"
"	cmp	al, '#'\n"
"	jne	.num\n"
"	call	skiptoeol\n"
"	jmp	short .bigloop\n"
"\n"
".num:\n"
"	; See if you got a number\n"
"	cmp	al, '0'\n"
"	jl	.bigloop\n"
"	cmp	al, '9'\n"
"	ja	.bigloop\n"
"\n"
"	; Yes, we have a number\n"
"	sub	ebp, ebp\n"
"	sub	edx, edx\n"
"\n"
".number:\n"
"	cmp	al, '0'\n"
"	je	.number0\n"
"	mov	dl, 1\n"
"\n"
".number0:\n"
"	or	dl, dl		; Skip leading 0's\n"
"	je	.nextnumber\n"
"	push	eax\n"
"	call	putchar\n"
"	pop	eax\n"
"	inc	ebp\n"
"	cmp	ebp, 19\n"
"	jae	.nextnumber\n"
"	mov	[dbuffer+ebp], al\n"
"\n"
".nextnumber:\n"
"	call	getchar\n"
"	jc	.work\n"
"	cmp	al, '#'\n"
"	je	.ungetc\n"
"	cmp	al, '0'\n"
"	jl	.work\n"
"	cmp	al, '9'\n"
"	ja	.work\n"
"	jmp	short .number\n"
"\n"
".ungetc:\n"
"	dec	esi\n"
"	inc	ebx\n"
"\n"
".work:\n"
"	; Now, do all the work\n"
"	or	dl, dl\n"
"	je	near .work0\n"
"\n"
"	cmp	ebp, 19\n"
"	jae	near .toobig\n"
"\n"
"	call	bcdload\n"
"\n"
"	; Calculate pinhole diameter\n"
"\n"
"	fld	st0	; save it\n"
"	fsqrt\n"
"	fmul	st0, st3\n"
"	fld	st0\n"
"	fmul	st5\n"
"	sub	ebp, ebp\n"
"\n"
"	; Round off to 4 significant digits\n"
".diameter:\n"
"	fcom	st0, st7\n"
"	fstsw	ax\n"
"	sahf\n"
"	jb	.printdiameter\n"
"	fmul	st0, st6\n"
"	inc	ebp\n"
"	jmp	short .diameter\n"
"\n"
".printdiameter:\n"
"	call	printnumber	; pinhole diameter\n"
"\n"
"	; Calculate F-number\n"
"\n"
"	fdivp	st1, st0\n"
"	fld	st0\n"
"\n"
"	sub	ebp, ebp\n"
"\n"
".fnumber:\n"
"	fcom	st0, st6\n"
"	fstsw	ax\n"
"	sahf\n"
"	jb	.printfnumber\n"
"	fmul	st0, st5\n"
"	inc	ebp\n"
"	jmp	short .fnumber\n"
"\n"
".printfnumber:\n"
"	call	printnumber	; F number\n"
"\n"
"	; Calculate normalized F-number\n"
"	fmul	st0, st0\n"
"	fld1\n"
"	fld	st1\n"
"	fyl2x\n"
"	frndint\n"
"	fld1\n"
"	fscale\n"
"	fsqrt\n"
"	fstp	st1\n"
"\n"
"	sub	ebp, ebp\n"
"	call	printnumber\n"
"\n"
"	; Calculate time multiplier from F-5.6\n"
"\n"
"	fscale\n"
"	fld	st0\n"
"\n"
"	; Round off to 4 significant digits\n"
".fmul:\n"
"	fcom	st0, st6\n"
"	fstsw	ax\n"
"	sahf\n"
"\n"
"	jb	.printfmul\n"
"	inc	ebp\n"
"	fmul	st0, st5\n"
"	jmp	short .fmul\n"
"\n"
".printfmul:\n"
"	call	printnumber	; F multiplier\n"
"\n"
"	; Calculate F-stops from 5.6\n"
"\n"
"	fld1\n"
"	fxch	st1\n"
"	fyl2x\n"
"\n"
"	sub	ebp, ebp\n"
"	call	printnumber\n"
"\n"
"	mov	al, 0Ah\n"
"	call	putchar\n"
"	jmp	.bigloop\n"
"\n"
".work0:\n"
"	mov	al, '0'\n"
"	call	putchar\n"
"\n"
"align 4\n"
".toobig:\n"
"	call	huh\n"
"	jmp	.bigloop\n"
"\n"
"align 4\n"
"done:\n"
"	call	write		; flush output buffer\n"
"\n"
"	; close files\n"
"	push	dword [fd.in]\n"
"	sys.close\n"
"\n"
"	push	dword [fd.out]\n"
"	sys.close\n"
"\n"
"	finit\n"
"\n"
"	; return success\n"
"	push	dword 0\n"
"	sys.exit\n"
"\n"
"align 4\n"
"skiptoeol:\n"
"	; Keep reading until you come to cr, lf, or eof\n"
"	call	getchar\n"
"	jc	done\n"
"	cmp	al, 0Ah\n"
"	jne	.cr\n"
"	ret\n"
"\n"
".cr:\n"
"	cmp	al, 0Dh\n"
"	jne	skiptoeol\n"
"	ret\n"
"\n"
"align 4\n"
"getchar:\n"
"	or	ebx, ebx\n"
"	jne	.fetch\n"
"\n"
"	call	read\n"
"\n"
".fetch:\n"
"	lodsb\n"
"	dec	ebx\n"
"	clc\n"
"	ret\n"
"\n"
"read:\n"
"	jecxz	.read\n"
"	call	write\n"
"\n"
".read:\n"
"	push	dword BUFSIZE\n"
"	mov	esi, ibuffer\n"
"	push	esi\n"
"	push	dword [fd.in]\n"
"	sys.read\n"
"	add	esp, byte 12\n"
"	mov	ebx, eax\n"
"	or	eax, eax\n"
