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1 | <?xml version='1.0'?> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
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5 | |
6 | <refentry id="sd_bus_send" | |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
9 | <refentryinfo> | |
10 | <title>sd_bus_send</title> | |
11 | <productname>systemd</productname> | |
12 | </refentryinfo> | |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd_bus_send</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd_bus_send</refname> | |
d7fbc680 | 21 | <refname>sd_bus_send_to</refname> |
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22 | |
23 | <refpurpose>Queue a D-Bus message for transfer</refpurpose> | |
24 | </refnamediv> | |
25 | ||
26 | <refsynopsisdiv> | |
27 | <funcsynopsis> | |
28 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
29 | ||
30 | <funcprototype> | |
31 | <funcdef>int <function>sd_bus_send</function></funcdef> | |
32 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
33 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
34 | <paramdef>uint64_t *<parameter>cookie</parameter></paramdef> | |
35 | </funcprototype> | |
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36 | |
37 | <funcprototype> | |
38 | <funcdef>int <function>sd_bus_send_to</function></funcdef> | |
39 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
40 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
41 | <paramdef>const char *<parameter>destination</parameter></paramdef> | |
42 | <paramdef>uint64_t *<parameter>cookie</parameter></paramdef> | |
43 | </funcprototype> | |
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44 | </funcsynopsis> |
45 | </refsynopsisdiv> | |
46 | ||
47 | <refsect1> | |
48 | <title>Description</title> | |
49 | ||
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50 | <para><function>sd_bus_send()</function> queues the bus message object <parameter>m</parameter> for |
51 | transfer. If <parameter>bus</parameter> is <constant>NULL</constant>, the bus that | |
52 | <parameter>m</parameter> is attached to is used. <parameter>bus</parameter> only needs to be set when the | |
53 | message is sent to a different bus than the one it's attached to, for example when forwarding messages. | |
54 | If the output parameter <parameter>cookie</parameter> is not <constant>NULL</constant>, it is set to the | |
55 | message identifier. This value can later be used to match incoming replies to their corresponding | |
56 | messages. If <parameter>cookie</parameter> is set to <constant>NULL</constant> and the message is not | |
57 | sealed, <function>sd_bus_send()</function> assumes the message <parameter>m</parameter> doesn't expect a | |
58 | reply and adds the necessary headers to indicate this.</para> | |
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59 | |
60 | <para>Note that in most scenarios, <function>sd_bus_send()</function> should not be called | |
61 | directly. Instead, use higher level functions such as | |
62 | <citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry> and | |
63 | <citerefentry><refentrytitle>sd_bus_reply_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
64 | which call <function>sd_bus_send()</function> internally.</para> | |
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65 | |
66 | <para><function>sd_bus_send_to()</function> is a shorthand for sending a message to a specific | |
67 | destination. It's main use case is to simplify sending unicast signal messages (signals that only have a | |
68 | single receiver). It's behavior is similar to calling | |
69 | <citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
70 | followed by calling <function>sd_bus_send()</function>.</para> | |
533ee38b LP |
71 | |
72 | <para><function>sd_bus_send()</function>/<function>sd_bus_send_to()</function> will write the message | |
73 | directly to the underlying transport (e.g. kernel socket buffer) if possible. If the connection is not | |
74 | set up fully yet the message is queued locally. If the transport buffers are congested any unwritten | |
75 | message data is queued locally, too. If the connection has been closed or is currently being closed the | |
76 | call fails. | |
77 | <citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry> should | |
78 | be invoked to write out any queued message data to the transport.</para> | |
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79 | </refsect1> |
80 | ||
81 | <refsect1> | |
82 | <title>Return Value</title> | |
83 | ||
d7fbc680 DDM |
84 | <para>On success, these functions return a non-negative integer. On failure, they return a negative |
85 | errno-style error code.</para> | |
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86 | |
87 | <refsect2 id='errors'> | |
88 | <title>Errors</title> | |
89 | ||
90 | <para>Returned errors may indicate the following problems:</para> | |
91 | ||
92 | <variablelist> | |
93 | <varlistentry> | |
94 | <term><constant>-EINVAL</constant></term> | |
95 | ||
96 | <listitem><para>The input parameter <parameter>m</parameter> is <constant>NULL</constant>. | |
97 | </para></listitem> | |
98 | </varlistentry> | |
99 | ||
100 | <varlistentry> | |
101 | <term><constant>-EOPNOTSUPP</constant></term> | |
102 | ||
103 | <listitem><para>The bus connection does not support sending file descriptors. | |
104 | </para></listitem> | |
105 | </varlistentry> | |
106 | ||
107 | <varlistentry> | |
108 | <term><constant>-ECHILD</constant></term> | |
109 | ||
d7fbc680 DDM |
110 | <listitem><para>The bus connection was allocated in a parent process and is being reused in a child |
111 | process after <function>fork()</function>.</para></listitem> | |
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112 | </varlistentry> |
113 | ||
114 | <varlistentry> | |
115 | <term><constant>-ENOBUFS</constant></term> | |
116 | ||
117 | <listitem><para>The bus connection's write queue is full.</para></listitem> | |
118 | </varlistentry> | |
119 | ||
120 | <varlistentry> | |
121 | <term><constant>-ENOTCONN</constant></term> | |
122 | ||
123 | <listitem><para>The input parameter <parameter>bus</parameter> is | |
124 | <constant>NULL</constant> or the bus is not connected.</para></listitem> | |
125 | </varlistentry> | |
126 | ||
127 | <varlistentry> | |
128 | <term><constant>-ECONNRESET</constant></term> | |
129 | ||
130 | <listitem><para>The bus connection was closed while waiting for the response. | |
131 | </para></listitem> | |
132 | </varlistentry> | |
133 | ||
134 | <varlistentry> | |
135 | <term><constant>-ENOMEM</constant></term> | |
136 | ||
137 | <listitem><para>Memory allocation failed.</para></listitem> | |
138 | </varlistentry> | |
139 | </variablelist> | |
140 | </refsect2> | |
141 | </refsect1> | |
142 | ||
143 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
144 | ||
145 | <refsect1> | |
146 | <title>See Also</title> | |
147 | ||
148 | <para> | |
149 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
150 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
151 | <citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
152 | <citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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153 | <citerefentry><refentrytitle>sd_bus_reply_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
154 | <citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
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155 | </para> |
156 | </refsect1> | |
157 | ||
158 | </refentry> |