-<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<?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+
- This file is part of systemd.
-
- Copyright 2016 Julian Orth
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
+ Copyright © 2016 Julian Orth
-->
-<refentry id="sd_bus_process">
+<refentry id="sd_bus_process" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_process</title>
<productname>systemd</productname>
-
- <authorgroup>
- <author>
- <firstname>Julian</firstname>
- <surname>Orth</surname>
- <email>ju.orth@gmail.com</email>
- </author>
- </authorgroup>
</refentryinfo>
<refmeta>
<funcprototype>
<funcdef>int <function>sd_bus_process</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
- <paramdef>sd_bus_message **<parameter>r</parameter></paramdef>
+ <paramdef>sd_bus_message **<parameter>ret</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
- <para>
- <function>sd_bus_process()</function> drives the connection between the
- message bus and the client. That is, it handles connecting,
- authentication, and message processing. It should be called in a loop
- until no further progress can be made or an error occurs.
+ <para><function>sd_bus_process()</function> drives the connection between the client and the message bus. That is,
+ it handles connecting, authentication, and message processing. When invoked pending I/O work is executed, and
+ queued incoming messages are dispatched to registered callbacks. Each time it is invoked a single operation is
+ executed. It returns zero when no operations were pending and positive if a message was processed. When zero is
+ returned the caller should synchronously poll for I/O events before calling into
+ <function>sd_bus_process()</function> again. For that either user the simple, synchronous
+ <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> call, or hook up
+ the bus connection object to an external or manual event loop using
+ <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
- <para>
- Once no further progress can be made,
- <citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- should be called. Alternatively the user can wait for incoming data on
- the file descriptor returned by
- <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- </para>
-
- <para>
- <function>sd_bus_process</function> processes at most one incoming
- message per call. If the parameter <parameter>r</parameter> is not NULL
- and the call processed a message, <code>*r</code> is set to this message.
- The caller owns a reference to this message and should call
- <citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- when the message is no longer needed. If <parameter>r</parameter> is not
- NULL, progress was made, but no message was processed, <code>*r</code> is
- set to NULL.
- </para>
+ <para><function>sd_bus_process()</function> processes at most one incoming message per call. If the parameter
+ <parameter>ret</parameter> is not <constant>NULL</constant> and the call processed a message,
+ <parameter>*ret</parameter> is set to this message. The caller owns a reference to this message and should call
+ <citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> when the
+ message is no longer needed. If <parameter>ret</parameter> is not NULL, progress was made, but no message was
+ processed, <parameter>*ret</parameter> is set to <constant>NULL</constant>.</para>
+
+ <para>If a the bus object is connected to an
+ <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> event loop (with
+ <citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it is not
+ necessary to call <function>sd_bus_process()</function> directly as it is invoked automatically when
+ necessary.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
- <para>
- If progress was made, a positive integer is returned. If no progress was
- made, 0 is returned. If an error occurs, a negative errno-style error code
- is returned.
- </para>
+ <para>If progress was made, a positive integer is returned. If no progress was made, 0 is returned. If an
+ error occurs, a negative <varname>errno</varname>-style error code is returned.</para>
+
+ <refsect2>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><constant>-EINVAL</constant></term>
+
+ <listitem><para>An invalid bus object was passed.</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 bus connection has been terminated already.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>-ECONNRESET</constant></term>
+
+ <listitem><para>The bus connection has been terminated just now.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>-EBUSY</constant></term>
+
+ <listitem><para>This function is already being called, i.e. <function>sd_bus_process()</function>
+ has been called from a callback function that itself was called by
+ <function>sd_bus_process()</function>.</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_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
projects / thirdparty / systemd.git / blobdiff