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3802a3d3 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
3144ebca | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
5de0ccff | 8 | This file is part of systemd. |
3144ebca | 9 | |
5de0ccff | 10 | Copyright 2014 Zbigniew Jędrzejewski-Szmek |
3144ebca | 11 | |
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12 | systemd is free software; you can redistribute it and/or modify it |
13 | under the terms of the GNU Lesser General Public License as published by | |
14 | the Free Software Foundation; either version 2.1 of the License, or | |
15 | (at your option) any later version. | |
3144ebca | 16 | |
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17 | systemd is distributed in the hope that it will be useful, but |
18 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | Lesser General Public License for more details. | |
3144ebca | 21 | |
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22 | You should have received a copy of the GNU Lesser General Public License |
23 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
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24 | --> |
25 | ||
dc83f27a | 26 | <refentry id="sd_event_add_signal" xmlns:xi="http://www.w3.org/2001/XInclude"> |
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27 | |
28 | <refentryinfo> | |
29 | <title>sd_event_add_signal</title> | |
30 | <productname>systemd</productname> | |
31 | ||
32 | <authorgroup> | |
33 | <author> | |
34 | <contrib>More text</contrib> | |
35 | <firstname>Zbigniew</firstname> | |
36 | <surname>Jędrzejewski-Szmek</surname> | |
37 | <email>zbyszek@in.waw.pl</email> | |
38 | </author> | |
39 | </authorgroup> | |
40 | </refentryinfo> | |
41 | ||
42 | <refmeta> | |
43 | <refentrytitle>sd_event_add_signal</refentrytitle> | |
44 | <manvolnum>3</manvolnum> | |
45 | </refmeta> | |
46 | ||
47 | <refnamediv> | |
48 | <refname>sd_event_add_signal</refname> | |
49 | <refname>sd_event_source_get_signal</refname> | |
dc83f27a | 50 | <refname>sd_event_signal_handler_t</refname> |
3144ebca | 51 | |
dc83f27a LP |
52 | <refpurpose>Add a UNIX process signal event source to an event |
53 | loop</refpurpose> | |
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54 | </refnamediv> |
55 | ||
56 | <refsynopsisdiv> | |
57 | <funcsynopsis> | |
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58 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> |
59 | ||
60 | <funcsynopsisinfo><token>typedef</token> struct sd_event_source sd_event_source;</funcsynopsisinfo> | |
61 | ||
62 | <funcprototype> | |
63 | <funcdef>typedef int (*<function>sd_event_signal_handler_t</function>)</funcdef> | |
64 | <paramdef>sd_event_source *<parameter>s</parameter></paramdef> | |
65 | <paramdef>const struct signalfd_siginfo *<parameter>si</parameter></paramdef> | |
66 | <paramdef>void *<parameter>userdata</parameter></paramdef> | |
67 | </funcprototype> | |
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68 | |
69 | <funcprototype> | |
70 | <funcdef>int <function>sd_event_add_signal</function></funcdef> | |
71 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
72 | <paramdef>sd_event_source **<parameter>source</parameter></paramdef> | |
73 | <paramdef>int <parameter>signal</parameter></paramdef> | |
74 | <paramdef>sd_event_signal_handler_t <parameter>handler</parameter></paramdef> | |
75 | <paramdef>void *<parameter>userdata</parameter></paramdef> | |
76 | </funcprototype> | |
77 | ||
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78 | <funcprototype> |
79 | <funcdef>int <function>sd_event_source_get_signal</function></funcdef> | |
80 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
81 | </funcprototype> | |
82 | ||
83 | </funcsynopsis> | |
84 | </refsynopsisdiv> | |
85 | ||
86 | <refsect1> | |
87 | <title>Description</title> | |
88 | ||
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89 | <para><function>sd_event_add_signal()</function> adds a new UNIX |
90 | process signal event source to an event loop. The event loop | |
91 | object is specified in the <parameter>event</parameter> parameter, | |
92 | and the event source object is returned in the | |
93 | <parameter>source</parameter> parameter. The | |
94 | <parameter>signal</parameter> parameter specifies the numeric | |
95 | signal to be handled (see <citerefentry | |
96 | project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>). | |
97 | The <parameter>handler</parameter> parameter must reference a | |
98 | function to call when the signal is received or be | |
99 | <constant>NULL</constant>. The handler function will be passed | |
100 | the <parameter>userdata</parameter> pointer, which may be chosen | |
3144ebca | 101 | freely by the caller. The handler also receives a pointer to a |
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102 | <structname>signalfd_siginfo</structname> structure containing |
103 | information about the received signal. See <citerefentry | |
104 | project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
922d948b | 105 | for further information.</para> |
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106 | |
107 | <para>Only a single handler may be installed for a specific | |
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108 | signal. The signal will be unblocked by this call, and must be |
109 | blocked before this function is called in all threads (using | |
110 | <citerefentry | |
111 | project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry>). If | |
112 | the handler is not specified (<parameter>handler</parameter> is | |
3144ebca | 113 | <constant>NULL</constant>), a default handler which causes the |
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114 | program to exit cleanly will be used.</para> |
115 | ||
