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https://github.com/systemd/systemd
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143 lines
6.2 KiB
XML
143 lines
6.2 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_bus_add_node_enumerator"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_bus_add_node_enumerator</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_add_node_enumerator</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_add_node_enumerator</refname>
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<refpurpose>Add a node enumerator for a D-Bus object path prefix</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>typedef int (*<function>sd_bus_node_enumerator_t</function>)</funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char *<parameter>prefix</parameter></paramdef>
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<paramdef>void *<parameter>userdata</parameter></paramdef>
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<paramdef>char ***<parameter>ret_nodes</parameter></paramdef>
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<paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_add_node_enumerator</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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<paramdef>sd_bus_node_enumerator_t <parameter>callback</parameter></paramdef>
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<paramdef>void *<parameter>userdata</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_bus_add_node_enumerator()</function> adds a D-Bus node enumerator for the
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given path prefix. The given callback is called to enumerate all the available objects with
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the given path prefix when required (e.g. when
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<constant>org.freedesktop.DBus.Introspectable.Introspect</constant> or
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<constant>org.freedesktop.DBus.ObjectManager.GetManagedObjects</constant> are called on a
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D-Bus service managed by sd-bus).</para>
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<para><parameter>callback</parameter> is called with the path and userdata pointer registered
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with <function>sd_bus_add_node_enumerator()</function>. When called, it should store all the
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child object paths of the given path prefix in <parameter>ret_nodes</parameter> with a NULL
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terminator item. The callback should return a non-negative value on success.
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If an error occurs, it can either return a
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negative integer, set <parameter>ret_error</parameter> to a non-empty error or do both. Any
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errors returned by the callback are encoded as D-Bus errors and sent back to the caller. Errors
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in <parameter>ret_error</parameter> take priority over negative return values.</para>
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<para>Note that a node enumerator callback will only ever be called for a single path prefix
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and hence, for normal operation, <parameter>prefix</parameter> can be ignored. Also, a node
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enumerator is only used to enumerate the available child objects under a given prefix. To
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install a handler for a set of dynamic child objects, use
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<citerefentry><refentrytitle>sd_bus_add_fallback_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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</para>
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<para>When <function>sd_bus_add_node_enumerator()</function> succeeds, a slot is created
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internally. If the output parameter <replaceable>slot</replaceable> is <constant>NULL</constant>,
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a "floating" slot object is created, see
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<citerefentry><refentrytitle>sd_bus_slot_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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Otherwise, a pointer to the slot object is returned. In that case, the reference to the slot
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object should be dropped when the node enumerator is not needed anymore, see
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<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, <function>sd_bus_add_node_enumerator()</function> returns a non-negative
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integer. On failure, it returns a negative errno-style error code.</para>
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<refsect2>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>One of the required parameters is <constant>NULL</constant> or
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<parameter>path</parameter> is not a valid object path.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOPKG</constant></term>
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<listitem><para>The bus cannot be resolved.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The bus was created in a different process, library or module instance.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>History</title>
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<para><function>sd_bus_node_enumerator_t()</function> and
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<function>sd_bus_add_node_enumerator()</function> were added in version 221.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>busctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_bus_add_fallback_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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