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f47781d8 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
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2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
e735f4d4 | 6 | This file is part of systemd. |
60f067b4 | 7 | |
e735f4d4 | 8 | Copyright 2014 Zbigniew Jędrzejewski-Szmek |
60f067b4 | 9 | |
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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. | |
60f067b4 | 14 | |
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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. | |
60f067b4 | 19 | |
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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/>. | |
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22 | --> |
23 | ||
24 | <refentry id="sd_bus_message_append" conditional="ENABLE_KDBUS" | |
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 | ||
49 | <refpurpose>Attach parts of message based on a format string</refpurpose> | |
50 | </refnamediv> | |
51 | ||
52 | <refsynopsisdiv> | |
53 | <funcsynopsis> | |
54 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
55 | ||
56 | <funcprototype> | |
57 | <funcdef>int sd_bus_message_append</funcdef> | |
58 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
59 | <paramdef>const char *<parameter>types</parameter></paramdef> | |
60 | <paramdef>...</paramdef> | |
61 | </funcprototype> | |
62 | </funcsynopsis> | |
63 | </refsynopsisdiv> | |
64 | ||
65 | <refsect1> | |
66 | <title>Description</title> | |
67 | ||
68 | <para>The <function>sd_bus_message_append</function> function appends | |
69 | a sequence of items to message <parameter>m</parameter>. The | |
70 | format string <parameter>types</parameter> describes the types of | |
71 | arguments that follow.</para> | |
72 | ||
73 | <para>The format string is composed of the elements shown in the | |
74 | table below. It contains zero or more single "complete types". | |
75 | Each complete type may be one of the basic types or a fully | |
76 | described container type. A container type may be a structure, a | |
77 | variant type code, an array with its element type, or a dictionary | |
78 | with its entry type. The format string is | |
79 | <constant>NUL</constant>-terminated.</para> | |
80 | ||
81 | <para>In case of a basic type, one argument of the corresponding | |
82 | type is expected.</para> | |
83 | ||
84 | <para>A structure is denoted by a sequence of complete types | |
85 | between <literal>(</literal> and <literal>)</literal>. This | |
86 | sequence cannot be empty — it must contain at least one type. | |
87 | Arguments corresponding to this nested sequence follow the same | |
88 | rules as if they were not nested.</para> | |
89 | ||
90 | <para>A variant is denoted by <literal>v</literal>. Correspoding | |
91 | arguments must include a format string denoting a complete type, | |
92 | and following that, arguments corresponding to the specified type. | |
93 | </para> | |
94 | ||
95 | <para>An array is denoted by <literal>a</literal> followed by a | |
96 | complete type. Corresponding arguments must include the size of | |
97 | the array, and then repeated this number of times, arguments | |
98 | corresponding to the nested type.</para> | |
99 | ||
100 | <para>A dictionary is an array of dictionary entries, denoted by | |
101 | <literal>a</literal> followed by a pair of complete types between | |
102 | <literal>{</literal> and <literal>}</literal>. The first of those | |
103 | types must be a basic type. Corresponding arguments must include | |
104 | the size of the dictionary, and then repeated this number of | |
105 | times, arguments corresponding to each of the two nested | |
106 | types.</para> | |
107 | ||
108 | <table> | |
109 | <title>Item format specifiers</title> | |
110 | ||
111 | <tgroup cols='4'> | |
112 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers'])//colspec" /> | |
113 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//thead)" /> | |
114 | ||
115 | <tbody> | |
116 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//tbody/*)" /> | |
117 | ||
118 | <row> | |
119 | <entry><literal>a</literal></entry> | |
120 | <entry><constant>SD_BUS_TYPE_ARRAY</constant></entry> | |
121 | <entry>array</entry> | |
122 | <entry>determined by array type and size</entry> | |
123 | </row> | |
124 | ||
125 | <row> | |
126 | <entry><literal>v</literal></entry> | |
127 | <entry><constant>SD_BUS_TYPE_VARIANT</constant></entry> | |
128 | <entry>variant</entry> | |
129 | <entry>determined by the type argument</entry> | |
130 | </row> | |
131 | ||
