ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson<?xml version='1.0'?> <!--*-nxml-*-->

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ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson<refentry id="sd_event_add_child" conditional="ENABLE_KDBUS">

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refentryinfo>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <title>sd_event_add_child</title>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <productname>systemd</productname>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <authorgroup>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <author>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <contrib>More text</contrib>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <firstname>Zbigniew</firstname>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <surname>Jędrzejewski-Szmek</surname>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <email>zbyszek@in.waw.pl</email>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson </author>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson </authorgroup>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson </refentryinfo>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refmeta>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refentrytitle>sd_event_add_child</refentrytitle>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <manvolnum>3</manvolnum>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson </refmeta>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refnamediv>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refname>sd_event_add_child</refname>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refname>sd_event_source_get_child_pid</refname>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refpurpose>Add a child state change event source to an event loop</refpurpose>

a4520e13fbf5218b78db2934e76ea1d869bbcdfdBob Halley </refnamediv>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refsynopsisdiv>

a4520e13fbf5218b78db2934e76ea1d869bbcdfdBob Halley <funcsynopsis>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <funcprototype>

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson <funcdef>int <function>sd_event_add_child</function></funcdef>

8468c5a2ff04508ba503e664c76f8a36c274ccfaAndreas Gustafsson <paramdef>sd_event *<parameter>event</parameter></paramdef>

8468c5a2ff04508ba503e664c76f8a36c274ccfaAndreas Gustafsson <paramdef>sd_event_source **<parameter>source</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>pid_t <parameter>pid</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>int <parameter>options</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>sd_event_child_handler_t <parameter>handler</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>void *<parameter>userdata</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson </funcprototype>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <funcprototype>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <funcdef>typedef int (*<function>sd_event_child_handler_t</function>)</funcdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>sd_event_source *<parameter>s</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>const siginfo_t *<parameter>si</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>void *<parameter>userdata</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson </funcprototype>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <funcprototype>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <funcdef>int <function>sd_event_source_get_child_pid</function></funcdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>sd_event_source *<parameter>source</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <paramdef>pid_t *<parameter>pid</parameter></paramdef>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson </funcprototype>

e57d7e30f1a2e3fbd71d6cf0f18629c8a00bd9b8Andreas Gustafsson

e57d7e30f1a2e3fbd71d6cf0f18629c8a00bd9b8Andreas Gustafsson </funcsynopsis>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson </refsynopsisdiv>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <refsect1>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <title>Description</title>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <para><function>sd_event_add_child()</function> adds a new child

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson state change event source to an event loop object. The event loop

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson is specified in <parameter>event</parameter>, the event source is

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson returned in the <parameter>source</parameter> parameter. The

a4520e13fbf5218b78db2934e76ea1d869bbcdfdBob Halley <parameter>pid</parameter> parameter specifies the process to

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson watch. The <parameter>handler</parameter> must reference a

a4520e13fbf5218b78db2934e76ea1d869bbcdfdBob Halley function to call when the process changes state. The handler

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson function will be passed the <parameter>userdata</parameter>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson pointer, which may be chosen freely by the caller. The handler

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson also receives a pointer to a <structname>const

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson siginfo_t</structname> structure containing the information about

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson the event. The <parameter>options</parameter> parameter determines

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson which state changes will be watched for. It must contain an OR-ed

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson mask of <constant>WEXITED</constant> (watch for the child

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson terminating), <constant>WSTOPPED</constant> (watch for the child

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson being stopped by a signal), and <constant>WCONTINUED</constant>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson (watch for the child being resumed by a signal). See

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <citerefentry><refentrytitle>waitid</refentrytitle><manvolnum>2</manvolnum></citerefentry>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson for futher information.</para>

a4520e13fbf5218b78db2934e76ea1d869bbcdfdBob Halley

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <para>Only a single handler may be installed for a specific

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson child. The handler is enabled

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson for a single event (<constant>SD_EVENT_ONESHOT</constant>),

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson but this may be

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson changed with

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson If the handler function returns a negative error code, it will be

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson disabled after the invocation, even if

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <constant>SD_EVENT_ON</constant> mode is set.

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson </para>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <para><function>sd_event_source_get_child_pid()</function>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson retrieves the configured <parameter>pid</parameter> of a child

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson state change event source created previously with

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson <function>sd_event_add_child()</function>. It takes the event

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson source object as the <parameter>source</parameter> parameter and a

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson pointer to <type>pid_t</type> to return the result in.

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson </para>

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson </refsect1>

a55d0a9080c8ef4117d2fc27f63220a56afb2434Andreas Gustafsson

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <refsect1>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <title>Return Value</title>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson <para>On success, these functions return 0 or a positive

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson integer. On failure, they return a negative errno-style error

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson code.</para>

559b10cc8f3e1dc4d93f55c9336f74839e9fa362Andreas Gustafsson </refsect1>

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson

ff64dc5d7f8072239e7c760e56551ad3c232da6fAndreas Gustafsson <refsect1>

<title>Errors</title>

<para>Returned errors may indicate the following problems:</para>

<variablelist>

<varlistentry>

<term><varname>-ENOMEM</varname></term>

<listitem><para>Not enough memory to allocate an object.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>-EINVAL</varname></term>

<listitem><para>An invalid argument has been passed. This includes

specyfing an empty mask in <parameter>options</parameter> or a mask

which constains values different than a combination of

<constant>WEXITED</constant>, <constant>WSTOPPED</constant>, and

<constant>WCONTINUED</constant>.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>-EBUSY</varname></term>

<listitem><para>An handler is already installed for this

child.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>-ESTALE</varname></term>

<listitem><para>The event loop is already terminated.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>-ECHILD</varname></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_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>