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https://github.com/systemd/systemd
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160 lines
6.8 KiB
XML
160 lines
6.8 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_event_exit" xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_event_exit</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_event_exit</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_event_exit</refname>
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<refname>sd_event_get_exit_code</refname>
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<refpurpose>Ask the event loop to exit</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_event_exit</function></funcdef>
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<paramdef>sd_event *<parameter>event</parameter></paramdef>
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<paramdef>int <parameter>code</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_get_exit_code</function></funcdef>
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<paramdef>sd_event *<parameter>event</parameter></paramdef>
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<paramdef>int *<parameter>code</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_event_exit()</function> requests the event loop
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specified in the <parameter>event</parameter> event loop object to
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exit. The <parameter>code</parameter> parameter may be any integer
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value and is returned as-is by
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<citerefentry><refentrytitle>sd_event_loop</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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after the last event loop iteration. It may also be queried
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using <function>sd_event_get_exit_code()</function>, see
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below. </para>
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<para>When exiting is requested the event loop will stop listening
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for and dispatching regular event sources. Instead it will proceed
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with executing only event sources registered with
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<citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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in the order defined by their priority. After all exit event
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sources have been dispatched the event loop is terminated.</para>
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<para>If <function>sd_event_exit()</function> is invoked a second
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time while the event loop is still processing exit event sources,
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the exit code stored in the event loop object is updated, but
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otherwise no further operation is executed.</para>
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<para><function>sd_event_get_exit_code()</function> may be used to query the exit code passed to an
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earlier call of <function>sd_event_exit()</function>. The return parameter <parameter>code</parameter>
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may be set to <constant>NULL</constant>, in order to simply check if <function>sd_event_exit()</function>
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has been called before (as <function>sd_event_get_exit_code()</function> fails with
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<constant>-ENODATA</constant> if that's not the case, see below).</para>
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<para>While the full positive and negative integer ranges may be used
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for the exit code, care should be taken not pick exit codes that
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conflict with regular exit codes returned by
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<function>sd_event_loop()</function>, if these exit codes shall be
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distinguishable.</para>
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<para>Note that for most event source types passing the callback pointer as <constant>NULL</constant> in
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the respective constructor call (i.e. in
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<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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…) has the effect of <function>sd_event_exit()</function> being invoked once the event source triggers,
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with the specified userdata pointer cast to an integer as the exit code parameter. This is useful to
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automatically terminate an event loop after some condition, such as a time-out or reception of
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<constant>SIGTERM</constant> or similar. See the documentation for the respective constructor call for
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details.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, <function>sd_event_exit()</function> and <function>sd_event_get_exit_code()</function>
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return 0 or a positive integer. On failure, they return a negative errno-style error code.</para>
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<refsect2>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>The event loop object or error code pointer are invalid.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The event loop was created in a different process, library or module instance.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ESTALE</constant></term>
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<listitem><para>The event loop has exited already and all exit handlers are already processed.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENODATA</constant></term>
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<listitem><para>Returned by <function>sd_event_get_exit_code()</function> in case the event loop has not
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been requested to exit yet.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>History</title>
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<para><function>sd_event_exit()</function> and
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<function>sd_event_get_exit_code()</function> were added in version 229.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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