summaryrefslogtreecommitdiffstats
path: root/man/sd_bus_add_node_enumerator.xml
blob: da3989ef94b367429bbb0c82fdc56ef1f1f83d12 (plain)
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
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="sd_bus_add_node_enumerator"
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>sd_bus_add_node_enumerator</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_add_node_enumerator</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_add_node_enumerator</refname>

    <refpurpose>Add a node enumerator for a D-Bus object path prefix</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

      <funcprototype>
        <funcdef>typedef int (*<function>sd_bus_node_enumerator_t</function>)</funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>const char *<parameter>prefix</parameter></paramdef>
        <paramdef>void *<parameter>userdata</parameter></paramdef>
        <paramdef>char ***<parameter>ret_nodes</parameter></paramdef>
        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_add_node_enumerator</function></funcdef>
        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
        <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
        <paramdef>const char *<parameter>path</parameter></paramdef>
        <paramdef>sd_bus_node_enumerator_t <parameter>callback</parameter></paramdef>
        <paramdef>void *<parameter>userdata</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><function>sd_bus_add_node_enumerator()</function> adds a D-Bus node enumerator for the
    given path prefix. The given callback is called to enumerate all the available objects with
    the given path prefix when required (e.g. when
    <constant>org.freedesktop.DBus.Introspectable.Introspect</constant> or
    <constant>org.freedesktop.DBus.ObjectManager.GetManagedObjects</constant> are called on a
    D-Bus service managed by sd-bus).</para>

    <para><parameter>callback</parameter> is called with the path and userdata pointer registered
    with <function>sd_bus_add_node_enumerator()</function>. When called, it should store all the
    child object paths of the given path prefix in <parameter>ret_nodes</parameter> and return the
    number of child objects under the given prefix. If an error occurs, it can either return a
    negative integer, set <parameter>ret_error</parameter> to a non-empty error or do both. Any
    errors returned by the callback are encoded as D-Bus errors and sent back to the caller. Errors
    in <parameter>ret_error</parameter> take priority over negative return values.</para>

    <para>Note that a node enumerator callback will only ever be called for a single  path prefix
    and hence, for normal operation, <parameter>prefix</parameter> can be ignored. Also, a node
    enumerator is only used to enumerate the available child objects under a given prefix. To
    install a handler for a set of dynamic child objects, use
    <citerefentry><refentrytitle>sd_bus_add_fallback_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>

    <para>When <function>sd_bus_add_node_enumerator()</function> succeeds, a slot is created
    internally. If the output parameter <replaceable>slot</replaceable> is <constant>NULL</constant>,
    a "floating" slot object is created, see
    <citerefentry><refentrytitle>sd_bus_slot_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    Otherwise, a pointer to the slot object is returned. In that case, the reference to the slot
    object should be dropped when the node enumerator is not needed anymore, see
    <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>
  </refsect1>

  <refsect1>
    <title>Return Value</title>

    <para>On success, <function>sd_bus_add_node_enumerator()</function> returns a non-negative
    integer. On failure, it returns a negative errno-style error code.</para>

    <refsect2>
      <title>Errors</title>

      <para>Returned errors may indicate the following problems:</para>

      <variablelist>
        <varlistentry>
          <term><constant>-EINVAL</constant></term>

          <listitem><para>One of the required parameters is <constant>NULL</constant> or
          <parameter>path</parameter> is not a valid object path.
          </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-ENOPKG</constant></term>

          <listitem><para>The bus cannot be resolved.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-ECHILD</constant></term>

          <listitem><para>The bus was created in a different process.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-ENOMEM</constant></term>

          <listitem><para>Memory allocation failed.</para></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
  </refsect1>

  <xi:include href="libsystemd-pkgconfig.xml" />

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>busctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_bus_add_fallback_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    </para>
  </refsect1>
</refentry>