man/sd_bus_is_open.xml

   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_is_open"
  10           xmlns:xi="http://www.w3.org/2001/XInclude">
  11
  12   <refentryinfo>
  13     <title>sd_bus_is_open</title>
  14     <productname>systemd</productname>
  15   </refentryinfo>
  16
  17   <refmeta>
  18     <refentrytitle>sd_bus_is_open</refentrytitle>
  19     <manvolnum>3</manvolnum>
  20   </refmeta>
  21
  22   <refnamediv>
  23     <refname>sd_bus_is_open</refname>
  24     <refname>sd_bus_is_ready</refname>
  25
  26     <refpurpose>Check whether the a bus connection is open or ready.</refpurpose>
  27   </refnamediv>
  28
  29   <refsynopsisdiv>
  30     <funcsynopsis>
  31       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  32
  33       <funcprototype>
  34         <funcdef>int <function>sd_bus_is_open</function></funcdef>
  35         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  36       </funcprototype>
  37
  38       <funcprototype>
  39         <funcdef>int <function>sd_bus_is_ready</function></funcdef>
  40         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  41       </funcprototype>
  42
  43     </funcsynopsis>
  44   </refsynopsisdiv>
  45
  46   <refsect1>
  47     <title>Description</title>
  48
  49     <para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
  50     process of being established, already established or in the process of being torn down. It returns zero when the
  51     connection has not been started yet
  52     (i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
  53     equivalent call has not been invoked yet), or is fully terminated again (for example after
  54     <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
  55     positive otherwise.</para>
  56
  57     <para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
  58     i.e. completed the connection and authentication phases of the protocol and received the
  59     <function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
  60     zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
  61     messages can be sent or received on the connection.</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>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
  75     error code.</para>
  76   </refsect1>
  77
  78   <refsect1>
  79     <title>Errors</title>
  80
  81     <para>Returned errors may indicate the following problems:</para>
  82
  83     <variablelist>
  84       <varlistentry>
  85         <term><constant>-ECHILD</constant></term>
  86
  87         <listitem><para>The bus connection has been created in a different process.</para></listitem>
  88       </varlistentry>
  89     </variablelist>
  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>