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2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
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4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
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> | |
21 | ||
22 | <refpurpose>Create a signal message</refpurpose> | |
23 | </refnamediv> | |
24 | ||
25 | <refsynopsisdiv> | |
26 | <funcsynopsis> | |
27 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
28 | ||
29 | <funcprototype> | |
30 | <funcdef>int sd_bus_message_new_signal</funcdef> | |
31 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
32 | <paramdef>sd_bus_message **<parameter>m</parameter></paramdef> | |
33 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
34 | <paramdef>const char *<parameter>interface</parameter></paramdef> | |
35 | <paramdef>const char *<parameter>member</parameter></paramdef> | |
36 | </funcprototype> | |
37 | </funcsynopsis> | |
38 | </refsynopsisdiv> | |
39 | ||
40 | <refsect1> | |
41 | <title>Description</title> | |
42 | ||
43 | <para>The <function>sd_bus_message_new_signal()</function> function creates a new bus message | |
44 | object that encapsulates a D-Bus signal, and returns it in the <parameter>m</parameter> output | |
45 | parameter. The signal will be sent to path <parameter>path</parameter>, on the interface | |
46 | <parameter>interface</parameter>, member <parameter>member</parameter>. When this message is | |
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47 | sent, no reply is expected. See |
48 | <citerefentry><refentrytitle>sd_bus_message_new_call</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
49 | for a short description of the meaning of the <parameter>path</parameter>, | |
50 | <parameter>interface</parameter>, and <parameter>member</parameter> parameters. | |
51 | </para> | |
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52 | </refsect1> |
53 | ||
54 | <refsect1> | |
55 | <title>Return Value</title> | |
56 | ||
57 | <para>This function returns 0 if the message object was successfully created, and a negative | |
58 | errno-style error code otherwise.</para> | |
e8b84fcc | 59 | |
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60 | <refsect2> |
61 | <title>Errors</title> | |
e8b84fcc | 62 | |
b1de39de | 63 | <para>Returned errors may indicate the following problems:</para> |
e8b84fcc | 64 | |
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65 | <variablelist> |
66 | <varlistentry> | |
67 | <term><constant>-EINVAL</constant></term> | |
e8b84fcc | 68 | |
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69 | <listitem><para>The output parameter <parameter>m</parameter> is |
70 | <constant>NULL</constant>.</para> | |
e8b84fcc | 71 | |
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72 | <para>The <parameter>path</parameter> parameter is not a valid D-Bus path |
73 | (<literal>/an/object/path</literal>), the <parameter>interface</parameter> parameter is not | |
74 | a valid D-Bus interface name (<literal>an.interface.name</literal>), or the | |
75 | <parameter>member</parameter> parameter is not a valid D-Bus member | |
76 | (<literal>Name</literal>).</para></listitem> | |
77 | </varlistentry> | |
e8b84fcc | 78 | |
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79 | <varlistentry> |
80 | <term><constant>-ENOTCONN</constant></term> | |
e8b84fcc | 81 | |
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82 | <listitem><para>The bus parameter <parameter>bus</parameter> is <constant>NULL</constant> or |
83 | the bus is not connected.</para></listitem> | |
84 | </varlistentry> | |
e8b84fcc | 85 | |
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86 | <varlistentry> |
87 | <term><constant>-ENOMEM</constant></term> | |
e8b84fcc | 88 | |
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89 | <listitem><para>Memory allocation failed.</para></listitem> |
90 | </varlistentry> | |
91 | </variablelist> | |
92 | </refsect2> | |
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93 | </refsect1> |
94 | ||
95 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
96 | ||
97 | <refsect1> | |
98 | <title>Examples</title> | |
99 | ||
100 | <example> | |
101 | <title>Send a simple signal</title> | |
102 | ||
103 | <programlisting><xi:include href="send-unit-files-changed.c" parse="text" /></programlisting> | |
104 | ||
105 | <para>This function in systemd sources is used to emit the | |
106 | <literal>UnitFilesChanged</literal> signal when the unit files have been changed. | |
107 | </para> | |
108 | </example> | |
109 | </refsect1> | |
110 | ||
111 | <refsect1> | |
112 | <title>See Also</title> | |
113 | ||
114 | <para> | |
115 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
ad300028 DDM |
116 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
117 | <citerefentry><refentrytitle>sd_bus_emit_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
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118 | </para> |
119 | </refsect1> | |
120 | ||
121 | </refentry> |