mirror of
https://github.com/systemd/systemd-stable.git
synced 2024-12-27 03:21:32 +03:00
7e922b0584
Same story as before: disabling a non-existent event source shouldn't need to be guarded by an if. I retained the wrapper so that that we don't have to say SD_EVENT_OFF in the many places where this is called.
157 lines
6.9 KiB
XML
157 lines
6.9 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_source_set_enabled" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_event_source_set_enabled</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_event_source_set_enabled</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_event_source_set_enabled</refname>
|
|
<refname>sd_event_source_get_enabled</refname>
|
|
<refname>SD_EVENT_ON</refname>
|
|
<refname>SD_EVENT_OFF</refname>
|
|
<refname>SD_EVENT_ONESHOT</refname>
|
|
|
|
<refpurpose>Enable or disable event sources</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
|
|
|
|
<funcsynopsisinfo><token>enum</token> {
|
|
<constant>SD_EVENT_OFF</constant> = 0,
|
|
<constant>SD_EVENT_ON</constant> = 1,
|
|
<constant>SD_EVENT_ONESHOT</constant> = -1,
|
|
};</funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_event_source_set_enabled</function></funcdef>
|
|
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
|
<paramdef>int <parameter>enabled</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_event_source_get_enabled</function></funcdef>
|
|
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
|
<paramdef>int *<parameter>enabled</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_event_source_set_enabled()</function> may be used to enable or disable the event
|
|
source object specified as <parameter>source</parameter>. The <parameter>enabled</parameter> parameter
|
|
takes one of <constant>SD_EVENT_ON</constant> (to enable), <constant>SD_EVENT_OFF</constant> (to disable)
|
|
or <constant>SD_EVENT_ONESHOT</constant>. If invoked with <constant>SD_EVENT_ONESHOT</constant> the event
|
|
source will be enabled but automatically reset to <constant>SD_EVENT_OFF</constant> after one dispatch.
|
|
For <constant>SD_EVENT_OFF</constant>, the event source <parameter>source</parameter> may be
|
|
<constant>NULL</constant>, in which case the function does nothing. Otherwise,
|
|
<parameter>source</parameter> must be a valid pointer to an <structname>sd_event_source</structname>
|
|
object.</para>
|
|
|
|
<para>Event sources that are disabled will not result in event
|
|
loop wakeups and will not be dispatched, until they are enabled
|
|
again.</para>
|
|
|
|
<para><function>sd_event_source_get_enabled()</function> may be used to query whether the event source
|
|
object <parameter>source</parameter> is currently enabled or not. If both the
|
|
<parameter>source</parameter> and the output parameter <parameter>enabled</parameter> are
|
|
<constant>NULL</constant>, this function returns false. Otherwise, <parameter>source</parameter> must be
|
|
a valid pointer to an <structname>sd_event_source</structname> object. If the output parameter
|
|
<parameter>enabled</parameter> is not <constant>NULL</constant>, it is set to the enablement state (one
|
|
of <constant>SD_EVENT_ON</constant>, <constant>SD_EVENT_OFF</constant>,
|
|
<constant>SD_EVENT_ONESHOT</constant>). The function also returns true if the event source is not
|
|
disabled.</para>
|
|
|
|
<para>Event source objects are enabled when they are first created
|
|
with calls such as
|
|
<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<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> returns a non-negative
|
|
integer. <function>sd_event_source_get_enabled()</function> returns zero if the source is disabled
|
|
(<constant>SD_EVENT_OFF</constant>) and a positive integer otherwise. 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>-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>
|
|
</refsect2>
|
|
</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_signal</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_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_event_source_set_ratelimit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|