man/sd_bus_is_open.xml

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  10   Copyright 2017 Lennart Poettering
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  25
  26 <refentry id="sd_bus_is_open">
  27
  28   <refentryinfo>
  29     <title>sd_bus_is_open</title>
  30     <productname>systemd</productname>
  31
  32     <authorgroup>
  33       <author>
  34         <contrib>Developer</contrib>
  35         <firstname>Lennart</firstname>
  36         <surname>Poettering</surname>
  37         <email>lennart@poettering.net</email>
  38       </author>
  39     </authorgroup>
  40   </refentryinfo>
  41
  42   <refmeta>
  43     <refentrytitle>sd_bus_is_open</refentrytitle>
  44     <manvolnum>3</manvolnum>
  45   </refmeta>
  46
  47   <refnamediv>
  48     <refname>sd_bus_is_open</refname>
  49     <refname>sd_bus_is_ready</refname>
  50
  51     <refpurpose>Check whether the a bus connection is open or ready.</refpurpose>
  52   </refnamediv>
  53
  54   <refsynopsisdiv>
  55     <funcsynopsis>
  56       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  57
  58       <funcprototype>
  59         <funcdef>int <function>sd_bus_is_open</function></funcdef>
  60         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  61       </funcprototype>
  62
  63       <funcprototype>
  64         <funcdef>int <function>sd_bus_is_ready</function></funcdef>
  65         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  66       </funcprototype>
  67
  68     </funcsynopsis>
  69   </refsynopsisdiv>
  70
  71   <refsect1>
  72     <title>Description</title>
  73
  74     <para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
  75     process of being established, already established or in the process of being torn down. It returns zero when the
  76     connection has not been started yet
  77     (i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
  78     equivalent call has not been invoked yet), or is fully terminated again (for example after
  79     <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
  80     positive otherwise.</para>
  81
  82     <para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
  83     i.e. completed the connection and authentication phases of the protocol and received the
  84     <function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
  85     zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
  86     messages can be sent or received on the connection.</para>
  87
  88     <para>To be notified when the connection is fully established, use
  89     <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
  90     install a match for the <function>Connected()</function> signal on the
  91     <literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
  92     install a match for the <function>Disconnected()</function> signal on the
  93     <literal>org.freedesktop.DBus.Local</literal> interface.</para>
  94   </refsect1>
  95
  96   <refsect1>
  97     <title>Return Value</title>
  98
  99     <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
 100     error code.</para>
 101   </refsect1>
 102
 103   <refsect1>
 104     <title>Errors</title>
 105
 106     <para>Returned errors may indicate the following problems:</para>
 107
 108     <variablelist>
 109       <varlistentry>
 110         <term><constant>-ECHILD</constant></term>
 111
 112         <listitem><para>The bus connection has been created in a different process.</para></listitem>
 113       </varlistentry>
 114     </variablelist>
 115   </refsect1>
 116
 117   <refsect1>
 118     <title>Notes</title>
 119
 120     <para><function>sd_bus_is_open()</function> and <function>sd_bus_is_ready()</function> are available as
 121     a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry
 122     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
 123   </refsect1>
 124
 125   <refsect1>
 126     <title>See Also</title>
 127
 128     <para>
 129       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 130       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 131       <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 132       <citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 133       <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 134     </para>
 135   </refsect1>
 136
 137 </refentry>