man/sd_bus_close.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="sd_bus_close"
   7           xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>sd_bus_close</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13
  14   <refmeta>
  15     <refentrytitle>sd_bus_close</refentrytitle>
  16     <manvolnum>3</manvolnum>
  17   </refmeta>
  18
  19   <refnamediv>
  20     <refname>sd_bus_close</refname>
  21     <refname>sd_bus_flush</refname>
  22     <refname>sd_bus_default_flush_close</refname>
  23
  24     <refpurpose>Close and flush a bus connection</refpurpose>
  25   </refnamediv>
  26
  27   <refsynopsisdiv>
  28     <funcsynopsis>
  29       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  30
  31       <funcprototype>
  32         <funcdef>void <function>sd_bus_close</function></funcdef>
  33         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  34       </funcprototype>
  35
  36       <funcprototype>
  37         <funcdef>int <function>sd_bus_flush</function></funcdef>
  38         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  39       </funcprototype>
  40
  41       <funcprototype>
  42         <funcdef>void <function>sd_bus_default_flush_close</function></funcdef>
  43         <paramdef>void</paramdef>
  44       </funcprototype>
  45     </funcsynopsis>
  46   </refsynopsisdiv>
  47
  48   <refsect1>
  49     <title>Description</title>
  50
  51     <para><function>sd_bus_close()</function> disconnects the specified bus connection. When this
  52     call is invoked and the specified bus object refers to an active connection it is immediately
  53     terminated. No further messages may be sent or received on it. Any messages queued in the bus
  54     object (both incoming and outgoing) are released. If invoked on <constant>NULL</constant> bus
  55     object or when the bus connection is already closed this function executes no operation. This
  56     call does not free or unreference the bus object itself. Use
  57     <citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  58     for that.</para>
  59
  60     <para><function>sd_bus_flush()</function> synchronously writes out all outgoing queued message
  61     on a bus connection if there are any. This function call may block if the peer is not processing
  62     bus messages quickly.</para>
  63
  64     <para>Before a program exits it is usually a good idea to flush any pending messages with
  65     <function>sd_bus_flush()</function> and then close connections with
  66     <function>sd_bus_close()</function> to ensure that no unwritten messages are lost, no further
  67     messages may be queued and all incoming but unprocessed messages are released. After both
  68     operations have been done, it is a good idea to  also drop any remaining references to the bus
  69     object so that it may be freed. Since these three operations are frequently done together a
  70     helper call
  71     <citerefentry><refentrytitle>sd_bus_flush_close_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  72     is provided that combines them into one.</para>
  73
  74     <para><function>sd_bus_default_flush_close()</function> is similar to
  75     <function>sd_bus_flush_close_unref</function>, but does not take a bus pointer argument and
  76     instead iterates over any of the "default" buses opened by
  77     <citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  78     <citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  79     <citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  80     and similar calls. <function>sd_bus_default_flush_close()</function> is particularly useful to
  81     clean up any buses opened using those calls before the program exits.</para>
  82   </refsect1>
  83
  84   <refsect1>
  85     <title>Return Value</title>
  86
  87     <para>On success, <function>sd_bus_flush()</function> returns a non-negative integer. On
  88     failure, it returns a negative errno-style error code.</para>
  89
  90     <refsect2>
  91       <title>Errors</title>
  92
  93       <para>Returned errors may indicate the following problems:</para>
  94
  95       <variablelist>
  96         <varlistentry>
  97           <term><constant>-ECHILD</constant></term>
  98
  99           <listitem><para>The bus connection has been created in a different process.</para>
 100           </listitem>
 101         </varlistentry>
 102       </variablelist>
 103     </refsect2>
 104   </refsect1>
 105
 106   <xi:include href="libsystemd-pkgconfig.xml" />
 107
 108   <refsect1>
 109     <title>See Also</title>
 110
 111     <para>
 112       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 113       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 114       <citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 115       <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 116     </para>
 117   </refsect1>
 118
 119 </refentry>