Merge pull request #12351 from keszybz/sd-bus-add-symbol

Add symbol to tell the linker that new libsystemd version is needed

18 files changed, 934 insertions, 222 deletions

diff --git a/man/busctl.xml b/man/busctl.xml
index e4c7fcb283..328c101622 100644
--- a/man/busctl.xml
+++ b/man/busctl.xml
@@ -141,6 +141,16 @@
       </varlistentry>
 
       <varlistentry>
+        <term><option>--xml-interface</option></term>
+
+        <listitem>
+          <para>When used with the <command>introspect</command> call, dump the XML description received from
+          the D-Bus <constant>org.freedesktop.DBus.Introspectable.Introspect</constant> call instead of the
+          normal output.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>--json=</option><replaceable>MODE</replaceable></term>
 
         <listitem>
diff --git a/man/rules/meson.build b/man/rules/meson.build
index 9674cbb30b..6894158466 100644
--- a/man/rules/meson.build
+++ b/man/rules/meson.build
@@ -115,6 +115,21 @@ manpages = [
    'sd_bus_match_signal',
    'sd_bus_match_signal_async'],
   ''],
+ ['sd_bus_add_object_vtable',
+  '3',
+  ['SD_BUS_METHOD',
+   'SD_BUS_METHOD_WITH_NAMES',
+   'SD_BUS_METHOD_WITH_NAMES_OFFSET',
+   'SD_BUS_METHOD_WITH_OFFSET',
+   'SD_BUS_PARAM',
+   'SD_BUS_PROPERTY',
+   'SD_BUS_SIGNAL',
+   'SD_BUS_SIGNAL_WITH_NAMES',
+   'SD_BUS_VTABLE_END',
+   'SD_BUS_VTABLE_START',
+   'SD_BUS_WRITABLE_PROPERTY',
+   'sd_bus_add_fallback_vtable'],
+  ''],
  ['sd_bus_attach_event', '3', ['sd_bus_detach_event', 'sd_bus_get_event'], ''],
  ['sd_bus_close', '3', ['sd_bus_flush'], ''],
  ['sd_bus_creds_get_pid',
diff --git a/man/sd-bus.xml b/man/sd-bus.xml
index 6c925e3161..e9a66d87dd 100644
--- a/man/sd-bus.xml
+++ b/man/sd-bus.xml
@@ -41,6 +41,7 @@
 
