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systemd-stable/man/sd_bus_message_get_cookie.xml
Zbigniew Jędrzejewski-Szmek 7d6b27238f man: xinclude the generic text to talk about libsystemd pkgconfig
The only difference is that functions are not individually listed by name,
but that seems completely pointless, since all functions that are documented
are always exported, so the generic text tells the user all she or he needs
to know.
2018-06-06 23:01:25 +02:00

128 lines
4.0 KiB
XML

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//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 2013 Lennart Poettering
-->
<refentry id="sd_bus_message_get_cookie"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_message_get_cookie</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_get_cookie</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_get_cookie</refname>
<refname>sd_bus_message_get_reply_cookie</refname>
<refpurpose>Returns the transaction cookie of a message</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_message_get_cookie</function></funcdef>
<paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
<paramdef>uint64_t *<parameter>cookie</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_message_get_reply_cookie</function></funcdef>
<paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
<paramdef>uint64_t *<parameter>cookie</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_message_get_cookie()</function> returns the
transaction cookie of a message. The cookie uniquely identifies a
message within each bus peer, but is not globally unique. It is
assigned when a message is sent.</para>
<para><function>sd_bus_message_get_reply_cookie()</function>
returns the transaction cookie of the message the specified
message is a response to. When a reply message is generated for a
method call message, its cookie is copied over into this field.
Note that while every message that is transferred is identified by
a cookie, only response messages carry a reply cookie
field.</para>
<para>Both functions take a message object as first parameter and
a place to store the 64-bit cookie in.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these calls return 0 or a positive integer. On
failure, these calls return a negative errno-style error
code.</para>
<para>On success, the cookie/reply cookie is returned in the
specified 64-bit unsigned integer variable.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>A specified parameter
is invalid.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENODATA</constant></term>
<listitem><para>No cookie has been assigned to this message.
This either indicates that the message has not been sent yet
and hence has no cookie assigned, or that the message is not a
method response message and hence carries a reply cookie
field.</para></listitem>
</varlistentry>
</variablelist>
</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_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>