mirror of
https://github.com/systemd/systemd.git
synced 2024-11-23 10:13:34 +08:00
151 lines
6.7 KiB
XML
151 lines
6.7 KiB
XML
<?xml version='1.0'?>
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
|
|
|
|
<!--
|
|
SPDX-License-Identifier: LGPL-2.1-or-later
|
|
|
|
Copyright © 2016 Julian Orth
|
|
-->
|
|
|
|
<refentry id="sd_bus_process" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_bus_process</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_bus_process</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_bus_process</refname>
|
|
|
|
<refpurpose>Drive the connection</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_bus_process</function></funcdef>
|
|
<paramdef>sd_bus *<parameter>bus</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 client and the message bus.
|
|
That is, it handles connecting, authentication, and processing of messages. 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 poll for I/O events before calling into
|
|
<function>sd_bus_process()</function> again. For that either use the simple, blocking
|
|
<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><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 <constant>NULL</constant> and
|
|
progress was made, but no message was processed, <parameter>*ret</parameter> is set to
|
|
<constant>NULL</constant>. Note that only messages not already handled by the various types of registered
|
|
message handlers (i.e. by filters registered via
|
|
<citerefentry><refentrytitle>sd_bus_add_filter</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
object handlers registered via
|
|
<citerefentry><refentrytitle>sd_bus_add_object</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
matches registered via
|
|
<citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
and related) will be returned through this parameter. Also note that if such a message handler returns a
|
|
zero return value (as opposed to some value > 0) an incoming message will not be considered handled,
|
|
and be passed to other suitable handlers (until one returns > > 0), or returned by
|
|
<function>sd_bus_process()</function> (in case none returns > 0).</para>
|
|
|
|
<para>If 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 <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>History</title>
|
|
<para><function>sd_bus_process()</function> was added in version 221.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<para><simplelist type="inline">
|
|
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_bus_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|