mirror of
https://github.com/systemd/systemd.git
synced 2024-11-01 17:51:22 +03:00
202 lines
9.2 KiB
XML
202 lines
9.2 KiB
XML
<?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>
|
|
|
|
<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>
|
|
|
|
<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>).
|
|
The <parameter>handler</parameter> parameter must reference a
|
|
function to call when the signal is received or be
|
|
<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.</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>).</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 be
|
|
disabled after the invocation, even if the
|
|
<constant>SD_EVENT_ON</constant> mode was requested before.
|
|
</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.</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>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>
|