     <para>See
     <literallayout><citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+<citerefentry><refentrytitle>sd_bus_add_object_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 <citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
diff --git a/man/sd_bus_add_object_vtable.xml b/man/sd_bus_add_object_vtable.xml
new file mode 100644
index 0000000000..92be236afd
--- /dev/null
+++ b/man/sd_bus_add_object_vtable.xml
@@ -0,0 +1,473 @@
+<?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+ -->
+
+<refentry id="sd_bus_add_object_vtable"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_bus_add_object_vtable</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_bus_add_object_vtable</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_bus_add_object_vtable</refname>
+    <refname>sd_bus_add_fallback_vtable</refname>
+    <refname>SD_BUS_VTABLE_START</refname>
+    <refname>SD_BUS_VTABLE_END</refname>
+    <refname>SD_BUS_METHOD_WITH_NAMES_OFFSET</refname>
+    <refname>SD_BUS_METHOD_WITH_NAMES</refname>
+    <refname>SD_BUS_METHOD_WITH_OFFSET</refname>
+    <refname>SD_BUS_METHOD</refname>
+    <refname>SD_BUS_SIGNAL_WITH_NAMES</refname>
+    <refname>SD_BUS_SIGNAL</refname>
+    <refname>SD_BUS_WRITABLE_PROPERTY</refname>
+    <refname>SD_BUS_PROPERTY</refname>
+    <refname>SD_BUS_PARAM</refname>
+
+    <refpurpose>Declare properties and methods for a D-Bus path</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-bus-vtable.h&gt;</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_bus_message_handler_t</function>)</funcdef>
+        <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_bus_property_get_t</function>)</funcdef>
+        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+        <paramdef>const char *<parameter>path</parameter></paramdef>
+        <paramdef>const char *<parameter>interface</parameter></paramdef>
+        <paramdef>const char *<parameter>property</parameter></paramdef>
+        <paramdef>sd_bus_message *<parameter>reply</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_bus_property_set_t</function>)</funcdef>
+        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+        <paramdef>const char *<parameter>path</parameter></paramdef>
+        <paramdef>const char *<parameter>interface</parameter></paramdef>
+        <paramdef>const char *<parameter>property</parameter></paramdef>
+        <paramdef>sd_bus_message *<parameter>value</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_bus_object_find_t</function>)</funcdef>
+        <paramdef>const char *<parameter>path</parameter></paramdef>
+        <paramdef>const char *<parameter>interface</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+        <paramdef>void **<parameter>ret_found</parameter></paramdef>
+        <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_bus_add_object_vtable</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>const char *<parameter>interface</parameter></paramdef>
+        <paramdef>const sd_bus_vtable *<parameter>vtable</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_bus_add_fallback_vtable</function></funcdef>
+        <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+        <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
+        <paramdef>const char *<parameter>prefix</parameter></paramdef>
+        <paramdef>const char *<parameter>interface</parameter></paramdef>
+        <paramdef>const sd_bus_vtable *<parameter>vtable</parameter></paramdef>
+        <paramdef>sd_bus_object_find_t <parameter>find</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <para>
+        <constant>SD_BUS_VTABLE_START(<replaceable>flags</replaceable>)</constant>
+      </para>
+      <para>
+        <constant>SD_BUS_VTABLE_END</constant>
+      </para>
+      <para>
+        <constant>SD_BUS_METHOD_WITH_NAMES_OFFSET(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>in_names</replaceable>,
+        <replaceable>result</replaceable>,
+        <replaceable>out_names</replaceable>,
+        <replaceable>handler</replaceable>,
+        <replaceable>offset</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_METHOD_WITH_NAMES(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>in_names</replaceable>,
+        <replaceable>result</replaceable>,
+        <replaceable>out_names</replaceable>,
+        <replaceable>handler</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_METHOD_WITH_OFFSET(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>result</replaceable>,
+        <replaceable>handler</replaceable>,
+        <replaceable>offset</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_METHOD(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>result</replaceable>,
+        <replaceable>handler</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_SIGNAL_WITH_NAMES(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>names</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_SIGNAL(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_WRITABLE_PROPERTY(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>get</replaceable>,
+        <replaceable>set</replaceable>,
+        <replaceable>offset</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_PROPERTY(
+        <replaceable>member</replaceable>,
+        <replaceable>signature</replaceable>,
+        <replaceable>get</replaceable>,
+        <replaceable>offset</replaceable>,
+        <replaceable>flags</replaceable>)
+        </constant>
+      </para>
+      <para>
+        <constant>SD_BUS_PARAM(<replaceable>name</replaceable>)</constant>
+      </para>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_bus_add_object_vtable()</function> is used to declare attributes for the path object
+    path <parameter>path</parameter> connected to the bus connection <parameter>bus</parameter> under the
+    interface <parameter>interface</parameter>. The table <parameter>vtable</parameter> may contain property
+    declarations using <constant>SD_BUS_PROPERTY()</constant> or
+    <constant>SD_BUS_WRITABLE_PROPERTY()</constant>, method declarations using
+    <constant>SD_BUS_METHOD()</constant>, <constant>SD_BUS_METHOD_WITH_NAMES()</constant>,
+    <constant>SD_BUS_METHOD_WITH_OFFSET()</constant>, or
+    <constant>SD_BUS_METHOD_WITH_NAMES_OFFSET()</constant>, and signal declarations using
+    <constant>SD_BUS_SIGNAL_WITH_NAMES()</constant> or <constant>SD_BUS_SIGNAL()</constant>, see below. The
+    <replaceable>userdata</replaceable> parameter contains a pointer that will be passed to various callback
+    functions. It may be specified as <constant>NULL</constant> if no value is necessary.</para>
+
+    <para><function>sd_bus_add_object_vtable()</function> is similar to
+    <function>sd_bus_add_object_vtable()</function>, but is used to register "fallback" attributes. When
+    looking for an attribute declaration, bus object paths registered with
+    <function>sd_bus_add_object_vtable()</function> are checked first. If no match is found, the fallback
+    vtables are checked for each prefix of the bus object path, i.e. with the last slash-separated components
+    successively removed. This allows the vtable to be used for an arbitrary number of dynamically created
+    objects.</para>
+
+    <para>Parameter <replaceable>find</replaceable> is a function which is used to locate the target object
+    based on the bus object path <replaceable>path</replaceable>. It must return <constant>1</constant> and
+    set the <parameter>ret_found</parameter> output parameter if the object is found, return
+    <constant>0</constant> if the object was not found, and return a negative errno-style error code or
+    initialize the error structure <replaceable>ret_error</replaceable> on error. The pointer passed in
+    <parameter>ret_found</parameter> will be used as the <parameter>userdata</parameter> parameter for the
+    callback functions (offset by the <parameter>offset</parameter> offsets as specified in the vtable
+    entries).</para>
+
+    <para>For both functions, a match 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 vtable is not needed anymore, see
+    <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    </para>
+
+    <refsect2>
+      <title>The <structname>sd_bus_vtable</structname> array</title>
+
+      <para>The array consists of the structures of type <structname>sd_bus_vtable</structname>, but it
+      should never be filled in manually, but through one of the following macros:</para>
+
+      <variablelist>
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_START()</constant></term>
+          <term><constant>SD_BUS_VTABLE_END</constant></term>
+
+          <listitem><para>Those must always be the first and last element.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_METHOD_WITH_NAMES_OFFSET()</constant></term>
+          <term><constant>SD_BUS_METHOD_WITH_NAMES()</constant></term>
+          <term><constant>SD_BUS_METHOD_WITH_OFFSET()</constant></term>
+          <term><constant>SD_BUS_METHOD()</constant></term>
+
+          <listitem><para>Declare a D-Bus method with the name <replaceable>member</replaceable>, parameter
+          signature <replaceable>signature</replaceable>, result signature <replaceable>result</replaceable>.
+          Parameters <replaceable>in_names</replaceable> and <replaceable>out_names</replaceable> specify the
+          argument names of the input and output arguments in the function signature. The handler function
+          <replaceable>handler</replaceable> must be of type <function>sd_bus_message_handler_t</function>.
+          It will be called to handle the incoming messages that call this method. It receives a pointer that
+          is the <replaceable>userdata</replaceable> parameter passed to the registration function offset by
+          <replaceable>offset</replaceable> bytes. This may be used to pass pointers to different fields in
+          the same data structure to different methods in the same
+          vtable. <replaceable>in_names</replaceable> and <replaceable>out_names</replaceable> should be
+          created using the <constant>SD_BUS_PARAM()</constant> macro, see below. Parameter
+          <replaceable>flags</replaceable> is a combination of flags, see below.</para>
+
+          <para><constant>SD_BUS_METHOD_WITH_NAMES()</constant>,
+          <constant>SD_BUS_METHOD_WITH_OFFSET()</constant>, and <constant>SD_BUS_METHOD()</constant> are
+          variants which specify zero offset (<replaceable>userdata</replaceable> parameter is passed with
+          no change), leave the names unset (i.e. no parameter names), or both.</para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_SIGNAL_WITH_NAMES()</constant></term>
+          <term><constant>SD_BUS_SIGNAL()</constant></term>
+
+          <listitem><para>Declare a D-Bus signal with the name <replaceable>member</replaceable>,
+          parameter signature <replaceable>signature</replaceable>, and argument names
+          <replaceable>names</replaceable>. <replaceable>names</replaceable> should be
+          created using the <constant>SD_BUS_PARAM()</constant> macro, see below.
+          Parameter <replaceable>flags</replaceable> is a combination of flags, see below.
+          </para>
+
+          <para>Equivalent to <constant>SD_BUS_SIGNAL_WITH_NAMES()</constant> with the
+          <replaceable>names</replaceable> paramater unset (i.e. no parameter names).</para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_WRITABLE_PROPERTY()</constant></term>
+          <term><constant>SD_BUS_PROPERTY()</constant></term>
+
+          <listitem><para>Declare a D-Bus property with the name <replaceable>member</replaceable> and value
+          signature <replaceable>signature</replaceable>. Parameters <replaceable>get</replaceable> and
+          <replaceable>set</replaceable> are the getter and setter methods. They are called with a pointer
+          that is the <replaceable>userdata</replaceable> parameter passed to the registration function
+          offset by <replaceable>offset</replaceable> bytes. This may be used pass pointers to different
+          fields in the same data structure to different setters and getters in the same vtable. Parameter
+          <replaceable>flags</replaceable> is a combination of flags, see below.</para>
+
+          <para>The setter and getter methods may be omitted (specified as <constant>NULL</constant>), if the
+          property has one of the basic types or <literal>as</literal> in case of read-only properties. In
+          those cases, the <replaceable>userdata</replaceable> and <replaceable>offset</replaceable>
+          parameters must together point to valid variable of the corresponding type. A default setter and
+          getters will be provided, which simply copy the argument between this variable and the message.
+          </para>
+
+          <para><constant>SD_BUS_PROPERTY()</constant> is used to define a read-only property.</para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_PARAM()</constant></term>
+          <listitem><para>Parameter names should be wrapped in this macro, see the example below.</para>
+          </listitem>
+        </varlistentry>
+      </variablelist>
+    </refsect2>
+
+    <refsect2>
+      <title>Flags</title>
+
+      <para>The <replaceable>flags</replaceable> parameter is used to specify a combination of
+      <ulink url="https://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format">D-Bus annotations</ulink>.
+      </para>
+
+      <variablelist>
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_DEPRECATED</constant></term>
+
+          <listitem><para>Mark this vtable entry as deprecated using the
+          <constant>org.freedesktop.DBus.Deprecated</constant> annotation in introspection data.  If
+          specified for <constant>SD_BUS_VTABLE_START()</constant>, the annotation is applied to the
+          enclosing interface.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_HIDDEN</constant></term>
+
+          <listitem><para>Make this vtable entry hidden. It will not be shown in introspection data.  If
+          specified for <constant>SD_BUS_VTABLE_START()</constant>, all entries in the array are hidden.
+          </para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_UNPRIVILEGED</constant></term>
+
+          <listitem><para>Mark this vtable entry as unprivileged. If not specified, the
+          <constant>org.freedesktop.systemd1.Privileged</constant> annotation with value
+          <literal>true</literal> will be shown in introspection data.</para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_METHOD_NO_REPLY</constant></term>
+
+          <listitem><para>Mark his vtable entry as a method that will not return a reply using the
+          <constant>org.freedesktop.DBus.Method.NoReply</constant> annotation in introspection data.
+          </para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_CONST</constant></term>
+          <term><constant>SD_BUS_VTABLE_EMITS_CHANGE</constant></term>
+          <term><constant>SD_BUS_VTABLE_EMITS_INVALIDATION</constant></term>
+
+          <listitem><para>Those three flags correspond to different values of the
+          <constant>org.freedesktop.DBus.Property.EmitsChangedSignal</constant> annotation, which specifies
+          whether the <constant>org.freedesktop.DBus.Properties.PropertiesChanged</constant> signal is
+          emitted whenever the property changes. <constant>SD_BUS_VTABLE_CONST</constant> corresponds to
+          <constant>const</constant> and means that the property never changes during the lifetime of the
+          object it belongs to, so no signal needs to be emitted.
+          <constant>SD_BUS_VTABLE_EMITS_CHANGE</constant> corresponds to <constant>true</constant> and means
+          that the signal is emitted. <constant>SD_BUS_VTABLE_EMITS_INVALIDATION</constant> corresponds to
+          <constant>invalides</constant> and means that the signal is emitted, but the value is not included
+          in the signal.</para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_PROPERTY_EXPLICIT</constant></term>
+
+          <listitem><para>Mark this vtable property entry as requiring explicit request to for the value to
+          be shown (generally because the value is large or slow to calculate). This entry cannot be combined
+          with <constant>SD_BUS_VTABLE_EMITS_CHANGE</constant>, and will not be shown in property listings by
+          default (e.g. <command>busctl introspect</command>).  This corresponds to the
+          <constant>org.freedesktop.systemd1.Explicit</constant> annotation in introspection data.</para>
+          </listitem>
+        </varlistentry>
+      </variablelist>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Examples</title>
+
+    <example>
+      <title>Create a simple listener on the bus</title>
+
+      <programlisting><xi:include href="vtable-example.c" parse="text" /></programlisting>
+
+      <para>This creates a simple client on the bus (the user bus, when run as normal user).
+      We may use the D-Bus <constant>org.freedesktop.DBus.Introspectable.Introspect</constant>
+      call to acquire the XML description of the interface:</para>
+
+      <programlisting><xi:include href="vtable-example.xml" parse="text" /></programlisting>
+    </example>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para>On success, <function>sd_bus_add_object_vtable</function> and
+    <function>sd_bus_add_fallback_vtable</function> calls return 0 or a positive integer. On failure, they
+    return 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 invalid. A reserved
+          D-Bus interface was passed as the <replaceable>interface</replaceable> parameter.</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>
+
+        <varlistentry>
+          <term><constant>-EPROTOTYPE</constant></term>
+
+          <listitem><para><function>sd_bus_add_object_vtable</function> and
+          <function>sd_bus_add_fallback_vtable</function> have been both called
+          for the same bus object path, which is not allowed.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EEXIST</constant></term>
+
+          <listitem><para>This vtable has already been registered for this
+          <replaceable>interface</replaceable> and <replaceable>path</replaceable>.
+          </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>
+    </para>
+  </refsect1>
+</refentry>
diff --git a/man/vtable-example.c b/man/vtable-example.c
new file mode 100644
index 0000000000..a2a6cd18d7
--- /dev/null
+++ b/man/vtable-example.c
@@ -0,0 +1,70 @@
+#include <errno.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <systemd/sd-bus.h>
+
+#define _cleanup_(f) __attribute__((cleanup(f)))
+
+typedef struct object {
+  char *name;
+  uint32_t number;
+} object;
+
+static int method(sd_bus_message *m, void *userdata, sd_bus_error *error) {
+  printf("Got called with userdata=%p\n", userdata);
+  return 1;
+}
+
+static const sd_bus_vtable vtable[] = {
+        SD_BUS_VTABLE_START(0),
+        SD_BUS_METHOD(
+            "Method1", "s", "s", method, 0),
+        SD_BUS_METHOD_WITH_NAMES_OFFSET(
+            "Method2",
+            "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
+            "s", SD_BUS_PARAM(returnstring),
+            method, offsetof(object, number),
+            SD_BUS_VTABLE_DEPRECATED),
+        SD_BUS_WRITABLE_PROPERTY(
+            "AutomaticStringProperty", "s", NULL, NULL,
+            offsetof(object, name),
+            SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
+        SD_BUS_WRITABLE_PROPERTY(
+            "AutomaticIntegerProperty", "u", NULL, NULL,
+            offsetof(object, number),
+            SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
+        SD_BUS_VTABLE_END
+};
+
+#define check(x) ({                             \
+  int r = x;                                    \
+  errno = r < 0 ? -r : 0;                       \
+  printf(#x ": %m\n");                          \
+  if (r < 0)                                    \
+    return EXIT_FAILURE;                        \
+  })
+
+int main(int argc, char **argv) {
+  _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
+
+  sd_bus_default(&bus);
+
+  object object = { .number = 666 };
+  check((object.name = strdup("name")) != NULL);
+
+  check(sd_bus_add_object_vtable(bus, NULL, "/object",
+                                 "org.freedesktop.systemd.VtableExample",
+                                 vtable,
+                                 &object));
+
+  while (true) {
+    check(sd_bus_wait(bus, UINT64_MAX));
+    check(sd_bus_process(bus, NULL));
+  }
+
+  free(object.name);
+
+  return 0;
+}
diff --git a/man/vtable-example.xml b/man/vtable-example.xml
new file mode 100644
index 0000000000..a3cdeae704
--- /dev/null
+++ b/man/vtable-example.xml
@@ -0,0 +1,54 @@
+<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
+"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
+<node>
+ <interface name="org.freedesktop.DBus.Peer">
+  <method name="Ping"/>
+  <method name="GetMachineId">
+   <arg type="s" name="machine_uuid" direction="out"/>
+  </method>
+ </interface>
+ <interface name="org.freedesktop.DBus.Introspectable">
+  <method name="Introspect">
+   <arg name="data" type="s" direction="out"/>
+  </method>
+ </interface>
+ <interface name="org.freedesktop.DBus.Properties">
+  <method name="Get">
+   <arg name="interface" direction="in" type="s"/>
+   <arg name="property" direction="in" type="s"/>
+   <arg name="value" direction="out" type="v"/>
+  </method>
+  <method name="GetAll">
+   <arg name="interface" direction="in" type="s"/>
+   <arg name="properties" direction="out" type="a{sv}"/>
+  </method>
+  <method name="Set">
+   <arg name="interface" direction="in" type="s"/>
+   <arg name="property" direction="in" type="s"/>
+   <arg name="value" direction="in" type="v"/>
+  </method>
+  <signal name="PropertiesChanged">
+   <arg type="s" name="interface"/>
+   <arg type="a{sv}" name="changed_properties"/>
+   <arg type="as" name="invalidated_properties"/>
+  </signal>
+ </interface>
+ <interface name="org.freedesktop.systemd.VtableExample">
+  <method name="Method1">
+   <arg type="s" direction="in"/>
+   <arg type="s" direction="out"/>
+  </method>
+  <method name="Method2">
+   <arg type="s" name="string" direction="in"/>
+   <arg type="o" name="path" direction="in"/>
+   <arg type="s" name="returnstring" direction="out"/>
+   <annotation name="org.freedesktop.DBus.Deprecated" value="true"/>
+  </method>
+  <property name="AutomaticStringProperty" type="s" access="readwrite">
+  </property>
+  <property name="AutomaticIntegerProperty" type="u" access="readwrite">
+   <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="invalidates"/>
+  </property>
+ </interface>
+</node>
+
diff --git a/src/busctl/busctl.c b/src/busctl/busctl.c
index 02f12dc701..86efc02bd8 100644
--- a/src/busctl/busctl.c
+++ b/src/busctl/busctl.c
@@ -50,6 +50,7 @@ static size_t arg_snaplen = 4096;
 static bool arg_list = false;
 static bool arg_quiet = false;
 static bool arg_verbose = false;
+static bool arg_xml_interface = false;
 static bool arg_expect_reply = true;
 static bool arg_auto_start = true;
 static bool arg_allow_interactive_authorization = true;
@@ -948,6 +949,12 @@ static int introspect(int argc, char **argv, void *userdata) {
         if (r < 0)
                 return bus_log_parse_error(r);
 
