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Author SHA1 Message Date
Zbigniew Jędrzejewski-Szmek 6829d8ce69
Merge pull request #15253 from DaanDeMeyer/object-vtable-error-docs
sd-bus: Add error handling info to sd_bus_add_object_vtable docs
2020-04-01 12:25:34 +02:00
Daan De Meyer 9b62e232ea sd-bus: Add note about sd_bus_reply_method_return to SD_BUS_METHOD docs 2020-03-31 20:38:54 +02:00
Daan De Meyer fc91667d77 sd-bus: Add sd_bus_add_object and callback docs 2020-03-31 20:16:30 +02:00
Daan De Meyer 6ba8071ca1 sd-bus: Fix typos in sd_bus_add_object_vtable docs 2020-03-31 20:16:30 +02:00
Daan De Meyer 50b88e87c8 sd-bus: Wrap add_object_vtable docs at 100 columns 2020-03-31 20:16:30 +02:00
3 changed files with 168 additions and 94 deletions

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@ -121,7 +121,7 @@ manpages = [
'sd_bus_match_signal', 'sd_bus_match_signal',
'sd_bus_match_signal_async'], 'sd_bus_match_signal_async'],
''], ''],
['sd_bus_add_object_vtable', ['sd_bus_add_object',
'3', '3',
['SD_BUS_METHOD', ['SD_BUS_METHOD',
'SD_BUS_METHOD_WITH_NAMES', 'SD_BUS_METHOD_WITH_NAMES',
@ -134,7 +134,9 @@ manpages = [
'SD_BUS_VTABLE_END', 'SD_BUS_VTABLE_END',
'SD_BUS_VTABLE_START', 'SD_BUS_VTABLE_START',
'SD_BUS_WRITABLE_PROPERTY', 'SD_BUS_WRITABLE_PROPERTY',
'sd_bus_add_fallback_vtable'], 'sd_bus_add_fallback',
'sd_bus_add_fallback_vtable',
'sd_bus_add_object_vtable'],
''], ''],
['sd_bus_attach_event', '3', ['sd_bus_detach_event', 'sd_bus_get_event'], ''], ['sd_bus_attach_event', '3', ['sd_bus_detach_event', 'sd_bus_get_event'], ''],
['sd_bus_call', '3', ['sd_bus_call_async'], ''], ['sd_bus_call', '3', ['sd_bus_call_async'], ''],

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@ -41,7 +41,10 @@
<para>See <para>See
<literallayout><citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <literallayout><citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_add_object</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_add_object_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_bus_add_object_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_add_fallback</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_add_fallback_vtable</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_bus_attach_event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_bus_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_call_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_bus_call_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

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@ -3,20 +3,22 @@
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ --> <!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="sd_bus_add_object_vtable" <refentry id="sd_bus_add_object"
xmlns:xi="http://www.w3.org/2001/XInclude"> xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo> <refentryinfo>
<title>sd_bus_add_object_vtable</title> <title>sd_bus_add_object</title>
<productname>systemd</productname> <productname>systemd</productname>
</refentryinfo> </refentryinfo>
<refmeta> <refmeta>
<refentrytitle>sd_bus_add_object_vtable</refentrytitle> <refentrytitle>sd_bus_add_object</refentrytitle>
<manvolnum>3</manvolnum> <manvolnum>3</manvolnum>
</refmeta> </refmeta>
<refnamediv> <refnamediv>
<refname>sd_bus_add_object</refname>
<refname>sd_bus_add_fallback</refname>
<refname>sd_bus_add_object_vtable</refname> <refname>sd_bus_add_object_vtable</refname>
<refname>sd_bus_add_fallback_vtable</refname> <refname>sd_bus_add_fallback_vtable</refname>
<refname>SD_BUS_VTABLE_START</refname> <refname>SD_BUS_VTABLE_START</refname>
@ -76,6 +78,24 @@
<paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef> <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef>
</funcprototype> </funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_add_object</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_message_handler_t <parameter>callback</parameter></paramdef>
<paramdef>void *<parameter>userdata</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_add_fallback</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_message_handler_t <parameter>callback</parameter></paramdef>
<paramdef>void *<parameter>userdata</parameter></paramdef>
</funcprototype>
<funcprototype> <funcprototype>
<funcdef>int <function>sd_bus_add_object_vtable</function></funcdef> <funcdef>int <function>sd_bus_add_object_vtable</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef> <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
