man/sd_bus_new.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   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   This file is part of systemd.
   7
   8   Copyright 2014 Zbigniew Jędrzejewski-Szmek
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="sd_bus_new">
  25
  26   <refentryinfo>
  27     <title>sd_bus_new</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>A monkey with a typewriter</contrib>
  33         <firstname>Zbigniew</firstname>
  34         <surname>Jędrzejewski-Szmek</surname>
  35         <email>zbyszek@in.waw.pl</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>sd_bus_new</refentrytitle>
  42     <manvolnum>3</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>sd_bus_new</refname>
  47     <refname>sd_bus_ref</refname>
  48     <refname>sd_bus_unref</refname>
  49
  50     <refpurpose>Create a new bus object and create or destroy references to it</refpurpose>
  51   </refnamediv>
  52
  53   <refsynopsisdiv>
  54     <funcsynopsis>
  55       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  56
  57       <funcprototype>
  58         <funcdef>int <function>sd_bus_new</function></funcdef>
  59         <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
  60       </funcprototype>
  61
  62       <funcprototype>
  63         <funcdef>sd_bus *<function>sd_bus_ref</function></funcdef>
  64         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  65       </funcprototype>
  66
  67       <funcprototype>
  68         <funcdef>sd_bus *<function>sd_bus_unref</function></funcdef>
  69         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  70       </funcprototype>
  71     </funcsynopsis>
  72   </refsynopsisdiv>
  73
  74   <refsect1>
  75     <title>Description</title>
  76
  77     <para><function>sd_bus_new()</function> creates a new bus
  78     object. This object is reference-counted, and will be destroyed
  79     when all references are gone. Initially, the caller of this
  80     function owns the sole reference and the bus object will not be
  81     connected to any bus. To connect it to a bus, make sure
  82     to set an address with
  83     <citerefentry><refentrytitle>sd_bus_set_address</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  84     or a related call, and then start the connection with
  85     <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  86
  87     <para>In most cases, it is a better idea to invoke
  88     <citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  89     <citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  90     or related calls instead of the more low-level
  91     <function>sd_bus_new()</function> and
  92     <function>sd_bus_start()</function>. The higher-level calls not
  93     only allocate a bus object but also start the connection to a
  94     well-known bus in a single function invocation.</para>
  95
  96     <para><function>sd_bus_ref()</function> creates a new reference to
  97     <parameter>bus</parameter>.</para>
  98
  99     <para><function>sd_bus_unref()</function> destroys a reference to
 100     <parameter>bus</parameter>. Once the reference count has dropped
 101     to zero, <parameter>bus</parameter> cannot be used anymore, so
 102     further calls to <function>sd_bus_ref()</function> or
 103     <function>sd_bus_unref()</function> are illegal.</para>
 104   </refsect1>
 105
 106   <refsect1>
 107     <title>Return Value</title>
 108
 109     <para>On success, <function>sd_bus_new()</function> returns 0 or a
 110     positive integer. On failure, it returns a negative errno-style
 111     error code.</para>
 112
 113     <para><function>sd_bus_ref</function> always returns the argument.
 114     </para>
 115
 116     <para><function>sd_bus_unref</function> always returns
 117     <constant>NULL</constant>.</para>
 118   </refsect1>
 119
 120   <refsect1>
 121     <title>Errors</title>
 122
 123     <para>Returned errors may indicate the following problems:</para>
 124
 125     <variablelist>
 126       <varlistentry>
 127         <term><constant>-ENOMEM</constant></term>
 128
 129         <listitem><para>Memory allocation failed.</para></listitem>
 130       </varlistentry>
 131     </variablelist>
 132   </refsect1>
 133
 134   <refsect1>
 135     <title>Notes</title>
 136
 137     <para><function>sd_bus_new()</function> and other functions
 138     described here are available as a shared library, which can be
 139     compiled and linked to with the
 140     <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 141     file.</para>
 142   </refsect1>
 143
 144   <refsect1>
 145     <title>See Also</title>
 146
 147     <para>
 148       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 149       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 150       <citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 151       <citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 152       <citerefentry><refentrytitle>sd_bus_open_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 153       <citerefentry><refentrytitle>sd_bus_open_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 154     </para>
 155   </refsect1>
 156
 157 </refentry>