+        if (arg_xml_interface) {
+                /* Just dump the received XML and finish */
+                puts(xml);
+                return 0;
+        }
+
         /* First, get list of all properties */
         r = parse_xml_introspect(argv[2], xml, &ops, members);
         if (r < 0)
@@ -2255,6 +2262,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_SIZE,
                 ARG_LIST,
                 ARG_VERBOSE,
+                ARG_XML_INTERFACE,
                 ARG_EXPECT_REPLY,
                 ARG_AUTO_START,
                 ARG_ALLOW_INTERACTIVE_AUTHORIZATION,
@@ -2284,6 +2292,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "list",                            no_argument,       NULL, ARG_LIST                            },
                 { "quiet",                           no_argument,       NULL, 'q'                                 },
                 { "verbose",                         no_argument,       NULL, ARG_VERBOSE                         },
+                { "xml-interface",                   no_argument,       NULL, ARG_XML_INTERFACE                   },
                 { "expect-reply",                    required_argument, NULL, ARG_EXPECT_REPLY                    },
                 { "auto-start",                      required_argument, NULL, ARG_AUTO_START                      },
                 { "allow-interactive-authorization", required_argument, NULL, ARG_ALLOW_INTERACTIVE_AUTHORIZATION },
@@ -2388,6 +2397,10 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_verbose = true;
                         break;
 