"	je	.empty\n"
"	sub	eax, eax\n"
"	ret\n"
"\n"
"align 4\n"
".empty:\n"
"	add	esp, byte 4\n"
"	stc\n"
"	ret\n"
"\n"
"align 4\n"
"putchar:\n"
"	stosb\n"
"	inc	ecx\n"
"	cmp	ecx, BUFSIZE\n"
"	je	write\n"
"	ret\n"
"\n"
"align 4\n"
"write:\n"
"	jecxz	.ret	; nothing to write\n"
"	sub	edi, ecx	; start of buffer\n"
"	push	ecx\n"
"	push	edi\n"
"	push	dword [fd.out]\n"
"	sys.write\n"
"	add	esp, byte 12\n"
"	sub	eax, eax\n"
"	sub	ecx, ecx	; buffer is empty now\n"
".ret:\n"
"	ret\n"
"\n"
"align 4\n"
"bcdload:\n"
"	; EBP contains the number of chars in dbuffer\n"
"	push	ecx\n"
"	push	esi\n"
"	push	edi\n"
"\n"
"	lea	ecx, [ebp+1]\n"
"	lea	esi, [dbuffer+ebp-1]\n"
"	shr	ecx, 1\n"
"\n"
"	std\n"
"\n"
"	mov	edi, bbuffer\n"
"	sub	eax, eax\n"
"	mov	[edi], eax\n"
"	mov	[edi+4], eax\n"
"	mov	[edi+2], ax\n"
"\n"
".loop:\n"
"	lodsw\n"
"	sub	ax, 3030h\n"
"	shl	al, 4\n"
"	or	al, ah\n"
"	mov	[edi], al\n"
"	inc	edi\n"
"	loop	.loop\n"
"\n"
"	fbld	[bbuffer]\n"
"\n"
"	cld\n"
"	pop	edi\n"
"	pop	esi\n"
"	pop	ecx\n"
"	sub	eax, eax\n"
"	ret\n"
"\n"
"align 4\n"
"printnumber:\n"
"	push	ebp\n"
"	mov	al, [separ]\n"
"	call	putchar\n"
"\n"
"	; Print the integer at the TOS\n"
"	mov	ebp, bbuffer+9\n"
"	fbstp	[bbuffer]\n"
"\n"
"	; Check the sign\n"
"	mov	al, [ebp]\n"
"	dec	ebp\n"
"	or	al, al\n"
"	jns	.leading\n"
"\n"
"	; We got a negative number (should never happen)\n"
"	mov	al, '-'\n"
"	call	putchar\n"
"\n"
".leading:\n"
"	; Skip leading zeros\n"
"	mov	al, [ebp]\n"
"	dec	ebp\n"
"	or	al, al\n"
"	jne	.first\n"
"	cmp	ebp, bbuffer\n"
"	jae	.leading\n"
"\n"
"	; We are here because the result was 0.\n"
"	; Print '0' and return\n"
"	mov	al, '0'\n"
"	jmp	putchar\n"
"\n"
".first:\n"
"	; We have found the first non-zero.\n"
"	; But it is still packed\n"
"	test	al, 0F0h\n"
"	jz	.second\n"
"	push	eax\n"
"	shr	al, 4\n"
"	add	al, '0'\n"
"	call	putchar\n"
"	pop	eax\n"
"	and	al, 0Fh\n"
"\n"
".second:\n"
"	add	al, '0'\n"
"	call	putchar\n"
"\n"
".next:\n"
"	cmp	ebp, bbuffer\n"
"	jb	.done\n"
"\n"
"	mov	al, [ebp]\n"
"	push	eax\n"
"	shr	al, 4\n"
"	add	al, '0'\n"
"	call	putchar\n"
"	pop	eax\n"
"	and	al, 0Fh\n"
"	add	al, '0'\n"
"	call	putchar\n"
"\n"
"	dec	ebp\n"
"	jmp	short .next\n"
"\n"
".done:\n"
"	pop	ebp\n"
"	or	ebp, ebp\n"
"	je	.ret\n"
"\n"
".zeros:\n"
"	mov	al, '0'\n"
"	call	putchar\n"
"	dec	ebp\n"
"	jne	.zeros\n"
"\n"
".ret:\n"
"	ret\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14870
msgid ""
"The code follows the same format as all the other filters we have seen "
"before, with one subtle exception:"
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14877
msgid ""
"We are no longer assuming that the end of input implies the end of things to "
"do, something we took for granted in the <emphasis>character–oriented</"
"emphasis> filters."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14884
msgid ""
"This filter does not process characters. It processes a <emphasis>language</"
"emphasis> (albeit a very simple one, consisting only of numbers)."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14891
msgid "When we have no more input, it can mean one of two things:"
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:14896
msgid "We are done and can quit. This is the same as before."
msgstr ""

