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<refentry id="sd_bus_new">

<refentryinfo>

<title>sd_bus_new</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_new</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_bus_new</refname>

<refname>sd_bus_ref</refname>

<refname>sd_bus_unref</refname>

<refpurpose>Create a new bus object and create or destroy references to it</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

<funcprototype>

<funcdef>int <function>sd_bus_new</function></funcdef>

<paramdef>sd_bus **<parameter>bus</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>sd_bus *<function>sd_bus_ref</function></funcdef>

<paramdef>sd_bus *<parameter>bus</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>sd_bus *<function>sd_bus_unref</function></funcdef>

<paramdef>sd_bus *<parameter>bus</parameter></paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para><function>sd_bus_new()</function> creates a new bus

object. This object is reference-counted, and will be destroyed

when all references are gone. Initially, the caller of this

function owns the sole reference. The bus object will not be

connected to any bus initially. To connect it to a bus, make sure

to set an address with

<citerefentry><refentrytitle>sd_bus_set_address</refentrytitle><manvolnum>3</manvolnum></citerefentry>

or a related call, and then start the connection with

<citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>

<para>In most cases it's a better idea to invoke

<citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>

or related calls instead of the more low-level

<function>sd_bus_new()</function> and

<function>sd_bus_start()</function>. The higher-level calls not

only allocate a bus object but also start the connection to a

well-known bus in a single function invocation.</para>

<para><function>sd_bus_ref()</function> creates a new reference to

<parameter>bus</parameter>. This bus object will not be destroyed

until <function>sd_bus_unref()</function> has been called as many

times plus once more. Once the reference count has dropped to

zero, <parameter>bus</parameter> cannot be used anymore, so

further calls to <function>sd_bus_ref()</function> or

<function>sd_bus_unref()</function> are illegal.</para>

<para><function>sd_bus_unref()</function> destroys a reference to

<parameter>bus</parameter>.</para>

</refsect1>

<refsect1>

<title>Return Value</title>

<para>On success, <function>sd_bus_new()</function> returns 0 or a

positive integer. On failure, it returns a negative errno-style

error code.</para>

<para><function>sd_bus_ref</function> always returns the argument.

</para>

<para><function>sd_bus_unref</function> always returns

<constant>NULL</constant>.</para>

</refsect1>

<refsect1>

<title>Errors</title>

<para>Returned errors may indicate the following problems:</para>

<variablelist>

<varlistentry>

<term><constant>-ENOMEM</constant></term>

<listitem><para>Memory allocation failed.</para></listitem>

</varlistentry>

</variablelist>

</refsect1>

<refsect1>

<title>Notes</title>

<para><function>sd_bus_new()</function> and other functions

described here are available as a shared library, which can be

compiled and linked to with the

<constant>libsystemd</constant> <citerefentry project='die-net'><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_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_bus_open_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_bus_open_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>