mirror of
https://github.com/systemd/systemd.git
synced 2024-12-27 07:22:31 +03:00
297 lines
14 KiB
XML
297 lines
14 KiB
XML
<?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_ALLF</refname>
|
|
<refname>SD_ID128_CONST_STR</refname>
|
|
<refname>SD_ID128_FORMAT_STR</refname>
|
|
<refname>SD_ID128_FORMAT_VAL</refname>
|
|
<refname>SD_ID128_MAKE</refname>
|
|
<refname>SD_ID128_MAKE_STR</refname>
|
|
<refname>SD_ID128_MAKE_UUID_STR</refname>
|
|
<refname>SD_ID128_NULL</refname>
|
|
<refname>SD_ID128_UUID_FORMAT_STR</refname>
|
|
<refname>sd_id128_equal</refname>
|
|
<refname>sd_id128_string_equal</refname>
|
|
<refname>sd_id128_in_set</refname>
|
|
<refname>sd_id128_in_set_sentinel</refname>
|
|
<refname>sd_id128_in_setv</refname>
|
|
<refname>sd_id128_is_allf</refname>
|
|
<refname>sd_id128_is_null</refname>
|
|
<refname>sd_id128_t</refname>
|
|
<refpurpose>APIs for processing 128-bit IDs</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
|
|
|
|
<para>
|
|
<constant>SD_ID128_ALLF</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_NULL</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_CONST_STR(<replaceable>id</replaceable>)</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_FORMAT_STR</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_FORMAT_VAL(<replaceable>id</replaceable>)</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_MAKE(<replaceable>v0</replaceable>, <replaceable>v1</replaceable>, <replaceable>v2</replaceable>, <replaceable>v3</replaceable>, <replaceable>v4</replaceable>, <replaceable>v5</replaceable>, <replaceable>v6</replaceable>, <replaceable>v7</replaceable>, <replaceable>v8</replaceable>, <replaceable>v9</replaceable>, <replaceable>vA</replaceable>, <replaceable>vB</replaceable>, <replaceable>vC</replaceable>, <replaceable>vD</replaceable>, <replaceable>vE</replaceable>, <replaceable>vF</replaceable>)</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_MAKE_STR(<replaceable>v0</replaceable>, <replaceable>v1</replaceable>, <replaceable>v2</replaceable>, <replaceable>v3</replaceable>, <replaceable>v4</replaceable>, <replaceable>v5</replaceable>, <replaceable>v6</replaceable>, <replaceable>v7</replaceable>, <replaceable>v8</replaceable>, <replaceable>v9</replaceable>, <replaceable>vA</replaceable>, <replaceable>vB</replaceable>, <replaceable>vC</replaceable>, <replaceable>vD</replaceable>, <replaceable>vE</replaceable>, <replaceable>vF</replaceable>)</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_MAKE_UUID_STR(<replaceable>v0</replaceable>, <replaceable>v1</replaceable>, <replaceable>v2</replaceable>, <replaceable>v3</replaceable>, <replaceable>v4</replaceable>, <replaceable>v5</replaceable>, <replaceable>v6</replaceable>, <replaceable>v7</replaceable>, <replaceable>v8</replaceable>, <replaceable>v9</replaceable>, <replaceable>vA</replaceable>, <replaceable>vB</replaceable>, <replaceable>vC</replaceable>, <replaceable>vD</replaceable>, <replaceable>vE</replaceable>, <replaceable>vF</replaceable>)</constant>
|
|
</para>
|
|
<para>
|
|
<constant>SD_ID128_UUID_FORMAT_STR</constant>
|
|
</para>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_equal</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>a</parameter></paramdef>
|
|
<paramdef>sd_id128_t <parameter>b</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_string_equal</function></funcdef>
|
|
<paramdef>const char *<parameter>a</parameter></paramdef>
|
|
<paramdef>sd_id128_t <parameter>b</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_is_null</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_is_allf</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_in_setv</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter></paramdef>
|
|
<paramdef>va_list <parameter>ap</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_in_set_sentinel</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter></paramdef>
|
|
<paramdef>…</paramdef>
|
|
<paramdef><parameter><constant>SD_ID128_NULL</constant></parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_in_set</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter></paramdef>
|
|
<paramdef>…</paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
|
|
<cmdsynopsis>
|
|
<command>pkg-config --cflags --libs libsystemd</command>
|
|
</cmdsynopsis>
|
|
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><filename>sd-id128.h</filename> is part of
|
|
<citerefentry><refentrytitle>libsystemd</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
|
|
provides APIs to generate, convert, and compare 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 mostly
|
|
compatible with those types of IDs.
