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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 | <!-- | |
b975b0d5 | 6 | This file is part of systemd. |
effbc8e4 | 7 | |
b975b0d5 | 8 | Copyright 2014 Zbigniew Jędrzejewski-Szmek |
effbc8e4 | 9 | |
b975b0d5 ZJS |
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. | |
effbc8e4 | 14 | |
b975b0d5 ZJS |
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. | |
effbc8e4 | 19 | |
b975b0d5 ZJS |
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/>. | |
effbc8e4 ZJS |
22 | --> |
23 | ||
48f69d8f | 24 | <refentry id="sd_bus_message_append" |
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25 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
26 | ||
27 | <refentryinfo> | |
28 | <title>sd_bus_message_append</title> | |
29 | <productname>systemd</productname> | |
30 | ||
31 | <authorgroup> | |
32 | <author> | |
33 | <contrib>A monkey with a typewriter</contrib> | |
34 | <firstname>Zbigniew</firstname> | |
35 | <surname>Jędrzejewski-Szmek</surname> | |
36 | <email>zbyszek@in.waw.pl</email> | |
37 | </author> | |
38 | </authorgroup> | |
39 | </refentryinfo> | |
40 | ||
41 | <refmeta> | |
42 | <refentrytitle>sd_bus_message_append</refentrytitle> | |
43 | <manvolnum>3</manvolnum> | |
44 | </refmeta> | |
45 | ||
46 | <refnamediv> | |
47 | <refname>sd_bus_message_append</refname> | |
48 | ||
e8216945 LP |
49 | <refpurpose>Attach fields to a D-Bus message based on a type |
50 | string</refpurpose> | |
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51 | </refnamediv> |
52 | ||
53 | <refsynopsisdiv> | |
54 | <funcsynopsis> | |
55 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
56 | ||
57 | <funcprototype> | |
58 | <funcdef>int sd_bus_message_append</funcdef> | |
59 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
60 | <paramdef>const char *<parameter>types</parameter></paramdef> | |
1eecafb8 | 61 | <paramdef>…</paramdef> |
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62 | </funcprototype> |
63 | </funcsynopsis> | |
64 | </refsynopsisdiv> | |
65 | ||
66 | <refsect1> | |
67 | <title>Description</title> | |
68 | ||
e8216945 LP |
69 | <para>The <function>sd_bus_message_append()</function> function |
70 | appends a sequence of fields to the D-Bus message object | |
71 | <parameter>m</parameter>. The type string | |
72 | <parameter>types</parameter> describes the types of the field | |
b938cb90 | 73 | arguments that follow. For each type specified in the type string, |
e8216945 LP |
74 | one or more arguments need to be specified, in the same order as |
75 | declared in the type string.</para> | |
effbc8e4 | 76 | |
e8216945 | 77 | <para>The type string is composed of the elements shown in the |
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78 | table below. It contains zero or more single "complete types". |
79 | Each complete type may be one of the basic types or a fully | |
e8216945 LP |
80 | described container type. A container type may be a structure with |
81 | the contained types, a variant, an array with its element type, or | |
82 | a dictionary entry with the contained types. The type string is | |
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83 | <constant>NUL</constant>-terminated.</para> |
84 | ||
85 | <para>In case of a basic type, one argument of the corresponding | |
86 | type is expected.</para> | |
87 | ||
88 | <para>A structure is denoted by a sequence of complete types | |
89 | between <literal>(</literal> and <literal>)</literal>. This | |
90 | sequence cannot be empty — it must contain at least one type. | |
91 | Arguments corresponding to this nested sequence follow the same | |
92 | rules as if they were not nested.</para> | |
93 | ||
ff9b60f3 | 94 | <para>A variant is denoted by <literal>v</literal>. Corresponding |
e8216945 | 95 | arguments must begin with a type string denoting a complete type, |
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96 | and following that, arguments corresponding to the specified type. |
97 | </para> | |
98 | ||
99 | <para>An array is denoted by <literal>a</literal> followed by a | |
e8216945 LP |
100 | complete type. Corresponding arguments must begin with the number of |
101 | entries in the array, followed by the entries themselves, | |
102 | matching the element type of the array.</para> | |
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103 | |
104 | <para>A dictionary is an array of dictionary entries, denoted by | |
105 | <literal>a</literal> followed by a pair of complete types between | |
106 | <literal>{</literal> and <literal>}</literal>. The first of those | |
e8216945 LP |
107 | types must be a basic type. Corresponding arguments must begin |
108 | with the number of dictionary entries, followed by a pair of | |
109 | values for each entry matching the element type of | |
110 | the dictionary entries.</para> | |
111 | ||
112 | <para>For further details on the D-Bus type system, please consult | |
113 | the <ulink | |
114 | url="http://dbus.freedesktop.org/doc/dbus-specification.html#type-system">D-Bus | |
115 | Specification</ulink>.</para> | |
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116 | |
117 | <table> | |
e8216945 | 118 | <title>Item type specifiers</title> |
effbc8e4 | 119 | |
e8216945 | 120 | <tgroup cols='5'> |
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121 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers'])//colspec" /> |
122 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//thead)" /> | |
123 | ||
124 | <tbody> | |
125 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//tbody/*)" /> | |
126 | ||
127 | <row> | |
128 | <entry><literal>a</literal></entry> | |
129 | <entry><constant>SD_BUS_TYPE_ARRAY</constant></entry> | |
130 | <entry>array</entry> | |
131 | <entry>determined by array type and size</entry> | |
