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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> | |
5 | ||
6 | <refentry id="sd_bus_emit_signal" | |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
9 | <refentryinfo> | |
10 | <title>sd_bus_emit_signal</title> | |
11 | <productname>systemd</productname> | |
12 | </refentryinfo> | |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd_bus_emit_signal</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd_bus_emit_signal</refname> | |
21 | <refname>sd_bus_emit_signalv</refname> | |
22 | <refname>sd_bus_emit_interfaces_added</refname> | |
23 | <refname>sd_bus_emit_interfaces_added_strv</refname> | |
24 | <refname>sd_bus_emit_interfaces_removed</refname> | |
25 | <refname>sd_bus_emit_interfaces_removed_strv</refname> | |
26 | <refname>sd_bus_emit_properties_changed</refname> | |
27 | <refname>sd_bus_emit_properties_changed_strv</refname> | |
28 | <refname>sd_bus_emit_object_added</refname> | |
29 | <refname>sd_bus_emit_object_removed</refname> | |
30 | ||
31 | <refpurpose>Convenience functions for emitting (standard) D-Bus signals</refpurpose> | |
32 | </refnamediv> | |
33 | ||
34 | <refsynopsisdiv> | |
35 | <funcsynopsis> | |
36 | <funcsynopsisinfo>#include <systemd/sd-bus-vtable.h></funcsynopsisinfo> | |
37 | ||
38 | <funcprototype> | |
39 | <funcdef>int <function>sd_bus_emit_signal</function></funcdef> | |
40 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
41 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
42 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
43 | <paramdef>const char *<parameter>member</parameter></paramdef> | |
44 | <paramdef>const char *<parameter>types</parameter></paramdef> | |
45 | <paramdef>...</paramdef> | |
46 | </funcprototype> | |
47 | ||
48 | <funcprototype> | |
49 | <funcdef>int <function>sd_bus_emit_signalv</function></funcdef> | |
50 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
51 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
52 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
53 | <paramdef>const char *<parameter>member</parameter></paramdef> | |
54 | <paramdef>const char *<parameter>types</parameter></paramdef> | |
55 | <paramdef>va_list <parameter>ap</parameter></paramdef> | |
56 | </funcprototype> | |
57 | ||
58 | <funcprototype> | |
59 | <funcdef>int <function>sd_bus_emit_interfaces_added</function></funcdef> | |
60 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
61 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
62 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
63 | <paramdef>...</paramdef> | |
64 | </funcprototype> | |
65 | ||
66 | <funcprototype> | |
67 | <funcdef>int <function>sd_bus_emit_interfaces_added_strv</function></funcdef> | |
68 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
69 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
70 | <paramdef>const char **<parameter>interfaces</parameter></paramdef> | |
71 | </funcprototype> | |
72 | ||
73 | <funcprototype> | |
74 | <funcdef>int <function>sd_bus_emit_interfaces_removed</function></funcdef> | |
75 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
76 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
77 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
78 | <paramdef>...</paramdef> | |
79 | </funcprototype> | |
80 | ||
81 | <funcprototype> | |
82 | <funcdef>int <function>sd_bus_emit_interfaces_removed_strv</function></funcdef> | |
83 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
84 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
85 | <paramdef>const char **<parameter>interfaces</parameter></paramdef> | |
86 | </funcprototype> | |
87 | ||
88 | <funcprototype> | |
89 | <funcdef>int <function>sd_bus_emit_properties_changed</function></funcdef> | |
90 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
91 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
92 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
93 | <paramdef>const char *<parameter>name</parameter></paramdef> | |
94 | <paramdef>...</paramdef> | |
95 | </funcprototype> | |
96 | ||
97 | <funcprototype> | |
98 | <funcdef>int <function>sd_bus_emit_properties_changed_strv</function></funcdef> | |
99 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
100 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
101 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
102 | <paramdef>const char **<parameter>names</parameter></paramdef> | |
103 | </funcprototype> | |
104 | ||
105 | <funcprototype> | |
106 | <funcdef>int <function>sd_bus_emit_object_added</function></funcdef> | |
107 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
108 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
109 | </funcprototype> | |
110 | ||
111 | <funcprototype> | |
112 | <funcdef>int <function>sd_bus_emit_object_removed</function></funcdef> | |
113 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
114 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
115 | </funcprototype> | |
116 | </funcsynopsis> | |
117 | </refsynopsisdiv> | |
118 | ||
119 | <refsect1> | |
120 | <title>Description</title> | |
121 | ||
122 | <para><function>sd_bus_emit_signal()</function> is a convenience function for initializing a | |
123 | bus message object and emitting the corresponding D-Bus signal. It combines the | |
124 | <citerefentry><refentrytitle>sd_bus_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
125 | <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry> and | |
126 | <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
127 | functions into a single function call. <function>sd_bus_emit_signalv()</function> is | |
128 | equivalent to <function>sd_bus_message_append()</function>, except that it is called with a | |
129 | <literal>va_list</literal> instead of a variable number of arguments.</para> | |
130 | ||
131 | <para><function>sd_bus_emit_interfaces_added()</function> and | |
132 | <function>sd_bus_emit_interfaces_removed()</function> are used to implement the | |