#. (itstool) path: listitem/para
#: book.translate.xml:14903
msgid ""
"The last character we have read was a digit. We have stored it at the end of "
"our <acronym>ASCII</acronym>–to–float conversion buffer. We now need to "
"convert the contents of that buffer into a number and write the last line of "
"our output."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14915
msgid ""
"For that reason, we have modified our <function>getchar</function> and our "
"<function>read</function> routines to return with the <varname role="
"\"register\">carry flag</varname> <emphasis>clear</emphasis> whenever we are "
"fetching another character from the input, or the <varname role="
"\"register\">carry flag</varname> <emphasis>set</emphasis> whenever there is "
"no more input."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14924
msgid ""
"Of course, we are still using assembly language magic to do that! Take a "
"good look at <function>getchar</function>. It <emphasis>always</emphasis> "
"returns with the <varname role=\"register\">carry flag</varname> "
"<emphasis>clear</emphasis>."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14931
msgid ""
"Yet, our main code relies on the <varname role=\"register\">carry flag</"
"varname> to tell it when to quit—and it works."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14936
msgid ""
"The magic is in <function>read</function>. Whenever it receives more input "
"from the system, it just returns to <function>getchar</function>, which "
"fetches a character from the input buffer, <emphasis>clears</emphasis> the "
"<varname role=\"register\">carry flag</varname> and returns."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14945
msgid ""
"But when <function>read</function> receives no more input from the system, "
"it does <emphasis>not</emphasis> return to <function>getchar</function> at "
"all. Instead, the <function role=\"opcode\">add esp, byte 4</function> op "
"code adds <constant>4</constant> to <varname role=\"register\">ESP</"
"varname>, <emphasis>sets</emphasis> the <varname role=\"register\">carry "
"flag</varname>, and returns."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14955
msgid ""
"So, where does it return to? Whenever a program uses the <function role="
"\"opcode\">call</function> op code, the microprocessor <function role="
"\"opcode\">push</function>es the return address, i.e., it stores it on the "
"top of the stack (not the <acronym>FPU</acronym> stack, the system stack, "
"which is in the memory). When a program uses the <function role="
"\"opcode\">ret</function> op code, the microprocessor <function role="
"\"opcode\">pop</function>s the return value from the stack, and jumps to the "
"address that was stored there."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14968
msgid ""
"But since we added <constant>4</constant> to <varname role=\"register\">ESP</"
"varname> (which is the stack pointer register), we have effectively given "
"the microprocessor a minor case of <emphasis>amnesia</emphasis>: It no "
"longer remembers it was <function>getchar</function> that <function role="
"\"opcode\">call</function>ed <function>read</function>."
msgstr ""

