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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
798d3a52 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2013 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU Lesser General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
7c071fda | 24 | <refentry id="sd_bus_message_get_cookie" conditional="ENABLE_KDBUS"> |
99e0f83e | 25 | |
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26 | <refentryinfo> |
27 | <title>sd_bus_message_get_cookie</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_bus_message_get_cookie</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_bus_message_get_cookie</refname> | |
47 | <refname>sd_bus_message_get_reply_cookie</refname> | |
48 | <refpurpose>Returns the transaction cookie of a message</refpurpose> | |
49 | </refnamediv> | |
50 | ||
51 | <refsynopsisdiv> | |
52 | <funcsynopsis> | |
53 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
54 | ||
55 | <funcprototype> | |
56 | <funcdef>int <function>sd_bus_message_get_cookie</function></funcdef> | |
57 | <paramdef>sd_bus_message *<parameter>message</parameter></paramdef> | |
58 | <paramdef>uint64_t *<parameter>cookie</parameter></paramdef> | |
59 | </funcprototype> | |
60 | ||
61 | <funcprototype> | |
62 | <funcdef>int <function>sd_bus_message_get_reply_cookie</function></funcdef> | |
63 | <paramdef>sd_bus_message *<parameter>message</parameter></paramdef> | |
64 | <paramdef>uint64_t *<parameter>cookie</parameter></paramdef> | |
65 | </funcprototype> | |
66 | </funcsynopsis> | |
67 | </refsynopsisdiv> | |
68 | ||
69 | <refsect1> | |
70 | <title>Description</title> | |
71 | ||
72 | <para><function>sd_bus_message_get_cookie()</function> returns the | |
73 | transaction cookie of a message. The cookie uniquely identifies a | |
74 | message within each bus peer, but is not globally unique. It is | |
75 | assigned when a message is sent.</para> | |
76 | ||
77 | <para><function>sd_bus_message_get_reply_cookie()</function> | |
78 | returns the transaction cookie of the message the specified | |
79 | message is a response to. When a reply message is generated for a | |
80 | method call message, its cookie is copied over into this field. | |
81 | Note that while every message that is transferred is identified by | |
82 | a cookie, only response messages carry a reply cookie | |
83 | field.</para> | |
84 | ||
85 | <para>Both functions take a message object as first parameter and | |
86 | a place to store the 64-bit cookie in.</para> | |
87 | </refsect1> | |
88 | ||
89 | <refsect1> | |
90 | <title>Return Value</title> | |
91 | ||
92 | <para>On success, these calls return 0 or a positive integer. On | |
93 | failure, these calls return a negative errno-style error | |
94 | code.</para> | |
95 | ||
96 | <para>On success, the cookie/reply cookie is returned in the | |
97 | specified 64-bit unsigned integer variable.</para> | |
98 | </refsect1> | |
99 | ||
100 | <refsect1> | |
101 | <title>Errors</title> | |
102 | ||
103 | <para>Returned errors may indicate the following problems:</para> | |
104 | ||
105 | <variablelist> | |
106 | <varlistentry> | |
107 | <term><constant>-EINVAL</constant></term> | |
108 | ||
109 | <listitem><para>A specified parameter | |
110 | is invalid.</para></listitem> | |
111 | </varlistentry> | |
112 | ||
113 | <varlistentry> | |
114 | <term><constant>-ENODATA</constant></term> | |
115 | ||
116 | <listitem><para>No cookie has been assigned to this message. | |
117 | This either indicates that the message has not been sent yet | |
118 | and hence has no cookie assigned, or that the message is not a | |
119 | method response message and hence carries a reply cookie | |
120 | field.</para></listitem> | |
121 | </varlistentry> | |
122 | </variablelist> | |
123 | </refsect1> | |
124 | ||
125 | <refsect1> | |
126 | <title>Notes</title> | |
127 | ||
128 | <para>The <function>sd_bus_message_get_cookie()</function> and | |
129 | <function>sd_bus_message_get_reply_cookie()</function> interfaces | |
130 | are available as a shared library, which can be compiled and | |
131 | linked to with the | |
132 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
133 | file.</para> | |
134 | </refsect1> | |
135 | ||
136 | <refsect1> | |
137 | <title>See Also</title> | |
138 | ||
139 | <para> | |
140 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
141 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
142 | <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
143 | </para> | |
144 | </refsect1> | |
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145 | |
146 | </refentry> |