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diff --git a/man/sd_event_add_signal.xml b/man/sd_event_add_signal.xml new file mode 100644 index 0000000..6fb0d1b --- /dev/null +++ b/man/sd_event_add_signal.xml @@ -0,0 +1,214 @@ +<?xml version='1.0'?> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="sd_event_add_signal" xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sd_event_add_signal</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_event_add_signal</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_event_add_signal</refname> + <refname>sd_event_source_get_signal</refname> + <refname>sd_event_signal_handler_t</refname> + <refname>SD_EVENT_SIGNAL_PROCMASK</refname> + + <refpurpose>Add a UNIX process signal event source to an event + loop</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> + + <funcsynopsisinfo><token>typedef</token> struct sd_event_source sd_event_source;</funcsynopsisinfo> + + <funcsynopsisinfo><constant>SD_EVENT_SIGNAL_PROCMASK</constant></funcsynopsisinfo> + + <funcprototype> + <funcdef>typedef int (*<function>sd_event_signal_handler_t</function>)</funcdef> + <paramdef>sd_event_source *<parameter>s</parameter></paramdef> + <paramdef>const struct signalfd_siginfo *<parameter>si</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_event_add_signal</function></funcdef> + <paramdef>sd_event *<parameter>event</parameter></paramdef> + <paramdef>sd_event_source **<parameter>source</parameter></paramdef> + <paramdef>int <parameter>signal</parameter></paramdef> + <paramdef>sd_event_signal_handler_t <parameter>handler</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_event_source_get_signal</function></funcdef> + <paramdef>sd_event_source *<parameter>source</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_event_add_signal()</function> adds a new UNIX process signal event source to an event + loop. The event loop object is specified in the <parameter>event</parameter> parameter, and the event + source object is returned in the <parameter>source</parameter> parameter. The + <parameter>signal</parameter> parameter specifies the numeric signal to be handled (see <citerefentry + project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>).</para> + + <para>The <parameter>handler</parameter> parameter is a function to call when the signal is received or + <constant>NULL</constant>. The handler function will be passed the <parameter>userdata</parameter> + pointer, which may be chosen freely by the caller. The handler also receives a pointer to a + <structname>signalfd_siginfo</structname> structure containing information about the received signal. See + <citerefentry + project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> for + further information. The handler may return negative to signal an error (see below), other return values + are ignored. If <parameter>handler</parameter> is <constant>NULL</constant>, a default handler that calls + <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> will be + used.</para> + + <para>Only a single handler may be installed for a specific signal. The signal must be blocked in all + threads before this function is called (using <citerefentry + project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry> or + <citerefentry + project='man-pages'><refentrytitle>pthread_sigmask</refentrytitle><manvolnum>3</manvolnum></citerefentry>). For + convenience, if the special flag <constant>SD_EVENT_SIGNAL_PROCMASK</constant> is ORed into the specified + signal the signal will be automatically masked as necessary, for the calling thread. Note that this only + works reliably if the signal is already masked in all other threads of the process, or if there are no + other threads at the moment of invocation.</para> + + <para>By default, the event source is enabled permanently (<constant>SD_EVENT_ON</constant>), but this + may be changed with + <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + If the handler function returns a negative error code, it will either be disabled after the invocation, + even if the <constant>SD_EVENT_ON</constant> mode was requested before, or it will cause the loop to + terminate, see + <citerefentry><refentrytitle>sd_event_source_set_exit_on_failure</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + </para> + + <para>To destroy an event source object use + <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + but note that the event source is only removed from the event loop + when all references to the event source are dropped. To make sure + an event source does not fire anymore, even if it is still referenced, + disable the event source using + <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> + with <constant>SD_EVENT_OFF</constant>.</para> + + <para>If the second parameter of + <function>sd_event_add_signal()</function> is + <constant>NULL</constant> no reference to the event source object + is returned. In this case the event source is considered + "floating", and will be destroyed implicitly when the event loop + itself is destroyed.</para> + + <para>If the <parameter>handler</parameter> parameter to <function>sd_event_add_signal()</function> is + <constant>NULL</constant>, and the event source fires, this will be considered a request to exit the + event loop. In this case, the <parameter>userdata</parameter> parameter, cast to an integer, is passed as + the exit code parameter to + <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> + + <para><function>sd_event_source_get_signal()</function> returns + the configured signal number of an event source created previously + with <function>sd_event_add_signal()</function>. It takes the + event source object as the <parameter>source</parameter> + parameter.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, these functions return 0 or a positive + integer. On failure, they return a negative errno-style error + code.</para> + + <refsect2> + <title>Errors</title> + + <para>Returned errors may indicate the following problems:</para> + + <variablelist> + <varlistentry> + <term><constant>-ENOMEM</constant></term> + + <listitem><para>Not enough memory to allocate an object.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-EINVAL</constant></term> + + <listitem><para>An invalid argument has been passed.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-EBUSY</constant></term> + + <listitem><para>A handler is already installed for this + signal or the signal was not blocked previously.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-ESTALE</constant></term> + + <listitem><para>The event loop is already terminated.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-ECHILD</constant></term> + + <listitem><para>The event loop has been created in a different process, library or module instance.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-EDOM</constant></term> + + <listitem><para>The passed event source is not a signal event source.</para></listitem> + </varlistentry> + + </variablelist> + </refsect2> + </refsect1> + + <xi:include href="libsystemd-pkgconfig.xml" /> + + <refsect1> + <title>History</title> + <para><function>sd_event_add_signal()</function>, + <function>sd_event_signal_handler_t()</function>, and + <function>sd_event_source_get_signal()</function> were added in version 217.</para> + </refsect1> + + <refsect1> + <title>See Also</title> + + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_now</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_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>pthread_sigmask</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |