mirror of
https://github.com/systemd/systemd.git
synced 2024-11-08 11:27:32 +03:00
207 lines
7.8 KiB
XML
207 lines
7.8 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
|
||
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||
|
||
<!--
|
||
This file is part of systemd.
|
||
|
||
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 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/>.
|
||
-->
|
||
|
||
<refentry id="sd_event_add_child" conditional="ENABLE_KDBUS">
|
||
|
||
<refentryinfo>
|
||
<title>sd_event_add_child</title>
|
||
<productname>systemd</productname>
|
||
|
||
<authorgroup>
|
||
<author>
|
||
<contrib>More text</contrib>
|
||
<firstname>Zbigniew</firstname>
|
||
<surname>Jędrzejewski-Szmek</surname>
|
||
<email>zbyszek@in.waw.pl</email>
|
||
</author>
|
||
</authorgroup>
|
||
</refentryinfo>
|
||
|
||
<refmeta>
|
||
<refentrytitle>sd_event_add_child</refentrytitle>
|
||
<manvolnum>3</manvolnum>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>sd_event_add_child</refname>
|
||
<refname>sd_event_source_get_child_pid</refname>
|
||
|
||
<refpurpose>Add a child state change event source to an event loop</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsynopsisdiv>
|
||
<funcsynopsis>
|
||
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_add_child</function></funcdef>
|
||
<paramdef>sd_event *<parameter>event</parameter></paramdef>
|
||
<paramdef>sd_event_source **<parameter>source</parameter></paramdef>
|
||
<paramdef>pid_t <parameter>pid</parameter></paramdef>
|
||
<paramdef>int <parameter>options</parameter></paramdef>
|
||
<paramdef>sd_event_child_handler_t <parameter>handler</parameter></paramdef>
|
||
<paramdef>void *<parameter>userdata</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>typedef int (*<function>sd_event_child_handler_t</function>)</funcdef>
|
||
<paramdef>sd_event_source *<parameter>s</parameter></paramdef>
|
||
<paramdef>const siginfo_t *<parameter>si</parameter></paramdef>
|
||
<paramdef>void *<parameter>userdata</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_source_get_child_pid</function></funcdef>
|
||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||
<paramdef>pid_t *<parameter>pid</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
</funcsynopsis>
|
||
</refsynopsisdiv>
|
||
|
||
<refsect1>
|
||
<title>Description</title>
|
||
|
||
<para><function>sd_event_add_child()</function> adds a new child
|
||
state change 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>pid</parameter> parameter specifies the process to
|
||
watch. The <parameter>handler</parameter> must reference a
|
||
function to call when the process changes state. 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
|
||
siginfo_t</structname> structure containing the information about
|
||
the event. The <parameter>options</parameter> parameter determines
|
||
which state changes will be watched for. It must contain an OR-ed
|
||
mask of <constant>WEXITED</constant> (watch for the child
|
||
terminating), <constant>WSTOPPED</constant> (watch for the child
|
||
being stopped by a signal), and <constant>WCONTINUED</constant>
|
||
(watch for the child being resumed by a signal). See
|
||
<citerefentry><refentrytitle>waitid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
for further information.</para>
|
||
|
||
<para>Only a single handler may be installed for a specific
|
||
child. The handler is enabled
|
||
for a single event (<constant>SD_EVENT_ONESHOT</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.
|
||
</para>
|
||
|
||
<para><function>sd_event_source_get_child_pid()</function>
|
||
retrieves the configured <parameter>pid</parameter> of a child
|
||
state change event source created previously with
|
||
<function>sd_event_add_child()</function>. It takes the event
|
||
source object as the <parameter>source</parameter> parameter and a
|
||
pointer to <type>pid_t</type> to return the result in.
|
||
</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>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<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. This includes
|
||
specifying an empty mask in <parameter>options</parameter> or a mask
|
||
which contains values different than a combination of
|
||
<constant>WEXITED</constant>, <constant>WSTOPPED</constant>, and
|
||
<constant>WCONTINUED</constant>.
|
||
</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>-EBUSY</constant></term>
|
||
|
||
<listitem><para>An handler is already installed for this
|
||
child.</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>
|
||
|
||
</variablelist>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Notes</title>
|
||
|
||
<para><function>sd_event_add_child()</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>
|
||
|
||
<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_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>sd_event_add_signal</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>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|