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_is_open"
7          xmlns:xi="http://www.w3.org/2001/XInclude">
8
9  <refentryinfo>
10    <title>sd_bus_is_open</title>
11    <productname>systemd</productname>
12  </refentryinfo>
13
14  <refmeta>
15    <refentrytitle>sd_bus_is_open</refentrytitle>
16    <manvolnum>3</manvolnum>
17  </refmeta>
18
19  <refnamediv>
20    <refname>sd_bus_is_open</refname>
21    <refname>sd_bus_is_ready</refname>
22
23    <refpurpose>Check whether the bus connection is open or ready</refpurpose>
24  </refnamediv>
25
26  <refsynopsisdiv>
27    <funcsynopsis>
28      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
29
30      <funcprototype>
31        <funcdef>int <function>sd_bus_is_open</function></funcdef>
32        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
33      </funcprototype>
34
35      <funcprototype>
36        <funcdef>int <function>sd_bus_is_ready</function></funcdef>
37        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
38      </funcprototype>
39
40    </funcsynopsis>
41  </refsynopsisdiv>
42
43  <refsect1>
44    <title>Description</title>
45
46    <para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
47    process of being established, already established or in the process of being torn down. It returns zero when the
48    connection has not been started yet
49    (i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
50    equivalent call has not been invoked yet), or is fully terminated again (for example after
51    <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
52    positive otherwise.</para>
53
54    <para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
55    i.e. completed the connection and authentication phases of the protocol and received the
56    <function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
57    zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
58    messages can be sent or received on the connection.</para>
59
60    <para>The <parameter>bus</parameter> argument may be <constant>NULL</constant>, zero is also returned in
61    that case.</para>
62
63    <para>To be notified when the connection is fully established, use
64    <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
65    install a match for the <function>Connected()</function> signal on the
66    <literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
67    install a match for the <function>Disconnected()</function> signal on the
68    <literal>org.freedesktop.DBus.Local</literal> interface.</para>
69  </refsect1>
70
71  <refsect1>
72    <title>Return Value</title>
73
74    <para>Those functions return 0 if the bus is <emphasis>not</emphasis> in the given state, and a positive
75    integer when it is. On failure, a negative errno-style error code is returned.</para>
76
77    <refsect2>
78      <title>Errors</title>
79
80      <para>Returned errors may indicate the following problems:</para>
81
82      <variablelist>
83        <varlistentry>
84          <term><constant>-ECHILD</constant></term>
85
86          <listitem><para>The bus connection has been created in a different process.</para></listitem>
87        </varlistentry>
88      </variablelist>
89    </refsect2>
90  </refsect1>
91
92  <xi:include href="libsystemd-pkgconfig.xml" />
93
94  <refsect1>
95    <title>See Also</title>
96
97    <para>
98      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
99      <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
100      <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
101      <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
102      <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
103    </para>
104  </refsect1>
105
106</refentry>
107