"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
-This file is part of systemd.
+ This file is part of systemd.
-Copyright 2014 Zbigniew Jędrzejewski-Szmek
+ Copyright 2014 Zbigniew Jędrzejewski-Szmek
-systemd is free software; you can redistribute it and/or modify it
-under the terms of the GNU Lesser General Public License as published by
-the Free Software Foundation; either version 2.1 of the License, or
-(at your option) any later version.
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
-systemd is distributed in the hope that it will be useful, but
-WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-Lesser General Public License for more details.
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
-You should have received a copy of the GNU Lesser General Public License
-along with systemd; If not, see <http://www.gnu.org/licenses/>.
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
-<refentry id="sd_event_add_signal" conditional="ENABLE_KDBUS">
+<refentry id="sd_event_add_signal" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_event_add_signal</title>
<refnamediv>
<refname>sd_event_add_signal</refname>
<refname>sd_event_source_get_signal</refname>
+ <refname>sd_event_signal_handler_t</refname>
- <refpurpose>Add a signal event source to an event loop</refpurpose>
+ <refpurpose>Add a UNIX process signal event source to an event
+ loop</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
- <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
+ <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>void *<parameter>userdata</parameter></paramdef>
</funcprototype>
- <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_source_get_signal</function></funcdef>
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
<refsect1>
<title>Description</title>
- <para><function>sd_event_add_signal()</function> adds a new signal
- event source to an event loop object. The event loop is specified
- in <parameter>event</parameter>, the event source is returned in
- the <parameter>source</parameter> parameter. The
- <parameter>signal</parameter> parameter specifies the signal to be handled
- (see
- <citerefentry><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
- The <parameter>handler</parameter> must reference a function to
- call when the signal is delivered or be <constant>NULL</constant>.
- The handler function will be passed the
- <parameter>userdata</parameter> pointer, which may be chosen
+ <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>const struct signalfd_siginfo</structname> containing
- the information about the received signal. See
- <citerefentry><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ <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 will be unblocked, and must be
- blocked when the function is called. If the handler is not
- specified (<parameter>handler</parameter> is
+ signal. The signal will be unblocked by this call, and must be
+ blocked before this function is called in all threads (using
+ <citerefentry
+ project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry>). If
+ the handler is not specified (<parameter>handler</parameter> is
<constant>NULL</constant>), a default handler which causes the
- program to exit will be used. By default, the handler is enabled
- permanently (<constant>SD_EVENT_ON</constant>), but this may be
- changed with
+ program to exit cleanly will be used.</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
- <constant>SD_EVENT_ON</constant> mode is set.
+ disabled after the invocation, even if the
+ <constant>SD_EVENT_ON</constant> mode was requested before.
</para>
- <para><function>sd_event_source_get_signal()</function> retrieves
- the configured signal number of a signal event source created
- previously with <function>sd_event_add_signal()</function>. It
- takes the event source object as the <parameter>source</parameter>
+ <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><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>
<para>On success, these functions return 0 or a positive
integer. On failure, they return a negative errno-style error
- code. </para>
+ code.</para>
</refsect1>
<refsect1>
<term><constant>-EINVAL</constant></term>
<listitem><para>An invalid argument has been passed.</para></listitem>
-
</varlistentry>
<varlistentry>
<term><constant>-EBUSY</constant></term>
- <listitem><para>An handler is already installed for this
+ <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>
</refsect1>
- <refsect1>
- <title>Notes</title>
-
- <para><function>sd_event_add_signal()</function> and the other functions
- described here are available as a shared library, which can be
- compiled and linked to with the
- <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- file.</para>
- </refsect1>
+ <xi:include href="libelogind-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<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_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_source_set_enabled</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 project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff