mirror of
https://github.com/systemd/systemd.git
synced 2024-12-22 17:35:35 +03:00
130 lines
6.2 KiB
XML
130 lines
6.2 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
|
|
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
|
|
|
|
<refentry id="sd_id128_to_string" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_id128_to_string</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_id128_to_string</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_id128_to_string</refname>
|
|
<refname>SD_ID128_TO_STRING</refname>
|
|
<refname>SD_ID128_STRING_MAX</refname>
|
|
<refname>sd_id128_to_uuid_string</refname>
|
|
<refname>SD_ID128_TO_UUID_STRING</refname>
|
|
<refname>SD_ID128_UUID_STRING_MAX</refname>
|
|
<refname>sd_id128_from_string</refname>
|
|
<refpurpose>Format or parse 128-bit IDs as strings</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
|
|
|
|
<funcsynopsisinfo>#define SD_ID128_STRING_MAX 33U</funcsynopsisinfo>
|
|
|
|
<funcsynopsisinfo>#define SD_ID128_UUID_STRING_MAX 37U</funcsynopsisinfo>
|
|
|
|
<funcsynopsisinfo>#define SD_ID128_TO_STRING(id) …</funcsynopsisinfo>
|
|
|
|
<funcsynopsisinfo>#define SD_ID128_TO_UUID_STRING(id) …</funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>char *<function>sd_id128_to_string</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[static SD_ID128_STRING_MAX]</paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>char *<function>sd_id128_uuid_string</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[static SD_ID128_UUID_STRING_MAX]</paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_from_string</function></funcdef>
|
|
<paramdef>const char *<parameter>s</parameter>, sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_id128_to_string()</function> formats a 128-bit ID as a character string. It expects
|
|
the ID and a string array capable of storing 33 characters
|
|
(<constant>SD_ID128_STRING_MAX</constant>). The ID will be formatted as 32 lowercase hexadecimal digits
|
|
and be terminated by a <constant>NUL</constant> byte.</para>
|
|
|
|
<para><function>SD_ID128_TO_STRING()</function> is a macro that wraps
|
|
<function>sd_id128_to_string()</function> and passes an appropriately sized buffer as second argument,
|
|
allocated as C99 compound literal. Each use will thus implicitly acquire a suitable buffer on the stack
|
|
which remains valid until the end of the current code block. This is usually the simplest way to acquire
|
|
a string representation of a 128-bit ID in a buffer that is valid in the current code block.</para>
|
|
|
|
<para><function>sd_id128_to_uuid_string()</function> and <function>SD_ID128_TO_UUID_STRING()</function>
|
|
are similar to these two functions/macros, but format the 128-bit values as RFC4122 UUIDs, i.e. a series
|
|
of 36 lowercase hexadeciaml digits and dashes, terminated by a <constant>NUL</constant> byte.</para>
|
|
|
|
<para><function>sd_id128_from_string()</function> implements the reverse operation: it takes a 33
|
|
character string with 32 hexadecimal digits (either lowercase or uppercase, terminated by
|
|
<constant>NUL</constant>) and parses them back into a 128-bit ID returned in
|
|
<parameter>ret</parameter>. Alternatively, this call can also parse a 37-character string with a 128-bit
|
|
ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as <constant>NULL</constant> the
|
|
function will validate the passed ID string, but not actually return it in parsed form.</para>
|
|
|
|
<para>Note that when formatting and parsing 36 character UUIDs this is done strictly in Big Endian byte order,
|
|
i.e. according to <ulink url="https://tools.ietf.org/html/rfc4122">RFC4122</ulink> Variant 1 rules, even
|
|
if the UUID encodes a different variant. This matches behaviour in various other Linux userspace
|
|
tools. It's probably wise to avoid UUIDs of other variant types.</para>
|
|
|
|
<para>For more information about the <literal>sd_id128_t</literal> type see
|
|
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Note that
|
|
these calls operate the same way on all architectures, i.e. the results do not depend on
|
|
endianness.</para>
|
|
|
|
<para>When formatting a 128-bit ID into a string, it is often easier to use a format string for
|
|
<citerefentry
|
|
project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
|
|
is easily done using the <constant>SD_ID128_FORMAT_STR</constant> and
|
|
<function>SD_ID128_FORMAT_VAL()</function> macros. For more information see
|
|
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para><function>sd_id128_to_string()</function> always succeeds and returns a pointer to the string array
|
|
passed in. <function>sd_id128_from_string()</function> returns 0 on success, in which case
|
|
<parameter>ret</parameter> is filled in, or a negative errno-style error code.</para>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><function>sd_id128_to_string()</function> and
|
|
<function>sd_id128_from_string()</function> were added in version 187.</para>
|
|
<para><function>sd_id128_uuid_string()</function> was added in version 251.</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</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|