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514094f9 1<?xml version='1.0'?>
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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">
0307f791 4<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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6<refentry id="sd_bus_set_watch_bind"
7 xmlns:xi="http://www.w3.org/2001/XInclude">
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8
9 <refentryinfo>
10 <title>sd_bus_set_watch_bind</title>
11 <productname>systemd</productname>
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12 </refentryinfo>
13
14 <refmeta>
15 <refentrytitle>sd_bus_set_watch_bind</refentrytitle>
16 <manvolnum>3</manvolnum>
17 </refmeta>
18
19 <refnamediv>
20 <refname>sd_bus_set_watch_bind</refname>
21 <refname>sd_bus_get_watch_bind</refname>
22
23 <refpurpose>Control socket binding watching on bus connections</refpurpose>
24 </refnamediv>
25
26 <refsynopsisdiv>
27 <funcsynopsis>
28 <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
29
30 <funcprototype>
31 <funcdef>int <function>sd_bus_set_watch_bind</function></funcdef>
32 <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
33 <paramdef>int <parameter>b</parameter></paramdef>
34 </funcprototype>
35
36 <funcprototype>
37 <funcdef>int <function>sd_bus_get_watch_bind</function></funcdef>
38 <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
39 </funcprototype>
40
41 </funcsynopsis>
42 </refsynopsisdiv>
43
44 <refsect1>
45 <title>Description</title>
46
47 <para><function>sd_bus_set_watch_bind()</function> may be used to enable or disable client-side watching of server
48 socket binding for a bus connection object. If the <parameter>b</parameter> is true, the feature is enabled,
49 otherwise disabled (which is the default). When enabled, and the selected bus address refers to an
50 <filename>AF_UNIX</filename> socket in the file system which does not exist while the connection attempt is made an
b7a47345 51 <citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry> watch is installed on
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52 it, waiting for the socket to appear. As soon as the socket appears the connection is made. This functionality is
53 useful in particular in early-boot programs that need to run before the system bus is available, but want to
54 connect to it the instant it may be connected to.</para>
55
56 <para><function>sd_bus_get_watch_bind()</function> may be used to query the current setting of this feature. It
57 returns zero when the feature is disabled, and positive if enabled.</para>
58
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59 <para>Note that no timeout is applied while we wait for the socket to appear. This means that any
60 synchronous remote operation (such as
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61 <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
62 <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry> or
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63 <citerefentry><refentrytitle>sd_bus_request_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>),
64 that is used on a connection with this feature enabled that hasn't been established yet, might block
65 forever if the socket is never created. However, asynchronous remote operations (such as
d97eac36 66 <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
55cf7779 67 <citerefentry><refentrytitle>sd_bus_call_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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68 <citerefentry><refentrytitle>sd_bus_add_match_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>)
69 do not block in this case, and safely enqueue the requested operations to be dispatched the instant the
70 connection is set up.</para>
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71
72 <para>Use <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry> to
73 determine whether the connection is fully established, i.e. whether the peer socket has been bound, connected to
74 and authenticated. Use
75 <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> to
76 be notified when the connection is fully established.</para>
77
78 </refsect1>
79
80 <refsect1>
81 <title>Return Value</title>
82
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83 <para>On success, these functions return 0 or a positive integer. On failure, they return a negative
84 errno-style error code.</para>
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86 <refsect2>
87 <title>Errors</title>
d97eac36 88
b1de39de 89 <para>Returned errors may indicate the following problems:</para>
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91 <variablelist>
92 <varlistentry>
93 <term><constant>-ECHILD</constant></term>
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95 <listitem><para>The bus connection has been created in a different process.</para></listitem>
96 </varlistentry>
97 </variablelist>
98 </refsect2>
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99 </refsect1>
100
7647c01d 101 <xi:include href="libsystemd-pkgconfig.xml" />
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102
103 <refsect1>
104 <title>See Also</title>
105
106 <para>
107 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
108 <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
b7a47345 109 <citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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110 <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
111 <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
112 <citerefentry><refentrytitle>sd_bus_request_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
113 <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
114 <citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
115 </para>
116 </refsect1>
117
118</refentry>