1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
9 <refentry id="sd_event_source_set_description" xmlns:xi="http://www.w3.org/2001/XInclude">
12 <title>sd_event_source_set_description</title>
13 <productname>elogind</productname>
17 <contrib>More text</contrib>
18 <firstname>Zbigniew</firstname>
19 <surname>Jędrzejewski-Szmek</surname>
20 <email>zbyszek@in.waw.pl</email>
26 <refentrytitle>sd_event_source_set_description</refentrytitle>
27 <manvolnum>3</manvolnum>
31 <refname>sd_event_source_set_description</refname>
32 <refname>sd_event_source_get_description</refname>
34 <refpurpose>Set or retrieve descriptive names of event sources</refpurpose>
39 <funcsynopsisinfo>#include <elogind/sd-event.h></funcsynopsisinfo>
42 <funcdef>int <function>sd_event_source_set_description</function></funcdef>
43 <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
44 <paramdef>const char *<parameter>description</parameter></paramdef>
48 <funcdef>int <function>sd_event_source_get_description</function></funcdef>
49 <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
50 <paramdef>const char **<parameter>description</parameter></paramdef>
57 <title>Description</title>
59 <para><function>sd_event_source_set_description()</function> may
60 be used to set an arbitrary descriptive name for the event source
61 object specified as <parameter>source</parameter>. This name will
62 be used in debugging messages generated by
63 <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>
64 for this event source, and may be queried using
65 <function>sd_event_source_get_description()</function> for
66 debugging purposes. The <parameter>description</parameter> parameter shall
67 point to a <constant>NUL</constant>-terminated string or be
68 <constant>NULL</constant>. In the latter case, the descriptive
69 name will be unset. The string is copied internally, hence the
70 <parameter>description</parameter> argument is not referenced
71 after the function returns.</para>
73 <para><function>sd_event_source_get_description()</function> may
74 be used to query the current descriptive name assigned to the
75 event source object <parameter>source</parameter>. It returns a
76 pointer to the current name in <parameter>description</parameter>,
77 stored in memory internal to the event source. The memory is
78 invalidated when the event source is destroyed or the descriptive
79 name is changed.</para>
81 <para>Event source objects generally have no description set when
82 they are created, except for UNIX signal event sources created
84 <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
85 whose descriptive name is initialized to the signal's C constant
86 name (e.g. <literal>SIGINT</literal> or
87 <literal>SIGTERM</literal>).</para>
91 <title>Return Value</title>
93 <para>On success, <function>sd_event_source_set_description()</function> and
94 <function>sd_event_source_get_description()</function> return a
95 non-negative integer. On failure, they return a negative
96 errno-style error code.</para>
100 <title>Errors</title>
102 <para>Returned errors may indicate the following problems:</para>
106 <term><constant>-EINVAL</constant></term>
108 <listitem><para><parameter>source</parameter> is not a valid
109 pointer to an <structname>sd_event_source</structname>
110 object or the <parameter>description</parameter> argument for
111 <function>sd_event_source_get_description()</function> is
112 <constant>NULL</constant>.</para></listitem>
116 <term><constant>-ENOMEM</constant></term>
118 <listitem><para>Not enough memory to copy the
119 name.</para></listitem>
123 <term><constant>-ECHILD</constant></term>
125 <listitem><para>The event loop has been created in a different process.</para></listitem>
130 <term><constant>-ENXIO</constant></term>
132 <listitem><para>No name was set for the event
133 source.</para></listitem>
139 <xi:include href="libelogind-pkgconfig.xml" />
142 <title>See Also</title>
145 <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
146 <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
147 <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
148 <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
149 <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
150 <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
151 <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>