+                case ARG_XML_INTERFACE:
+                        arg_xml_interface = true;
+                        break;
+
                 case ARG_EXPECT_REPLY:
                         r = parse_boolean(optarg);
                         if (r < 0)
diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym
index a6748ceb20..a9ab0605ce 100644
--- a/src/libsystemd/libsystemd.sym
+++ b/src/libsystemd/libsystemd.sym
@@ -676,3 +676,8 @@ LIBSYSTEMD_241 {
 global:
         sd_bus_close_unref;
 } LIBSYSTEMD_240;
+
+LIBSYSTEMD_243 {
+global:
+        sd_bus_object_vtable_format;
+} LIBSYSTEMD_241;
diff --git a/src/libsystemd/sd-bus/bus-introspect.c b/src/libsystemd/sd-bus/bus-introspect.c
index 022eddb10f..beab80687d 100644
--- a/src/libsystemd/sd-bus/bus-introspect.c
+++ b/src/libsystemd/sd-bus/bus-introspect.c
@@ -172,13 +172,10 @@ int introspect_write_interface(struct introspect *i, const sd_bus_vtable *v) {
         return 0;
 }
 
-int introspect_finish(struct introspect *i, sd_bus *bus, sd_bus_message *m, sd_bus_message **reply) {
-        sd_bus_message *q;
+int introspect_finish(struct introspect *i, char **ret) {
         int r;
 
         assert(i);
-        assert(m);
-        assert(reply);
 
         fputs("</node>\n", i->f);
 
@@ -186,25 +183,17 @@ int introspect_finish(struct introspect *i, sd_bus *bus, sd_bus_message *m, sd_b
         if (r < 0)
                 return r;
 
-        r = sd_bus_message_new_method_return(m, &q);
-        if (r < 0)
-                return r;
-
-        r = sd_bus_message_append(q, "s", i->introspection);
-        if (r < 0) {
-                sd_bus_message_unref(q);
-                return r;
-        }
+        i->f = safe_fclose(i->f);
+        *ret = TAKE_PTR(i->introspection);
 
-        *reply = q;
         return 0;
 }
 
 void introspect_free(struct introspect *i) {
         assert(i);
 
-        safe_fclose(i->f);
+        /* Normally introspect_finish() does all the work, this is just a backup for error paths */
 
+        safe_fclose(i->f);
         free(i->introspection);
-        zero(*i);
 }
diff --git a/src/libsystemd/sd-bus/bus-introspect.h b/src/libsystemd/sd-bus/bus-introspect.h
index bb2dd7ef7b..ccbb543d0c 100644
--- a/src/libsystemd/sd-bus/bus-introspect.h
+++ b/src/libsystemd/sd-bus/bus-introspect.h
@@ -18,5 +18,5 @@ int introspect_begin(struct introspect *i, bool trusted);
 int introspect_write_default_interfaces(struct introspect *i, bool object_manager);
 int introspect_write_child_nodes(struct introspect *i, Set *s, const char *prefix);
 int introspect_write_interface(struct introspect *i, const sd_bus_vtable *v);
-int introspect_finish(struct introspect *i, sd_bus *bus, sd_bus_message *m, sd_bus_message **reply);
+int introspect_finish(struct introspect *i, char **ret);
 void introspect_free(struct introspect *i);
diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c
index d9fc25605a..fe3b9feea6 100644
--- a/src/libsystemd/sd-bus/bus-objects.c
+++ b/src/libsystemd/sd-bus/bus-objects.c
@@ -22,7 +22,7 @@ static int node_vtable_get_userdata(
                 sd_bus_error *error) {
 
         sd_bus_slot *s;
-        void *u, *found_u;
+        void *u, *found_u = NULL;
         int r;
 
         assert(bus);
@@ -883,31 +883,33 @@ static int bus_node_exists(
         return 0;
 }
 
-static int process_introspect(
+int introspect_path(
                 sd_bus *bus,
-                sd_bus_message *m,
+                const char *path,
                 struct node *n,
                 bool require_fallback,
-                bool *found_object) {
+                bool ignore_nodes_modified,
+                bool *found_object,
+                char **ret,
+                sd_bus_error *error) {
 
-        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
-        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         _cleanup_set_free_free_ Set *s = NULL;
         const char *previous_interface = NULL;
-        struct introspect intro;
+        _cleanup_(introspect_free) struct introspect intro = {};
         struct node_vtable *c;
         bool empty;
         int r;
 
