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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"> |
effbc8e4 ZJS |
4 | |
5 | <!-- | |
572eb058 ZJS |
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 |
effbc8e4 | 11 | |
b975b0d5 ZJS |
12 | systemd is free software; you can redistribute it and/or modify it |
13 | under the terms of the GNU Lesser General Public License as published by | |
14 | the Free Software Foundation; either version 2.1 of the License, or | |
15 | (at your option) any later version. | |
effbc8e4 | 16 | |
b975b0d5 ZJS |
17 | systemd is distributed in the hope that it will be useful, but |
18 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | Lesser General Public License for more details. | |
effbc8e4 | 21 | |
b975b0d5 ZJS |
22 | You should have received a copy of the GNU Lesser General Public License |
23 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
effbc8e4 ZJS |
24 | --> |
25 | ||
48f69d8f | 26 | <refentry id="sd_bus_message_append" |
effbc8e4 ZJS |
27 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
28 | ||
29 | <refentryinfo> | |
30 | <title>sd_bus_message_append</title> | |
31 | <productname>systemd</productname> | |
32 | ||
33 | <authorgroup> | |
34 | <author> | |
35 | <contrib>A monkey with a typewriter</contrib> | |
36 | <firstname>Zbigniew</firstname> | |
37 | <surname>Jędrzejewski-Szmek</surname> | |
38 | <email>zbyszek@in.waw.pl</email> | |
39 | </author> | |
40 | </authorgroup> | |
41 | </refentryinfo> | |
42 | ||
43 | <refmeta> | |
44 | <refentrytitle>sd_bus_message_append</refentrytitle> | |
45 | <manvolnum>3</manvolnum> | |
46 | </refmeta> | |
47 | ||
48 | <refnamediv> | |
49 | <refname>sd_bus_message_append</refname> | |
19fe49f6 | 50 | <refname>sd_bus_message_appendv</refname> |
effbc8e4 | 51 | |
e8216945 LP |
52 | <refpurpose>Attach fields to a D-Bus message based on a type |
53 | string</refpurpose> | |
effbc8e4 ZJS |
54 | </refnamediv> |
55 | ||
56 | <refsynopsisdiv> | |
57 | <funcsynopsis> | |
58 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
59 | ||
60 | <funcprototype> | |
61 | <funcdef>int sd_bus_message_append</funcdef> | |
62 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
63 | <paramdef>const char *<parameter>types</parameter></paramdef> | |
1eecafb8 | 64 | <paramdef>…</paramdef> |
effbc8e4 | 65 | </funcprototype> |
19fe49f6 FDP |
66 | |
67 | <funcprototype> | |
68 | <funcdef>int sd_bus_message_appendv</funcdef> | |
69 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
70 | <paramdef>const char *<parameter>types</parameter></paramdef> | |
71 | <paramdef>va_list <parameter>ap</parameter></paramdef> | |
72 | </funcprototype> | |
73 | ||
effbc8e4 ZJS |
74 | </funcsynopsis> |
75 | </refsynopsisdiv> | |
76 | ||
77 | <refsect1> | |
78 | <title>Description</title> | |
79 | ||
e8216945 LP |
80 | <para>The <function>sd_bus_message_append()</function> function |
81 | appends a sequence of fields to the D-Bus message object | |
82 | <parameter>m</parameter>. The type string | |
83 | <parameter>types</parameter> describes the types of the field | |
b938cb90 | 84 | arguments that follow. For each type specified in the type string, |
e8216945 LP |
85 | one or more arguments need to be specified, in the same order as |
86 | declared in the type string.</para> | |
effbc8e4 | 87 | |
e8216945 | 88 | <para>The type string is composed of the elements shown in the |
effbc8e4 ZJS |
89 | table below. It contains zero or more single "complete types". |
90 | Each complete type may be one of the basic types or a fully | |
e8216945 LP |
91 | described container type. A container type may be a structure with |
92 | the contained types, a variant, an array with its element type, or | |
93 | a dictionary entry with the contained types. The type string is | |
effbc8e4 ZJS |
94 | <constant>NUL</constant>-terminated.</para> |
95 | ||
96 | <para>In case of a basic type, one argument of the corresponding | |
97 | type is expected.</para> | |
98 | ||
99 | <para>A structure is denoted by a sequence of complete types | |
100 | between <literal>(</literal> and <literal>)</literal>. This | |
