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3802a3d3 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
effbc8e4 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
b975b0d5 | 8 | This file is part of systemd. |
effbc8e4 | 9 | |
b975b0d5 | 10 | Copyright 2014 Zbigniew Jędrzejewski-Szmek |
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11 | --> |
12 | ||
48f69d8f | 13 | <refentry id="sd_bus_message_append_basic"> |
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14 | |
15 | <refentryinfo> | |
16 | <title>sd_bus_message_append_basic</title> | |
17 | <productname>systemd</productname> | |
18 | ||
19 | <authorgroup> | |
20 | <author> | |
21 | <contrib>A monkey with a typewriter</contrib> | |
22 | <firstname>Zbigniew</firstname> | |
23 | <surname>Jędrzejewski-Szmek</surname> | |
24 | <email>zbyszek@in.waw.pl</email> | |
25 | </author> | |
26 | </authorgroup> | |
27 | </refentryinfo> | |
28 | ||
29 | <refmeta> | |
30 | <refentrytitle>sd_bus_message_append_basic</refentrytitle> | |
31 | <manvolnum>3</manvolnum> | |
32 | </refmeta> | |
33 | ||
34 | <refnamediv> | |
35 | <refname>sd_bus_message_append_basic</refname> | |
36 | ||
e8216945 | 37 | <refpurpose>Attach a single field to a message</refpurpose> |
effbc8e4 ZJS |
38 | </refnamediv> |
39 | ||
40 | <refsynopsisdiv> | |
41 | <funcsynopsis> | |
42 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
43 | ||
44 | <funcprototype> | |
45 | <funcdef>int sd_bus_message_append_basic</funcdef> | |
46 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
47 | <paramdef>char <parameter>type</parameter></paramdef> | |
e8216945 | 48 | <paramdef>const void *<parameter>p</parameter></paramdef> |
effbc8e4 ZJS |
49 | </funcprototype> |
50 | </funcsynopsis> | |
51 | </refsynopsisdiv> | |
52 | ||
53 | <refsect1> | |
54 | <title>Description</title> | |
55 | ||
e8216945 LP |
56 | <para><function>sd_bus_message_append_basic()</function> appends a |
57 | single field to the message <parameter>m</parameter>. The | |
58 | parameter <parameter>type</parameter> determines how the pointer | |
effbc8e4 | 59 | <parameter>p</parameter> is interpreted. |
e8216945 LP |
60 | <parameter>type</parameter> must be one of the basic types as |
61 | defined by the <ulink | |
62 | url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic | |
63 | Types</ulink> section of the D-Bus specification, and listed in | |
64 | the table below. | |
effbc8e4 ZJS |
65 | </para> |
66 | ||
67 | <table id='format-specifiers'> | |
e8216945 | 68 | <title>Item type specifiers</title> |
effbc8e4 | 69 | |
e8216945 | 70 | <tgroup cols='5'> |
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71 | <colspec colname='specifier' /> |
72 | <colspec colname='constant' /> | |
73 | <colspec colname='description' /> | |
74 | <colspec colname='size' /> | |
e8216945 | 75 | <colspec colname='ctype' /> |
effbc8e4 ZJS |
76 | <thead> |
77 | <row> | |
78 | <entry>Specifier</entry> | |
79 | <entry>Constant</entry> | |
80 | <entry>Description</entry> | |
81 | <entry>Size</entry> | |
e8216945 | 82 | <entry>Expected C Type</entry> |
effbc8e4 ZJS |
83 | </row> |
84 | </thead> | |
85 | <tbody> | |
86 | <row> | |
87 | <entry><literal>y</literal></entry> | |
88 | <entry><constant>SD_BUS_TYPE_BYTE</constant></entry> | |
06b643e7 | 89 | <entry>unsigned integer</entry> |
effbc8e4 | 90 | <entry>1 byte</entry> |
e8216945 | 91 | <entry>uint8_t</entry> |
effbc8e4 ZJS |
92 | </row> |
93 | ||
94 | <row> | |
95 | <entry><literal>b</literal></entry> | |
