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">
4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6<refentry id="sd_bus_set_watch_bind"
7          xmlns:xi="http://www.w3.org/2001/XInclude">
8
9  <refentryinfo>
10    <title>sd_bus_set_watch_bind</title>
11    <productname>systemd</productname>
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
51    <citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry> watch is installed on
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
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
61    <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
62    <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry> or
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
66    <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
67    <citerefentry><refentrytitle>sd_bus_call_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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>
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
83    <para>On success, these functions return 0 or a positive integer. On failure, they return a negative
84    errno-style error code.</para>
85
86    <refsect2>
87      <title>Errors</title>
88
89      <para>Returned errors may indicate the following problems:</para>
90
91      <variablelist>
92        <varlistentry>
93          <term><constant>-ECHILD</constant></term>
94
95          <listitem><para>The bus connection has been created in a different process.</para></listitem>
96        </varlistentry>
97      </variablelist>
98    </refsect2>
99  </refsect1>
100
101  <xi:include href="libsystemd-pkgconfig.xml" />
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>,
109      <citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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>
119