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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="sd_event_source_set_description" xmlns:xi="http://www.w3.org/2001/XInclude">

<refentryinfo>

<title>sd_event_source_set_description</title>

<productname>systemd</productname>

<authorgroup>

<author>

<contrib>More text</contrib>

<firstname>Zbigniew</firstname>

<surname>Jędrzejewski-Szmek</surname>

<email>zbyszek@in.waw.pl</email>

</author>

</authorgroup>

</refentryinfo>

<refmeta>

<refentrytitle>sd_event_source_set_description</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_event_source_set_description</refname>

<refname>sd_event_source_get_description</refname>

<refpurpose>Set or retrieve descriptive names of event sources</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>

<funcprototype>

<funcdef>int <function>sd_event_source_set_description</function></funcdef>

<paramdef>sd_event_source *<parameter>source</parameter></paramdef>

<paramdef>const char *<parameter>description</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_event_source_get_description</function></funcdef>

<paramdef>sd_event_source *<parameter>source</parameter></paramdef>

<paramdef>const char **<parameter>description</parameter></paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para><function>sd_event_source_set_description()</function> may

be used to set an arbitrary descriptive name for the event source

object specified as <parameter>source</parameter>. This name will

be used in debugging messages generated by

<citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>

for this event source, and may be queried using

<function>sd_event_source_get_description()</function> for

debugging purposes. The <parameter>description</parameter> parameter shall

point to a <constant>NUL</constant>-terminated string or be

<constant>NULL</constant>. In the latter case, the descriptive

name will be unset. The string is copied internally, hence the

<parameter>description</parameter> argument is not referenced

after the function returns.</para>

<para><function>sd_event_source_get_description()</function> may

be used to query the current descriptive name assigned to the

event source object <parameter>source</parameter>. It returns a

pointer to the current name in <parameter>description</parameter>,

stored in memory internal to the event source. The memory is

invalidated when the event source is destroyed or the descriptive

name is changed.</para>

<para>Event source objects generally have no description set when

they are created, except for UNIX signal event sources created

with

<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

whose descriptive name is initialized to the signal's C constant

name (e.g. <literal>SIGINT</literal> or

<literal>SIGTERM</literal>).</para>

</refsect1>

<refsect1>

<title>Return Value</title>

<para>On success, <function>sd_event_source_set_description()</function> and

<function>sd_event_source_get_description()</function> return a

non-negative integer. On failure, they return a negative

errno-style error code.</para>

</refsect1>

<refsect1>

<title>Errors</title>

<para>Returned errors may indicate the following problems:</para>

<variablelist>

<varlistentry>

<term><constant>-EINVAL</constant></term>

<listitem><para><parameter>source</parameter> is not a valid

pointer to an <structname>sd_event_source</structname>

object or the <parameter>description</parameter> argument for

<function>sd_event_source_get_description()</function> is

<constant>NULL</constant>.</para></listitem>

</varlistentry>

<varlistentry>

<term><constant>-ENOMEM</constant></term>

<listitem><para>Not enough memory to copy the

name.</para></listitem>

</varlistentry>

<varlistentry>

<term><constant>-ECHILD</constant></term>

<listitem><para>The event loop has been created in a different process.</para></listitem>

</varlistentry>

<varlistentry>

<term><constant>-ENXIO</constant></term>

<listitem><para>No name was set for the event

source.</para></listitem>

</varlistentry>

</variablelist>

</refsect1>

<xi:include href="libsystemd-pkgconfig.xml" />

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>