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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/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 <systemd/sd-bus.h></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> with a NULL
terminator item. The callback should return a non-negative value on success.
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, library or module instance.</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>History</title>
<para><function>sd_bus_node_enumerator_t()</function> and
<function>sd_bus_add_node_enumerator()</function> were added in version 221.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>busctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd_bus_add_fallback_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
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