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514094f9 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
eea10b26 | 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
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5 | |
6 | <refentry id="sd_event_source_set_enabled" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
7 | ||
8 | <refentryinfo> | |
9 | <title>sd_event_source_set_enabled</title> | |
10 | <productname>systemd</productname> | |
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11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_event_source_set_enabled</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_event_source_set_enabled</refname> | |
20 | <refname>sd_event_source_get_enabled</refname> | |
21 | <refname>SD_EVENT_ON</refname> | |
22 | <refname>SD_EVENT_OFF</refname> | |
23 | <refname>SD_EVENT_ONESHOT</refname> | |
24 | ||
25 | <refpurpose>Enable or disable event sources</refpurpose> | |
26 | </refnamediv> | |
27 | ||
28 | <refsynopsisdiv> | |
29 | <funcsynopsis> | |
30 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> | |
31 | ||
32 | <funcsynopsisinfo><token>enum</token> { | |
33 | <constant>SD_EVENT_OFF</constant> = 0, | |
34 | <constant>SD_EVENT_ON</constant> = 1, | |
35 | <constant>SD_EVENT_ONESHOT</constant> = -1, | |
36 | };</funcsynopsisinfo> | |
37 | ||
38 | <funcprototype> | |
39 | <funcdef>int <function>sd_event_source_set_enabled</function></funcdef> | |
40 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
41 | <paramdef>int <parameter>enabled</parameter></paramdef> | |
42 | </funcprototype> | |
43 | ||
44 | <funcprototype> | |
45 | <funcdef>int <function>sd_event_source_get_enabled</function></funcdef> | |
46 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
47 | <paramdef>int *<parameter>enabled</parameter></paramdef> | |
48 | </funcprototype> | |
49 | ||
50 | </funcsynopsis> | |
51 | </refsynopsisdiv> | |
52 | ||
53 | <refsect1> | |
54 | <title>Description</title> | |
55 | ||
7e922b05 ZJS |
56 | <para><function>sd_event_source_set_enabled()</function> may be used to enable or disable the event |
57 | source object specified as <parameter>source</parameter>. The <parameter>enabled</parameter> parameter | |
58 | takes one of <constant>SD_EVENT_ON</constant> (to enable), <constant>SD_EVENT_OFF</constant> (to disable) | |
59 | or <constant>SD_EVENT_ONESHOT</constant>. If invoked with <constant>SD_EVENT_ONESHOT</constant> the event | |
60 | source will be enabled but automatically reset to <constant>SD_EVENT_OFF</constant> after one dispatch. | |
61 | For <constant>SD_EVENT_OFF</constant>, the event source <parameter>source</parameter> may be | |
62 | <constant>NULL</constant>, in which case the function does nothing. Otherwise, | |
63 | <parameter>source</parameter> must be a valid pointer to an <structname>sd_event_source</structname> | |
64 | object.</para> | |
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65 | |
66 | <para>Event sources that are disabled will not result in event | |
67 | loop wakeups and will not be dispatched, until they are enabled | |
68 | again.</para> | |
69 | ||
71193c0b ZJS |
70 | <para><function>sd_event_source_get_enabled()</function> may be used to query whether the event source |
71 | object <parameter>source</parameter> is currently enabled or not. If both the | |
72 | <parameter>source</parameter> and the output parameter <parameter>enabled</parameter> are | |
73 | <constant>NULL</constant>, this function returns false. Otherwise, <parameter>source</parameter> must be | |
74 | a valid pointer to an <structname>sd_event_source</structname> object. If the output parameter | |
75 | <parameter>enabled</parameter> is not <constant>NULL</constant>, it is set to the enablement state (one | |
76 | of <constant>SD_EVENT_ON</constant>, <constant>SD_EVENT_OFF</constant>, | |
77 | <constant>SD_EVENT_ONESHOT</constant>). The function also returns true if the event source is not | |
78 | disabled.</para> | |
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79 | |
80 | <para>Event source objects are enabled when they are first created | |
81 | with calls such as | |
82 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
83 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. However, | |
7f3fdb7f | 84 | depending on the event source type they are enabled continuously |
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85 | (<constant>SD_EVENT_ON</constant>) or only for a single invocation |
86 | of the event source handler | |
87 | (<constant>SD_EVENT_ONESHOT</constant>). For details see the | |
88 | respective manual pages.</para> | |
89 | ||
90 | <para>As event source objects stay active and may be dispatched as | |
91 | long as there is at least one reference to them, in many cases it | |
92 | is a good idea to combine a call to | |
93 | <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
94 | with a prior call to | |
95 | <function>sd_event_source_set_enabled()</function> with | |
96 | <constant>SD_EVENT_OFF</constant>, to ensure the event source is | |
97 | not dispatched again until all other remaining references are dropped.</para> | |
98 | </refsect1> | |
99 | ||
100 | <refsect1> | |
101 | <title>Return Value</title> | |
102 | ||
08c1eb0e | 103 | <para>On success, <function>sd_event_source_set_enabled()</function> returns a non-negative |
b1de39de ZJS |
104 | integer. <function>sd_event_source_get_enabled()</function> returns zero if the source is disabled |
105 | (<constant>SD_EVENT_OFF</constant>) and a positive integer otherwise. On failure, they return a negative | |
106 | errno-style error code.</para> | |
dc83f27a | 107 | |
b1de39de ZJS |
108 | <refsect2> |
109 | <title>Errors</title> | |
dc83f27a | 110 | |
b1de39de | 111 | <para>Returned errors may indicate the following problems:</para> |
dc83f27a | 112 | |
b1de39de ZJS |
113 | <variablelist> |
114 | <varlistentry> | |
115 | <term><constant>-EINVAL</constant></term> | |
dc83f27a | 116 | |
b1de39de ZJS |
117 | <listitem><para><parameter>source</parameter> is not a valid pointer to an |
118 | <structname>sd_event_source</structname> object.</para></listitem> | |
119 | </varlistentry> | |
dc83f27a | 120 | |
b1de39de ZJS |
121 | <varlistentry> |
122 | <term><constant>-ENOMEM</constant></term> | |
dc83f27a | 123 | |
b1de39de ZJS |
124 | <listitem><para>Not enough memory.</para></listitem> |
125 | </varlistentry> | |
dc83f27a | 126 | |
b1de39de ZJS |
127 | <varlistentry> |
128 | <term><constant>-ECHILD</constant></term> | |
dc83f27a | 129 | |
2eeff0f4 | 130 | <listitem><para>The event loop has been created in a different process, library or module instance.</para></listitem> |
dc83f27a | 131 | |
b1de39de | 132 | </varlistentry> |
dc83f27a | 133 | |
b1de39de ZJS |
134 | </variablelist> |
135 | </refsect2> | |
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136 | </refsect1> |
137 | ||
138 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
139 | ||
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140 | <refsect1> |
141 | <title>History</title> | |
00f95506 AK |
142 | <para><function>sd_event_source_set_enabled()</function> and |
143 | <function>sd_event_source_get_enabled()</function> were added in version 229.</para> | |
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144 | </refsect1> |
145 | ||
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146 | <refsect1> |
147 | <title>See Also</title> | |
148 | ||
13a69c12 DT |
149 | <para><simplelist type="inline"> |
150 | <member><citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
151 | <member><citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
152 | <member><citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
153 | <member><citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
154 | <member><citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
155 | <member><citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
156 | <member><citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
157 | <member><citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
158 | <member><citerefentry><refentrytitle>sd_event_source_set_ratelimit</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
159 | </simplelist></para> | |
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160 | </refsect1> |
161 | ||
162 | </refentry> |