Systemd/man/sd_bus_set_server.xml

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<!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>