12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
167 lines
6.5 KiB
XML
167 lines
6.5 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd-id128"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd-id128</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd-id128</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd-id128</refname>
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<refname>sd_id128_t</refname>
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<refname>SD_ID128_MAKE</refname>
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<refname>SD_ID128_CONST_STR</refname>
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<refname>SD_ID128_FORMAT_STR</refname>
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<refname>SD_ID128_FORMAT_VAL</refname>
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<refname>sd_id128_equal</refname>
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<refpurpose>APIs for processing 128-bit IDs</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
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</funcsynopsis>
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<cmdsynopsis>
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<command>pkg-config --cflags --libs libsystemd</command>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>sd-id128.h</filename> provides APIs to process and
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generate 128-bit ID values. The 128-bit ID values processed and
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generated by these APIs are a generalization of OSF UUIDs as
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defined by <ulink url="https://tools.ietf.org/html/rfc4122">RFC
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4122</ulink> but use a simpler string format. These functions
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impose no structure on the used IDs, much unlike OSF UUIDs or
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Microsoft GUIDs, but are fully compatible with those types of IDs.
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</para>
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<para>See
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<citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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and
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<citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for more information about the implemented functions.</para>
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<para>A 128-bit ID is implemented as the following
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union type:</para>
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<programlisting>typedef union sd_id128 {
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uint8_t bytes[16];
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uint64_t qwords[2];
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} sd_id128_t;</programlisting>
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<para>This union type allows accessing the 128-bit ID as 16
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separate bytes or two 64-bit words. It is generally safer to
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access the ID components by their 8-bit array to avoid endianness
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issues. This union is intended to be passed call-by-value (as
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opposed to call-by-reference) and may be directly manipulated by
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clients.</para>
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<para>A couple of macros are defined to denote and decode 128-bit
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IDs:</para>
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<para><function>SD_ID128_MAKE()</function> may be used to denote a
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constant 128-bit ID in source code. A commonly used idiom is to
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assign a name to a 128-bit ID using this macro:</para>
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<programlisting>#define SD_MESSAGE_COREDUMP SD_ID128_MAKE(fc,2e,22,bc,6e,e6,47,b6,b9,07,29,ab,34,a2,50,b1)</programlisting>
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<para><function>SD_ID128_CONST_STR()</function> may be used to
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convert constant 128-bit IDs into constant strings for output. The
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following example code will output the string
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"fc2e22bc6ee647b6b90729ab34a250b1":</para>
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<programlisting>int main(int argc, char *argv[]) {
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puts(SD_ID128_CONST_STR(SD_MESSAGE_COREDUMP));
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}</programlisting>
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<para><function>SD_ID128_FORMAT_STR</function> and
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<function>SD_ID128_FORMAT_VAL()</function> may be used to format a
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128-bit ID in a
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<citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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format string, as shown in the following example:</para>
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<programlisting>int main(int argc, char *argv[]) {
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sd_id128_t id;
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id = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
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printf("The ID encoded in this C file is " SD_ID128_FORMAT_STR ".\n", SD_ID128_FORMAT_VAL(id));
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return 0;
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}</programlisting>
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<para>Use <function>sd_id128_equal()</function> to compare two 128-bit IDs:</para>
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<programlisting>int main(int argc, char *argv[]) {
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sd_id128_t a, b, c;
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a = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
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b = SD_ID128_MAKE(f2,28,88,9c,5f,09,44,15,9d,d7,04,77,58,cb,e7,3e);
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c = a;
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assert(sd_id128_equal(a, c));
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assert(!sd_id128_equal(a, b));
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return 0;
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}</programlisting>
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<para>Note that new, randomized IDs may be generated with
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<option>--new-id</option> option.</para>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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