-        assert(bus);
-        assert(m);
-        assert(n);
-        assert(found_object);
+        if (!n) {
+                n = hashmap_get(bus->nodes, path);
+                if (!n)
+                        return -ENOENT;
+        }
 
-        r = get_child_nodes(bus, m->path, n, 0, &s, &error);
+        r = get_child_nodes(bus, path, n, 0, &s, error);
         if (r < 0)
-                return bus_maybe_reply_error(m, r, &error);
-        if (bus->nodes_modified)
+                return r;
+        if (bus->nodes_modified && !ignore_nodes_modified)
                 return 0;
 
         r = introspect_begin(&intro, bus->trusted);
@@ -924,15 +926,11 @@ static int process_introspect(
                 if (require_fallback && !c->is_fallback)
                         continue;
 
-                r = node_vtable_get_userdata(bus, m->path, c, NULL, &error);
-                if (r < 0) {
-                        r = bus_maybe_reply_error(m, r, &error);
-                        goto finish;
-                }
-                if (bus->nodes_modified) {
-                        r = 0;
-                        goto finish;
-                }
+                r = node_vtable_get_userdata(bus, path, c, NULL, error);
+                if (r < 0)
+                        return r;
+                if (bus->nodes_modified && !ignore_nodes_modified)
+                        return 0;
                 if (r == 0)
                         continue;
 
@@ -942,7 +940,6 @@ static int process_introspect(
                         continue;
 
                 if (!streq_ptr(previous_interface, c->interface)) {
-
                         if (previous_interface)
                                 fputs(" </interface>\n", intro.f);
 
@@ -951,7 +948,7 @@ static int process_introspect(
 
                 r = introspect_write_interface(&intro, c->vtable);
                 if (r < 0)
-                        goto finish;
+                        return r;
 
                 previous_interface = c->interface;
         }
@@ -962,36 +959,64 @@ static int process_introspect(
         if (empty) {
                 /* Nothing?, let's see if we exist at all, and if not
                  * refuse to do anything */
-                r = bus_node_exists(bus, n, m->path, require_fallback);
-                if (r <= 0) {
-                        r = bus_maybe_reply_error(m, r, &error);
-                        goto finish;
-                }
-                if (bus->nodes_modified) {
-                        r = 0;
-                        goto finish;
-                }
+                r = bus_node_exists(bus, n, path, require_fallback);
+                if (r <= 0)
+                        return r;
+                if (bus->nodes_modified && !ignore_nodes_modified)
+                        return 0;
         }
 
-        *found_object = true;
+        if (found_object)
+                *found_object = true;
 
-        r = introspect_write_child_nodes(&intro, s, m->path);
+        r = introspect_write_child_nodes(&intro, s, path);
         if (r < 0)
-                goto finish;
+                return r;
 
-        r = introspect_finish(&intro, bus, m, &reply);
+        r = introspect_finish(&intro, ret);
         if (r < 0)
-                goto finish;
+                return r;
 
-        r = sd_bus_send(bus, reply, NULL);
+        return 1;
+}
+
+static int process_introspect(
+                sd_bus *bus,
+                sd_bus_message *m,
+                struct node *n,
+                bool require_fallback,
+                bool *found_object) {
+
+        _cleanup_free_ char *s = NULL;
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        int r;
+
+        assert(bus);
+        assert(m);
+        assert(n);
+        assert(found_object);
+
+        r = introspect_path(bus, m->path, n, require_fallback, false, found_object, &s, &error);
         if (r < 0)
-                goto finish;
+                return bus_maybe_reply_error(m, r, &error);
+        if (r == 0)
+                /* nodes_modified == true */
+                return 0;
 
-        r = 1;
+        r = sd_bus_message_new_method_return(m, &reply);
+        if (r < 0)
+                return r;
 
-finish:
-        introspect_free(&intro);
-        return r;
+        r = sd_bus_message_append(reply, "s", s);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_send(bus, reply, NULL);
+        if (r < 0)
+                return r;
+
+        return 1;
 }
 
 static int object_manager_serialize_path(
@@ -1668,7 +1693,7 @@ static bool names_are_valid(const char *signature, const char **names, names_fla
 
 /* the current version of this struct is defined in sd-bus-vtable.h, but we need to list here the historical versions
    to make sure the calling code is compatible with one of these */
-struct sd_bus_vtable_original {
+struct sd_bus_vtable_221 {
         uint8_t type:8;
         uint64_t flags:56;
         union {
@@ -1696,12 +1721,16 @@ struct sd_bus_vtable_original {
         } x;
 };
 /* Structure size up to v241 */
-#define VTABLE_ELEMENT_SIZE_ORIGINAL sizeof(struct sd_bus_vtable_original)
-/* Current structure size */
-#define VTABLE_ELEMENT_SIZE sizeof(struct sd_bus_vtable)
+#define VTABLE_ELEMENT_SIZE_221 sizeof(struct sd_bus_vtable_221)
+
+/* Size of the structure when "features" field was added. If the structure definition is augmented, a copy of
+ * the structure definition will need to be made (similarly to the sd_bus_vtable_221 above), and this
+ * definition updated to refer to it. */
+#define VTABLE_ELEMENT_SIZE_242 sizeof(struct sd_bus_vtable)
 
 static int vtable_features(const sd_bus_vtable *vtable) {
-        if (vtable[0].x.start.element_size == VTABLE_ELEMENT_SIZE_ORIGINAL)
+        if (vtable[0].x.start.element_size < VTABLE_ELEMENT_SIZE_242 ||
+            !vtable[0].x.start.vtable_format_reference)
                 return 0;
         return vtable[0].x.start.features;
 }
@@ -1711,13 +1740,7 @@ bool bus_vtable_has_names(const sd_bus_vtable *vtable) {
 }
 
 const sd_bus_vtable* bus_vtable_next(const sd_bus_vtable *vtable, const sd_bus_vtable *v) {
-        if (vtable[0].x.start.element_size == VTABLE_ELEMENT_SIZE_ORIGINAL) {
-                const struct sd_bus_vtable_original *v2 = (const struct sd_bus_vtable_original *)v;
-                v2++;
-                v = (const sd_bus_vtable*)v2;
-        } else /* current version */
-                v++;
-        return v;
+        return (const sd_bus_vtable*) ((char*) v + vtable[0].x.start.element_size);
 }
 
 static int add_object_vtable_internal(
@@ -1744,8 +1767,8 @@ static int add_object_vtable_internal(
         assert_return(interface_name_is_valid(interface), -EINVAL);
         assert_return(vtable, -EINVAL);
         assert_return(vtable[0].type == _SD_BUS_VTABLE_START, -EINVAL);
-        assert_return(vtable[0].x.start.element_size == VTABLE_ELEMENT_SIZE_ORIGINAL ||
-                      vtable[0].x.start.element_size == VTABLE_ELEMENT_SIZE,
+        assert_return(vtable[0].x.start.element_size == VTABLE_ELEMENT_SIZE_221 ||
+                      vtable[0].x.start.element_size >= VTABLE_ELEMENT_SIZE_242,
                       -EINVAL);
         assert_return(!bus_pid_changed(bus), -ECHILD);
         assert_return(!streq(interface, "org.freedesktop.DBus.Properties") &&
@@ -1928,6 +1951,9 @@ fail:
         return r;
 }
 
