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514094f9 | 1 | <?xml version='1.0'?> |
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2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
0307f791 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
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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 | ||
56 | <para><function>sd_event_source_set_enabled()</function> may be | |
57 | used to enable or disable the event source object specified as | |
58 | <parameter>source</parameter>. The <parameter>enabled</parameter> | |
59 | parameter takes one of <constant>SD_EVENT_ON</constant> (to | |
60 | enable), <constant>SD_EVENT_OFF</constant> (to disable) or | |
61 | <constant>SD_EVENT_ONESHOT</constant>. If invoked with | |
62 | <constant>SD_EVENT_ONESHOT</constant> the event source will be | |
63 | enabled but automatically reset to | |
64 | <constant>SD_EVENT_OFF</constant> after the event source was | |
65 | dispatched once.</para> | |
66 | ||
67 | <para>Event sources that are disabled will not result in event | |
68 | loop wakeups and will not be dispatched, until they are enabled | |
69 | again.</para> | |
70 | ||
71 | <para><function>sd_event_source_get_enabled()</function> may be | |
72 | used to query whether the event source object | |
73 | <parameter>source</parameter> is currently enabled or not. It | |
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74 | returns the enablement state (one of <constant>SD_EVENT_ON</constant>, |
75 | <constant>SD_EVENT_OFF</constant>, <constant>SD_EVENT_ONESHOT</constant>) | |
76 | in <parameter>enabled</parameter>, if it is not <constant>NULL</constant>. | |
77 | It also returns true if the event source is not disabled.</para> | |
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78 | |
79 | <para>Event source objects are enabled when they are first created | |
80 | with calls such as | |
81 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
82 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. However, | |
7f3fdb7f | 83 | depending on the event source type they are enabled continuously |
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84 | (<constant>SD_EVENT_ON</constant>) or only for a single invocation |
85 | of the event source handler | |
86 | (<constant>SD_EVENT_ONESHOT</constant>). For details see the | |
87 | respective manual pages.</para> | |
88 | ||
89 | <para>As event source objects stay active and may be dispatched as | |
90 | long as there is at least one reference to them, in many cases it | |
91 | is a good idea to combine a call to | |
92 | <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
93 | with a prior call to | |
94 | <function>sd_event_source_set_enabled()</function> with | |
95 | <constant>SD_EVENT_OFF</constant>, to ensure the event source is | |
96 | not dispatched again until all other remaining references are dropped.</para> | |
97 | </refsect1> | |
98 | ||
99 | <refsect1> | |
100 | <title>Return Value</title> | |
101 | ||
08c1eb0e | 102 | <para>On success, <function>sd_event_source_set_enabled()</function> returns a non-negative |
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103 | integer. <function>sd_event_source_get_enabled()</function> returns zero if the source is disabled |
104 | (<constant>SD_EVENT_OFF</constant>) and a positive integer otherwise. On failure, they return a negative | |
105 | errno-style error code.</para> | |
dc83f27a | 106 | |
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107 | <refsect2> |
108 | <title>Errors</title> | |
dc83f27a | 109 | |
b1de39de | 110 | <para>Returned errors may indicate the following problems:</para> |
dc83f27a | 111 | |
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112 | <variablelist> |
113 | <varlistentry> | |
114 | <term><constant>-EINVAL</constant></term> | |
dc83f27a | 115 | |
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116 | <listitem><para><parameter>source</parameter> is not a valid pointer to an |
117 | <structname>sd_event_source</structname> object.</para></listitem> | |
118 | </varlistentry> | |
dc83f27a | 119 | |
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120 | <varlistentry> |
121 | <term><constant>-ENOMEM</constant></term> | |
dc83f27a | 122 | |
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123 | <listitem><para>Not enough memory.</para></listitem> |
124 | </varlistentry> | |
dc83f27a | 125 | |
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126 | <varlistentry> |
127 | <term><constant>-ECHILD</constant></term> | |
dc83f27a | 128 | |
b1de39de | 129 | <listitem><para>The event loop has been created in a different process.</para></listitem> |
dc83f27a | 130 | |
b1de39de | 131 | </varlistentry> |
dc83f27a | 132 | |
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133 | </variablelist> |
134 | </refsect2> | |
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135 | </refsect1> |
136 | ||
137 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
138 | ||
139 | <refsect1> | |
140 | <title>See Also</title> | |
141 | ||
142 | <para> | |
143 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
144 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
145 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
dc83f27a | 146 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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147 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
148 | <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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149 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
150 | <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
151 | </para> | |
152 | </refsect1> | |
153 | ||
154 | </refentry> |