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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_call"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_call</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_call</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_call</refname>
<refname>sd_bus_call_async</refname>
<refpurpose>Invoke a D-Bus method call</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_call</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>uint64_t <parameter>usec</parameter></paramdef>
<paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
<paramdef>sd_bus_message **<parameter>reply</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_call_async</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef>
<paramdef>void *<parameter>userdata</parameter></paramdef>
<paramdef>uint64_t <parameter>usec</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_call()</function> takes a complete bus message object and calls the
corresponding D-Bus method. The response is stored in <parameter>reply</parameter>.
<parameter>usec</parameter> indicates the timeout in microseconds. If
<parameter>ret_error</parameter> is not <constant>NULL</constant> and
<function>sd_bus_call()</function> returns an error, <parameter>ret_error</parameter> is
initialized to an instance of <structname>sd_bus_error</structname> describing the error.</para>
<para><function>sd_bus_call_async()</function> is like <function>sd_bus_call()</function> but
works asynchronously. The <parameter>callback</parameter> shall reference a function to call
when the event source is triggered. The <parameter>userdata</parameter> pointer will be passed
to the callback function, and may be chosen freely by the caller. If <parameter>slot</parameter>
is not <constant>NULL</constant> and <function>sd_bus_call_async()</function> succeeds,
<parameter>slot</parameter> is set to a slot object which can be used to cancel the method call
at a later time using
<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
If <parameter>slot</parameter> is <constant>NULL</constant>, the lifetime of the method call is
bound to the lifetime of the bus object itself, and it cannot be cancelled independently. See
<citerefentry><refentrytitle>sd_bus_slot_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for details. The <parameter>callback</parameter> function is called when the response arrives
and receives the response, <parameter>userdata</parameter> and a
<structname>sd_bus_error</structname> object as its arguments. The
<structname>sd_bus_error</structname> object is unused here and should be ignored. If
<parameter>callback</parameter> returns a non-negative integer when called, a debug message is
logged along with details about the response.</para>
<para>To determine whether the method call succeeded, use
<citerefentry><refentrytitle>sd_bus_message_is_method_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>
on the reply object returned by <function>sd_bus_call()</function> or passed to the callback of
<function>sd_bus_call_async()</function>.</para>
<para>If <parameter>usec</parameter> is zero, the default D-Bus method call timeout is used. See
<citerefentry><refentrytitle>sd_bus_get_method_call_timeout</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</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>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>The input parameter <parameter>m</parameter> is <constant>NULL</constant>.
</para></listitem>
<listitem><para>The input parameter <parameter>m</parameter> is not a D-Bus method call.
To create a new D-Bus method call, use
<citerefentry><refentrytitle>sd_bus_message_new_method_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para></listitem>
<listitem><para>The input parameter <parameter>m</parameter> has the
<constant>BUS_MESSAGE_NO_REPLY_EXPECTED</constant> flag set.</para></listitem>
<listitem><para>The input parameter <parameter>error</parameter> is
non-<constant>NULL</constant> but was not set to <constant>SD_BUS_ERROR_NULL</constant>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The bus connection was allocated in a parent process and is being reused
in a child process after <function>fork()</function>.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOTCONN</constant></term>
<listitem><para>The input parameter <parameter>bus</parameter> is
<constant>NULL</constant> or the bus is not connected.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECONNRESET</constant></term>
<listitem><para>The bus connection was closed while waiting for the response.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ETIMEDOUT</constant></term>
<listitem><para>A response was not received within the given timeout.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ELOOP</constant></term>
<listitem><para>The message <parameter>m</parameter> is addressed to its own client.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</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>,
<citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_call_method_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_new_method_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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