1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2014 Zbigniew Jędrzejewski-Szmek
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_bus_open_user">
<refentryinfo>
<title>sd_bus_open_user</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>A monkey with a typewriter</contrib>
<firstname>Zbigniew</firstname>
<surname>Jędrzejewski-Szmek</surname>
<email>zbyszek@in.waw.pl</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_open_user</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_open_user</refname>
<refname>sd_bus_open_system</refname>
<refname>sd_bus_open_system_remote</refname>
<refname>sd_bus_open_system_container</refname>
<refname>sd_bus_default_user</refname>
<refname>sd_bus_default_system</refname>
<refpurpose>Open a connection to the system or user bus</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_open_user</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system_remote</function></funcdef>
<paramdef>const char *<parameter>host</parameter></paramdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system_container</function></funcdef>
<paramdef>const char *<parameter>machine</parameter></paramdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_default_user</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_default_system</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_open_user()</function> creates a new bus
object and opens a connection to the the user bus.
<function>sd_bus_open_system()</function> does the same, but
connects to the system bus.</para>
<para>If the <varname>$DBUS_SESSION_BUS_ADDRESS</varname> environment
variable is set
(c.f. <citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
it will be used as the address of the user bus. This variable can
contain multiple addresses separated by <literal>;</literal>. If
this variable is not set, a suitable default for the default user
D-Bus instance will be used.</para>
<para>If the <varname>$DBUS_SYSTEM_BUS_ADDRESS</varname> environment
variable is set, it will be used as the address of the system
bus. This variable uses the same syntax as
<varname>$DBUS_SESSION_BUS_ADDRESS</varname>/. If this variable is
not set, a suitable default for the default system D-Bus instance
will be used.</para>
<para><function>sd_bus_open_system_remote()</function> connects to
the system bus on the specified <parameter>host</parameter> using
SSH. <parameter>host</parameter> consists of an optional user name
followed by the <literal>@</literal> symbol, and the hostname.
</para>
<para><function>sd_bus_open_system_remote()</function> connects to
the system bus in the specified <parameter>machine</parameter>,
where <parameter>machine</parameter> is the name of a container.
See
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
for more information about "machines".</para>
<para><function>sd_bus_default_user()</function> returns a bus
object connected to the user bus. Each thread has its own object, but it
may be passed around. It is created on the first invocation of
<function>sd_bus_default_user()</function>, and subsequent
invocations returns a reference to the same object.</para>
<para><function>sd_bus_default_system()</function> is similar to
<function>sd_bus_default_user()</function>, but connects to the
system bus.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these calls return 0 or a positive
integer. On failure, these calls return a negative
errno-style error code.</para>
</refsect1>
<refsect1>
<title>Reference ownership</title>
<para>Functions <function>sd_bus_open_user()</function>,
<function>sd_bus_open_system()</function>,
<function>sd_bus_open_system_remote()</function>, and
<function>sd_bus_open_system_machine()</function> return a new
object and the caller owns the sole reference. When not needed
anymore, this reference should be destroyed with
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
<para>The functions <function>sd_bus_default_user()</function> and
<function>sd_bus_default_system()</function> do not create a new
reference.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><varname>-EINVAL</varname></term>
<listitem><para>Specified parameter is invalid
(<constant>NULL</constant> in case of output
parameters).</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>-ENOMEM</varname></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
<para>In addition, any further connection-related errors may be
by returned. See <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_bus_open_user()</function> and other functions
described here are available as a shared library, which can be
compiled and linked to with the
<constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
