1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
|
<?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">
<!--
SPDX-License-Identifier: LGPL-2.1+
This file is part of systemd.
Copyright 2014 Zbigniew Jędrzejewski-Szmek
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/>.
-->
<refentry id="sd_bus_message_append_basic">
<refentryinfo>
<title>sd_bus_message_append_basic</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>A monkey with a typewriter</contrib>
<firstname>Zbigniew</firstname>
<surname>Jędrzejewski-Szmek</surname>
<email>zbyszek@in.waw.pl</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_append_basic</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_append_basic</refname>
<refpurpose>Attach a single field to a message</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int sd_bus_message_append_basic</funcdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char <parameter>type</parameter></paramdef>
<paramdef>const void *<parameter>p</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_message_append_basic()</function> appends a
single field to the message <parameter>m</parameter>. The
parameter <parameter>type</parameter> determines how the pointer
<parameter>p</parameter> is interpreted.
<parameter>type</parameter> must be one of the basic types as
defined by the <ulink
url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
Types</ulink> section of the D-Bus specification, and listed in
the table below.
</para>
<table id='format-specifiers'>
<title>Item type specifiers</title>
<tgroup cols='5'>
<colspec colname='specifier' />
<colspec colname='constant' />
<colspec colname='description' />
<colspec colname='size' />
<colspec colname='ctype' />
<thead>
<row>
<entry>Specifier</entry>
<entry>Constant</entry>
<entry>Description</entry>
<entry>Size</entry>
<entry>Expected C Type</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>y</literal></entry>
<entry><constant>SD_BUS_TYPE_BYTE</constant></entry>
<entry>unsigned integer</entry>
<entry>1 byte</entry>
<entry>uint8_t</entry>
</row>
<row>
<entry><literal>b</literal></entry>
<entry><constant>SD_BUS_TYPE_BOOLEAN</constant></entry>
<entry>boolean</entry>
<entry>4 bytes</entry>
<entry>int</entry>
</row>
<row>
<entry><literal>n</literal></entry>
<entry><constant>SD_BUS_TYPE_INT16</constant></entry>
<entry>signed integer</entry>
<entry>2 bytes</entry>
<entry>int16_t</entry>
</row>
<row>
<entry><literal>q</literal></entry>
<entry><constant>SD_BUS_TYPE_UINT16</constant></entry>
<entry>unsigned integer</entry>
<entry>2 bytes</entry>
<entry>uint16_t</entry>
</row>
<row>
<entry><literal>i</literal></entry>
<entry><constant>SD_BUS_TYPE_INT32</constant></entry>
<entry>signed integer</entry>
<entry>4 bytes</entry>
<entry>int32_t</entry>
</row>
<row>
<entry><literal>u</literal></entry>
<entry><constant>SD_BUS_TYPE_UINT32</constant></entry>
<entry>unsigned integer</entry>
<entry>4 bytes</entry>
<entry>uint32_t</entry>
</row>
<row>
<entry><literal>x</literal></entry>
<entry><constant>SD_BUS_TYPE_INT64</constant></entry>
<entry>signed integer</entry>
<entry>8 bytes</entry>
<entry>int64_t</entry>
</row>
<row>
<entry><literal>t</literal></entry>
<entry><constant>SD_BUS_TYPE_UINT64</constant></entry>
<entry>unsigned integer</entry>
<entry>8 bytes</entry>
<entry>uint64_t</entry>
</row>
<row>
<entry><literal>d</literal></entry>
<entry><constant>SD_BUS_TYPE_DOUBLE</constant></entry>
<entry>floating-point</entry>
<entry>8 bytes</entry>
<entry>double</entry>
</row>
<row>
<entry><literal>s</literal></entry>
<entry><constant>SD_BUS_TYPE_STRING</constant></entry>
<entry>Unicode string</entry>
<entry>variable</entry>
<entry>char[]</entry>
</row>
<row>
<entry><literal>o</literal></entry>
<entry><constant>SD_BUS_TYPE_OBJECT_PATH</constant></entry>
<entry>object path</entry>
<entry>variable</entry>
<entry>char[]</entry>
</row>
<row>
<entry><literal>g</literal></entry>
<entry><constant>SD_BUS_TYPE_SIGNATURE</constant></entry>
<entry>signature</entry>
<entry>variable</entry>
<entry>char[]</entry>
</row>
<row>
<entry><literal>h</literal></entry>
<entry><constant>SD_BUS_TYPE_UNIX_FD</constant></entry>
<entry>UNIX file descriptor</entry>
<entry>4 bytes</entry>
<entry>int</entry>
</row>
</tbody>
</tgroup>
</table>
<para>The value of the parameter is copied into a memory area held
by the message object, stays in the possession of the caller and
may hence be freely changed after this call without affecting the
bus message it has been added to. If <parameter>type</parameter>
is <literal>h</literal> (UNIX file descriptor), the descriptor is
duplicated by this call and the passed descriptor stays in
possession of the caller.</para>
<para>For types <literal>s</literal>, <literal>o</literal>, and
<literal>g</literal>, the parameter <parameter>p</parameter> is
interpreted as a pointer to a <constant>NUL</constant>-terminated
character sequence. As a special case, a <constant>NULL</constant>
pointer is interpreted as an empty string. The string should be
valid Unicode string encoded as UTF-8. In case of the two latter
types, the additional requirements for a D-Bus object path or
type signature should be satisfied. Those requirements should be
verified by the recipient of the message.
</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, this call returns 0 or a positive integer. On
failure, it returns a negative errno-style error code.</para>
</refsect1>
<refsect1 id='errors'>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>Specified parameter is invalid.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EPERM</constant></term>
<listitem><para>Message has been sealed.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ESTALE</constant></term>
<listitem><para>Message is in invalid state.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENXIO</constant></term>
<listitem><para>Message cannot be appended to.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_bus_append_basic()</function> function
described here is available as a shared library, which can be
compiled and linked to with the
<constant>libelogind</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<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_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink>
</para>
</refsect1>
</refentry>
|