@ -188,40 +208,82 @@
<refsect1> <refsect1>
<title>Description</title> <title>Description</title>
<para><function>sd_bus_add_object_vtable()</function> is used to declare attributes for the path object <para><function>sd_bus_add_object_vtable()</function> is used to declare attributes for the
path <parameter>path</parameter> connected to the bus connection <parameter>bus</parameter> under the object path <parameter>path</parameter> connected to the bus connection
interface <parameter>interface</parameter>. The table <parameter>vtable</parameter> may contain property <parameter>bus</parameter> under the interface <parameter>interface</parameter>. The table
declarations using <constant>SD_BUS_PROPERTY()</constant> or <parameter>vtable</parameter> may contain property declarations using
<constant>SD_BUS_WRITABLE_PROPERTY()</constant>, method declarations using <constant>SD_BUS_PROPERTY()</constant> or <constant>SD_BUS_WRITABLE_PROPERTY()</constant>,
<constant>SD_BUS_METHOD()</constant>, <constant>SD_BUS_METHOD_WITH_NAMES()</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_OFFSET()</constant>, or
<constant>SD_BUS_METHOD_WITH_NAMES_OFFSET()</constant>, and signal declarations using <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 <constant>SD_BUS_SIGNAL_WITH_NAMES()</constant> or <constant>SD_BUS_SIGNAL()</constant>, see
<replaceable>userdata</replaceable> parameter contains a pointer that will be passed to various callback below. The <replaceable>userdata</replaceable> parameter contains a pointer that will be passed
functions. It may be specified as <constant>NULL</constant> if no value is necessary.</para> to various callback functions. It may be specified as <constant>NULL</constant> if no value is
necessary. An interface can have any number of vtables attached to it.</para>
<para><function>sd_bus_add_fallback_vtable()</function> is similar to <para><function>sd_bus_add_fallback_vtable()</function> is similar to
<function>sd_bus_add_object_vtable()</function>, but is used to register "fallback" attributes. When <function>sd_bus_add_object_vtable()</function>, but is used to register "fallback" attributes.
looking for an attribute declaration, bus object paths registered with 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 <function>sd_bus_add_object_vtable()</function> are checked first. If no match is found, the
vtables are checked for each prefix of the bus object path, i.e. with the last slash-separated components fallback vtables are checked for each prefix of the bus object path, i.e. with the last
successively removed. This allows the vtable to be used for an arbitrary number of dynamically created slash-separated components successively removed. This allows the vtable to be used for an
objects.</para> arbitrary number of dynamically created objects.</para>
<para>Parameter <replaceable>find</replaceable> is a function which is used to locate the target object <para>Parameter <replaceable>find</replaceable> is a function which is used to locate the target
based on the bus object path <replaceable>path</replaceable>. It must return <constant>1</constant> and object based on the bus object path <replaceable>path</replaceable>. It must return
set the <parameter>ret_found</parameter> output parameter if the object is found, return <constant>1</constant> and set the <parameter>ret_found</parameter> output parameter if the
<constant>0</constant> if the object was not found, and return a negative errno-style error code or object is found, return <constant>0</constant> if the object was not found, and return a
initialize the error structure <replaceable>ret_error</replaceable> on error. The pointer passed in negative errno-style error code or initialize the error structure
<parameter>ret_found</parameter> will be used as the <parameter>userdata</parameter> parameter for the <replaceable>ret_error</replaceable> on error. The pointer passed in
callback functions (offset by the <parameter>offset</parameter> offsets as specified in the vtable <parameter>ret_found</parameter> will be used as the <parameter>userdata</parameter> parameter
entries).</para> 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 <para><function>sd_bus_add_object()</function> attaches a callback directly to the object path
<replaceable>slot</replaceable> is <constant>NULL</constant>, a "floating" slot object is created, see <parameter>path</parameter>. An object path can have any number of callbacks attached to it.