133 | <function>InterfacesAdded</function> and <function>InterfacesRemoved</function> signals of the | |
134 | <constant>org.freedesktop.DBus.ObjectManager</constant> interface. They take a path whose | |
135 | interfaces have been modified as an argument and a variable list of interfaces that have been | |
136 | added or removed, respectively. The final argument passed to | |
137 | <function>sd_bus_emit_interfaces_added()</function> and | |
138 | <function>sd_bus_emit_interfaces_removed()</function> <emphasis>must</emphasis> be | |
139 | <constant>NULL</constant>. This allows both functions to safely determine the number of passed | |
140 | interface arguments. <function>sd_bus_emit_interfaces_added_strv()</function> and | |
141 | <function>sd_bus_emit_interfaces_removed_strv()</function> are identical to their respective | |
142 | counterparts but both take the list of interfaces as a single argument instead of a variable | |
143 | number of arguments.</para> | |
144 | ||
145 | <para><function>sd_bus_emit_properties_changed()</function> is used to implement the | |
146 | <function>PropertiesChanged</function> signal of the | |
147 | <constant>org.freedesktop.DBus.Properties</constant> interface. It takes an object path, | |
148 | interface and a variable list of property names as its arguments. The final argument passed to | |
149 | <function>sd_bus_emit_properties_changed()</function> <emphasis>must</emphasis> be | |
150 | <constant>NULL</constant>. This allows it to safely determine the number of passed property | |
151 | names. <function>sd_bus_emit_properties_changed_strv()</function> is identical to | |
152 | <function>sd_bus_emit_properties_changed()</function> but takes the list of property names as a | |
153 | single argument instead of a variable number of arguments.</para> | |
154 | ||
155 | <para><function>sd_bus_emit_object_added()</function> and | |
156 | <function>sd_bus_emit_object_removed()</function> are convenience functions for emitting the | |
157 | <function>InterfacesAdded</function> or <function>InterfacesRemoved</function> signals for all | |
158 | interfaces registered on a specific object path, respectively. This includes any parent fallback | |
159 | vtables if they are not overridden by a more applicable child vtable. It also includes all the | |
160 | standard D-Bus interfaces implemented by sd-bus itself on any registered object.</para> | |
161 | ||
162 | <para>Note that <function>sd_bus_emit_interfaces_added()</function>, | |
163 | <function>sd_bus_emit_interfaces_removed()</function>, | |
164 | <function>sd_bus_emit_object_added()</function> and | |
165 | <function>sd_bus_emit_object_removed()</function> require an object manager to have been | |
166 | registered on the given object path or one of its parent object paths using | |
167 | <citerefentry><refentrytitle>sd_bus_add_object_manager</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
168 | </para> | |
169 | </refsect1> | |
170 | ||
171 | <refsect1> | |
172 | <title>Return Value</title> | |
173 | ||
174 | <para>On success, these functions return a non-negative integer. On failure, they return a | |
175 | negative errno-style error code.</para> | |
176 | ||
177 | <refsect2> | |
178 | <title>Errors</title> | |
179 | ||
180 | <para>Returned errors may indicate the following problems:</para> | |
181 | ||
182 | <variablelist> | |
183 | <varlistentry> | |
184 | <term><constant>-EINVAL</constant></term> | |
185 | ||
186 | <listitem><para>One of the required parameters is <constant>NULL</constant> or invalid. A | |
187 | reserved D-Bus interface was passed as the <replaceable>interface</replaceable> parameter. | |
188 | </para></listitem> | |
189 | </varlistentry> | |
190 | ||
191 | <varlistentry> | |
192 | <term><constant>-ENOPKG</constant></term> | |
193 | ||
194 | <listitem><para>The bus cannot be resolved.</para></listitem> | |
195 | </varlistentry> | |
196 | ||
197 | <varlistentry> | |
198 | <term><constant>-ECHILD</constant></term> | |
199 | ||
200 | <listitem><para>The bus was created in a different process.</para></listitem> | |
201 | </varlistentry> | |
202 | ||
203 | <varlistentry> | |
204 | <term><constant>-ENOMEM</constant></term> | |
205 | ||
206 | <listitem><para>Memory allocation failed.</para></listitem> | |
207 | </varlistentry> | |
208 | ||
209 | <varlistentry> | |
210 | <term><constant>-ESRCH</constant></term> | |
211 | ||
212 | <listitem><para>One of <function>sd_bus_emit_interfaces_added()</function>, | |
213 | <function>sd_bus_emit_interfaces_removed()</function>, | |
214 | <function>sd_bus_emit_object_added()</function> or | |
215 | <function>sd_bus_emit_object_removed()</function> was called on an object without an | |
216 | object manager registered on its own object path or one of its parent object paths. | |
217 | </para></listitem> | |
218 | </varlistentry> | |
219 | </variablelist> | |
220 | ||
221 | <para>See the man pages of | |
222 | <citerefentry><refentrytitle>sd_bus_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
223 | <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry> and | |
224 | <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
225 | for more possible errors.</para> | |
226 | </refsect2> | |
227 | </refsect1> | |
228 | ||
229 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
230 | ||
231 | <refsect1> | |
232 | <title>See Also</title> | |
233 | ||
234 | <para> | |
235 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
236 | <citerefentry><refentrytitle>busctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
237 | <citerefentry><refentrytitle>sd_bus_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
238 | <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
239 | <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
240 | <citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
241 | </para> | |
242 | </refsect1> | |
243 | </refentry> |