96 | <entry><constant>SD_BUS_TYPE_BOOLEAN</constant></entry> | |
97 | <entry>boolean</entry> | |
98 | <entry>4 bytes</entry> | |
e8216945 | 99 | <entry>int</entry> |
effbc8e4 ZJS |
100 | </row> |
101 | ||
102 | <row> | |
103 | <entry><literal>n</literal></entry> | |
104 | <entry><constant>SD_BUS_TYPE_INT16</constant></entry> | |
105 | <entry>signed integer</entry> | |
106 | <entry>2 bytes</entry> | |
e8216945 | 107 | <entry>int16_t</entry> |
effbc8e4 ZJS |
108 | </row> |
109 | ||
110 | <row> | |
111 | <entry><literal>q</literal></entry> | |
112 | <entry><constant>SD_BUS_TYPE_UINT16</constant></entry> | |
113 | <entry>unsigned integer</entry> | |
114 | <entry>2 bytes</entry> | |
e8216945 | 115 | <entry>uint16_t</entry> |
effbc8e4 ZJS |
116 | </row> |
117 | ||
118 | <row> | |
119 | <entry><literal>i</literal></entry> | |
120 | <entry><constant>SD_BUS_TYPE_INT32</constant></entry> | |
121 | <entry>signed integer</entry> | |
122 | <entry>4 bytes</entry> | |
e8216945 | 123 | <entry>int32_t</entry> |
effbc8e4 ZJS |
124 | </row> |
125 | ||
126 | <row> | |
127 | <entry><literal>u</literal></entry> | |
128 | <entry><constant>SD_BUS_TYPE_UINT32</constant></entry> | |
129 | <entry>unsigned integer</entry> | |
130 | <entry>4 bytes</entry> | |
e8216945 | 131 | <entry>uint32_t</entry> |
effbc8e4 ZJS |
132 | </row> |
133 | ||
134 | <row> | |
135 | <entry><literal>x</literal></entry> | |
136 | <entry><constant>SD_BUS_TYPE_INT64</constant></entry> | |
137 | <entry>signed integer</entry> | |
138 | <entry>8 bytes</entry> | |
e8216945 | 139 | <entry>int64_t</entry> |
effbc8e4 ZJS |
140 | </row> |
141 | ||
142 | <row> | |
143 | <entry><literal>t</literal></entry> | |
144 | <entry><constant>SD_BUS_TYPE_UINT64</constant></entry> | |
145 | <entry>unsigned integer</entry> | |
146 | <entry>8 bytes</entry> | |
e8216945 | 147 | <entry>uint64_t</entry> |
effbc8e4 ZJS |
148 | </row> |
149 | ||
150 | <row> | |
151 | <entry><literal>d</literal></entry> | |
152 | <entry><constant>SD_BUS_TYPE_DOUBLE</constant></entry> | |
153 | <entry>floating-point</entry> | |
154 | <entry>8 bytes</entry> | |
e8216945 | 155 | <entry>double</entry> |
effbc8e4 ZJS |
156 | </row> |
157 | ||
158 | <row> | |
159 | <entry><literal>s</literal></entry> | |
160 | <entry><constant>SD_BUS_TYPE_STRING</constant></entry> | |
161 | <entry>Unicode string</entry> | |
162 | <entry>variable</entry> | |
e8216945 | 163 | <entry>char[]</entry> |
effbc8e4 ZJS |
164 | </row> |
165 | ||
166 | <row> | |
167 | <entry><literal>o</literal></entry> | |
168 | <entry><constant>SD_BUS_TYPE_OBJECT_PATH</constant></entry> | |
169 | <entry>object path</entry> | |
170 | <entry>variable</entry> | |
e8216945 | 171 | <entry>char[]</entry> |
effbc8e4 ZJS |
172 | </row> |
173 | ||
174 | <row> | |
175 | <entry><literal>g</literal></entry> | |
176 | <entry><constant>SD_BUS_TYPE_SIGNATURE</constant></entry> | |
177 | <entry>signature</entry> | |
178 | <entry>variable</entry> | |
e8216945 | 179 | <entry>char[]</entry> |
effbc8e4 ZJS |
180 | </row> |
181 | ||
182 | <row> | |
183 | <entry><literal>h</literal></entry> | |
184 | <entry><constant>SD_BUS_TYPE_UNIX_FD</constant></entry> | |
185 | <entry>UNIX file descriptor</entry> | |
186 | <entry>4 bytes</entry> | |
e8216945 | 187 | <entry>int</entry> |
effbc8e4 ZJS |
188 | </row> |
189 | </tbody> | |
190 | </tgroup> | |
191 | </table> | |
192 | ||
e8216945 LP |
193 | <para>The value of the parameter is copied into a memory area held |
194 | by the message object, stays in the possession of the caller and | |