e8216945 | 132 | <entry>int, followed by array contents</entry> |
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133 | </row> |
134 | ||
135 | <row> | |
136 | <entry><literal>v</literal></entry> | |
137 | <entry><constant>SD_BUS_TYPE_VARIANT</constant></entry> | |
138 | <entry>variant</entry> | |
139 | <entry>determined by the type argument</entry> | |
e8216945 | 140 | <entry>signature string, followed by variant contents</entry> |
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141 | </row> |
142 | ||
143 | <row> | |
144 | <entry><literal>(</literal></entry> | |
145 | <entry><constant>SD_BUS_TYPE_STRUCT_BEGIN</constant></entry> | |
146 | <entry>array start</entry> | |
147 | <entry morerows="1">determined by the nested types</entry> | |
e8216945 | 148 | <entry morerows="1">structure contents</entry> |
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149 | </row> |
150 | <row> | |
151 | <entry><literal>)</literal></entry> | |
152 | <entry><constant>SD_BUS_TYPE_STRUCT_END</constant></entry> | |
153 | <entry>array end</entry> | |
154 | </row> | |
155 | ||
156 | <row> | |
157 | <entry><literal>{</literal></entry> | |
158 | <entry><constant>SD_BUS_TYPE_DICT_ENTRY_BEGIN</constant></entry> | |
159 | <entry>dictionary entry start</entry> | |
160 | <entry morerows="1">determined by the nested types</entry> | |
e8216945 | 161 | <entry morerows="1">dictionary contents</entry> |
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162 | </row> |
163 | <row> | |
164 | <entry><literal>}</literal></entry> | |
165 | <entry><constant>SD_BUS_TYPE_DICT_ENTRY_END</constant></entry> | |
166 | <entry>dictionary entry end</entry> | |
167 | </row> | |
168 | </tbody> | |
169 | </tgroup> | |
170 | </table> | |
e8216945 | 171 | |
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172 | <para>For types "s" and "g" (unicode string or signature), the pointer may be |
173 | <constant>NULL</constant>, which is equivalent to an empty string. See | |
174 | <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
175 | for the precise interpretation of those and other types.</para> | |
176 | ||
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177 | </refsect1> |
178 | ||
179 | <refsect1> | |
e8216945 | 180 | <title>Types String Grammar</title> |
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181 | |
182 | <programlisting>types ::= complete_type* | |
183 | complete_type ::= basic_type | variant | structure | array | dictionary | |
184 | basic_type ::= "y" | "n" | "q" | "u" | "i" | "x" | "t" | "d" | | |
185 | "b" | "h" | | |
186 | "s" | "o" | "g" | |
187 | variant ::= "v" | |
188 | structure ::= "(" complete_type+ ")" | |
189 | array ::= "a" complete_type | |
190 | dictionary ::= "a" "{" basic_type complete_type "}" | |
191 | </programlisting> | |
192 | </refsect1> | |
193 | ||
194 | <refsect1> | |
195 | <title>Examples</title> | |
196 | ||
197 | <para>Append a single basic type (the string <literal>a string</literal>): | |
198 | </para> | |
199 | ||
200 | <programlisting>sd_bus_message *m; | |
1eecafb8 | 201 | … |
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202 | sd_bus_message_append(m, "s", "a string");</programlisting> |
203 | ||
204 | <para>Append all types of integers:</para> | |
205 | ||
206 | <programlisting>uint8_t y = 1; | |
207 | int16_t n = 2; | |
208 | uint16_t q = 3; | |
209 | int32_t i = 4; | |
210 | uint32_t u = 5; | |
211 | int32_t x = 6; | |
212 | uint32_t t = 7; | |
213 | double d = 8.0; | |
214 | sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting> | |
215 | ||
e8216945 | 216 | <para>Append a structure composed of a string and a D-Bus path:</para> |
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217 | |
218 | <programlisting>sd_bus_message_append(m, "(so)", "a string", "/a/path"); | |
219 | </programlisting> | |
220 | ||
221 | <para>Append an array of UNIX file descriptors:</para> | |
222 | ||
223 | <programlisting>sd_bus_message_append(m, "ah", 3, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO); | |
224 | </programlisting> | |
225 | ||
226 | <para>Append a variant, with the real type "g" (signature), | |
227 | and value "sdbusisgood":</para> | |
228 | ||
229 | <programlisting>sd_bus_message_append(m, "v", "g", "sdbusisgood");</programlisting> | |
230 | ||
231 | <para>Append a dictionary containing the mapping {1=>"a", 2=>"b", 3=>""}: | |
232 | </para> | |
233 | ||
234 | <programlisting>sd_bus_message_append(m, "a{is}", 3, 1, "a", 2, "b", 3, NULL); | |
235 | </programlisting> | |
236 | </refsect1> | |
237 | ||
238 | <refsect1> | |
239 | <title>Return Value</title> | |
240 | ||
241 | <para>On success, this call returns 0 or a positive | |
242 | integer. On failure, this call returns a negative | |
243 | errno-style error code.</para> | |
244 | </refsect1> | |
245 | ||
246 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="errors" /> | |
247 | ||
248 | <refsect1> | |
249 | <title>Notes</title> | |
250 | ||
251 | <para><function>sd_bus_open_user()</function> and other functions | |
252 | described here are available as a shared library, which can be | |
253 | compiled and linked to with the | |
5aded369 | 254 | <constant>libsystemd-bus</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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255 | file.</para> |
256 | </refsect1> | |
257 | ||
258 | <refsect1> | |
259 | <title>See Also</title> | |
260 | ||
261 | <para> | |
262 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
263 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
e8216945 LP |
264 | <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
265 | <citerefentry><refentrytitle>sd_bus_message_append_array</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
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266 | </para> |
267 | </refsect1> | |
268 | ||
269 | </refentry> |