|
|
</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 by value (as opposed to pass-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> is used to write a constant ID in source code. A commonly used
|
|
idiom is to assign a name to an 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> defines an ID consisting of only <constant>NUL</constant> bytes
|
|
(i.e. all bits off).</para>
|
|
|
|
<para><constant>SD_ID128_ALLF</constant> defines an ID consisting of only <constant>0xFF</constant> bytes
|
|
(i.e. all bits on).</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 <stdio.h>
|
|
#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> converts constant 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> is used to
|
|
format an 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> and <function>SD_ID128_MAKE_UUID_STR()</function>
|
|
are similar to
|
|
<constant>SD_ID128_FORMAT_STR</constant> and <function>SD_ID128_MAKE_STR()</function>,
|
|
but include separating hyphens to conform to the
|
|
"<ulink url="https://en.wikipedia.org/wiki/Universally_unique_identifier#Format">UUID canonical representation</ulink>".
|
|
They format the string based on <ulink
|
|
url="https://tools.ietf.org/html/rfc4122">RFC4122</ulink> Variant 1 rules, i.e. converting from Big
|
|
Endian byte order. This matches behaviour of most other Linux userspace infrastructure. It's probably
|
|
best to avoid UUIDs of other variants, in order to avoid unnecessary ambiguities. All 128-bit IDs
|
|
generated by the sd-id128 APIs strictly conform to Variant 1 Version 4 UUIDs, as per RFC 4122.</para>
|
|
|
|
<para><function>sd_id128_equal()</function> compares 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><function>sd_id128_string_equal()</function> is similar to <function>sd_id128_equal()</function>,
|
|
but the first ID is formatted as <type>const char*</type>. The same restrictions apply as to the first
|
|
argument of <function>sd_id128_from_string()</function>.</para>
|
|
|
|
<para><function>sd_id128_is_null()</function> checks if an ID consists of only <constant>NUL</constant>
|
|
bytes:</para>
|
|
|
|
<programlisting>assert(sd_id128_is_null(SD_ID128_NULL));</programlisting>
|
|
|
|
<para>Similarly, <function>sd_id128_is_allf()</function> checks if an ID consists of only
|
|
<constant>0xFF</constant> bytes (all bits on):</para>
|
|
|
|
<programlisting>assert(sd_id128_is_allf(SD_ID128_ALLF));</programlisting>
|
|
|
|
<para><function>sd_id128_in_set_sentinel()</function> takes a list of IDs and returns true if the first
|
|
argument is equal to any of the subsequent arguments. The argument list is terminated by an
|
|
<constant>SD_ID128_NULL</constant> sentinel, which must be present.</para>
|
|
|
|
<para><function>sd_id128_in_set()</function> is a convenience function that takes a list of IDs and
|
|
returns true if the first argument is equal to any of the subsequent arguments:</para>
|
|
|
|
<programlisting>int main(int argc, char *argv[]) {
|
|
sd_id12_t a = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
|
|
assert(sd_id128_in_set(a, a));
|
|
assert(sd_id128_in_set(a, a, a));
|
|
assert(!sd_id128_in_set(a));
|
|
assert(!sd_id128_in_set(a,
|
|
SD_ID128_MAKE(f2,28,88,9c,5f,09,44,15,9d,d7,04,77,58,cb,e7,3e)
|
|
SD_ID128_MAKE(2f,88,28,5f,9c,44,09,9d,d7,15,77,04,bc,85,7e,e3)
|
|
SD_ID128_ALLF));
|
|
return 0;
|
|
}
|
|
</programlisting>
|
|
|
|
<para><function>sd_id128_in_set()</function> is defined as a macro over
|
|
<function>sd_id128_in_set_sentinel()</function>, adding the <constant>SD_ID128_NULL</constant> sentinel
|
|
automatically. Since <function>sd_id128_in_set_sentinel()</function> uses
|
|
<constant>SD_ID128_NULL</constant> as the sentinel, <constant>SD_ID128_NULL</constant> cannot be
|
|
otherwise placed in the argument list.</para>
|
|
|
|
<para><function>sd_id128_in_setv()</function> is similar to
|
|
<function>sd_id128_in_set_sentinel()</function>, but takes a <structname>struct varargs</structname>
|
|
argument.</para>
|
|
|
|
<para>New randomized IDs may be generated with
|
|
<citerefentry><refentrytitle>systemd-id128</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
|
|
<command>new</command> command.</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 information about other implemented functions.</para>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><function>sd_id128_equal()</function>,
|
|
<function>sd_id128_string_equal()</function>,
|
|
<function>sd_id128_is_null()</function>,
|
|
<function>sd_id128_is_allf()</function>,
|
|
<function>sd_id128_in_setv()</function>,
|
|
<function>sd_id128_in_set_sentinel()</function>, and
|
|
<function>sd_id128_in_set()</function> were added in version 252.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
<para><simplelist type="inline">
|
|
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|