Each callback is prepended to the list of callbacks which are always called in order.
<function>sd_bus_add_fallback()</function> is similar to
<function>sd_bus_add_object()</function> but applies to fallback paths instead.</para>
<para>When a request is received, any associated callbacks are called sequentially until a
callback returns a non-zero integer. Return zero from a callback to give other callbacks the
chance to process the request. Callbacks are called in the following order: first, callbacks
attached directly to the request object path are called, followed by any D-Bus method callbacks
attached to the request object path, interface and member. Finally, the property callbacks
attached to the request object path, interface and member are called. If the final callback
returns zero, an error reply is sent back to the caller indicating no matching object for the
request was found. Note that you can return a positive integer from a callback without
immediately sending a reply. This informs sd-bus this callback will take responsibility for
replying to the request without forcing the callback to produce a reply immediately. This allows
a callback to perform any number of asynchronous operations required to construct a reply. Note
that if producing a reply takes too long, the method call will time out at the caller.</para>
<para>If a callback was invoked to handle a request that expects a reply and the callback
returns a negative value, the value is interpreted as a negative errno-style error code and sent
back to the caller as a D-Bus error as if
<citerefentry><refentrytitle>sd_bus_reply_method_errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
was called. Additionally, all callbacks take a <structname>sd_bus_error</structname> output
parameter that can be used to provide more detailed error information. If
<parameter>ret_error</parameter> is set when the callback finishes, the corresponding D-Bus
error is sent back to the caller as if
<citerefentry><refentrytitle>sd_bus_reply_method_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>
was called. Any error stored in <parameter>ret_error</parameter> takes priority over any
negative values returned by the same callback when determining which error to send back to
the caller. Use
<citerefentry><refentrytitle>sd_bus_error_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>
or one of its variants to set <parameter>ret_error</parameter> and return a negative integer
from a callback with a single function call. To send an error reply after a callback has already
finished, use
<citerefentry><refentrytitle>sd_bus_reply_method_errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
or one of its variants.</para>
<para>For all 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>. <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 Otherwise, a pointer to the slot object is returned. In that case, the reference to the slot
should be dropped when the vtable is not needed anymore, see object should be dropped when the vtable is not needed anymore, see
<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>. <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para> </para>
@ -245,23 +307,28 @@
<term><constant>SD_BUS_METHOD_WITH_OFFSET()</constant></term> <term><constant>SD_BUS_METHOD_WITH_OFFSET()</constant></term>
<term><constant>SD_BUS_METHOD()</constant></term> <term><constant>SD_BUS_METHOD()</constant></term>
<listitem><para>Declare a D-Bus method with the name <replaceable>member</replaceable>, parameter <listitem><para>Declare a D-Bus method with the name <replaceable>member</replaceable>,
signature <replaceable>signature</replaceable>, result signature <replaceable>result</replaceable>. parameter signature <replaceable>signature</replaceable>, result signature
Parameters <replaceable>in_names</replaceable> and <replaceable>out_names</replaceable> specify the <replaceable>result</replaceable>. Parameters <replaceable>in_names</replaceable> and
argument names of the input and output arguments in the function signature. The handler function <replaceable>out_names</replaceable> specify the argument names of the input and output
<replaceable>handler</replaceable> must be of type <function>sd_bus_message_handler_t</function>. arguments in the function signature. The handler function
It will be called to handle the incoming messages that call this method. It receives a pointer that <replaceable>handler</replaceable> must be of type
