man/sd_bus_is_open.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="sd_bus_is_open">
  10
  11   <refentryinfo>
  12     <title>sd_bus_is_open</title>
  13     <productname>elogind</productname>
  14
  15     <authorgroup>
  16       <author>
  17         <contrib>Developer</contrib>
  18         <firstname>Lennart</firstname>
  19         <surname>Poettering</surname>
  20         <email>lennart@poettering.net</email>
  21       </author>
  22     </authorgroup>
  23   </refentryinfo>
  24
  25   <refmeta>
  26     <refentrytitle>sd_bus_is_open</refentrytitle>
  27     <manvolnum>3</manvolnum>
  28   </refmeta>
  29
  30   <refnamediv>
  31     <refname>sd_bus_is_open</refname>
  32     <refname>sd_bus_is_ready</refname>
  33
  34     <refpurpose>Check whether the a bus connection is open or ready.</refpurpose>
  35   </refnamediv>
  36
  37   <refsynopsisdiv>
  38     <funcsynopsis>
  39       <funcsynopsisinfo>#include &lt;elogind/sd-bus.h&gt;</funcsynopsisinfo>
  40
  41       <funcprototype>
  42         <funcdef>int <function>sd_bus_is_open</function></funcdef>
  43         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  44       </funcprototype>
  45
  46       <funcprototype>
  47         <funcdef>int <function>sd_bus_is_ready</function></funcdef>
  48         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  49       </funcprototype>
  50
  51     </funcsynopsis>
  52   </refsynopsisdiv>
  53
  54   <refsect1>
  55     <title>Description</title>
  56
  57     <para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
  58     process of being established, already established or in the process of being torn down. It returns zero when the
  59     connection has not been started yet
  60     (i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
  61     equivalent call has not been invoked yet), or is fully terminated again (for example after
  62     <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
  63     positive otherwise.</para>
  64
  65     <para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
  66     i.e. completed the connection and authentication phases of the protocol and received the
  67     <function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
  68     zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
  69     messages can be sent or received on the connection.</para>
  70
  71     <para>To be notified when the connection is fully established, use
  72     <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
  73     install a match for the <function>Connected()</function> signal on the
  74     <literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
  75     install a match for the <function>Disconnected()</function> signal on the
  76     <literal>org.freedesktop.DBus.Local</literal> interface.</para>
  77   </refsect1>
  78
  79   <refsect1>
  80     <title>Return Value</title>
  81
  82     <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
  83     error code.</para>
  84   </refsect1>
  85
  86   <refsect1>
  87     <title>Errors</title>
  88
  89     <para>Returned errors may indicate the following problems:</para>
  90
  91     <variablelist>
  92       <varlistentry>
  93         <term><constant>-ECHILD</constant></term>
  94
  95         <listitem><para>The bus connection has been created in a different process.</para></listitem>
  96       </varlistentry>
  97     </variablelist>
  98   </refsect1>
  99
 100   <refsect1>
 101     <title>Notes</title>
 102
 103     <para><function>sd_bus_is_open()</function> and <function>sd_bus_is_ready()</function> are available as
 104     a shared library, which can be compiled and linked to with the <constant>libelogind</constant> <citerefentry
 105     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
 106   </refsect1>
 107
 108   <refsect1>
 109     <title>See Also</title>
 110
 111     <para>
 112       <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 113       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 114       <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 115       <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 116       <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 117     </para>
 118   </refsect1>
 119
 120 </refentry>