1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of systemd.
8 Copyright 2012 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_id128_to_string">
27 <title>sd_id128_to_string</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_id128_to_string</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_id128_to_string</refname>
47 <refname>sd_id128_from_string</refname>
48 <refpurpose>Format or parse 128 bit IDs as strings</refpurpose>
53 <funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
56 <funcdef>char* <function>sd_id128_to_string</function></funcdef>
57 <paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[33]</paramdef>
61 <funcdef>int <function>sd_id128_from_string</function></funcdef>
62 <paramdef>const char* <parameter>s</parameter>, sd_id128_t* <parameter>ret</parameter></paramdef>
69 <title>Description</title>
71 <para><function>sd_id128_to_string()</function>
72 formats a 128 bit ID as character string. It expects
73 the ID and a string array capable of storing 33
74 characters. The ID will be formatted as 32 lowercase
75 hexadecimal digits and be terminated by a NUL
78 <para><function>sd_id128_from_string()</function>
79 implements the reverse operation: it takes a 33
80 character string with 32 hexadecimal digits
81 (either lowercase or uppercase, terminated by NUL) and parses them back into an 128
83 <parameter>ret</parameter>. Alternatively, this call
84 can also parse a 37 character string with a 128bit ID
85 formatted as RFC UUID.</para>
87 <para>For more information about the
88 <literal>sd_id128_t</literal> type see
89 <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Note
90 that these calls operate the same way on all
91 architectures, i.e. the results do not depend on
94 <para>When formatting a 128 bit ID into a string it is
95 often easier to use a format string for
96 <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
97 is easily done using the
98 <function>SD_ID128_FORMAT_STR</function> and
99 <function>SD_ID128_FORMAT_VAL()</function> macros. For
101 <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
105 <title>Return Value</title>
107 <para><function>sd_id128_to_string()</function> always
108 succeeds and returns a pointer to the string array
109 passed in. <function>sd_id128_from_string</function>
110 returns 0 on success (in which case
111 <parameter>ret</parameter> is filled in), or a negative
112 errno-style error code.</para>
118 <para>The <function>sd_id128_to_string()</function>
119 and <function>sd_id128_from_string()</function> interfaces are
120 available as shared library, which can be compiled and
121 linked to with the <literal>libsystemd-id128</literal>
122 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
127 <title>See Also</title>
130 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
131 <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
132 <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>