116 | <para>By default, the event source is enabled permanently | |
117 | (<constant>SD_EVENT_ON</constant>), but this may be changed with | |
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118 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
119 | If the handler function returns a negative error code, it will be | |
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120 | disabled after the invocation, even if the |
121 | <constant>SD_EVENT_ON</constant> mode was requested before. | |
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122 | </para> |
123 | ||
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124 | <para>To destroy an event source object use |
125 | <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
126 | but note that the event source is only removed from the event loop | |
127 | when all references to the event source are dropped. To make sure | |
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128 | an event source does not fire anymore, even if it is still referenced, |
129 | disable the event source using | |
130 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
131 | with <constant>SD_EVENT_OFF</constant>.</para> | |
dc83f27a | 132 | |
7f3fdb7f | 133 | <para>If the second parameter of |
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134 | <function>sd_event_add_signal()</function> is |
135 | <constant>NULL</constant> no reference to the event source object | |
136 | is returned. In this case the event source is considered | |
137 | "floating", and will be destroyed implicitly when the event loop | |
138 | itself is destroyed.</para> | |
139 | ||
140 | <para><function>sd_event_source_get_signal()</function> returns | |
141 | the configured signal number of an event source created previously | |
142 | with <function>sd_event_add_signal()</function>. It takes the | |
143 | event source object as the <parameter>source</parameter> | |
3144ebca | 144 | parameter.</para> |
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145 | </refsect1> |
146 | ||
147 | <refsect1> | |
148 | <title>Return Value</title> | |
149 | ||
150 | <para>On success, these functions return 0 or a positive | |
151 | integer. On failure, they return a negative errno-style error | |
f23e83b1 | 152 | code.</para> |
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153 | </refsect1> |
154 | ||
155 | <refsect1> | |
156 | <title>Errors</title> | |
157 | ||
158 | <para>Returned errors may indicate the following problems:</para> | |
159 | ||
160 | <variablelist> | |
161 | <varlistentry> | |
8474b70c | 162 | <term><constant>-ENOMEM</constant></term> |
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163 | |
164 | <listitem><para>Not enough memory to allocate an object.</para></listitem> | |
165 | </varlistentry> | |
166 | ||
167 | <varlistentry> | |
8474b70c | 168 | <term><constant>-EINVAL</constant></term> |
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169 | |
170 | <listitem><para>An invalid argument has been passed.</para></listitem> | |
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171 | </varlistentry> |
172 | ||
173 | <varlistentry> | |
8474b70c | 174 | <term><constant>-EBUSY</constant></term> |
3144ebca | 175 | |
a8eaaee7 | 176 | <listitem><para>A handler is already installed for this |
3144ebca | 177 | signal or the signal was not blocked previously.</para></listitem> |
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178 | </varlistentry> |
179 | ||
180 | <varlistentry> | |
8474b70c | 181 | <term><constant>-ESTALE</constant></term> |
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182 | |
183 | <listitem><para>The event loop is already terminated.</para></listitem> | |
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184 | </varlistentry> |
185 | ||
186 | <varlistentry> | |
8474b70c | 187 | <term><constant>-ECHILD</constant></term> |
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188 | |
189 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
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190 | </varlistentry> |
191 | ||
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192 | <varlistentry> |
193 | <term><constant>-EDOM</constant></term> | |
3144ebca | 194 | |
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195 | <listitem><para>The passed event source is not a signal event source.</para></listitem> |
196 | </varlistentry> | |
3144ebca | 197 | |
dc83f27a | 198 | </variablelist> |
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199 | </refsect1> |
200 | ||
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201 | <xi:include href="libsystemd-pkgconfig.xml" /> |
202 | ||
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203 | <refsect1> |
204 | <title>See Also</title> | |
205 | ||
206 | <para> | |
207 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
208 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
209 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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210 | <citerefentry><refentrytitle>sd_event_now</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
211 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
3144ebca | 212 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
edf25737 | 213 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
4dfefc19 | 214 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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215 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
216 | <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
217 | <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
218 | <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
219 | <citerefentry project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
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220 | </para> |
221 | </refsect1> | |
222 | ||
223 | </refentry> |