132 | <row> | |
133 | <entry><literal>(</literal></entry> | |
134 | <entry><constant>SD_BUS_TYPE_STRUCT_BEGIN</constant></entry> | |
135 | <entry>array start</entry> | |
136 | <entry morerows="1">determined by the nested types</entry> | |
137 | </row> | |
138 | <row> | |
139 | <entry><literal>)</literal></entry> | |
140 | <entry><constant>SD_BUS_TYPE_STRUCT_END</constant></entry> | |
141 | <entry>array end</entry> | |
142 | </row> | |
143 | ||
144 | <row> | |
145 | <entry><literal>{</literal></entry> | |
146 | <entry><constant>SD_BUS_TYPE_DICT_ENTRY_BEGIN</constant></entry> | |
147 | <entry>dictionary entry start</entry> | |
148 | <entry morerows="1">determined by the nested types</entry> | |
149 | </row> | |
150 | <row> | |
151 | <entry><literal>}</literal></entry> | |
152 | <entry><constant>SD_BUS_TYPE_DICT_ENTRY_END</constant></entry> | |
153 | <entry>dictionary entry end</entry> | |
154 | </row> | |
155 | </tbody> | |
156 | </tgroup> | |
157 | </table> | |
158 | </refsect1> | |
159 | ||
160 | <refsect1> | |
161 | <title>Types string grammar</title> | |
162 | ||
163 | <programlisting>types ::= complete_type* | |
164 | complete_type ::= basic_type | variant | structure | array | dictionary | |
165 | basic_type ::= "y" | "n" | "q" | "u" | "i" | "x" | "t" | "d" | | |
166 | "b" | "h" | | |
167 | "s" | "o" | "g" | |
168 | variant ::= "v" | |
169 | structure ::= "(" complete_type+ ")" | |
170 | array ::= "a" complete_type | |
171 | dictionary ::= "a" "{" basic_type complete_type "}" | |
172 | </programlisting> | |
173 | </refsect1> | |
174 | ||
175 | <refsect1> | |
176 | <title>Examples</title> | |
177 | ||
178 | <para>Append a single basic type (the string <literal>a string</literal>): | |
179 | </para> | |
180 | ||
181 | <programlisting>sd_bus_message *m; | |
182 | ... | |
183 | sd_bus_message_append(m, "s", "a string");</programlisting> | |
184 | ||
185 | <para>Append all types of integers:</para> | |
186 | ||
187 | <programlisting>uint8_t y = 1; | |
188 | int16_t n = 2; | |
189 | uint16_t q = 3; | |
190 | int32_t i = 4; | |
191 | uint32_t u = 5; | |
192 | int32_t x = 6; | |
193 | uint32_t t = 7; | |
194 | double d = 8.0; | |
195 | sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting> | |
196 | ||
197 | <para>Append a structure composed of string and a D-Bus path:</para> | |
198 | ||
199 | <programlisting>sd_bus_message_append(m, "(so)", "a string", "/a/path"); | |
200 | </programlisting> | |
201 | ||
202 | <para>Append an array of UNIX file descriptors:</para> | |
203 | ||
204 | <programlisting>sd_bus_message_append(m, "ah", 3, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO); | |
205 | </programlisting> | |
206 | ||
207 | <para>Append a variant, with the real type "g" (signature), | |
208 | and value "sdbusisgood":</para> | |
209 | ||
210 | <programlisting>sd_bus_message_append(m, "v", "g", "sdbusisgood");</programlisting> | |
211 | ||
212 | <para>Append a dictionary containing the mapping {1=>"a", 2=>"b", 3=>""}: | |
213 | </para> | |
214 | ||
215 | <programlisting>sd_bus_message_append(m, "a{is}", 3, 1, "a", 2, "b", 3, NULL); | |
216 | </programlisting> | |
217 | </refsect1> | |
218 | ||
219 | <refsect1> | |
220 | <title>Return Value</title> | |
221 | ||
222 | <para>On success, this call returns 0 or a positive | |
223 | integer. On failure, this call returns a negative | |
224 | errno-style error code.</para> | |
225 | </refsect1> | |
226 | ||
227 | <xi:include href="sd_bus_message_append_basic.xml" xpointer="errors" /> | |
228 | ||
229 | <refsect1> | |
230 | <title>Notes</title> | |
231 | ||
232 | <para><function>sd_bus_open_user()</function> and other functions | |
233 | described here are available as a shared library, which can be | |
234 | compiled and linked to with the | |
5eef597e | 235 | <constant>libsystemd-bus</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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236 | file.</para> |
237 | </refsect1> | |
238 | ||
239 | <refsect1> | |
240 | <title>See Also</title> | |
241 | ||
242 | <para> | |
243 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
244 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
245 | <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
246 | <citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
247 | <citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
248 | <citerefentry><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
249 | <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
250 | <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
251 | </para> | |
252 | </refsect1> | |
253 | ||
254 | </refentry> |