#. (itstool) path: blockquote/para
#: book.translate.xml:14978
msgid ""
"And since <function>getchar</function> never <function role=\"opcode\">push</"
"function>ed anything before <function role=\"opcode\">call</function>ing "
"<function>read</function>, the top of the stack now contains the return "
"address to whatever or whoever <function role=\"opcode\">call</function>ed "
"<function>getchar</function>. As far as that caller is concerned, he "
"<function role=\"opcode\">call</function>ed <function>getchar</function>, "
"which <function role=\"opcode\">ret</function>urned with the <varname role="
"\"register\">carry flag</varname> set!"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14992
msgid ""
"Other than that, the <function>bcdload</function> routine is caught up in "
"the middle of a Lilliputian conflict between the Big–Endians and the "
"Little–Endians."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:14999
msgid ""
"It is converting the text representation of a number into that number: The "
"text is stored in the big–endian order, but the <emphasis>packed decimal</"
"emphasis> is little–endian."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15006
msgid ""
"To solve the conflict, we use the <function>std</function> op code early on. "
"We cancel it with <function>cld</function> later on: It is quite important "
"we do not <function>call</function> anything that may depend on the default "
"setting of the <emphasis>direction flag</emphasis> while <function>std</"
"function> is active."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15015
msgid ""
"Everything else in this code should be quite clear, providing you have read "
"the entire chapter that precedes it."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15021
msgid ""
"It is a classical example of the adage that programming requires a lot of "
"thought and only a little coding. Once we have thought through every tiny "
"detail, the code almost writes itself."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:15031
msgid "Using <application>pinhole</application>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15032
msgid ""
"Because we have decided to make the program <emphasis>ignore</emphasis> any "
"input except for numbers (and even those inside a comment), we can actually "
"perform <emphasis>textual queries</emphasis>. We do not <emphasis>have to</"
"emphasis>, but we <emphasis>can</emphasis>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15040
msgid ""
"In my humble opinion, forming a textual query, instead of having to follow a "
"very strict syntax, makes software much more user friendly."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15046
msgid ""
"Suppose we want to build a pinhole camera to use the 4x5 inch film. The "
"standard focal length for that film is about 150mm. We want to "
"<emphasis>fine–tune</emphasis> our focal length so the pinhole diameter is "
"as round a number as possible. Let us also suppose we are quite comfortable "
"with cameras but somewhat intimidated by computers. Rather than just have to "
"type in a bunch of numbers, we want to <emphasis>ask</emphasis> a couple of "
"questions."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15058
msgid "Our session might look like this:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15061
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>pinhole\n"
"\n"
"Computer,\n"
"\n"
"What size pinhole do I need for the focal length of 150?</userinput>\n"
"150	490	306	362	2930	12\n"
"<userinput>Hmmm... How about 160?</userinput>\n"
"160	506	316	362	3125	12\n"
"<userinput>Let's make it 155, please.</userinput>\n"
"155	498	311	362	3027	12\n"
"<userinput>Ah, let's try 157...</userinput>\n"
"157	501	313	362	3066	12\n"
"<userinput>156?</userinput>\n"
"156	500	312	362	3047	12\n"
"<userinput>That's it! Perfect! Thank you very much!\n"
"^D</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15077
msgid ""
"We have found that while for the focal length of 150, our pinhole diameter "
"should be 490 microns, or 0.49 mm, if we go with the almost identical focal "
"length of 156 mm, we can get away with a pinhole diameter of exactly one "
"half of a millimeter."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:15089
msgid "Scripting"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15090
msgid ""
"Because we have chosen the <constant>#</constant> character to denote the "
"start of a comment, we can treat our <application>pinhole</application> "
"software as a <emphasis>scripting language</emphasis>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15097
msgid ""
"You have probably seen <application>shell</application> <emphasis>scripts</"
"emphasis> that start with:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:15101
#, no-wrap
msgid "\n"
"#! /bin/sh\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15104
msgid "...or..."
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:15107
#, no-wrap
msgid "\n"
"#!/bin/sh\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15109
msgid ""
"...because the blank space after the <function>#!</function> is optional."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15114
msgid ""
"Whenever <trademark class=\"registered\">UNIX</trademark> is asked to run an "
"executable file which starts with the <function>#!</function>, it assumes "
"the file is a script. It adds the command to the rest of the first line of "
"the script, and tries to execute that."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15122
msgid ""
"Suppose now that we have installed <application>pinhole</application> in "
"<application>/usr/local/bin/</application>, we can now write a script to "
"calculate various pinhole diameters suitable for various focal lengths "
"commonly used with the 120 film."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15129
msgid "The script might look something like this:"
msgstr ""

