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48c35122 | 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_bus_attach_event" | |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
9 | <refentryinfo> | |
10 | <title>sd_bus_attach_event</title> | |
11 | <productname>systemd</productname> | |
12 | </refentryinfo> | |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd_bus_attach_event</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd_bus_attach_event</refname> | |
21 | <refname>sd_bus_detach_event</refname> | |
22 | <refname>sd_bus_get_event</refname> | |
23 | ||
24 | <refpurpose>Attach a bus connection object to an event loop</refpurpose> | |
25 | </refnamediv> | |
26 | ||
27 | <refsynopsisdiv> | |
28 | <funcsynopsis> | |
29 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
30 | ||
31 | <funcprototype> | |
32 | <funcdef>int <function>sd_bus_attach_event</function></funcdef> | |
33 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
34 | <paramdef>sd_event *<parameter>e</parameter></paramdef> | |
35 | <paramdef>int <parameter>priority</parameter></paramdef> | |
36 | </funcprototype> | |
37 | ||
38 | <funcprototype> | |
39 | <funcdef>int <function>sd_bus_detach_event</function></funcdef> | |
40 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
41 | </funcprototype> | |
42 | ||
43 | <funcprototype> | |
44 | <funcdef>sd_event *<function>sd_bus_get_event</function></funcdef> | |
45 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
46 | </funcprototype> | |
47 | </funcsynopsis> | |
48 | </refsynopsisdiv> | |
49 | ||
50 | <refsect1> | |
51 | <title>Description</title> | |
52 | ||
53 | <para><function>sd_bus_attach_event()</function> attaches the specified bus connection object to an | |
54 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> event loop object at | |
55 | the specified priority (see | |
56 | <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
57 | for details on event loop priorities). When a bus connection object is attached to an event loop incoming messages | |
58 | will be automatically read and processed, and outgoing messages written, whenever the event loop is run. When the | |
59 | event loop is about to terminate, the bus connection is automatically flushed and closed (see | |
60 | <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> for | |
61 | details on this). By default bus connection objects are not attached to any event loop. When a bus connection | |
62 | object is attached to one it is not necessary to invoke | |
63 | <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
64 | <citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry> as this | |
65 | functionality is handled automatically by the event loop.</para> | |
66 | ||
67 | <para><function>sd_bus_detach_event()</function> detaches a bus object from its event loop.</para> | |
68 | ||
69 | <para>The <function>sd_bus_get_event()</function> returns the event loop object the specified bus object is | |
70 | currently attached to, or <constant>NULL</constant> if it is currently not attached to any.</para> | |
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71 | |
72 | <para>Note that <function>sd_bus_attach_event()</function> is only one of three supported ways to implement I/O | |
73 | event handling for bus connections. Alternatively use | |
74 | <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry> for hooking up a | |
75 | bus connection object with external or manual event loops. Or use | |
76 | <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> as a simple | |
77 | synchronous, blocking I/O waiting call.</para> | |
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78 | </refsect1> |
79 | ||
80 | <refsect1> | |
81 | <title>Return Value</title> | |
82 | ||
83 | <para>On success, <function>sd_bus_attach_event()</function> and <function>sd_bus_detach_event()</function> return | |
84 | 0 or a positive integer. On failure, they return a negative errno-style error code.</para> | |
85 | ||
86 | <para><function>sd_bus_get_event()</function> returns an event loop object or <constant>NULL</constant>.</para> | |
48c35122 | 87 | |
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88 | <refsect2> |
89 | <title>Errors</title> | |
48c35122 | 90 | |
b1de39de | 91 | <para>Returned errors may indicate the following problems:</para> |
48c35122 | 92 | |
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93 | <variablelist> |
94 | <varlistentry> | |
95 | <term><constant>-ECHILD</constant></term> | |
48c35122 | 96 | |
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97 | <listitem><para>The bus connection has been created in a different process.</para></listitem> |
98 | </varlistentry> | |
99 | </variablelist> | |
100 | </refsect2> | |
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101 | </refsect1> |
102 | ||
103 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
104 | ||
105 | <refsect1> | |
106 | <title>See Also</title> | |
107 | ||
108 | <para> | |
109 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
110 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
111 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
112 | <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
113 | <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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114 | <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
115 | <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
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116 | </para> |
117 | </refsect1> | |
118 | ||
119 | </refentry> |