101 | sequence cannot be empty — it must contain at least one type. | |
102 | Arguments corresponding to this nested sequence follow the same | |
103 | rules as if they were not nested.</para> | |
104 | ||
ff9b60f3 | 105 | <para>A variant is denoted by <literal>v</literal>. Corresponding |
e8216945 | 106 | arguments must begin with a type string denoting a complete type, |
effbc8e4 ZJS |
107 | and following that, arguments corresponding to the specified type. |
108 | </para> | |
109 | ||
110 | <para>An array is denoted by <literal>a</literal> followed by a | |
e8216945 LP |
111 | complete type. Corresponding arguments must begin with the number of |
112 | entries in the array, followed by the entries themselves, | |
113 | matching the element type of the array.</para> | |
effbc8e4 ZJS |
114 | |
115 | <para>A dictionary is an array of dictionary entries, denoted by | |
116 | <literal>a</literal> followed by a pair of complete types between | |
117 | <literal>{</literal> and <literal>}</literal>. The first of those | |
e8216945 LP |
118 | types must be a basic type. Corresponding arguments must begin |
119 | with the number of dictionary entries, followed by a pair of | |
120 | values for each entry matching the element type of | |
121 | the dictionary entries.</para> | |
122 | ||
19fe49f6 FDP |
123 | <para>The <function>sd_bus_message_appendv()</function> is equivalent to |
124 | the function <function>sd_bus_message_append()</function>, | |
125 | except that it is called with a <literal>va_list</literal> instead of | |
126 | a variable number of arguments. This function does not call the | |
127 | <function>va_end()</function> macro. Because it invokes the | |
128 | <function>va_arg()</function> macro, the value of ap | |
129 | is undefined after the call.</para> | |
130 | ||
e8216945 LP |
131 | <para>For further details on the D-Bus type system, please consult |
132 | the <ulink | |
133 | url="http://dbus.freedesktop.org/doc/dbus-specification.html#type-system">D-Bus | |
134 | Specification</ulink>.</para> | |
effbc8e4 ZJS |
135 | |
136 | <table> | |
e8216945 | 137 | <title>Item type specifiers</title> |
effbc8e4 | 138 | |
e8216945 | 139 | <tgroup cols='5'> |
effbc8e4 ZJS |
140 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers'])//colspec" /> |
141 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//thead)" /> | |
142 | ||
143 | <tbody> | |
144 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//tbody/*)" /> | |
145 | ||
146 | <row> | |
147 | <entry><literal>a</literal></entry> | |
148 | <entry><constant>SD_BUS_TYPE_ARRAY</constant></entry> | |
149 | <entry>array</entry> | |
150 | <entry>determined by array type and size</entry> | |
e8216945 | 151 | <entry>int, followed by array contents</entry> |
effbc8e4 ZJS |
152 | </row> |
153 | ||
154 | <row> | |
155 | <entry><literal>v</literal></entry> | |
156 | <entry><constant>SD_BUS_TYPE_VARIANT</constant></entry> | |
157 | <entry>variant</entry> | |
158 | <entry>determined by the type argument</entry> | |
e8216945 | 159 | <entry>signature string, followed by variant contents</entry> |
effbc8e4 ZJS |
160 | </row> |
161 | ||
162 | <row> | |
163 | <entry><literal>(</literal></entry> | |
164 | <entry><constant>SD_BUS_TYPE_STRUCT_BEGIN</constant></entry> | |
165 | <entry>array start</entry> | |
166 | <entry morerows="1">determined by the nested types</entry> | |
e8216945 | 167 | <entry morerows="1">structure contents</entry> |
effbc8e4 ZJS |
168 | </row> |
169 | <row> | |
170 | <entry><literal>)</literal></entry> | |
171 | <entry><constant>SD_BUS_TYPE_STRUCT_END</constant></entry> | |
172 | <entry>array end</entry> | |
173 | </row> | |
174 | ||
175 | <row> | |
176 | <entry><literal>{</literal></entry> | |
177 | <entry><constant>SD_BUS_TYPE_DICT_ENTRY_BEGIN</constant></entry> | |
178 | <entry>dictionary entry start</entry> | |
179 | <entry morerows="1">determined by the nested types</entry> | |
e8216945 | 180 | <entry morerows="1">dictionary contents</entry> |
effbc8e4 ZJS |
181 | </row> |
182 | <row> | |
183 | <entry><literal>}</literal></entry> | |