is the <replaceable>userdata</replaceable> parameter passed to the registration function offset by <function>sd_bus_message_handler_t</function>. It will be called to handle the incoming
<replaceable>offset</replaceable> bytes. This may be used to pass pointers to different fields in messages that call this method. It receives a pointer that is the
the same data structure to different methods in the same <replaceable>userdata</replaceable> parameter passed to the registration function offset
vtable. <replaceable>in_names</replaceable> and <replaceable>out_names</replaceable> should be by <replaceable>offset</replaceable> bytes. This may be used to pass pointers to different
created using the <constant>SD_BUS_PARAM()</constant> macro, see below. Parameter fields in the same data structure to different methods in the same vtable. To send a reply
from <parameter>handler</parameter>, call
<citerefentry><refentrytitle>sd_bus_reply_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry>
with the message the callback was invoked with. <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> <replaceable>flags</replaceable> is a combination of flags, see below.</para>
<para><constant>SD_BUS_METHOD_WITH_NAMES()</constant>, <para><constant>SD_BUS_METHOD_WITH_NAMES()</constant>,
<constant>SD_BUS_METHOD_WITH_OFFSET()</constant>, and <constant>SD_BUS_METHOD()</constant> are <constant>SD_BUS_METHOD_WITH_OFFSET()</constant>, and <constant>SD_BUS_METHOD()</constant>
variants which specify zero offset (<replaceable>userdata</replaceable> parameter is passed with are variants which specify zero offset (<replaceable>userdata</replaceable> parameter is
no change), leave the names unset (i.e. no parameter names), or both.</para> passed with no change), leave the names unset (i.e. no parameter names), or both.</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -285,29 +352,31 @@
<term><constant>SD_BUS_WRITABLE_PROPERTY()</constant></term> <term><constant>SD_BUS_WRITABLE_PROPERTY()</constant></term>
<term><constant>SD_BUS_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 <listitem><para>Declare a D-Bus property with the name <replaceable>member</replaceable>
signature <replaceable>signature</replaceable>. Parameters <replaceable>get</replaceable> and and value signature <replaceable>signature</replaceable>. Parameters
<replaceable>set</replaceable> are the getter and setter methods. They are called with a pointer <replaceable>get</replaceable> and <replaceable>set</replaceable> are the getter and
that is the <replaceable>userdata</replaceable> parameter passed to the registration function setter methods. They are called with a pointer that is the
offset by <replaceable>offset</replaceable> bytes. This may be used pass pointers to different <replaceable>userdata</replaceable> parameter passed to the registration function offset
fields in the same data structure to different setters and getters in the same vtable. Parameter by <replaceable>offset</replaceable> bytes. This may be used pass pointers to different
<replaceable>flags</replaceable> is a combination of flags, see below.</para> 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 <para>The setter and getter methods may be omitted (specified as
property has one of the basic types or <literal>as</literal> in case of read-only properties. In <constant>NULL</constant>), if the property is one of the basic types or
those cases, the <replaceable>userdata</replaceable> and <replaceable>offset</replaceable> <literal>as</literal> in case of read-only properties. In those cases, the
parameters must together point to valid variable of the corresponding type. A default setter and <replaceable>userdata</replaceable> and <replaceable>offset</replaceable> parameters must
getters will be provided, which simply copy the argument between this variable and the message. together point to a valid variable of the corresponding type. A default setter and getter
will be provided, which simply copy the argument between this variable and the message.
</para> </para>
<para><constant>SD_BUS_PROPERTY()</constant> is used to define a read-only property.</para> <para><constant>SD_BUS_PROPERTY()</constant> is used to define a read-only property.
</listitem> </para></listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><constant>SD_BUS_PARAM()</constant></term> <term><constant>SD_BUS_PARAM()</constant></term>
<listitem><para>Parameter names should be wrapped in this macro, see the example below.</para> <listitem><para>Parameter names should be wrapped in this macro, see the example below.
