man/sd_bus_is_open.xml

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   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   Copyright 2017 Lennart Poettering
   9 -->
  10
  11 <refentry id="sd_bus_is_open">
  12
  13   <refentryinfo>
  14     <title>sd_bus_is_open</title>
  15     <productname>elogind</productname>
  16
  17     <authorgroup>
  18       <author>
  19         <contrib>Developer</contrib>
  20         <firstname>Lennart</firstname>
  21         <surname>Poettering</surname>
  22         <email>lennart@poettering.net</email>
  23       </author>
  24     </authorgroup>
  25   </refentryinfo>
  26
  27   <refmeta>
  28     <refentrytitle>sd_bus_is_open</refentrytitle>
  29     <manvolnum>3</manvolnum>
  30   </refmeta>
  31
  32   <refnamediv>
  33     <refname>sd_bus_is_open</refname>
  34     <refname>sd_bus_is_ready</refname>
  35
  36     <refpurpose>Check whether the a bus connection is open or ready.</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <funcsynopsis>
  41       <funcsynopsisinfo>#include &lt;elogind/sd-bus.h&gt;</funcsynopsisinfo>
  42
  43       <funcprototype>
  44         <funcdef>int <function>sd_bus_is_open</function></funcdef>
  45         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  46       </funcprototype>
  47
  48       <funcprototype>
  49         <funcdef>int <function>sd_bus_is_ready</function></funcdef>
  50         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  51       </funcprototype>
  52
  53     </funcsynopsis>
  54   </refsynopsisdiv>
  55
  56   <refsect1>
  57     <title>Description</title>
  58
  59     <para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
  60     process of being established, already established or in the process of being torn down. It returns zero when the
  61     connection has not been started yet
  62     (i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
  63     equivalent call has not been invoked yet), or is fully terminated again (for example after
  64     <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
  65     positive otherwise.</para>
  66
  67     <para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
  68     i.e. completed the connection and authentication phases of the protocol and received the
  69     <function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
  70     zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
  71     messages can be sent or received on the connection.</para>
  72
  73     <para>To be notified when the connection is fully established, use
  74     <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
  75     install a match for the <function>Connected()</function> signal on the
  76     <literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
  77     install a match for the <function>Disconnected()</function> signal on the
  78     <literal>org.freedesktop.DBus.Local</literal> interface.</para>
  79   </refsect1>
  80
  81   <refsect1>
  82     <title>Return Value</title>
  83
  84     <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
  85     error code.</para>
  86   </refsect1>
  87
  88   <refsect1>
  89     <title>Errors</title>
  90
  91     <para>Returned errors may indicate the following problems:</para>
  92
  93     <variablelist>
  94       <varlistentry>
  95         <term><constant>-ECHILD</constant></term>
  96
  97         <listitem><para>The bus connection has been created in a different process.</para></listitem>
  98       </varlistentry>
  99     </variablelist>
 100   </refsect1>
 101
 102   <refsect1>
 103     <title>Notes</title>
 104
 105     <para><function>sd_bus_is_open()</function> and <function>sd_bus_is_ready()</function> are available as
 106     a shared library, which can be compiled and linked to with the <constant>libelogind</constant> <citerefentry
 107     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
 108   </refsect1>
 109
 110   <refsect1>
 111     <title>See Also</title>
 112
 113     <para>
 114       <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 115       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 116       <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 117       <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 118       <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 119     </para>
 120   </refsect1>
 121
 122 </refentry>