#. (itstool) path: sect2/programlisting
#: book.translate.xml:15132
#, no-wrap
msgid ""
"\n"
"#! /usr/local/bin/pinhole -b -i\n"
"# Find the best pinhole diameter\n"
"# for the 120 film\n"
"\n"
"### Standard\n"
"80\n"
"\n"
"### Wide angle\n"
"30, 40, 50, 60, 70\n"
"\n"
"### Telephoto\n"
"100, 120, 140\n"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15146
msgid ""
"Because 120 is a medium size film, we may name this file "
"<application>medium</application>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15151
msgid ""
"We can set its permissions to execute, and run it as if it were a program:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15156
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>chmod 755 medium</userinput>\n"
"<prompt>%</prompt> <userinput>./medium</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15158
msgid ""
"<trademark class=\"registered\">UNIX</trademark> will interpret that last "
"command as:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15161
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>/usr/local/bin/pinhole -b -i ./medium</"
"userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15162
msgid "It will run that command and display:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15166
#, no-wrap
msgid ""
"80	358	224	256	1562	11\n"
"30	219	137	128	586	9\n"
"40	253	158	181	781	10\n"
"50	283	177	181	977	10\n"
"60	310	194	181	1172	10\n"
"70	335	209	181	1367	10\n"
"100	400	250	256	1953	11\n"
"120	438	274	256	2344	11\n"
"140	473	296	256	2734	11"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15175
msgid "Now, let us enter:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15179
#, no-wrap
msgid "<prompt>%</prompt> <userinput>./medium -c</userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15180
msgid "<trademark class=\"registered\">UNIX</trademark> will treat that as:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15183
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>/usr/local/bin/pinhole -b -i ./medium -c</"
"userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15184
msgid ""
"That gives it two conflicting options: <parameter>-b</parameter> and "
"<parameter>-c</parameter> (Use Bender's constant and use Connors' constant). "
"We have programmed it so later options override early ones—our program will "
"calculate everything using Connors' constant:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15194
#, no-wrap
msgid ""
"80	331	242	256	1826	11\n"
"30	203	148	128	685	9\n"
"40	234	171	181	913	10\n"
"50	262	191	181	1141	10\n"
"60	287	209	181	1370	10\n"
"70	310	226	256	1598	11\n"
"100	370	270	256	2283	11\n"
"120	405	296	256	2739	11\n"
"140	438	320	362	3196	12"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15203
msgid ""
"We decide we want to go with Bender's constant after all. We want to save "
"its values as a comma–separated file:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15209
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>./medium -b -e &gt; bender</userinput>\n"
"<prompt>%</prompt> <userinput>cat bender</userinput>\n"
"focal length in millimeters,pinhole diameter in microns,F-number,normalized "
"F-number,F-5.6 multiplier,stops from F-5.6\n"
"80,358,224,256,1562,11\n"
"30,219,137,128,586,9\n"
"40,253,158,181,781,10\n"
"50,283,177,181,977,10\n"
"60,310,194,181,1172,10\n"
"70,335,209,181,1367,10\n"
"100,400,250,256,1953,11\n"
"120,438,274,256,2344,11\n"
"140,473,296,256,2734,11\n"
"<prompt>%</prompt>"
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:15227
msgid "Caveats"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15229
msgid ""
"Assembly language programmers who \"grew up\" under <acronym><trademark "
"class=\"registered\">MS-DOS</trademark></acronym> and <trademark class="
"\"registered\">Windows</trademark> often tend to take shortcuts. Reading the "
"keyboard scan codes and writing directly to video memory are two classical "
"examples of practices which, under <acronym><trademark class="
"\"registered\">MS-DOS</trademark></acronym> are not frowned upon but "
"considered the right thing to do."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15238
msgid ""
"The reason? Both the <acronym>PC BIOS</acronym> and <acronym><trademark "
"class=\"registered\">MS-DOS</trademark></acronym> are notoriously slow when "
"performing these operations."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15244
msgid ""
"You may be tempted to continue similar practices in the <trademark class="
"\"registered\">UNIX</trademark> environment. For example, I have seen a web "
"site which explains how to access the keyboard scan codes on a popular "
"<trademark class=\"registered\">UNIX</trademark> clone."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15250
msgid ""
"That is generally a <emphasis>very bad idea</emphasis> in <trademark class="
"\"registered\">UNIX</trademark> environment! Let me explain why."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:15256
msgid "<trademark class=\"registered\">UNIX</trademark> Is Protected"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15258
msgid ""
"For one thing, it may simply not be possible. <trademark class="
"\"registered\">UNIX</trademark> runs in protected mode. Only the kernel and "
"device drivers are allowed to access hardware directly. Perhaps a particular "
"<trademark class=\"registered\">UNIX</trademark> clone will let you read the "
"keyboard scan codes, but chances are a real <trademark class="
"\"registered\">UNIX</trademark> operating system will not. And even if one "
"version may let you do it, the next one may not, so your carefully crafted "
"software may become a dinosaur overnight."
msgstr ""

