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systemd-stable/man/sd_bus_set_server.xml

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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="sd_bus_set_server"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_set_server</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_set_server</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_set_server</refname>
<refname>sd_bus_is_server</refname>
<refname>sd_bus_get_bus_id</refname>
<refname>sd_bus_set_bus_client</refname>
<refname>sd_bus_is_bus_client</refname>
<refpurpose>Configure direct connection mode for a bus object</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_set_server</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>int <parameter>b</parameter></paramdef>
<paramdef>sd_id128_t <parameter>id</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_is_server</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_get_bus_id</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>sd_id128_t *<parameter>id</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_set_bus_client</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>int <parameter>b</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_is_bus_client</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_set_server()</function> configures the bus object as a server for direct D-Bus
connections. <parameter>b</parameter> enables/disables the server mode. If zero, the server mode is
disabled. Otherwise, the server mode is enabled. Configuring a bus object as a server is required to
allow establishing direct connections between two peers without going via the D-Bus daemon.
<parameter>id</parameter> must contain a 128-bit integer id for the server. If clients add a guid field
to their D-Bus address string, the server id must match this guid or the D-Bus authentication handshake
will fail. If no specific id is defined for the server,
<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>
can be used to generate a random id instead.</para>
<para><function>sd_bus_is_server()</function> returns whether the server mode is enabled for the given
bus object.</para>
<para><function>sd_bus_get_bus_id()</function> stores the D-Bus server id configured using
<function>sd_bus_set_server()</function> (for server bus objects) or received during D-Bus authentication
(for client bus objects) in <parameter>id</parameter>.</para>
<para><function>sd_bus_set_bus_client()</function> configures the bus object as a D-Bus daemon client.
<parameter>b</parameter> enables/disables the client mode. If zero, the client mode is disabled and the
bus object should connect directly to a D-Bus server. Otherwise, the client mode is enabled and the bus
object should connect to a D-Bus daemon. When connecting to an existing bus using any of the functions in
the <citerefentry><refentrytitle>sd_bus_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>
family of functions or any of the functions in the
<citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry> family
of functions, the bus object is automatically configured as a bus client. However, when connecting to a
D-Bus daemon by calling
<citerefentry><refentrytitle>sd_bus_set_address</refentrytitle><manvolnum>3</manvolnum></citerefentry>
followed by
<citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>, the bus
object should be manually configured as a bus client using <function>sd_bus_set_bus_client()</function>.
By default, a bus object is not configured as a D-Bus daemon client.</para>
<para><function>sd_bus_is_bus_client()</function> returns whether the client mode is enabled/disabled for
the given bus object.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_bus_set_server()</function>,
<function>sd_bus_get_bus_id()</function> and <function>sd_bus_set_bus_client()</function> return a
non-negative integer. On failure, they return a negative errno-style error code.</para>
<para><function>sd_bus_is_server()</function> and <function>sd_bus_is_bus_client()</function> return a
positive integer when the server or client mode is enabled, respectively. Otherwise, they return zero.
</para>
<refsect2>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The bus connection has been created in a different process.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EPERM</constant></term>
<listitem><para>The bus connection has already been started.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOPKG</constant></term>
<listitem><para>The bus cannot be resolved.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>A required parameter was <constant>NULL</constant> or
<parameter>b</parameter> was zero and <parameter>id</parameter> did not equal
<constant>SD_ID128_NULL</constant>.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOTCONN</constant></term>
<listitem><para>The bus is not connected.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>