195 | may hence be freely changed after this call without affecting the | |
196 | bus message it has been added to. If <parameter>type</parameter> | |
197 | is <literal>h</literal> (UNIX file descriptor), the descriptor is | |
198 | duplicated by this call and the passed descriptor stays in | |
199 | possession of the caller.</para> | |
effbc8e4 ZJS |
200 | |
201 | <para>For types <literal>s</literal>, <literal>o</literal>, and | |
202 | <literal>g</literal>, the parameter <parameter>p</parameter> is | |
203 | interpreted as a pointer to a <constant>NUL</constant>-terminated | |
204 | character sequence. As a special case, a <constant>NULL</constant> | |
205 | pointer is interpreted as an empty string. The string should be | |
206 | valid Unicode string encoded as UTF-8. In case of the two latter | |
b8bde116 | 207 | types, the additional requirements for a D-Bus object path or |
effbc8e4 | 208 | type signature should be satisfied. Those requirements should be |
06b643e7 | 209 | verified by the recipient of the message. |
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210 | </para> |
211 | </refsect1> | |
212 | ||
213 | <refsect1> | |
214 | <title>Return Value</title> | |
215 | ||
216 | <para>On success, this call returns 0 or a positive integer. On | |
217 | failure, it returns a negative errno-style error code.</para> | |
218 | </refsect1> | |
219 | ||
220 | <refsect1 id='errors'> | |
221 | <title>Errors</title> | |
222 | ||
223 | <para>Returned errors may indicate the following problems:</para> | |
224 | ||
225 | <variablelist> | |
226 | ||
227 | <varlistentry> | |
8474b70c | 228 | <term><constant>-EINVAL</constant></term> |
effbc8e4 ZJS |
229 | |
230 | <listitem><para>Specified parameter is invalid. | |
231 | </para></listitem> | |
232 | </varlistentry> | |
233 | ||
234 | <varlistentry> | |
8474b70c | 235 | <term><constant>-EPERM</constant></term> |
effbc8e4 ZJS |
236 | |
237 | <listitem><para>Message has been sealed. | |
238 | </para></listitem> | |
239 | </varlistentry> | |
240 | ||
241 | <varlistentry> | |
8474b70c | 242 | <term><constant>-ESTALE</constant></term> |
effbc8e4 ZJS |
243 | |
244 | <listitem><para>Message is in invalid state. | |
245 | </para></listitem> | |
246 | </varlistentry> | |
247 | ||
248 | <varlistentry> | |
8474b70c | 249 | <term><constant>-ENXIO</constant></term> |
effbc8e4 ZJS |
250 | |
251 | <listitem><para>Message cannot be appended to. | |
252 | </para></listitem> | |
253 | </varlistentry> | |
254 | ||
255 | <varlistentry> | |
8474b70c | 256 | <term><constant>-ENOMEM</constant></term> |
effbc8e4 ZJS |
257 | |
258 | <listitem><para>Memory allocation failed.</para></listitem> | |
259 | </varlistentry> | |
260 | </variablelist> | |
261 | </refsect1> | |
262 | ||
263 | <refsect1> | |
264 | <title>Notes</title> | |
265 | ||
b8bde116 | 266 | <para>The <function>sd_bus_append_basic()</function> function |
effbc8e4 ZJS |
267 | described here is available as a shared library, which can be |
268 | compiled and linked to with the | |
5aded369 | 269 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
effbc8e4 ZJS |
270 | file.</para> |
271 | </refsect1> | |
272 | ||
273 | <refsect1> | |
274 | <title>See Also</title> | |
275 | ||
276 | <para> | |
277 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
278 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
279 | <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
280 | <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink> | |
281 | </para> | |
282 | </refsect1> | |
283 | ||
284 | </refentry> |