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1 | <?xml version='1.0'?> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | SPDX-License-Identifier: LGPL-2.1+ | |
7 | --> | |
8 | ||
9 | <refentry id="sd_bus_attach_event" | |
10 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
11 | ||
12 | <refentryinfo> | |
13 | <title>sd_bus_attach_event</title> | |
14 | <productname>systemd</productname> | |
15 | </refentryinfo> | |
16 | ||
17 | <refmeta> | |
18 | <refentrytitle>sd_bus_attach_event</refentrytitle> | |
19 | <manvolnum>3</manvolnum> | |
20 | </refmeta> | |
21 | ||
22 | <refnamediv> | |
23 | <refname>sd_bus_attach_event</refname> | |
24 | <refname>sd_bus_detach_event</refname> | |
25 | <refname>sd_bus_get_event</refname> | |
26 | ||
27 | <refpurpose>Attach a bus connection object to an event loop</refpurpose> | |
28 | </refnamediv> | |
29 | ||
30 | <refsynopsisdiv> | |
31 | <funcsynopsis> | |
32 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
33 | ||
34 | <funcprototype> | |
35 | <funcdef>int <function>sd_bus_attach_event</function></funcdef> | |
36 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
37 | <paramdef>sd_event *<parameter>e</parameter></paramdef> | |
38 | <paramdef>int <parameter>priority</parameter></paramdef> | |
39 | </funcprototype> | |
40 | ||
41 | <funcprototype> | |
42 | <funcdef>int <function>sd_bus_detach_event</function></funcdef> | |
43 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
44 | </funcprototype> | |
45 | ||
46 | <funcprototype> | |
47 | <funcdef>sd_event *<function>sd_bus_get_event</function></funcdef> | |
48 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
49 | </funcprototype> | |
50 | </funcsynopsis> | |
51 | </refsynopsisdiv> | |
52 | ||
53 | <refsect1> | |
54 | <title>Description</title> | |
55 | ||
56 | <para><function>sd_bus_attach_event()</function> attaches the specified bus connection object to an | |
57 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> event loop object at | |
58 | the specified priority (see | |
59 | <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
60 | for details on event loop priorities). When a bus connection object is attached to an event loop incoming messages | |
61 | will be automatically read and processed, and outgoing messages written, whenever the event loop is run. When the | |
62 | event loop is about to terminate, the bus connection is automatically flushed and closed (see | |
63 | <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> for | |
64 | details on this). By default bus connection objects are not attached to any event loop. When a bus connection | |
65 | object is attached to one it is not necessary to invoke | |
66 | <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
67 | <citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry> as this | |
68 | functionality is handled automatically by the event loop.</para> | |
69 | ||
70 | <para><function>sd_bus_detach_event()</function> detaches a bus object from its event loop.</para> | |
71 | ||
72 | <para>The <function>sd_bus_get_event()</function> returns the event loop object the specified bus object is | |
73 | currently attached to, or <constant>NULL</constant> if it is currently not attached to any.</para> | |
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74 | |
75 | <para>Note that <function>sd_bus_attach_event()</function> is only one of three supported ways to implement I/O | |
76 | event handling for bus connections. Alternatively use | |
77 | <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry> for hooking up a | |
78 | bus connection object with external or manual event loops. Or use | |
79 | <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> as a simple | |
80 | synchronous, blocking I/O waiting call.</para> | |
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81 | </refsect1> |
82 | ||
83 | <refsect1> | |
84 | <title>Return Value</title> | |
85 | ||
86 | <para>On success, <function>sd_bus_attach_event()</function> and <function>sd_bus_detach_event()</function> return | |
87 | 0 or a positive integer. On failure, they return a negative errno-style error code.</para> | |
88 | ||
89 | <para><function>sd_bus_get_event()</function> returns an event loop object or <constant>NULL</constant>.</para> | |
90 | </refsect1> | |
91 | ||
92 | <refsect1> | |
93 | <title>Errors</title> | |
94 | ||
95 | <para>Returned errors may indicate the following problems:</para> | |
96 | ||
97 | <variablelist> | |
98 | <varlistentry> | |
99 | <term><constant>-ECHILD</constant></term> | |
100 | ||
101 | <listitem><para>The bus connection has been created in a different process.</para></listitem> | |
102 | </varlistentry> | |
103 | </variablelist> | |
104 | </refsect1> | |
105 | ||
106 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
107 | ||
108 | <refsect1> | |
109 | <title>See Also</title> | |
110 | ||
111 | <para> | |
112 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
113 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
114 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
115 | <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
116 | <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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117 | <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
118 | <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
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119 | </para> |
120 | </refsect1> | |
121 | ||
122 | </refentry> |