man/sd_event_exit.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   5
   6 <refentry id="sd_event_exit" xmlns:xi="http://www.w3.org/2001/XInclude">
   7
   8   <refentryinfo>
   9     <title>sd_event_exit</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>sd_event_exit</refentrytitle>
  15     <manvolnum>3</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>sd_event_exit</refname>
  20     <refname>sd_event_get_exit_code</refname>
  21
  22     <refpurpose>Ask the event loop to exit</refpurpose>
  23   </refnamediv>
  24
  25   <refsynopsisdiv>
  26     <funcsynopsis>
  27       <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
  28
  29       <funcprototype>
  30         <funcdef>int <function>sd_event_exit</function></funcdef>
  31         <paramdef>sd_event *<parameter>event</parameter></paramdef>
  32         <paramdef>int <parameter>code</parameter></paramdef>
  33       </funcprototype>
  34
  35       <funcprototype>
  36         <funcdef>int <function>sd_event_get_exit_code</function></funcdef>
  37         <paramdef>sd_event *<parameter>event</parameter></paramdef>
  38         <paramdef>int *<parameter>code</parameter></paramdef>
  39       </funcprototype>
  40
  41     </funcsynopsis>
  42   </refsynopsisdiv>
  43
  44   <refsect1>
  45     <title>Description</title>
  46
  47     <para><function>sd_event_exit()</function> requests the event loop
  48     specified in the <parameter>event</parameter> event loop object to
  49     exit. The <parameter>code</parameter> parameter may be any integer
  50     value and is returned as-is by
  51     <citerefentry><refentrytitle>sd_event_loop</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  52     after the last event loop iteration. It may also be queried
  53     using <function>sd_event_get_exit_code()</function>, see
  54     below. </para>
  55
  56     <para>When exiting is requested the event loop will stop listening
  57     for and dispatching regular event sources. Instead it will proceed
  58     with executing only event sources registered with
  59     <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  60     in the order defined by their priority. After all exit event
  61     sources have been dispatched the event loop is terminated.</para>
  62
  63     <para>If <function>sd_event_exit()</function> is invoked a second
  64     time while the event loop is still processing exit event sources,
  65     the exit code stored in the event loop object is updated, but
  66     otherwise no further operation is executed.</para>
  67
  68     <para><function>sd_event_get_exit_code()</function> may be used to
  69     query the exit code passed into
  70     <function>sd_event_exit()</function> earlier.</para>
  71
  72     <para>While the full positive and negative integer ranges may be used
  73     for the exit code, care should be taken not pick exit codes that
  74     conflict with regular exit codes returned by
  75     <function>sd_event_loop()</function>, if these exit codes shall be
  76     distinguishable.</para>
  77
  78     <para>Note that for most event source types passing the callback pointer as <constant>NULL</constant> in
  79     the respective constructor call (i.e. in
  80     <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  81     <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  82     …) has the effect of <function>sd_event_exit()</function> being invoked once the event source triggers,
  83     with the specified userdata pointer cast to an integer as the exit code parameter. This is useful to
  84     automatically terminate an event loop after some condition, such as a time-out or reception of
  85     <constant>SIGTERM</constant> or similar. See the documentation for the respective constructor call for
  86     details.</para>
  87   </refsect1>
  88
  89   <refsect1>
  90     <title>Return Value</title>
  91
  92     <para>On success, <function>sd_event_exit()</function> and <function>sd_event_get_exit_code()</function>
  93     return 0 or a positive integer. On failure, they return a negative errno-style error code.</para>
  94
  95     <refsect2>
  96       <title>Errors</title>
  97
  98       <para>Returned errors may indicate the following problems:</para>
  99
 100       <variablelist>
 101
 102         <varlistentry>
 103           <term><constant>-EINVAL</constant></term>
 104
 105           <listitem><para>The event loop object or error code pointer are invalid.</para></listitem>
 106
 107         </varlistentry>
 108
 109         <varlistentry>
 110           <term><constant>-ECHILD</constant></term>
 111
 112           <listitem><para>The event loop was created in a different process, library or module instance.</para></listitem>
 113         </varlistentry>
 114
 115         <varlistentry>
 116           <term><constant>-ESTALE</constant></term>
 117
 118           <listitem><para>The event loop has exited already and all exit handlers are already processed.
 119           </para></listitem>
 120         </varlistentry>
 121
 122         <varlistentry>
 123           <term><constant>-ENODATA</constant></term>
 124
 125           <listitem><para>The event loop has not been requested to exit yet.</para></listitem>
 126         </varlistentry>
 127
 128       </variablelist>
 129     </refsect2>
 130   </refsect1>
 131
 132   <xi:include href="libsystemd-pkgconfig.xml" />
 133
 134   <refsect1>
 135     <title>History</title>
 136     <para><function>sd_event_exit()</function> and
 137     <function>sd_event_get_exit_code()</function> were added in version 229.</para>
 138   </refsect1>
 139
 140   <refsect1>
 141     <title>See Also</title>
 142
 143     <para><simplelist type="inline">
 144       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 145       <member><citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 146       <member><citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 147       <member><citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 148       <member><citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 149       <member><citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 150       <member><citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 151       <member><citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 152       <member><citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
 153     </simplelist></para>
 154   </refsect1>
 155
 156 </refentry>