1<?xml version='1.0'?>
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6<refentry id="sd_bus_close"
7          xmlns:xi="http://www.w3.org/2001/XInclude">
8
9  <refentryinfo>
10    <title>sd_bus_close</title>
11    <productname>systemd</productname>
12  </refentryinfo>
13
14  <refmeta>
15    <refentrytitle>sd_bus_close</refentrytitle>
16    <manvolnum>3</manvolnum>
17  </refmeta>
18
19  <refnamediv>
20    <refname>sd_bus_close</refname>
21    <refname>sd_bus_flush</refname>
22    <refname>sd_bus_default_flush_close</refname>
23
24    <refpurpose>Close and flush a bus connection</refpurpose>
25  </refnamediv>
26
27  <refsynopsisdiv>
28    <funcsynopsis>
29      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
30
31      <funcprototype>
32        <funcdef>void <function>sd_bus_close</function></funcdef>
33        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
34      </funcprototype>
35
36      <funcprototype>
37        <funcdef>int <function>sd_bus_flush</function></funcdef>
38        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
39      </funcprototype>
40
41      <funcprototype>
42        <funcdef>void <function>sd_bus_default_flush_close</function></funcdef>
43        <paramdef>void</paramdef>
44      </funcprototype>
45    </funcsynopsis>
46  </refsynopsisdiv>
47
48  <refsect1>
49    <title>Description</title>
50
51    <para><function>sd_bus_close()</function> disconnects the specified bus connection. When this
52    call is invoked and the specified bus object refers to an active connection it is immediately
53    terminated. No further messages may be sent or received on it. Any messages queued in the bus
54    object (both incoming and outgoing) are released. If invoked on <constant>NULL</constant> bus
55    object or when the bus connection is already closed this function executes no operation. This
56    call does not free or unreference the bus object itself. Use
57    <citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
58    for that.</para>
59
60    <para><function>sd_bus_flush()</function> synchronously writes out all outgoing queued message
61    on a bus connection if there are any. This function call may block if the peer is not processing
62    bus messages quickly.</para>
63
64    <para>Before a program exits it is usually a good idea to flush any pending messages with
65    <function>sd_bus_flush()</function> and then close connections with
66    <function>sd_bus_close()</function> to ensure that no unwritten messages are lost, no further
67    messages may be queued and all incoming but unprocessed messages are released. After both
68    operations have been done, it is a good idea to  also drop any remaining references to the bus
69    object so that it may be freed. Since these three operations are frequently done together a
70    helper call
71    <citerefentry><refentrytitle>sd_bus_flush_close_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
72    is provided that combines them into one.</para>
73
74    <para><function>sd_bus_default_flush_close()</function> is similar to
75    <function>sd_bus_flush_close_unref()</function>, but does not take a bus pointer argument and
76    instead iterates over any of the "default" buses opened by
77    <citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
78    <citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
79    <citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
80    and similar calls. <function>sd_bus_default_flush_close()</function> is particularly useful to
81    clean up any buses opened using those calls before the program exits.</para>
82  </refsect1>
83
84  <refsect1>
85    <title>Return Value</title>
86
87    <para>On success, <function>sd_bus_flush()</function> returns a non-negative integer. On
88    failure, it returns a negative errno-style error code.</para>
89
90    <refsect2>
91      <title>Errors</title>
92
93      <para>Returned errors may indicate the following problems:</para>
94
95      <variablelist>
96        <varlistentry>
97          <term><constant>-ECHILD</constant></term>
98
99          <listitem><para>The bus connection has been created in a different process.</para>
100          </listitem>
101        </varlistentry>
102      </variablelist>
103    </refsect2>
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_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
115      <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
116    </para>
117  </refsect1>
118
119</refentry>
120