+/* This symbol exists solely to tell the linker that the "new" vtable format is used. */
+_public_ const unsigned sd_bus_object_vtable_format = 242;
+
 _public_ int sd_bus_add_object_vtable(
                 sd_bus *bus,
                 sd_bus_slot **slot,
diff --git a/src/libsystemd/sd-bus/bus-objects.h b/src/libsystemd/sd-bus/bus-objects.h
index b45fe6323e..f650196a54 100644
--- a/src/libsystemd/sd-bus/bus-objects.h
+++ b/src/libsystemd/sd-bus/bus-objects.h
@@ -2,8 +2,19 @@
 #pragma once
 
 #include "bus-internal.h"
+#include "bus-introspect.h"
 
 const sd_bus_vtable* bus_vtable_next(const sd_bus_vtable *vtable, const sd_bus_vtable *v);
 bool bus_vtable_has_names(const sd_bus_vtable *vtable);
 int bus_process_object(sd_bus *bus, sd_bus_message *m);
 void bus_node_gc(sd_bus *b, struct node *n);
+
+int introspect_path(
+                sd_bus *bus,
+                const char *path,
+                struct node *n,
+                bool require_fallback,
+                bool ignore_nodes_modified,
+                bool *found_object,
+                char **ret,
+                sd_bus_error *error);
diff --git a/src/libsystemd/sd-bus/test-bus-introspect.c b/src/libsystemd/sd-bus/test-bus-introspect.c
index 9c8e93e897..9c8d1434b1 100644
--- a/src/libsystemd/sd-bus/test-bus-introspect.c
+++ b/src/libsystemd/sd-bus/test-bus-introspect.c
@@ -4,33 +4,13 @@
 #include "log.h"
 #include "tests.h"
 
-static int prop_get(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error) {
-        return -EINVAL;
-}
-
-static int prop_set(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error) {
-        return -EINVAL;
-}
+#include "test-vtable-data.h"
 
-static const sd_bus_vtable vtable[] = {
-        SD_BUS_VTABLE_START(0),
-        SD_BUS_METHOD("Hello", "ssas", "a(uu)", NULL, 0),
-        SD_BUS_METHOD("DeprecatedHello", "", "", NULL, SD_BUS_VTABLE_DEPRECATED),
-        SD_BUS_METHOD("DeprecatedHelloNoReply", "", "", NULL, SD_BUS_VTABLE_DEPRECATED|SD_BUS_VTABLE_METHOD_NO_REPLY),
-        SD_BUS_SIGNAL("Wowza", "sss", 0),
-        SD_BUS_SIGNAL("DeprecatedWowza", "ut", SD_BUS_VTABLE_DEPRECATED),
-        SD_BUS_WRITABLE_PROPERTY("AProperty", "s", prop_get, prop_set, 0, 0),
-        SD_BUS_PROPERTY("AReadOnlyDeprecatedProperty", "(ut)", prop_get, 0, SD_BUS_VTABLE_DEPRECATED),
-        SD_BUS_PROPERTY("ChangingProperty", "t", prop_get, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
-        SD_BUS_PROPERTY("Invalidating", "t", prop_get, 0, SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
-        SD_BUS_PROPERTY("Constant", "t", prop_get, 0, SD_BUS_VTABLE_PROPERTY_CONST|SD_BUS_VTABLE_PROPERTY_EXPLICIT),
-        SD_BUS_VTABLE_END
-};
-
-int main(int argc, char *argv[]) {
-        struct introspect intro;
+static void test_manual_introspection(const sd_bus_vtable vtable[]) {
+        struct introspect intro = {};
+        _cleanup_free_ char *s = NULL;
 
-        test_setup_logging(LOG_DEBUG);
+        log_info("/* %s */", __func__);
 
         assert_se(introspect_begin(&intro, false) >= 0);
 
@@ -38,10 +18,18 @@ int main(int argc, char *argv[]) {
         assert_se(introspect_write_interface(&intro, vtable) >= 0);
         fputs(" </interface>\n", intro.f);
 
-        fflush(intro.f);
-        fputs(intro.introspection, stdout);
+        assert_se(introspect_finish(&intro, &s) == 0);
+        fputs(s, stdout);
+        fputs("\n", stdout);
+}
+
+int main(int argc, char *argv[]) {
+        test_setup_logging(LOG_DEBUG);
 
-        introspect_free(&intro);
+        test_manual_introspection(test_vtable_1);
+        test_manual_introspection(test_vtable_2);
+        test_manual_introspection(test_vtable_deprecated);
+        test_manual_introspection((const sd_bus_vtable *) vtable_format_221);
 
         return 0;
 }
diff --git a/src/libsystemd/sd-bus/test-bus-vtable.c b/src/libsystemd/sd-bus/test-bus-vtable.c
index b278094fad..d69ca6ac97 100644
--- a/src/libsystemd/sd-bus/test-bus-vtable.c
+++ b/src/libsystemd/sd-bus/test-bus-vtable.c
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
 #include <stdbool.h>
 #include <stddef.h>
 
@@ -5,119 +7,17 @@
 #undef NDEBUG
 #include <assert.h>
 #include <errno.h>
+#include <stdio.h>
 
 #include "sd-bus-vtable.h"
 
-#define DEFAULT_BUS_PATH "unix:path=/run/dbus/system_bus_socket"
-
-struct context {
-        bool quit;
-        char *something;
-        char *automatic_string_property;
-        uint32_t automatic_integer_property;
-};
-
-static int handler(sd_bus_message *m, void *userdata, sd_bus_error *error) {
-        return 1;
-}
-
-static int value_handler(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error) {
-        return 1;
-}
+#ifndef __cplusplus
+#  include "bus-objects.h"
+#endif
 
-static int get_handler(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error) {
-        return 1;
-}
+#include "test-vtable-data.h"
 
