mirror of
https://github.com/systemd/systemd.git
synced 2024-11-23 18:23:32 +08:00
179 lines
7.4 KiB
XML
179 lines
7.4 KiB
XML
<?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_message_new_method_call"
|
|
xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_bus_message_new_method_call</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_bus_message_new_method_call</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_bus_message_new_method_call</refname>
|
|
<refname>sd_bus_message_new_method_return</refname>
|
|
|
|
<refpurpose>Create a method call message</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_bus_message_new_method_call</function></funcdef>
|
|
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
|
|
<paramdef>sd_bus_message **<parameter>m</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>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_bus_message_new_method_return</function></funcdef>
|
|
<paramdef>sd_bus_message *<parameter>call</parameter></paramdef>
|
|
<paramdef>sd_bus_message **<parameter>m</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para>The <function>sd_bus_message_new_method_call()</function> function creates a new bus
|
|
message object that encapsulates a D-Bus method call, and returns it in the
|
|
<parameter>m</parameter> output parameter. The call will be made on the destination
|
|
<parameter>destination</parameter>, path <parameter>path</parameter>, on the interface
|
|
<parameter>interface</parameter>, member <parameter>member</parameter>.</para>
|
|
|
|
<para>Briefly, the <emphasis>destination</emphasis> is a dot-separated name that identifies a
|
|
service connected to the bus. The <emphasis>path</emphasis> is a slash-separated identifier of
|
|
an object within the destination that resembles a file system path. The meaning of this path is
|
|
defined by the destination. The <emphasis>interface</emphasis> is a dot-separated name that
|
|
resembles a Java interface name that identifies a group of methods and signals supported by the
|
|
object identified by path. Methods and signals are collectively called
|
|
<emphasis>members</emphasis> and are identified by a simple name composed of ASCII letters,
|
|
numbers, and underscores. See the <ulink
|
|
url="https://dbus.freedesktop.org/doc/dbus-tutorial.html#concepts">D-Bus Tutorial</ulink> for an
|
|
in-depth explanation.</para>
|
|
|
|
<para>The <parameter>destination</parameter> parameter may be <constant>NULL</constant>. The
|
|
<parameter>interface</parameter> parameter may be <constant>NULL</constant>, if the destination
|
|
has only a single member with the given name and there is no ambiguity if the interface name is
|
|
omitted.</para>
|
|
|
|
<para>Note that this is a low level interface. See
|
|
<citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
for a more convenient way of calling D-Bus methods.</para>
|
|
|
|
<para>The <function>sd_bus_message_new_method_return()</function> function creates a new bus
|
|
message object that is a reply to the method call <parameter>call</parameter> and returns it in
|
|
the <parameter>m</parameter> output parameter. The <parameter>call</parameter> parameter must be
|
|
a method call message. The sender of <parameter>call</parameter> is used as the destination.
|
|
</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 output parameter <parameter>m</parameter> is
|
|
<constant>NULL</constant>.</para>
|
|
|
|
<para>The <parameter>destination</parameter> parameter is non-null and is not a valid D-Bus
|
|
service name (<literal>org.somewhere.Something</literal>), the <parameter>path</parameter>
|
|
parameter is not a valid D-Bus path (<literal>/an/object/path</literal>), the
|
|
<parameter>interface</parameter> parameter is non-null and is not a valid D-Bus interface
|
|
name (<literal>an.interface.name</literal>), or the <parameter>member</parameter> parameter
|
|
is not a valid D-Bus member (<literal>Name</literal>).</para>
|
|
|
|
<para>The <parameter>call</parameter> parameter is not a method call object.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ENOTCONN</constant></term>
|
|
|
|
<listitem><para>The bus parameter <parameter>bus</parameter> is <constant>NULL</constant> or
|
|
the bus is not connected.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ENOMEM</constant></term>
|
|
|
|
<listitem><para>Memory allocation failed.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EPERM</constant></term>
|
|
|
|
<listitem>
|
|
<para>The <parameter>call</parameter> parameter is not sealed.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EOPNOTSUPP</constant></term>
|
|
|
|
<listitem>
|
|
<para>The <parameter>call</parameter> message does not have a cookie.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<example>
|
|
<title>Make a call to a D-Bus method that takes a single parameter</title>
|
|
|
|
<programlisting><xi:include href="print-unit-path.c" parse="text" /></programlisting>
|
|
<para>This defines a minimally useful program that will open a connection to the bus, create a
|
|
message object, send it, wait for the reply, and finally extract and print the answer. It does
|
|
error handling and proper memory management.</para>
|
|
</example>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><function>sd_bus_message_new_method_call()</function> and
|
|
<function>sd_bus_message_new_method_return()</function> were added in version 246.</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_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_bus_path_encode</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|