man/sd_bus_set_property.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-or-later -->

<refentry id="sd_bus_set_property"
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>sd_bus_set_property</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_set_property</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_set_property</refname>
    <refname>sd_bus_set_propertyv</refname>
    <refname>sd_bus_get_property</refname>
    <refname>sd_bus_get_property_trivial</refname>
    <refname>sd_bus_get_property_string</refname>
    <refname>sd_bus_get_property_strv</refname>

    <refpurpose>Set or query D-Bus service properties</refpurpose>
  </refnamediv>

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

      <funcprototype>
        <funcdef>int <function>sd_bus_set_property</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>destination</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>const char *<parameter>interface</parameter></paramdef>
        <paramdef>const char *<parameter>member</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
        <paramdef>const char *<parameter>type</parameter></paramdef>
        <paramdef>...</paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_set_propertyv</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>destination</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>const char *<parameter>interface</parameter></paramdef>
        <paramdef>const char *<parameter>member</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
        <paramdef>const char *<parameter>type</parameter></paramdef>
        <paramdef>va_list <parameter>ap</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_get_property</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>destination</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>const char *<parameter>interface</parameter></paramdef>
        <paramdef>const char *<parameter>member</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
        <paramdef>sd_bus_message **<parameter>reply</parameter></paramdef>
        <paramdef>const char *<parameter>type</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_get_property_trivial</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>destination</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>const char *<parameter>interface</parameter></paramdef>
        <paramdef>const char *<parameter>member</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
        <paramdef>char <parameter>type</parameter></paramdef>
        <paramdef>void *<parameter>ret_ptr</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_get_property_string</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>destination</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>const char *<parameter>interface</parameter></paramdef>
        <paramdef>const char *<parameter>member</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
        <paramdef>char **<parameter>ret</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_get_property_strv</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>destination</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>const char *<parameter>interface</parameter></paramdef>
        <paramdef>const char *<parameter>member</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
        <paramdef>char ***<parameter>ret</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>These functions set or query D-Bus properties. D-Bus properties are service fields exposed
    via the <constant>org.freedesktop.DBus.Properties</constant> interface. Under the hood, these
    functions call methods of the <constant>org.freedesktop.DBus.Properties</constant> interface and
    as a result their semantics are similar to
    <citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>

    <para><function>sd_bus_set_property()</function> sets a D-Bus property. If setting the property
    fails or an internal error occurs, an error is returned and an extended description of the error
    is optionally stored in <parameter>ret_error</parameter> if it is not <constant>NULL</constant>.
    <parameter>type</parameter> and the arguments that follow it describe the new value of the
    property and must follow the format described in
    <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>

    <para><function>sd_bus_set_propertyv()</function> is equivalent to
    <function>sd_bus_set_property()</function>, except that it is called with a
    <literal>va_list</literal> instead of a variable number of arguments.</para>

    <para><function>sd_bus_get_property()</function> queries a D-Bus property. If retrieving the
    property fails or an internal error occurs, an error is returned and an extended description of
    the error is optionally stored in <parameter>ret_error</parameter> if it is not
    <constant>NULL</constant>. On success, the property is stored in <parameter>reply</parameter>.
    <parameter>type</parameter> describes the property type and must follow the format described in
    <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>

    <para><function>sd_bus_get_property_trivial()</function>,
    <function>sd_bus_get_property_string()</function> and
    <function>sd_bus_get_property_strv()</function> are shorthands for
    <function>sd_bus_get_property()</function> that are used to query basic, string and string
    vector properties respectively. The caller is responsible for freeing the string and string
    vector results stored in <parameter>ret</parameter> by
    <function>sd_bus_get_property_string()</function> and
    <function>sd_bus_get_property_strv()</function>.</para>
  </refsect1>

  <refsect1>
    <title>Return Value</title>

    <para>On success, these functions return a non-negative integer. On failure, they return a
    negative errno-style error code.</para>

    <refsect2 id='errors'>
      <title>Errors</title>

      <para>See the
      <citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>
      man page for a list of possible errors.</para>
    </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>,
      <citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>