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+
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   8
   9 <refentry id="sd_bus_is_open">
  10
  11   <refentryinfo>
  12     <title>sd_bus_is_open</title>
  13     <productname>systemd</productname>
  14   </refentryinfo>
  15
  16   <refmeta>
  17     <refentrytitle>sd_bus_is_open</refentrytitle>
  18     <manvolnum>3</manvolnum>
  19   </refmeta>
  20
  21   <refnamediv>
  22     <refname>sd_bus_is_open</refname>
  23     <refname>sd_bus_is_ready</refname>
  24
  25     <refpurpose>Check whether the a bus connection is open or ready.</refpurpose>
  26   </refnamediv>
  27
  28   <refsynopsisdiv>
  29     <funcsynopsis>
  30       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  31
  32       <funcprototype>
  33         <funcdef>int <function>sd_bus_is_open</function></funcdef>
  34         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  35       </funcprototype>
  36
  37       <funcprototype>
  38         <funcdef>int <function>sd_bus_is_ready</function></funcdef>
  39         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  40       </funcprototype>
  41
  42     </funcsynopsis>
  43   </refsynopsisdiv>
  44
  45   <refsect1>
  46     <title>Description</title>
  47
  48     <para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
  49     process of being established, already established or in the process of being torn down. It returns zero when the
  50     connection has not been started yet
  51     (i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
  52     equivalent call has not been invoked yet), or is fully terminated again (for example after
  53     <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
  54     positive otherwise.</para>
  55
  56     <para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
  57     i.e. completed the connection and authentication phases of the protocol and received the
  58     <function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
  59     zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
  60     messages can be sent or received on the connection.</para>
  61
  62     <para>To be notified when the connection is fully established, use
  63     <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
  64     install a match for the <function>Connected()</function> signal on the
  65     <literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
  66     install a match for the <function>Disconnected()</function> signal on the
  67     <literal>org.freedesktop.DBus.Local</literal> interface.</para>
  68   </refsect1>
  69
  70   <refsect1>
  71     <title>Return Value</title>
  72
  73     <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
  74     error code.</para>
  75   </refsect1>
  76
  77   <refsect1>
  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   </refsect1>
  90
  91   <refsect1>
  92     <title>Notes</title>
  93
  94     <para><function>sd_bus_is_open()</function> and <function>sd_bus_is_ready()</function> are available as
  95     a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry
  96     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
  97   </refsect1>
  98
  99   <refsect1>
 100     <title>See Also</title>
 101
 102     <para>
 103       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 104       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 105       <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 106       <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 107       <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 108     </para>
 109   </refsect1>
 110
 111 </refentry>