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3802a3d3 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
ba4b3566 | 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 | <!-- | |
5de0ccff | 6 | This file is part of systemd. |
ba4b3566 | 7 | |
5de0ccff | 8 | Copyright 2014 Zbigniew Jędrzejewski-Szmek |
ba4b3566 | 9 | |
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10 | systemd is free software; you can redistribute it and/or modify it |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
ba4b3566 | 14 | |
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15 | systemd is distributed in the hope that it will be useful, but |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
ba4b3566 | 19 | |
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20 | You should have received a copy of the GNU Lesser General Public License |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
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22 | --> |
23 | ||
dc83f27a | 24 | <refentry id="sd_event_get_fd" xmlns:xi="http://www.w3.org/2001/XInclude"> |
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25 | |
26 | <refentryinfo> | |
27 | <title>sd_event_get_fd</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>More text</contrib> | |
33 | <firstname>Zbigniew</firstname> | |
34 | <surname>Jędrzejewski-Szmek</surname> | |
35 | <email>zbyszek@in.waw.pl</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_event_get_fd</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_event_get_fd</refname> | |
47 | ||
48 | <refpurpose>Obtain a file descriptor to poll for event loop events</refpurpose> | |
49 | </refnamediv> | |
50 | ||
51 | <refsynopsisdiv> | |
52 | <funcsynopsis> | |
dc83f27a | 53 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> |
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54 | |
55 | <funcprototype> | |
56 | <funcdef>int <function>sd_event_get_fd</function></funcdef> | |
dc83f27a | 57 | <paramdef>sd_event *<parameter>event</parameter></paramdef> |
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58 | </funcprototype> |
59 | ||
60 | </funcsynopsis> | |
61 | </refsynopsisdiv> | |
62 | ||
63 | <refsect1> | |
64 | <title>Description</title> | |
65 | ||
66 | <para><function>sd_event_get_fd()</function> returns the file | |
dc83f27a | 67 | descriptor that an event loop object returned by the |
ba4b3566 | 68 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
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69 | function uses to wait for events. This file descriptor may itself |
70 | be polled for | |
71 | <constant>POLLIN</constant>/<constant>EPOLLIN</constant> | |
72 | events. This makes it possible to embed an | |
ba4b3566 | 73 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
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74 | event loop into another, possibly foreign, event loop.</para> |
75 | ||
76 | <para>The returned file descriptor refers to an <citerefentry | |
77 | project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
78 | object. It is recommended not to alter it by invoking | |
79 | <citerefentry | |
80 | project='man-pages'><refentrytitle>epoll_ctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
81 | on it, in order to avoid interference with the event loop's inner | |
82 | logic and assumptions.</para> | |
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83 | </refsect1> |
84 | ||
85 | <refsect1> | |
86 | <title>Return Value</title> | |
87 | ||
88 | <para>On success, <function>sd_event_get_fd()</function> returns a | |
dc83f27a | 89 | non-negative file descriptor. On failure, it returns a negative |
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90 | errno-style error code.</para> |
91 | </refsect1> | |
92 | ||
93 | <refsect1> | |
94 | <title>Errors</title> | |
95 | ||
96 | <para>Returned errors may indicate the following problems:</para> | |
97 | ||
98 | <variablelist> | |
99 | <varlistentry> | |
100 | <term><constant>-EINVAL</constant></term> | |
101 | ||
102 | <listitem><para><parameter>event</parameter> is not a valid | |
103 | pointer to an <structname>sd_event</structname> structure. | |
104 | </para></listitem> | |
105 | </varlistentry> | |
106 | ||
107 | <varlistentry> | |
108 | <term><constant>-ECHILD</constant></term> | |
109 | ||
110 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
111 | ||
112 | </varlistentry> | |
113 | </variablelist> | |
114 | </refsect1> | |
115 | ||
116 | <refsect1> | |
117 | <title>Examples</title> | |
118 | ||
119 | <example> | |
dc83f27a | 120 | <title>Integration in the GLib event loop</title> |
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121 | |
122 | <programlisting><xi:include href="glib-event-glue.c" parse="text" /></programlisting> | |
123 | </example> | |
124 | </refsect1> | |
125 | ||
dc83f27a | 126 | <xi:include href="libsystemd-pkgconfig.xml" /> |
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127 | |
128 | <refsect1> | |
129 | <title>See Also</title> | |
130 | ||
131 | <para> | |
132 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
133 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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134 | <citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
135 | <citerefentry project='man-pages'><refentrytitle>epoll_ctl</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
136 | <citerefentry project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
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137 | </para> |
138 | </refsect1> | |
139 | ||
140 | </refentry> |