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baf3fdec27
In many (most?) of our event loops we want to exit once SIGTERM/SIGINT is seen. Add a common helper for that, that does the right things in a single call.
102 lines
3.9 KiB
XML
102 lines
3.9 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/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_event_set_signal_exit" xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_event_set_signal_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_set_signal_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_set_signal_exit</refname>
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<refpurpose>Automatically leave event loop on <constant>SIGINT</constant> and <constant>SIGTERM</constant></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_set_signal_exit</function></funcdef>
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<paramdef>sd_event *<parameter>event</parameter></paramdef>
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<paramdef>int b</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_set_signal_exit()</function> may be used to ensure the event loop terminates
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once a <constant>SIGINT</constant> or <constant>SIGTERM</constant> signal is received. It is a
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convencience wrapper around invocations of
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<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for both signals. The two signals are automatically added to the calling thread's signal mask (if a
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program is multi-threaded care should be taken to either invoke this function before the first thread is
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started or to manually block the two signals process-wide first).</para>
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<para>If the parameter <parameter>b</parameter> is specified as true, the event loop will terminate on
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<constant>SIGINT</constant> and <constant>SIGTERM</constant>. If specified as false, it will no
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longer. When this functionality is turned off the calling thread's signal mask is restored to match the
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state before it was turned on, for the two signals. By default the two signals are not handled by the
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event loop, and Linux' default signal handling for them is in effect.</para>
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<para>It's customary for UNIX programs to exit on either of these two signals, hence it's typically a
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good idea to enable this functionality for the main event loop of a program.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para><function>sd_event_set_signal_exit()</function> returns a positive non-zero value when the setting
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was successfully changed. It returns a zero when the specified setting was already in effect. On failure,
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it returns 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>-ECHILD</constant></term>
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<listitem><para>The event loop has been created in a different process.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>The passed event loop object was invalid.</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>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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