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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 | |
d97eac36 LP |
11 | --> |
12 | ||
13 | <refentry id="sd_bus_set_watch_bind"> | |
14 | ||
15 | <refentryinfo> | |
16 | <title>sd_bus_set_watch_bind</title> | |
17 | <productname>systemd</productname> | |
18 | ||
19 | <authorgroup> | |
20 | <author> | |
21 | <contrib>Developer</contrib> | |
22 | <firstname>Lennart</firstname> | |
23 | <surname>Poettering</surname> | |
24 | <email>lennart@poettering.net</email> | |
25 | </author> | |
26 | </authorgroup> | |
27 | </refentryinfo> | |
28 | ||
29 | <refmeta> | |
30 | <refentrytitle>sd_bus_set_watch_bind</refentrytitle> | |
31 | <manvolnum>3</manvolnum> | |
32 | </refmeta> | |
33 | ||
34 | <refnamediv> | |
35 | <refname>sd_bus_set_watch_bind</refname> | |
36 | <refname>sd_bus_get_watch_bind</refname> | |
37 | ||
38 | <refpurpose>Control socket binding watching on bus connections</refpurpose> | |
39 | </refnamediv> | |
40 | ||
41 | <refsynopsisdiv> | |
42 | <funcsynopsis> | |
43 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
44 | ||
45 | <funcprototype> | |
46 | <funcdef>int <function>sd_bus_set_watch_bind</function></funcdef> | |
47 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
48 | <paramdef>int <parameter>b</parameter></paramdef> | |
49 | </funcprototype> | |
50 | ||
51 | <funcprototype> | |
52 | <funcdef>int <function>sd_bus_get_watch_bind</function></funcdef> | |
53 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
54 | </funcprototype> | |
55 | ||
56 | </funcsynopsis> | |
57 | </refsynopsisdiv> | |
58 | ||
59 | <refsect1> | |
60 | <title>Description</title> | |
61 | ||
62 | <para><function>sd_bus_set_watch_bind()</function> may be used to enable or disable client-side watching of server | |
63 | socket binding for a bus connection object. If the <parameter>b</parameter> is true, the feature is enabled, | |
64 | otherwise disabled (which is the default). When enabled, and the selected bus address refers to an | |
65 | <filename>AF_UNIX</filename> socket in the file system which does not exist while the connection attempt is made an | |
66 | <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry> watch is installed on | |
67 | it, waiting for the socket to appear. As soon as the socket appears the connection is made. This functionality is | |
68 | useful in particular in early-boot programs that need to run before the system bus is available, but want to | |
69 | connect to it the instant it may be connected to.</para> | |
70 | ||
71 | <para><function>sd_bus_get_watch_bind()</function> may be used to query the current setting of this feature. It | |
72 | returns zero when the feature is disabled, and positive if enabled.</para> | |
73 | ||
74 | <para>Note that no timeout is applied while it is waited for the socket to appear. This means that any synchronous | |
75 | remote operation (such as | |
76 | <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
77 | <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
78 | <citerefentry><refentrytitle>sd_bus_request_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>), that is | |
79 | used on a connection with this feature enabled that is not established yet might block unbounded if the socket is | |
80 | never created. However, asynchronous remote operations (such as | |
81 | <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
82 | <citerefentry><refentrytitle>sd_bus_add_match_async</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
83 | <citerefentry><refentrytitle>sd_bus_request_match_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>) do | |
84 | not block in this case, and safely enqueue the requested operations to be dispatched the instant the connection is | |
85 | set up.</para> | |
86 | ||
87 | <para>Use <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry> to | |
88 | determine whether the connection is fully established, i.e. whether the peer socket has been bound, connected to | |
89 | and authenticated. Use | |
90 | <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> to | |
91 | be notified when the connection is fully established.</para> | |
92 | ||
93 | </refsect1> | |
94 | ||
95 | <refsect1> | |
96 | <title>Return Value</title> | |
97 | ||
98 | <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style | |
99 | error code.</para> | |
100 | </refsect1> | |
101 | ||
102 | <refsect1> | |
103 | <title>Errors</title> | |
104 | ||
105 | <para>Returned errors may indicate the following problems:</para> | |
106 | ||
107 | <variablelist> | |
108 | <varlistentry> | |
109 | <term><constant>-ECHILD</constant></term> | |
110 | ||
111 | <listitem><para>The bus connection has been created in a different process.</para></listitem> | |
112 | </varlistentry> | |
113 | </variablelist> | |
114 | </refsect1> | |
115 | ||
116 | <refsect1> | |
117 | <title>Notes</title> | |
118 | ||
119 | <para><function>sd_bus_set_watch_bind()</function> and <function>sd_bus_get_watch_bind()</function> are available as | |
120 | a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry | |
121 | project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para> | |
122 | </refsect1> | |
123 | ||
124 | <refsect1> | |
125 | <title>See Also</title> | |
126 | ||
127 | <para> | |
128 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
129 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
130 | <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
131 | <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
132 | <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
133 | <citerefentry><refentrytitle>sd_bus_request_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
134 | <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
135 | <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
136 | </para> | |
137 | </refsect1> | |
138 | ||
139 | </refentry> |