#. (itstool) path: sect2/title
#: book.translate.xml:15271
msgid "<trademark class=\"registered\">UNIX</trademark> Is an Abstraction"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15273
msgid ""
"But there is a much more important reason not to try accessing the hardware "
"directly (unless, of course, you are writing a device driver), even on the "
"<trademark class=\"registered\">UNIX</trademark> like systems that let you "
"do it:"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15280
msgid ""
"<emphasis><trademark class=\"registered\">UNIX</trademark> is an "
"abstraction! </emphasis>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15284
msgid ""
"There is a major difference in the philosophy of design between "
"<acronym><trademark class=\"registered\">MS-DOS</trademark></acronym> and "
"<trademark class=\"registered\">UNIX</trademark>. <acronym><trademark class="
"\"registered\">MS-DOS</trademark></acronym> was designed as a single-user "
"system. It is run on a computer with a keyboard and a video screen attached "
"directly to that computer. User input is almost guaranteed to come from that "
"keyboard. Your program's output virtually always ends up on that screen."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15294
msgid ""
"This is NEVER guaranteed under <trademark class=\"registered\">UNIX</"
"trademark>. It is quite common for a <trademark class=\"registered\">UNIX</"
"trademark> user to pipe and redirect program input and output:"
msgstr ""

#. (itstool) path: sect2/screen
#: book.translate.xml:15299
#, no-wrap
msgid ""
"<prompt>%</prompt> <userinput>program1 | program2 | program3 &gt; file1</"
"userinput>"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15301
msgid ""
"If you have written <application>program2</application>, your input does not "
"come from the keyboard but from the output of <application>program1</"
"application>. Similarly, your output does not go to the screen but becomes "
"the input for <application>program3</application> whose output, in turn, "
"goes to <filename>file1</filename>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15310
msgid ""
"But there is more! Even if you made sure that your input comes from, and "
"your output goes to, the terminal, there is no guarantee the terminal is a "
"PC: It may not have its video memory where you expect it, nor may its "
"keyboard be producing <acronym>PC</acronym>-style scan codes. It may be a "
"<trademark class=\"registered\">Macintosh</trademark>, or any other computer."
""
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15319
msgid ""
"Now you may be shaking your head: My software is in <acronym>PC</acronym> "
"assembly language, how can it run on a <trademark class="
"\"registered\">Macintosh</trademark>? But I did not say your software would "
"be running on a <trademark class=\"registered\">Macintosh</trademark>, only "
"that its terminal may be a <trademark class=\"registered\">Macintosh</"
"trademark>."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15327
msgid ""
"Under <trademark class=\"registered\">UNIX</trademark>, the terminal does "
"not have to be directly attached to the computer that runs your software, it "
"can even be on another continent, or, for that matter, on another planet. It "
"is perfectly possible that a <trademark class=\"registered\">Macintosh</"
"trademark> user in Australia connects to a <trademark class="
"\"registered\">UNIX</trademark> system in North America (or anywhere else) "
"via <application>telnet</application>. The software then runs on one "
"computer, while the terminal is on a different computer: If you try to read "
"the scan codes, you will get the wrong input!"
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15339
msgid ""
"Same holds true about any other hardware: A file you are reading may be on a "
"disk you have no direct access to. A camera you are reading images from may "
"be on a space shuttle, connected to you via satellites."
msgstr ""