184 | <entry><constant>SD_BUS_TYPE_DICT_ENTRY_END</constant></entry> | |
185 | <entry>dictionary entry end</entry> | |
186 | </row> | |
187 | </tbody> | |
188 | </tgroup> | |
189 | </table> | |
e8216945 | 190 | |
caf15ff0 ZJS |
191 | <para>For types "s" and "g" (unicode string or signature), the pointer may be |
192 | <constant>NULL</constant>, which is equivalent to an empty string. See | |
193 | <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
194 | for the precise interpretation of those and other types.</para> | |
195 | ||
effbc8e4 ZJS |
196 | </refsect1> |
197 | ||
198 | <refsect1> | |
e8216945 | 199 | <title>Types String Grammar</title> |
effbc8e4 ZJS |
200 | |
201 | <programlisting>types ::= complete_type* | |
202 | complete_type ::= basic_type | variant | structure | array | dictionary | |
203 | basic_type ::= "y" | "n" | "q" | "u" | "i" | "x" | "t" | "d" | | |
204 | "b" | "h" | | |
205 | "s" | "o" | "g" | |
206 | variant ::= "v" | |
207 | structure ::= "(" complete_type+ ")" | |
208 | array ::= "a" complete_type | |
209 | dictionary ::= "a" "{" basic_type complete_type "}" | |
210 | </programlisting> | |
211 | </refsect1> | |
212 | ||
213 | <refsect1> | |
214 | <title>Examples</title> | |
215 | ||
216 | <para>Append a single basic type (the string <literal>a string</literal>): | |
217 | </para> | |
218 | ||
219 | <programlisting>sd_bus_message *m; | |
1eecafb8 | 220 | … |
effbc8e4 ZJS |
221 | sd_bus_message_append(m, "s", "a string");</programlisting> |
222 | ||
223 | <para>Append all types of integers:</para> | |
224 | ||
225 | <programlisting>uint8_t y = 1; | |
226 | int16_t n = 2; | |
227 | uint16_t q = 3; | |
228 | int32_t i = 4; | |
229 | uint32_t u = 5; | |
230 | int32_t x = 6; | |
231 | uint32_t t = 7; | |
232 | double d = 8.0; | |
233 | sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting> | |
234 | ||
e8216945 | 235 | <para>Append a structure composed of a string and a D-Bus path:</para> |
effbc8e4 ZJS |
236 | |
237 | <programlisting>sd_bus_message_append(m, "(so)", "a string", "/a/path"); | |
238 | </programlisting> | |
239 | ||
240 | <para>Append an array of UNIX file descriptors:</para> | |
241 | ||
242 | <programlisting>sd_bus_message_append(m, "ah", 3, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO); | |
243 | </programlisting> | |
244 | ||
245 | <para>Append a variant, with the real type "g" (signature), | |
246 | and value "sdbusisgood":</para> | |
247 | ||
248 | <programlisting>sd_bus_message_append(m, "v", "g", "sdbusisgood");</programlisting> | |
249 | ||
250 | <para>Append a dictionary containing the mapping {1=>"a", 2=>"b", 3=>""}: | |
251 | </para> | |
252 | ||
253 | <programlisting>sd_bus_message_append(m, "a{is}", 3, 1, "a", 2, "b", 3, NULL); | |
254 | </programlisting> | |
255 | </refsect1> | |
256 | ||
257 | <refsect1> | |
258 | <title>Return Value</title> | |
259 | ||
19fe49f6 FDP |
260 | <para>On success, these functions return 0 or a positive |
261 | integer. On failure, these functions return a negative | |
effbc8e4 ZJS |
262 | errno-style error code.</para> |
263 | </refsect1> | |
264 | ||
265 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="errors" /> | |
266 | ||
267 | <refsect1> | |
268 | <title>Notes</title> | |
269 | ||
270 | <para><function>sd_bus_open_user()</function> and other functions | |
271 | described here are available as a shared library, which can be | |
272 | compiled and linked to with the | |
5aded369 | 273 | <constant>libsystemd-bus</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
effbc8e4 ZJS |
274 | file.</para> |
275 | </refsect1> | |
276 | ||
277 | <refsect1> | |
278 | <title>See Also</title> | |
279 | ||
280 | <para> | |
281 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
282 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
e8216945 LP |
283 | <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
284 | <citerefentry><refentrytitle>sd_bus_message_append_array</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
effbc8e4 ZJS |
285 | </para> |
286 | </refsect1> | |
287 | ||
288 | </refentry> |