Adding upstream version 247.3.upstream/247.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 168 insertions, 0 deletions

diff --git a/man/sd-id128.xml b/man/sd-id128.xml
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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="sd-id128"
+  xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd-id128</title>
+    <productname>systemd</productname>
+  </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_MAKE_STR</refname>
+    <refname>SD_ID128_NULL</refname>
+    <refname>SD_ID128_CONST_STR</refname>
+    <refname>SD_ID128_FORMAT_STR</refname>
+    <refname>SD_ID128_UUID_FORMAT_STR</refname>
+    <refname>SD_ID128_FORMAT_VAL</refname>
+    <refname>sd_id128_equal</refname>
+    <refname>sd_id128_is_null</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><constant>SD_ID128_NULL</constant> may be used to refer to the 128bit ID consisting of only
+    <constant>NUL</constant> bytes.</para>
+
+    <para><function>SD_ID128_MAKE_STR()</function> is similar to <function>SD_ID128_MAKE()</function>, but creates a
+    <type>const char*</type> expression that can be conveniently used in message formats and such:</para>
+
+    <programlisting>#include &lt;stdio.h&gt;
+#define SD_MESSAGE_COREDUMP_STR SD_ID128_MAKE_STR(fc,2e,22,bc,6e,e6,47,b6,b9,07,29,ab,34,a2,50,b1)
+
+int main(int argc, char **argv) {
+        puts("Match for coredumps: MESSAGE_ID=" SD_MESSAGE_COREDUMP_STR);
+}
+    </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("Match for coredumps: %s", SD_ID128_CONST_STR(SD_MESSAGE_COREDUMP));
+}</programlisting>
+
+    <para><constant>SD_ID128_FORMAT_STR</constant> 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><constant>SD_ID128_UUID_FORMAT_STR</constant> is similar to
+    <constant>SD_ID128_FORMAT_STR</constant> but includes separating hyphens to conform to the
+    "<ulink url="https://en.wikipedia.org/wiki/Universally_unique_identifier#Format">canonical representation</ulink>".
+    </para>
+
+    <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>Use <function>sd_id128_is_null()</function> to check if an 128bit ID consists of only
+    <constant>NUL</constant> bytes:</para>
+
+    <programlisting>int main(int argc, char *argv[]) {
+        assert(sd_id128_is_null(SD_ID128_NULL));
+}</programlisting>
+
+    <para>Note that new, randomized IDs may be generated with
+    <citerefentry><refentrytitle>systemd-id128</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+    <command>new</command> command.</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>