sd_event_source_set_enabled.xml revision 7f3fdb7f19a109fa3d1be92926bfe4cea1817da5
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6674N/A
6674N/A<refentry id="sd_event_source_set_enabled" xmlns:xi="http://www.w3.org/2001/XInclude">
6674N/A
6674N/A <refentryinfo>
6674N/A <title>sd_event_source_set_enabled</title>
6674N/A <productname>systemd</productname>
6674N/A
6674N/A <authorgroup>
6674N/A <author>
6674N/A <contrib>Developer</contrib>
6674N/A <firstname>Lennart</firstname>
6674N/A <surname>Poettering</surname>
6674N/A <email>lennart@poettering.net</email>
6674N/A </author>
6674N/A </authorgroup>
6674N/A </refentryinfo>
6674N/A
6674N/A <refmeta>
6674N/A <refentrytitle>sd_event_source_set_enabled</refentrytitle>
6674N/A <manvolnum>3</manvolnum>
6674N/A </refmeta>
6674N/A
6674N/A <refnamediv>
6674N/A <refname>sd_event_source_set_enabled</refname>
6674N/A <refname>sd_event_source_get_enabled</refname>
6674N/A <refname>SD_EVENT_ON</refname>
6674N/A <refname>SD_EVENT_OFF</refname>
6674N/A <refname>SD_EVENT_ONESHOT</refname>
6674N/A
6674N/A <refpurpose>Enable or disable event sources</refpurpose>
6674N/A </refnamediv>
6674N/A
6674N/A <refsynopsisdiv>
6674N/A <funcsynopsis>
6674N/A <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
6674N/A
6674N/A <funcsynopsisinfo><token>enum</token> {
6674N/A <constant>SD_EVENT_OFF</constant> = 0,
6674N/A <constant>SD_EVENT_ON</constant> = 1,
6674N/A <constant>SD_EVENT_ONESHOT</constant> = -1,
6674N/A};</funcsynopsisinfo>
6674N/A
6674N/A <funcprototype>
6674N/A <funcdef>int <function>sd_event_source_set_enabled</function></funcdef>
6674N/A <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
6674N/A <paramdef>int <parameter>enabled</parameter></paramdef>
6674N/A </funcprototype>
6674N/A
6674N/A <funcprototype>
6674N/A <funcdef>int <function>sd_event_source_get_enabled</function></funcdef>
6674N/A <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
6674N/A <paramdef>int *<parameter>enabled</parameter></paramdef>
6674N/A </funcprototype>
6674N/A
6674N/A </funcsynopsis>
6674N/A </refsynopsisdiv>
6674N/A
6674N/A <refsect1>
6674N/A <title>Description</title>
6674N/A
6674N/A <para><function>sd_event_source_set_enabled()</function> may be
6674N/A used to enable or disable the event source object specified as
6674N/A <parameter>source</parameter>. The <parameter>enabled</parameter>
6674N/A parameter takes one of <constant>SD_EVENT_ON</constant> (to
6674N/A enable), <constant>SD_EVENT_OFF</constant> (to disable) or
6674N/A <constant>SD_EVENT_ONESHOT</constant>. If invoked with
6674N/A <constant>SD_EVENT_ONESHOT</constant> the event source will be
6674N/A enabled but automatically reset to
6674N/A <constant>SD_EVENT_OFF</constant> after the event source was
6674N/A dispatched once.</para>
6674N/A
6674N/A <para>Event sources that are disabled will not result in event
6674N/A loop wakeups and will not be dispatched, until they are enabled
6674N/A again.</para>
6674N/A
6674N/A <para><function>sd_event_source_get_enabled()</function> may be
6674N/A used to query whether the event source object
6674N/A <parameter>source</parameter> is currently enabled or not. It
6674N/A returns the enablement state in
6674N/A <parameter>enabled</parameter>.</para>
6674N/A
6674N/A <para>Event source objects are enabled when they are first created
6674N/A with calls such as
6674N/A <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
6674N/A <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. However,
depending on the event source type they are enabled continuously
(<constant>SD_EVENT_ON</constant>) or only for a single invocation
of the event source handler
(<constant>SD_EVENT_ONESHOT</constant>). For details see the
respective manual pages.</para>
<para>As event source objects stay active and may be dispatched as
long as there is at least one reference to them, in many cases it
is a good idea to combine a call to
<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
with a prior call to
<function>sd_event_source_set_enabled()</function> with
<constant>SD_EVENT_OFF</constant>, to ensure the event source is
not dispatched again until all other remaining references are dropped.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_event_source_set_enabled()</function> and
<function>sd_event_source_get_enabled()</function> return a
non-negative 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>-EINVAL</constant></term>
<listitem><para><parameter>source</parameter> is not a valid
pointer to an <structname>sd_event_source</structname>
object.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Not enough memory.</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>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>sd-event</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_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>