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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2014 Zbigniew Jędrzejewski-Szmek
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_bus_open_user">
<refentryinfo>
<title>sd_bus_open_user</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>A monkey with a typewriter</contrib>
<firstname>Zbigniew</firstname>
<surname>Jędrzejewski-Szmek</surname>
<email>zbyszek@in.waw.pl</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_open_user</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_open_user</refname>
<refname>sd_bus_open_system</refname>
<refname>sd_bus_open_system_remote</refname>
<refname>sd_bus_open_system_container</refname>
<refname>sd_bus_default_user</refname>
<refname>sd_bus_default_system</refname>
<refpurpose>Open a connection to the system or user bus</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_open_user</function></funcdef>
<paramdef>sd_bus** <parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system</function></funcdef>
<paramdef>sd_bus** <parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system_remote</function></funcdef>
<paramdef>const char *<parameter>host</parameter></paramdef>
<paramdef>sd_bus** <parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system_container</function></funcdef>
<paramdef>const char *<parameter>machine</parameter></paramdef>
<paramdef>sd_bus** <parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_default_user</function></funcdef>
<paramdef>sd_bus** <parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_default_system</function></funcdef>
<paramdef>sd_bus** <parameter>bus</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_open_user()</function> creates a new bus
object and opens a connection to the the user bus.
<function>sd_bus_open_system()</function> does the same, but
connects to the system bus.</para>
<para>If <varname>$DBUS_SESSION_BUS_ADDRESS</varname> environment
variable is set
(c.f. <citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
it will be used as the address of the user bus. This variable can
contain multiple addresses separated by <literal>;</literal>. If
this variable is not set, a suitable default for the default user
D-Bus instance will be used.</para>
<para>If <varname>$DBUS_SYSTEM_BUS_ADDRESS</varname> environment
variable is set, it will be used as the address of the system
bus. This variable uses the same syntax as
<varname>$DBUS_SESSION_BUS_ADDRESS</varname>/. If this variable is
not set, a suitable default for the default system D-Bus instance
will be used.</para>
<para><function>sd_bus_open_system_remote()</function> connects to
the system bus on the specified <parameter>host</parameter> using
SSH. <parameter>host</parameter> consists of an optional user name
followed by the <literal>@</literal> symbol, and the hostname.
</para>
<para><function>sd_bus_open_system_remote()</function> connects to
the system bus in the specified <parameter>machine</parameter>,
where <parameter>machine</parameter> is the name of a container.
See
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
for more information about "machines".</para>
<para><function>sd_bus_default_user()</function> returns a bus
object connected to the user bus. This bus object is shared
per-thread. It is created on the first invocation of
<function>sd_bus_default_user()</function>, and subsequent
invocations returns a reference to the same object.</para>
<para><function>sd_bus_default_system()</function> is similar to
<function>sd_bus_default_user()</function>, but connects to the
system bus.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these calls return 0 or a positive
integer. On failure, these calls return a negative
errno-style error code.</para>
</refsect1>
<refsect1>
<title>Reference ownership</title>
<para>Functions <function>sd_bus_open_user()</function>,
<function>sd_bus_open_system()</function>,
<function>sd_bus_open_system_remote()</function>, and
<function>sd_bus_open_system_machine()</function> return a new
object and the caller owns the sole reference. When not needed
anymore, this reference should be destroyed with
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
<para>Functions <function>sd_bus_default_user()</function> and
<function>sd_bus_default_system()</function> do not create a new
reference.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><varname>-EINVAL</varname></term>
<listitem><para>Specified parameter is invalid
(<constant>NULL</constant> in case of output
parameters).</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>-ENOMEM</varname></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
<para>In addition, any further connection-related errors may be
by returned. See <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_bus_open_user()</function> and other functions
described here are available as a shared library, which can be
compiled and linked to with the
<constant>libsystemd-bus</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
