man/sd_event_source_set_description.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2014 Zbigniew Jędrzejewski-Szmek
  11 -->
  12
  13 <refentry id="sd_event_source_set_description" xmlns:xi="http://www.w3.org/2001/XInclude">
  14
  15   <refentryinfo>
  16     <title>sd_event_source_set_description</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>More text</contrib>
  22         <firstname>Zbigniew</firstname>
  23         <surname>Jędrzejewski-Szmek</surname>
  24         <email>zbyszek@in.waw.pl</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>sd_event_source_set_description</refentrytitle>
  31     <manvolnum>3</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>sd_event_source_set_description</refname>
  36     <refname>sd_event_source_get_description</refname>
  37
  38     <refpurpose>Set or retrieve descriptive names of event sources</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <funcsynopsis>
  43       <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
  44
  45       <funcprototype>
  46         <funcdef>int <function>sd_event_source_set_description</function></funcdef>
  47         <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
  48         <paramdef>const char *<parameter>description</parameter></paramdef>
  49       </funcprototype>
  50
  51       <funcprototype>
  52         <funcdef>int <function>sd_event_source_get_description</function></funcdef>
  53         <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
  54         <paramdef>const char **<parameter>description</parameter></paramdef>
  55       </funcprototype>
  56
  57     </funcsynopsis>
  58   </refsynopsisdiv>
  59
  60   <refsect1>
  61     <title>Description</title>
  62
  63     <para><function>sd_event_source_set_description()</function> may
  64     be used to set an arbitrary descriptive name for the event source
  65     object specified as <parameter>source</parameter>. This name will
  66     be used in debugging messages generated by
  67     <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  68     for this event source, and may be queried using
  69     <function>sd_event_source_get_description()</function> for
  70     debugging purposes. The <parameter>description</parameter> parameter shall
  71     point to a <constant>NUL</constant>-terminated string or be
  72     <constant>NULL</constant>. In the latter case, the descriptive
  73     name will be unset. The string is copied internally, hence the
  74     <parameter>description</parameter> argument is not referenced
  75     after the function returns.</para>
  76
  77     <para><function>sd_event_source_get_description()</function> may
  78     be used to query the current descriptive name assigned to the
  79     event source object <parameter>source</parameter>. It returns a
  80     pointer to the current name in <parameter>description</parameter>,
  81     stored in memory internal to the event source. The memory is
  82     invalidated when the event source is destroyed or the descriptive
  83     name is changed.</para>
  84
  85     <para>Event source objects generally have no description set when
  86     they are created, except for UNIX signal event sources created
  87     with
  88     <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  89     whose descriptive name is initialized to the signal's C constant
  90     name (e.g. <literal>SIGINT</literal> or
  91     <literal>SIGTERM</literal>).</para>
  92   </refsect1>
  93
  94   <refsect1>
  95     <title>Return Value</title>
  96
  97     <para>On success, <function>sd_event_source_set_description()</function> and
  98     <function>sd_event_source_get_description()</function> return a
  99     non-negative integer. On failure, they return a negative
 100     errno-style error code.</para>
 101   </refsect1>
 102
 103   <refsect1>
 104     <title>Errors</title>
 105
 106     <para>Returned errors may indicate the following problems:</para>
 107
 108     <variablelist>
 109       <varlistentry>
 110         <term><constant>-EINVAL</constant></term>
 111
 112         <listitem><para><parameter>source</parameter> is not a valid
 113         pointer to an <structname>sd_event_source</structname>
 114         object or the <parameter>description</parameter> argument for
 115         <function>sd_event_source_get_description()</function> is
 116         <constant>NULL</constant>.</para></listitem>
 117       </varlistentry>
 118
 119       <varlistentry>
 120         <term><constant>-ENOMEM</constant></term>
 121
 122         <listitem><para>Not enough memory to copy the
 123         name.</para></listitem>
 124       </varlistentry>
 125
 126       <varlistentry>
 127         <term><constant>-ECHILD</constant></term>
 128
 129         <listitem><para>The event loop has been created in a different process.</para></listitem>
 130
 131       </varlistentry>
 132
 133       <varlistentry>
 134         <term><constant>-ENXIO</constant></term>
 135
 136         <listitem><para>No name was set for the event
 137         source.</para></listitem>
 138       </varlistentry>
 139
 140     </variablelist>
 141   </refsect1>
 142
 143   <xi:include href="libsystemd-pkgconfig.xml" />
 144
 145   <refsect1>
 146     <title>See Also</title>
 147
 148     <para>
 149       <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 150       <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 151       <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 152       <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 153       <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 154       <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 155       <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 156     </para>
 157   </refsect1>
 158
 159 </refentry>