<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2014 Zbigniew Jędrzejewski-Szmek systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <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 <systemd/sd-event.h></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>