summaryrefslogtreecommitdiff
path: root/src/libsystemd/sd-id128.xml
diff options
context:
space:
mode:
authorLuke Shumaker <lukeshu@sbcglobal.net>2016-09-13 21:24:07 -0400
committerLuke Shumaker <lukeshu@sbcglobal.net>2016-09-13 21:24:07 -0400
commitce31ec116f9bf4ad45952b6a200f4181fac311a3 (patch)
tree95bc9042a11e7f4773f10d72745396c9f46ed0ef /src/libsystemd/sd-id128.xml
parentc73c7c774cbd1f0e778254d51da819490a333ab4 (diff)
./tools/notsd-move
Diffstat (limited to 'src/libsystemd/sd-id128.xml')
-rw-r--r--src/libsystemd/sd-id128.xml166
1 files changed, 166 insertions, 0 deletions
diff --git a/src/libsystemd/sd-id128.xml b/src/libsystemd/sd-id128.xml
new file mode 100644
index 0000000000..ea7972055d
--- /dev/null
+++ b/src/libsystemd/sd-id128.xml
@@ -0,0 +1,166 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ This file is part of systemd.
+
+ Copyright 2012 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd-id128"
+ xmlns:xi="http://www.w3.org/2001/XInclude">
+
+ <refentryinfo>
+ <title>sd-id128</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd-id128</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd-id128</refname>
+ <refname>sd_id128_t</refname>
+ <refname>SD_ID128_MAKE</refname>
+ <refname>SD_ID128_CONST_STR</refname>
+ <refname>SD_ID128_FORMAT_STR</refname>
+ <refname>SD_ID128_FORMAT_VAL</refname>
+ <refname>sd_id128_equal</refname>
+ <refpurpose>APIs for processing 128-bit IDs</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
+ </funcsynopsis>
+
+ <cmdsynopsis>
+ <command>pkg-config --cflags --libs libsystemd</command>
+ </cmdsynopsis>
+
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>sd-id128.h</filename> provides APIs to process and
+ generate 128-bit ID values. The 128-bit ID values processed and
+ generated by these APIs are a generalization of OSF UUIDs as
+ defined by <ulink url="https://tools.ietf.org/html/rfc4122">RFC
+ 4122</ulink> but use a simpler string format. These functions
+ impose no structure on the used IDs, much unlike OSF UUIDs or
+ Microsoft GUIDs, but are fully compatible with those types of IDs.
+ </para>
+
+ <para>See
+ <citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for more information about the implemented functions.</para>
+
+ <para>A 128-bit ID is implemented as the following
+ union type:</para>
+
+ <programlisting>typedef union sd_id128 {
+ uint8_t bytes[16];
+ uint64_t qwords[2];
+} sd_id128_t;</programlisting>
+
+ <para>This union type allows accessing the 128-bit ID as 16
+ separate bytes or two 64-bit words. It is generally safer to
+ access the ID components by their 8-bit array to avoid endianness
+ issues. This union is intended to be passed call-by-value (as
+ opposed to call-by-reference) and may be directly manipulated by
+ clients.</para>
+
+ <para>A couple of macros are defined to denote and decode 128-bit
+ IDs:</para>
+
+ <para><function>SD_ID128_MAKE()</function> may be used to denote a
+ constant 128-bit ID in source code. A commonly used idiom is to
+ assign a name to a 128-bit ID using this macro:</para>
+
+ <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>
+
+ <para><function>SD_ID128_CONST_STR()</function> may be used to
+ convert constant 128-bit IDs into constant strings for output. The
+ following example code will output the string
+ "fc2e22bc6ee647b6b90729ab34a250b1":</para>
+ <programlisting>int main(int argc, char *argv[]) {
+ puts(SD_ID128_CONST_STR(SD_MESSAGE_COREDUMP));
+}</programlisting>
+
+ <para><function>SD_ID128_FORMAT_STR</function> and
+ <function>SD_ID128_FORMAT_VAL()</function> may be used to format a
+ 128-bit ID in a
+ <citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ format string, as shown in the following example:</para>
+
+ <programlisting>int main(int argc, char *argv[]) {
+ sd_id128_t id;
+ id = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
+ printf("The ID encoded in this C file is " SD_ID128_FORMAT_STR ".\n", SD_ID128_FORMAT_VAL(id));
+ return 0;
+}</programlisting>
+
+ <para>Use <function>sd_id128_equal()</function> to compare two 128-bit IDs:</para>
+
+ <programlisting>int main(int argc, char *argv[]) {
+ sd_id128_t a, b, c;
+ a = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
+ b = SD_ID128_MAKE(f2,28,88,9c,5f,09,44,15,9d,d7,04,77,58,cb,e7,3e);
+ c = a;
+ assert(sd_id128_equal(a, c));
+ assert(!sd_id128_equal(a, b));
+ return 0;
+}</programlisting>
+
+ <para>Note that new, randomized IDs may be generated with
+ <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <option>--new-id</option> option.</para>
+ </refsect1>
+
+ <xi:include href="libsystemd-pkgconfig.xml" />
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>