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121 lines
4.1 KiB
XML
121 lines
4.1 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="sd_bus_message_new_signal"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_bus_message_new_signal</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_message_new_signal</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_message_new_signal</refname>
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<refpurpose>Create a signal message</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int sd_bus_message_new_signal</funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>sd_bus_message **<parameter>m</parameter></paramdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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<paramdef>const char *<parameter>interface</parameter></paramdef>
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<paramdef>const char *<parameter>member</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>The <function>sd_bus_message_new_signal()</function> function creates a new bus message
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object that encapsulates a D-Bus signal, and returns it in the <parameter>m</parameter> output
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parameter. The signal will be sent to path <parameter>path</parameter>, on the interface
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<parameter>interface</parameter>, member <parameter>member</parameter>. When this message is
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sent, no reply is expected. See
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<citerefentry><refentrytitle>sd_bus_message_new_call</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for a short description of the meaning of the <parameter>path</parameter>,
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<parameter>interface</parameter>, and <parameter>member</parameter> parameters.
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</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>This function returns 0 if the message object was successfully created, and a negative
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errno-style error code otherwise.</para>
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</refsect1>
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<refsect1 id='errors'>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>The output parameter <parameter>m</parameter> is
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<constant>NULL</constant>.</para>
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<para>The <parameter>path</parameter> parameter is not a valid D-Bus path
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(<literal>/an/object/path</literal>), the <parameter>interface</parameter> parameter is not
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a valid D-Bus interface name (<literal>an.interface.name</literal>), or the
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<parameter>member</parameter> parameter is not a valid D-Bus member
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(<literal>Name</literal>).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOTCONN</constant></term>
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<listitem><para>The bus parameter <parameter>bus</parameter> is <constant>NULL</constant> or
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the bus is not connected.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>Examples</title>
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<example>
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<title>Send a simple signal</title>
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<programlisting><xi:include href="send-unit-files-changed.c" parse="text" /></programlisting>
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<para>This function in systemd sources is used to emit the
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<literal>UnitFilesChanged</literal> signal when the unit files have been changed.
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</para>
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</example>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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