-static int set_handler(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *value, void *userdata, sd_bus_error *error) {
-        return 1;
-}
-
-static const sd_bus_vtable vtable[] = {
-        SD_BUS_VTABLE_START(0),
-        SD_BUS_METHOD("AlterSomething", "s", "s", handler, 0),
-        SD_BUS_METHOD("Exit", "", "", handler, 0),
-        SD_BUS_METHOD_WITH_OFFSET("AlterSomething2", "s", "s", handler, 200, 0),
-        SD_BUS_METHOD_WITH_OFFSET("Exit2", "", "", handler, 200, 0),
-        SD_BUS_METHOD_WITH_NAMES_OFFSET("AlterSomething3", "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
-                        "s", SD_BUS_PARAM(returnstring), handler, 200, 0),
-        SD_BUS_METHOD_WITH_NAMES("Exit3", "bx", SD_BUS_PARAM(with_confirmation) SD_BUS_PARAM(after_msec),
-                        "bb", SD_BUS_PARAM(accepted) SD_BUS_PARAM(scheduled), handler, 0),
-        SD_BUS_PROPERTY("Value", "s", value_handler, 10, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
-        SD_BUS_PROPERTY("Value2", "s", value_handler, 10, SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
-        SD_BUS_PROPERTY("Value3", "s", value_handler, 10, SD_BUS_VTABLE_PROPERTY_CONST),
-        SD_BUS_PROPERTY("Value4", "s", value_handler, 10, 0),
-        SD_BUS_PROPERTY("AnExplicitProperty", "s", NULL, offsetof(struct context, something),
-                        SD_BUS_VTABLE_PROPERTY_EXPLICIT|SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
-        SD_BUS_WRITABLE_PROPERTY("Something", "s", get_handler, set_handler, 0, 0),
-        SD_BUS_WRITABLE_PROPERTY("AutomaticStringProperty", "s", NULL, NULL,
-                                 offsetof(struct context, automatic_string_property), 0),
-        SD_BUS_WRITABLE_PROPERTY("AutomaticIntegerProperty", "u", NULL, NULL,
-                                 offsetof(struct context, automatic_integer_property), 0),
-        SD_BUS_METHOD("NoOperation", NULL, NULL, NULL, 0),
-        SD_BUS_SIGNAL("DummySignal", "b", 0),
-        SD_BUS_SIGNAL("DummySignal2", "so", 0),
-        SD_BUS_SIGNAL_WITH_NAMES("DummySignal3", "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path), 0),
-        SD_BUS_VTABLE_END
-};
-
-struct sd_bus_vtable_original {
-        uint8_t type:8;
-        uint64_t flags:56;
-        union {
-                struct {
-                        size_t element_size;
-                } start;
-                struct {
-                        const char *member;
-                        const char *signature;
-                        const char *result;
-                        sd_bus_message_handler_t handler;
-                        size_t offset;
-                } method;
-                struct {
-                        const char *member;
-                        const char *signature;
-                } signal;
-                struct {
-                        const char *member;
-                        const char *signature;
-                        sd_bus_property_get_t get;
-                        sd_bus_property_set_t set;
-                        size_t offset;
-                } property;
-        } x;
-};
-
-static const struct sd_bus_vtable_original vtable_format_original[] = {
-        {
-                .type = _SD_BUS_VTABLE_START,
-                .flags = 0,
-                .x = {
-                        .start = {
-                                .element_size = sizeof(struct sd_bus_vtable_original)
-                        },
-                },
-        },
-        {
-                .type = _SD_BUS_VTABLE_METHOD,
-                .flags = 0,
-                .x = {
-                        .method = {
-                                .member = "Exit",
-                                .signature = "",
-                                .result = "",
-                                .handler = handler,
-                                .offset = 0,
-                        },
-                },
-        },
-        {
-                .type = _SD_BUS_VTABLE_END,
-                .flags = 0,
-                .x = { { 0 } },
-        }
-};
+#define DEFAULT_BUS_PATH "unix:path=/run/dbus/system_bus_socket"
 
 static void test_vtable(void) {
         sd_bus *bus = NULL;
@@ -126,16 +26,24 @@ static void test_vtable(void) {
 
         assert(sd_bus_new(&bus) >= 0);
 
-        assert(sd_bus_add_object_vtable(bus, NULL, "/foo", "org.freedesktop.systemd.testVtable", vtable, &c) >= 0);
-        assert(sd_bus_add_object_vtable(bus, NULL, "/foo", "org.freedesktop.systemd.testVtable2", vtable, &c) >= 0);
+        assert(sd_bus_add_object_vtable(bus, NULL, "/foo", "org.freedesktop.systemd.testVtable", test_vtable_2, &c) >= 0);
+        assert(sd_bus_add_object_vtable(bus, NULL, "/foo", "org.freedesktop.systemd.testVtable2", test_vtable_2, &c) >= 0);
         /* the cast on the line below is needed to test with the old version of the table */
-        assert(sd_bus_add_object_vtable(bus, NULL, "/foo", "org.freedesktop.systemd.testVtableOriginal", (const sd_bus_vtable *)vtable_format_original, &c) >= 0);
+        assert(sd_bus_add_object_vtable(bus, NULL, "/foo", "org.freedesktop.systemd.testVtable221",
+                                        (const sd_bus_vtable *)vtable_format_221, &c) >= 0);
 
         assert(sd_bus_set_address(bus, DEFAULT_BUS_PATH) >= 0);
         r = sd_bus_start(bus);
         assert(r == 0 ||     /* success */
                r == -ENOENT  /* dbus is inactive */ );
 
+#ifndef __cplusplus
+        _cleanup_free_ char *s = NULL;
+
+        assert_se(introspect_path(bus, "/foo", NULL, false, true, NULL, &s, NULL) == 1);
+        fputs(s, stdout);
+#endif
+
         sd_bus_unref(bus);
 }
 
