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+
8 Copyright © 2014 Zbigniew Jędrzejewski-Szmek
11 <refentry id="sd_event_source_set_description" xmlns:xi="http://www.w3.org/2001/XInclude">
14 <title>sd_event_source_set_description</title>
15 <productname>elogind</productname>
19 <refentrytitle>sd_event_source_set_description</refentrytitle>
20 <manvolnum>3</manvolnum>
24 <refname>sd_event_source_set_description</refname>
25 <refname>sd_event_source_get_description</refname>
27 <refpurpose>Set or retrieve descriptive names of event sources</refpurpose>
32 <funcsynopsisinfo>#include <elogind/sd-event.h></funcsynopsisinfo>
35 <funcdef>int <function>sd_event_source_set_description</function></funcdef>
36 <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
37 <paramdef>const char *<parameter>description</parameter></paramdef>
41 <funcdef>int <function>sd_event_source_get_description</function></funcdef>
42 <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
43 <paramdef>const char **<parameter>description</parameter></paramdef>
50 <title>Description</title>
52 <para><function>sd_event_source_set_description()</function> may
53 be used to set an arbitrary descriptive name for the event source
54 object specified as <parameter>source</parameter>. This name will
55 be used in debugging messages generated by
56 <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>
57 for this event source, and may be queried using
58 <function>sd_event_source_get_description()</function> for
59 debugging purposes. The <parameter>description</parameter> parameter shall
60 point to a <constant>NUL</constant>-terminated string or be
61 <constant>NULL</constant>. In the latter case, the descriptive
62 name will be unset. The string is copied internally, hence the
63 <parameter>description</parameter> argument is not referenced
64 after the function returns.</para>
66 <para><function>sd_event_source_get_description()</function> may
67 be used to query the current descriptive name assigned to the
68 event source object <parameter>source</parameter>. It returns a
69 pointer to the current name in <parameter>description</parameter>,
70 stored in memory internal to the event source. The memory is
71 invalidated when the event source is destroyed or the descriptive
72 name is changed.</para>
74 <para>Event source objects generally have no description set when
75 they are created, except for UNIX signal event sources created
77 <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
78 whose descriptive name is initialized to the signal's C constant
79 name (e.g. <literal>SIGINT</literal> or
80 <literal>SIGTERM</literal>).</para>
84 <title>Return Value</title>
86 <para>On success, <function>sd_event_source_set_description()</function> and
87 <function>sd_event_source_get_description()</function> return a
88 non-negative integer. On failure, they return a negative
89 errno-style error code.</para>
95 <para>Returned errors may indicate the following problems:</para>
99 <term><constant>-EINVAL</constant></term>
101 <listitem><para><parameter>source</parameter> is not a valid
102 pointer to an <structname>sd_event_source</structname>
103 object or the <parameter>description</parameter> argument for
104 <function>sd_event_source_get_description()</function> is
105 <constant>NULL</constant>.</para></listitem>
109 <term><constant>-ENOMEM</constant></term>
111 <listitem><para>Not enough memory to copy the
112 name.</para></listitem>
116 <term><constant>-ECHILD</constant></term>
118 <listitem><para>The event loop has been created in a different process.</para></listitem>
123 <term><constant>-ENXIO</constant></term>
125 <listitem><para>No name was set for the event
126 source.</para></listitem>
132 <xi:include href="libelogind-pkgconfig.xml" />
135 <title>See Also</title>
138 <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
139 <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
140 <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
141 <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
142 <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
143 <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
144 <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>