man/sd_id128_to_string.xml

   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">
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   8   Copyright 2012 Lennart Poettering
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  23
  24 <refentry id="sd_id128_to_string">
  25
  26         <refentryinfo>
  27                 <title>sd_id128_to_string</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>sd_id128_to_string</refentrytitle>
  42                 <manvolnum>3</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  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>
  49         </refnamediv>
  50
  51         <refsynopsisdiv>
  52                 <funcsynopsis>
  53                         <funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
  54
  55                         <funcprototype>
  56                                 <funcdef>char* <function>sd_id128_to_string</function></funcdef>
  57                                 <paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[33]</paramdef>
  58                         </funcprototype>
  59
  60                         <funcprototype>
  61                                 <funcdef>int <function>sd_id128_from_string</function></funcdef>
  62                                 <paramdef>const char* <parameter>s</parameter>, sd_id128_t* <parameter>ret</parameter></paramdef>
  63                         </funcprototype>
  64
  65                 </funcsynopsis>
  66         </refsynopsisdiv>
  67
  68         <refsect1>
  69                 <title>Description</title>
  70
  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
  76                 byte.</para>
  77
  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
  82                 bit ID returned in
  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>
  86
  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
  92                 endianess.</para>
  93
  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
 100                 more information see
 101                 <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 102         </refsect1>
 103
 104         <refsect1>
 105                 <title>Return Value</title>
 106
 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>
 113         </refsect1>
 114
 115         <refsect1>
 116                 <title>Notes</title>
 117
 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> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 122                 file.</para>
 123         </refsect1>
 124
 125         <refsect1>
 126                 <title>See Also</title>
 127
 128                 <para>
 129                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 130                         <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 131                         <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 132                 </para>
 133         </refsect1>
 134
 135 </refentry>