diff --git a/src/libsystemd/sd-bus/test-vtable-data.h b/src/libsystemd/sd-bus/test-vtable-data.h
new file mode 100644
index 0000000000..333dbd5b12
--- /dev/null
+++ b/src/libsystemd/sd-bus/test-vtable-data.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+/* This is meant to be included in other files, hence no headers */
+
+struct context {
+        bool quit;
+        char *something;
+        char *automatic_string_property;
+        uint32_t automatic_integer_property;
+};
+
+static int handler(sd_bus_message *m, void *userdata, sd_bus_error *error) {
+        return 1;
+}
+
+static int value_handler(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error) {
+        return 1;
+}
+
+static int get_handler(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error) {
+        return 1;
+}
+
+static int set_handler(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *value, void *userdata, sd_bus_error *error) {
+        return 1;
+}
+
+static const sd_bus_vtable test_vtable_1[] = {
+        SD_BUS_VTABLE_START(0),
+        SD_BUS_METHOD("Hello", "ssas", "a(uu)", NULL, 0),
+        SD_BUS_METHOD("DeprecatedHello", "", "", NULL, SD_BUS_VTABLE_DEPRECATED),
+        SD_BUS_METHOD("DeprecatedHelloNoReply", "", "", NULL, SD_BUS_VTABLE_DEPRECATED|SD_BUS_VTABLE_METHOD_NO_REPLY),
+        SD_BUS_SIGNAL("Wowza", "sss", 0),
+        SD_BUS_SIGNAL("DeprecatedWowza", "ut", SD_BUS_VTABLE_DEPRECATED),
+        SD_BUS_WRITABLE_PROPERTY("AProperty", "s", get_handler, set_handler, 0, 0),
+        SD_BUS_PROPERTY("AReadOnlyDeprecatedProperty", "(ut)", get_handler, 0, SD_BUS_VTABLE_DEPRECATED),
+        SD_BUS_PROPERTY("ChangingProperty", "t", get_handler, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
+        SD_BUS_PROPERTY("Invalidating", "t", get_handler, 0, SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
+        SD_BUS_PROPERTY("Constant", "t", get_handler, 0, SD_BUS_VTABLE_PROPERTY_CONST|SD_BUS_VTABLE_PROPERTY_EXPLICIT),
+        SD_BUS_VTABLE_END
+};
+
+static const sd_bus_vtable test_vtable_2[] = {
+        SD_BUS_VTABLE_START(0),
+        SD_BUS_METHOD("AlterSomething", "s", "s", handler, 0),
+        SD_BUS_METHOD("Exit", "", "", handler, 0),
+        SD_BUS_METHOD_WITH_OFFSET("AlterSomething2", "s", "s", handler, 200, 0),
+        SD_BUS_METHOD_WITH_OFFSET("Exit2", "", "", handler, 200, 0),
+        SD_BUS_METHOD_WITH_NAMES_OFFSET("AlterSomething3", "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
+                        "s", SD_BUS_PARAM(returnstring), handler, 200, 0),
+        SD_BUS_METHOD_WITH_NAMES("Exit3", "bx", SD_BUS_PARAM(with_confirmation) SD_BUS_PARAM(after_msec),
+                        "bb", SD_BUS_PARAM(accepted) SD_BUS_PARAM(scheduled), handler, 0),
+        SD_BUS_PROPERTY("Value", "s", value_handler, 10, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
+        SD_BUS_PROPERTY("Value2", "s", value_handler, 10, SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
+        SD_BUS_PROPERTY("Value3", "s", value_handler, 10, SD_BUS_VTABLE_PROPERTY_CONST),
+        SD_BUS_PROPERTY("Value4", "s", value_handler, 10, 0),
+        SD_BUS_PROPERTY("AnExplicitProperty", "s", NULL, offsetof(struct context, something),
+                        SD_BUS_VTABLE_PROPERTY_EXPLICIT|SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
+        SD_BUS_WRITABLE_PROPERTY("Something", "s", get_handler, set_handler, 0, 0),
+        SD_BUS_WRITABLE_PROPERTY("AutomaticStringProperty", "s", NULL, NULL,
+                                 offsetof(struct context, automatic_string_property), 0),
+        SD_BUS_WRITABLE_PROPERTY("AutomaticIntegerProperty", "u", NULL, NULL,
+                                 offsetof(struct context, automatic_integer_property), 0),
+        SD_BUS_METHOD("NoOperation", NULL, NULL, NULL, 0),
+        SD_BUS_SIGNAL("DummySignal", "b", 0),
+        SD_BUS_SIGNAL("DummySignal2", "so", 0),
+        SD_BUS_SIGNAL_WITH_NAMES("DummySignal3", "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path), 0),
+        SD_BUS_VTABLE_END
+};
+
+static const sd_bus_vtable test_vtable_deprecated[] = {
+        SD_BUS_VTABLE_START(SD_BUS_VTABLE_DEPRECATED),
+        SD_BUS_VTABLE_END
+};
+
+struct sd_bus_vtable_221 {
+        uint8_t type:8;
+        uint64_t flags:56;
+        union {
+                struct {
+                        size_t element_size;
+                } start;
+                struct {
+                        const char *member;
+                        const char *signature;
+                        const char *result;
+                        sd_bus_message_handler_t handler;
+                        size_t offset;
+                } method;
+                struct {
+                        const char *member;
+                        const char *signature;
+                } signal;
+                struct {
+                        const char *member;
+                        const char *signature;
+                        sd_bus_property_get_t get;
+                        sd_bus_property_set_t set;
+                        size_t offset;
+                } property;
+        } x;
+};
+
+static const struct sd_bus_vtable_221 vtable_format_221[] = {
+        {
+                .type = _SD_BUS_VTABLE_START,
+                .flags = 0,
+                .x = {
+                        .start = {
+                                .element_size = sizeof(struct sd_bus_vtable_221)
+                        },
+                },
+        },
+        {
+                .type = _SD_BUS_VTABLE_METHOD,
+                .flags = 0,
+                .x = {
+                        .method = {
+                                .member = "Exit",
+                                .signature = "",
+                                .result = "",
+                                .handler = handler,
+                                .offset = 0,
+                        },
+                },
+        },
+        {
+                .type = _SD_BUS_VTABLE_END,
+                .flags = 0,
+                .x = { { 0 } },
+        }
+};
diff --git a/src/systemd/sd-bus-vtable.h b/src/systemd/sd-bus-vtable.h
index 8a73ef0503..e3804e203c 100644
--- a/src/systemd/sd-bus-vtable.h
+++ b/src/systemd/sd-bus-vtable.h
@@ -52,6 +52,15 @@ enum {
         _SD_BUS_VTABLE_PARAM_NAMES     = 1 << 0,
 };
 
+extern const unsigned sd_bus_object_vtable_format;
+
+/* Note: unused areas in the sd_bus_vtable[] array must be initalized to 0. The stucture contains an embedded
+ * union, and the compiler is NOT required to initalize the unused areas of the union when the rest of the
+ * structure is initalized. Normally the array is defined as read-only data, in which case the linker places
+ * it in the BSS section, which is always fully initalized, so this is not a concern. But if the array is
+ * created on the stack or on the heap, care must be taken to initalize the unused areas, for examply by
+ * first memsetting the whole region to zero before filling the data in. */
+
 struct sd_bus_vtable {
         /* Please do not initialize this structure directly, use the
          * macros below instead */
@@ -62,6 +71,7 @@ struct sd_bus_vtable {
                 struct {
                         size_t element_size;
                         uint64_t features;
+                        const unsigned *vtable_format_reference;
                 } start;
                 struct {
                         const char *member;
@@ -93,7 +103,8 @@ struct sd_bus_vtable {
                 .x = {                                                  \
                     .start = {                                          \
                         .element_size = sizeof(sd_bus_vtable),          \
-                        .features = _SD_BUS_VTABLE_PARAM_NAMES          \
+                        .features = _SD_BUS_VTABLE_PARAM_NAMES,         \
+                        .vtable_format_reference = &sd_bus_object_vtable_format, \
                     },                                                  \
                 },                                                      \
         }
diff --git a/src/test/generate-sym-test.py b/src/test/generate-sym-test.py
index 357cce8e44..4d358b8e34 100755
--- a/src/test/generate-sym-test.py
+++ b/src/test/generate-sym-test.py
@@ -6,18 +6,22 @@ for header in sys.argv[2:]:
     print('#include "{}"'.format(header.split('/')[-1]))
 
 print('''
-void* functions[] = {''')
+const void* symbols[] = {''')
 
 for line in open(sys.argv[1]):
     match = re.search('^ +([a-zA-Z0-9_]+);', line)
     if match:
-        print('    {},'.format(match.group(1)))
+        s = match.group(1)
+        if s == 'sd_bus_object_vtable_format':
+            print('    &{},'.format(s))
+        else:
+            print('    {},'.format(s))
 
 print('''};
 
 int main(void) {
     unsigned i;
-    for (i = 0; i < sizeof(functions)/sizeof(void*); i++)
-         printf("%p\\n", functions[i]);
+    for (i = 0; i < sizeof(symbols)/sizeof(void*); i++)
+         printf("%p\\n", symbols[i]);
     return 0;
 }''')
diff --git a/src/test/meson.build b/src/test/meson.build
index 521985b927..e58e1cc73d 100644
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -911,7 +911,8 @@ tests += [
          [],
          [threads]],
 
-        [['src/libsystemd/sd-bus/test-bus-vtable.c'],
+        [['src/libsystemd/sd-bus/test-bus-vtable.c',
+          'src/libsystemd/sd-bus/test-vtable-data.h'],
          [],
          []],
 
@@ -934,7 +935,8 @@ tests += [
          [threads],
          '', 'manual'],
 
-        [['src/libsystemd/sd-bus/test-bus-introspect.c'],
+        [['src/libsystemd/sd-bus/test-bus-introspect.c',
+          'src/libsystemd/sd-bus/test-vtable-data.h'],
          [],
          []],