#. (itstool) path: sect2/para
#: book.translate.xml:15346
msgid ""
"That is why under <trademark class=\"registered\">UNIX</trademark> you must "
"never make any assumptions about where your data is coming from and going to."
" Always let the system handle the physical access to the hardware."
msgstr ""

#. (itstool) path: note/para
#: book.translate.xml:15353
msgid ""
"These are caveats, not absolute rules. Exceptions are possible. For example, "
"if a text editor has determined it is running on a local machine, it may "
"want to read the scan codes directly for improved control. I am not "
"mentioning these caveats to tell you what to do or what not to do, just to "
"make you aware of certain pitfalls that await you if you have just arrived "
"to <trademark class=\"registered\">UNIX</trademark> form <acronym><trademark "
"class=\"registered\">MS-DOS</trademark></acronym>. Of course, creative "
"people often break rules, and it is OK as long as they know they are "
"breaking them and why."
msgstr ""

#. (itstool) path: sect1/title
#: book.translate.xml:15372
msgid "Acknowledgements"
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15374
msgid ""
"This tutorial would never have been possible without the help of many "
"experienced FreeBSD programmers from the <link xlink:href=\"http://lists."
"FreeBSD.org/mailman/listinfo/freebsd-hackers\">FreeBSD technical discussions "
"mailing list</link>, many of whom have patiently answered my questions, and "
"pointed me in the right direction in my attempts to explore the inner "
"workings of <trademark class=\"registered\">UNIX</trademark> system "
"programming in general and FreeBSD in particular."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15383
msgid ""
"Thomas M. Sommers opened the door for me. His <link xlink:href=\"https://web."
"archive.org/web/20090914064615/http://www.codebreakers-journal.com/content/"
"view/262/27\">How do I write \"Hello, world\" in FreeBSD assembler?</link> "
"web page was my first encounter with an example of assembly language "
"programming under FreeBSD."
msgstr ""

#. (itstool) path: sect1/para
#: book.translate.xml:15390
msgid ""
"Jake Burkholder has kept the door open by willingly answering all of my "
"questions and supplying me with example assembly language source code."
msgstr ""

#. (itstool) path: part/title
#: book.translate.xml:15409
msgid "Appendices"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15415
msgid ""
"<personname><firstname>Dave</firstname><othername role=\"MI\">A</"
"othername><surname>Patterson</surname></personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15416
msgid ""
"<personname><firstname>John</firstname><othername role=\"MI\">L</"
"othername><surname>Hennessy</surname></personname>"
msgstr ""

