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e8b84fcc | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
eea10b26 | 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
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5 | |
6 | <refentry id="sd_bus_message_new_signal" | |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
9 | <refentryinfo> | |
10 | <title>sd_bus_message_new_signal</title> | |
11 | <productname>systemd</productname> | |
12 | </refentryinfo> | |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd_bus_message_new_signal</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd_bus_message_new_signal</refname> | |
85bc6b05 | 21 | <refname>sd_bus_message_new_signal_to</refname> |
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22 | |
23 | <refpurpose>Create a signal message</refpurpose> | |
24 | </refnamediv> | |
25 | ||
26 | <refsynopsisdiv> | |
27 | <funcsynopsis> | |
28 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
29 | ||
30 | <funcprototype> | |
31 | <funcdef>int sd_bus_message_new_signal</funcdef> | |
32 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
33 | <paramdef>sd_bus_message **<parameter>m</parameter></paramdef> | |
34 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
35 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
36 | <paramdef>const char *<parameter>member</parameter></paramdef> | |
37 | </funcprototype> | |
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38 | |
39 | <funcprototype> | |
40 | <funcdef>int sd_bus_message_new_signal_to</funcdef> | |
41 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
42 | <paramdef>sd_bus_message **<parameter>m</parameter></paramdef> | |
43 | <paramdef>const char *<parameter>destination</parameter></paramdef> | |
44 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
45 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
46 | <paramdef>const char *<parameter>member</parameter></paramdef> | |
47 | </funcprototype> | |
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48 | </funcsynopsis> |
49 | </refsynopsisdiv> | |
50 | ||
51 | <refsect1> | |
52 | <title>Description</title> | |
53 | ||
54 | <para>The <function>sd_bus_message_new_signal()</function> function creates a new bus message | |
55 | object that encapsulates a D-Bus signal, and returns it in the <parameter>m</parameter> output | |
56 | parameter. The signal will be sent to path <parameter>path</parameter>, on the interface | |
57 | <parameter>interface</parameter>, member <parameter>member</parameter>. When this message is | |
cfe8ee46 | 58 | sent, no reply is expected. See |
55cf7779 | 59 | <citerefentry><refentrytitle>sd_bus_message_new_method_call</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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60 | for a short description of the meaning of the <parameter>path</parameter>, |
61 | <parameter>interface</parameter>, and <parameter>member</parameter> parameters. | |
62 | </para> | |
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63 | |
64 | <para><function>sd_bus_message_new_signal_to()</function> is a shorthand for creating a new bus message | |
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65 | to a specific destination. It's behavior is similar to calling |
66 | <function>sd_bus_message_new_signal()</function> followed by calling | |
67 | <citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
68 | </para> | |
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69 | </refsect1> |
70 | ||
71 | <refsect1> | |
72 | <title>Return Value</title> | |
73 | ||
74 | <para>This function returns 0 if the message object was successfully created, and a negative | |
75 | errno-style error code otherwise.</para> | |
e8b84fcc | 76 | |
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77 | <refsect2> |
78 | <title>Errors</title> | |
e8b84fcc | 79 | |
b1de39de | 80 | <para>Returned errors may indicate the following problems:</para> |
e8b84fcc | 81 | |
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82 | <variablelist> |
83 | <varlistentry> | |
84 | <term><constant>-EINVAL</constant></term> | |
e8b84fcc | 85 | |
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86 | <listitem><para>The output parameter <parameter>m</parameter> is |
87 | <constant>NULL</constant>.</para> | |
e8b84fcc | 88 | |
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89 | <para>The <parameter>path</parameter> parameter is not a valid D-Bus path |
90 | (<literal>/an/object/path</literal>), the <parameter>interface</parameter> parameter is not | |
91 | a valid D-Bus interface name (<literal>an.interface.name</literal>), or the | |
92 | <parameter>member</parameter> parameter is not a valid D-Bus member | |
93 | (<literal>Name</literal>).</para></listitem> | |
94 | </varlistentry> | |
e8b84fcc | 95 | |
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96 | <varlistentry> |
97 | <term><constant>-ENOTCONN</constant></term> | |
e8b84fcc | 98 | |
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99 | <listitem><para>The bus parameter <parameter>bus</parameter> is <constant>NULL</constant> or |
100 | the bus is not connected.</para></listitem> | |
101 | </varlistentry> | |
e8b84fcc | 102 | |
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103 | <varlistentry> |
104 | <term><constant>-ENOMEM</constant></term> | |
e8b84fcc | 105 | |
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106 | <listitem><para>Memory allocation failed.</para></listitem> |
107 | </varlistentry> | |
108 | </variablelist> | |
109 | </refsect2> | |
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110 | </refsect1> |
111 | ||
112 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
113 | ||
114 | <refsect1> | |
115 | <title>Examples</title> | |
116 | ||
117 | <example> | |
118 | <title>Send a simple signal</title> | |
119 | ||
120 | <programlisting><xi:include href="send-unit-files-changed.c" parse="text" /></programlisting> | |
121 | ||
122 | <para>This function in systemd sources is used to emit the | |
123 | <literal>UnitFilesChanged</literal> signal when the unit files have been changed. | |
124 | </para> | |
125 | </example> | |
126 | </refsect1> | |
127 | ||
128 | <refsect1> | |
129 | <title>See Also</title> | |
130 | ||
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131 | <para><simplelist type="inline"> |
132 | <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> | |
133 | <member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
134 | <member><citerefentry><refentrytitle>sd_bus_emit_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
135 | <member><citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
136 | </simplelist></para> | |
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137 | </refsect1> |
138 | ||
139 | </refentry> |