]>
Commit | Line | Data |
---|---|---|
d97eac36 LP |
1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | SPDX-License-Identifier: LGPL-2.1+ | |
7 | ||
8 | This file is part of systemd. | |
9 | ||
10 | Copyright 2017 Lennart Poettering | |
11 | ||
12 | systemd is free software; you can redistribute it and/or modify it | |
13 | under the terms of the GNU Lesser General Public License as published by | |
14 | the Free Software Foundation; either version 2.1 of the License, or | |
15 | (at your option) any later version. | |
16 | ||
17 | systemd is distributed in the hope that it will be useful, but | |
18 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | Lesser General Public License for more details. | |
21 | ||
22 | You should have received a copy of the GNU Lesser General Public License | |
23 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
24 | --> | |
25 | ||
26 | <refentry id="sd_bus_set_watch_bind"> | |
27 | ||
28 | <refentryinfo> | |
29 | <title>sd_bus_set_watch_bind</title> | |
30 | <productname>systemd</productname> | |
31 | ||
32 | <authorgroup> | |
33 | <author> | |
34 | <contrib>Developer</contrib> | |
35 | <firstname>Lennart</firstname> | |
36 | <surname>Poettering</surname> | |
37 | <email>lennart@poettering.net</email> | |
38 | </author> | |
39 | </authorgroup> | |
40 | </refentryinfo> | |
41 | ||
42 | <refmeta> | |
43 | <refentrytitle>sd_bus_set_watch_bind</refentrytitle> | |
44 | <manvolnum>3</manvolnum> | |
45 | </refmeta> | |
46 | ||
47 | <refnamediv> | |
48 | <refname>sd_bus_set_watch_bind</refname> | |
49 | <refname>sd_bus_get_watch_bind</refname> | |
50 | ||
51 | <refpurpose>Control socket binding watching on bus connections</refpurpose> | |
52 | </refnamediv> | |
53 | ||
54 | <refsynopsisdiv> | |
55 | <funcsynopsis> | |
56 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
57 | ||
58 | <funcprototype> | |
59 | <funcdef>int <function>sd_bus_set_watch_bind</function></funcdef> | |
60 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
61 | <paramdef>int <parameter>b</parameter></paramdef> | |
62 | </funcprototype> | |
63 | ||
64 | <funcprototype> | |
65 | <funcdef>int <function>sd_bus_get_watch_bind</function></funcdef> | |
66 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
67 | </funcprototype> | |
68 | ||
69 | </funcsynopsis> | |
70 | </refsynopsisdiv> | |
71 | ||
72 | <refsect1> | |
73 | <title>Description</title> | |
74 | ||
75 | <para><function>sd_bus_set_watch_bind()</function> may be used to enable or disable client-side watching of server | |
76 | socket binding for a bus connection object. If the <parameter>b</parameter> is true, the feature is enabled, | |
77 | otherwise disabled (which is the default). When enabled, and the selected bus address refers to an | |
78 | <filename>AF_UNIX</filename> socket in the file system which does not exist while the connection attempt is made an | |
79 | <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry> watch is installed on | |
80 | it, waiting for the socket to appear. As soon as the socket appears the connection is made. This functionality is | |
81 | useful in particular in early-boot programs that need to run before the system bus is available, but want to | |
82 | connect to it the instant it may be connected to.</para> | |
83 | ||
84 | <para><function>sd_bus_get_watch_bind()</function> may be used to query the current setting of this feature. It | |
85 | returns zero when the feature is disabled, and positive if enabled.</para> | |
86 | ||
87 | <para>Note that no timeout is applied while it is waited for the socket to appear. This means that any synchronous | |
88 | remote operation (such as | |
89 | <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
90 | <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
91 | <citerefentry><refentrytitle>sd_bus_request_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>), that is | |
92 | used on a connection with this feature enabled that is not established yet might block unbounded if the socket is | |
93 | never created. However, asynchronous remote operations (such as | |
94 | <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
95 | <citerefentry><refentrytitle>sd_bus_add_match_async</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
96 | <citerefentry><refentrytitle>sd_bus_request_match_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>) do | |
97 | not block in this case, and safely enqueue the requested operations to be dispatched the instant the connection is | |
98 | set up.</para> | |
99 | ||
100 | <para>Use <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry> to | |
101 | determine whether the connection is fully established, i.e. whether the peer socket has been bound, connected to | |
102 | and authenticated. Use | |
103 | <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> to | |
104 | be notified when the connection is fully established.</para> | |
105 | ||
106 | </refsect1> | |
107 | ||
108 | <refsect1> | |
109 | <title>Return Value</title> | |
110 | ||
111 | <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style | |
112 | error code.</para> | |
113 | </refsect1> | |
114 | ||
115 | <refsect1> | |
116 | <title>Errors</title> | |
117 | ||
118 | <para>Returned errors may indicate the following problems:</para> | |
119 | ||
120 | <variablelist> | |
121 | <varlistentry> | |
122 | <term><constant>-ECHILD</constant></term> | |
123 | ||
124 | <listitem><para>The bus connection has been created in a different process.</para></listitem> | |
125 | </varlistentry> | |
126 | </variablelist> | |
127 | </refsect1> | |
128 | ||
129 | <refsect1> | |
130 | <title>Notes</title> | |
131 | ||
132 | <para><function>sd_bus_set_watch_bind()</function> and <function>sd_bus_get_watch_bind()</function> are available as | |
133 | a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry | |
134 | project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para> | |
135 | </refsect1> | |
136 | ||
137 | <refsect1> | |
138 | <title>See Also</title> | |
139 | ||
140 | <para> | |
141 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
142 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
143 | <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
144 | <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
145 | <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
146 | <citerefentry><refentrytitle>sd_bus_request_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
147 | <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
148 | <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
149 | </para> | |
150 | </refsect1> | |
151 | ||
152 | </refentry> |