#. (itstool) path: biblioentry/copyright
#: book.translate.xml:15418
msgid "<year>1998</year><holder>Morgan Kaufmann Publishers, Inc.</holder>"
msgstr ""

#. (itstool) path: biblioentry/biblioid
#: book.translate.xml:15420
msgid "1-55860-428-6"
msgstr ""

#. (itstool) path: publisher/publishername
#: book.translate.xml:15422
msgid "Morgan Kaufmann Publishers, Inc."
msgstr ""

#. (itstool) path: biblioentry/citetitle
#: book.translate.xml:15424
msgid "Computer Organization and Design"
msgstr ""

#. (itstool) path: biblioentry/subtitle
#: book.translate.xml:15425
msgid "The Hardware / Software Interface"
msgstr ""

#. (itstool) path: biblioentry/pagenums
#: book.translate.xml:15426 book.translate.xml:15440 book.translate.xml:15454
msgid "1-2"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15431
msgid ""
"<personname><firstname>W.</firstname><othername role=\"Middle\">Richard</"
"othername><surname>Stevens</surname></personname>"
msgstr ""

#. (itstool) path: biblioentry/copyright
#: book.translate.xml:15433
msgid "<year>1993</year><holder>Addison Wesley Longman, Inc.</holder>"
msgstr ""

#. (itstool) path: biblioentry/biblioid
#: book.translate.xml:15435
msgid "0-201-56317-7"
msgstr ""

#. (itstool) path: publisher/publishername
#: book.translate.xml:15437
msgid "Addison Wesley Longman, Inc."
msgstr ""

#. (itstool) path: biblioentry/citetitle
#: book.translate.xml:15439
msgid "Advanced Programming in the Unix Environment"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15445
msgid ""
"<personname><firstname>Marshall</firstname><othername role=\"Middle\">Kirk</"
"othername><surname>McKusick</surname></personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15446
msgid ""
"<personname><firstname>George</firstname><surname>Neville-Neil</surname></"
"personname>"
msgstr ""

#. (itstool) path: biblioentry/copyright
#: book.translate.xml:15448
msgid "<year>2004</year><holder>Addison-Wesley</holder>"
msgstr ""

#. (itstool) path: biblioentry/biblioid
#: book.translate.xml:15449
msgid "0-201-70245-2"
msgstr ""

#. (itstool) path: publisher/publishername
#: book.translate.xml:15451
msgid "Addison-Wesley"
msgstr ""

#. (itstool) path: biblioentry/citetitle
#: book.translate.xml:15453
msgid "The Design and Implementation of the FreeBSD Operating System"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15459
msgid ""
"<personname><firstname>Aleph</firstname><surname>One</surname></personname>"
msgstr ""

#. (itstool) path: biblioentry/citetitle
#: book.translate.xml:15461
msgid "Phrack 49; \"Smashing the Stack for Fun and Profit\""
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15466
msgid ""
"<personname><firstname>Chrispin</firstname><surname>Cowan</surname></"
"personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15467
msgid ""
"<personname><firstname>Calton</firstname><surname>Pu</surname></personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15468
msgid ""
"<personname><firstname>Dave</firstname><surname>Maier</surname></personname>"
msgstr ""

#. (itstool) path: biblioentry/citetitle
#: book.translate.xml:15470
msgid ""
"StackGuard; Automatic Adaptive Detection and Prevention of Buffer-Overflow "
"Attacks"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15476
msgid ""
"<personname><firstname>Todd</firstname><surname>Miller</surname></"
"personname>"
msgstr ""

#. (itstool) path: authorgroup/author
#: book.translate.xml:15477
msgid ""
"<personname><firstname>Theo</firstname><surname>de Raadt</surname></"
"personname>"
msgstr ""

#. (itstool) path: biblioentry/citetitle
#: book.translate.xml:15479
msgid "strlcpy and strlcat -- consistent, safe string copy and concatenation."
msgstr ""