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ffd1a3f6 | 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"> | |
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4 | |
5 | <!-- | |
6 | SPDX-License-Identifier: LGPL-2.1+ | |
7 | ||
8 | Copyright © 2016 Julian Orth | |
9 | --> | |
10 | ||
11 | <refentry id="sd_bus_wait" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
12 | ||
13 | <refentryinfo> | |
14 | <title>sd_bus_wait</title> | |
15 | <productname>systemd</productname> | |
16 | </refentryinfo> | |
17 | ||
18 | <refmeta> | |
19 | <refentrytitle>sd_bus_wait</refentrytitle> | |
20 | <manvolnum>3</manvolnum> | |
21 | </refmeta> | |
22 | ||
23 | <refnamediv> | |
24 | <refname>sd_bus_wait</refname> | |
25 | ||
26 | <refpurpose>Wait for I/O on a bus connection</refpurpose> | |
27 | </refnamediv> | |
28 | ||
29 | <refsynopsisdiv> | |
30 | <funcsynopsis> | |
31 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
32 | ||
33 | <funcprototype> | |
34 | <funcdef>int <function>sd_bus_wait</function></funcdef> | |
35 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
36 | <paramdef>uint64_t <parameter>timeout_usec</parameter></paramdef> | |
37 | </funcprototype> | |
38 | </funcsynopsis> | |
39 | </refsynopsisdiv> | |
40 | ||
41 | <refsect1> | |
42 | <title>Description</title> | |
43 | ||
44 | <para><function>sd_bus_wait()</function> synchronously waits for I/O on the specified bus connection object. This | |
45 | function is supposed to be called whenever | |
46 | <citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry> returns zero, | |
47 | indicating that no work is pending on the connection. Internally, this call invokes <citerefentry | |
48 | project='man-pages'><refentrytitle>ppoll</refentrytitle><manvolnum>3</manvolnum></citerefentry>, to wait for I/O on | |
49 | the bus connection. If the <parameter>timeout_sec</parameter> parameter is specified, the call will block at most | |
50 | for the specified amount of time in µs. Pass <constant>UINT64_MAX</constant> to permit it to sleep | |
51 | indefinitely.</para> | |
52 | ||
53 | <para>After each invocation of <function>sd_bus_wait()</function> the <function>sd_bus_process()</function> call | |
54 | should be invoked in order to process any now pending I/O work.</para> | |
55 | ||
56 | <para>Note that <function>sd_bus_wait()</function> is suitable only for simple programs as it does not permit | |
57 | waiting for other I/O events. For more complex programs either connect the bus connection object to an external | |
58 | event loop using <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
59 | or to an <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> event loop | |
60 | using | |
61 | <citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
62 | </refsect1> | |
63 | ||
64 | <refsect1> | |
65 | <title>Return Value</title> | |
66 | ||
67 | <para>If any I/O was seen, a positive value is returned, zero otherwise. If an error occurs, a negative | |
68 | <varname>errno</varname>-style error code is returned.</para> | |
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70 | <refsect2> |
71 | <title>Errors</title> | |
ffd1a3f6 | 72 | |
b1de39de | 73 | <para>Returned errors may indicate the following problems:</para> |
ffd1a3f6 | 74 | |
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75 | <variablelist> |
76 | <varlistentry> | |
77 | <term><constant>-EINVAL</constant></term> | |
ffd1a3f6 | 78 | |
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79 | <listitem><para>An invalid bus object was passed.</para></listitem> |
80 | </varlistentry> | |
ffd1a3f6 | 81 | |
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82 | <varlistentry> |
83 | <term><constant>-ECHILD</constant></term> | |
ffd1a3f6 | 84 | |
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85 | <listitem><para>The bus connection was allocated in a parent process and is being reused in a child |
86 | process after <function>fork()</function>.</para></listitem> | |
87 | </varlistentry> | |
ffd1a3f6 | 88 | |
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89 | <varlistentry> |
90 | <term><constant>-ENOTCONN</constant></term> | |
ffd1a3f6 | 91 | |
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92 | <listitem><para>The bus connection has been terminated already.</para></listitem> |
93 | </varlistentry> | |
94 | </variablelist> | |
95 | </refsect2> | |
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96 | </refsect1> |
97 | ||
98 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
99 | ||
100 | <refsect1> | |
101 | <title>See Also</title> | |
102 | ||
103 | <para> | |
104 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
105 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
106 | <citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
107 | <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
108 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
109 | <citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
110 | </para> | |
111 | </refsect1> | |
112 | ||
113 | </refentry> |