</listitem> </para></listitem>
</varlistentry> </varlistentry>
</variablelist> </variablelist>
</refsect2> </refsect2>
@ -324,7 +393,7 @@
<term><constant>SD_BUS_VTABLE_DEPRECATED</constant></term> <term><constant>SD_BUS_VTABLE_DEPRECATED</constant></term>
<listitem><para>Mark this vtable entry as deprecated using the <listitem><para>Mark this vtable entry as deprecated using the
<constant>org.freedesktop.DBus.Deprecated</constant> annotation in introspection data. If <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 specified for <constant>SD_BUS_VTABLE_START()</constant>, the annotation is applied to the
enclosing interface.</para></listitem> enclosing interface.</para></listitem>
</varlistentry> </varlistentry>
@ -332,10 +401,9 @@
<varlistentry> <varlistentry>
<term><constant>SD_BUS_VTABLE_HIDDEN</constant></term> <term><constant>SD_BUS_VTABLE_HIDDEN</constant></term>
<listitem><para>Make this vtable entry hidden. It will not be shown in introspection data. If <listitem><para>Make this vtable entry hidden. It will not be shown in introspection data.
specified for <constant>SD_BUS_VTABLE_START()</constant>, all entries in the array are hidden. If specified for <constant>SD_BUS_VTABLE_START()</constant>, all entries in the array are
</para> hidden.</para></listitem>
</listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
@ -343,8 +411,7 @@
<listitem><para>Mark this vtable entry as unprivileged. If not specified, the <listitem><para>Mark this vtable entry as unprivileged. If not specified, the
<constant>org.freedesktop.systemd1.Privileged</constant> annotation with value <constant>org.freedesktop.systemd1.Privileged</constant> annotation with value
<literal>true</literal> will be shown in introspection data.</para> <literal>true</literal> will be shown in introspection data.</para></listitem>
</listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
@ -361,27 +428,28 @@
<term><constant>SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION</constant></term> <term><constant>SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION</constant></term>
<listitem><para>Those three flags correspond to different values of the <listitem><para>Those three flags correspond to different values of the
<constant>org.freedesktop.DBus.Property.EmitsChangedSignal</constant> annotation, which specifies <constant>org.freedesktop.DBus.Property.EmitsChangedSignal</constant> annotation, which
whether the <constant>org.freedesktop.DBus.Properties.PropertiesChanged</constant> signal is specifies whether the
emitted whenever the property changes. <constant>SD_BUS_VTABLE_PROPERTY_CONST</constant> corresponds to <constant>org.freedesktop.DBus.Properties.PropertiesChanged</constant> signal is emitted
<constant>const</constant> and means that the property never changes during the lifetime of the whenever the property changes. <constant>SD_BUS_VTABLE_PROPERTY_CONST</constant>
object it belongs to, so no signal needs to be emitted. corresponds to <constant>const</constant> and means that the property never changes during
<constant>SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE</constant> corresponds to <constant>true</constant> and means the lifetime of the object it belongs to, so no signal needs to be emitted.
that the signal is emitted. <constant>SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION</constant> corresponds to <constant>SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE</constant> corresponds to
<constant>invalidates</constant> and means that the signal is emitted, but the value is not included <constant>true</constant> and means that the signal is emitted.
in the signal.</para> <constant>SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION</constant> corresponds to
</listitem> <constant>invalidates</constant> and means that the signal is emitted, but the value is
not included in the signal.</para></listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><constant>SD_BUS_VTABLE_PROPERTY_EXPLICIT</constant></term> <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 <listitem><para>Mark this vtable property entry as requiring explicit request to for the
be shown (generally because the value is large or slow to calculate). This entry cannot be combined value to be shown (generally because the value is large or slow to calculate). This entry
with <constant>SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE</constant>, and will not be shown in property listings by cannot be combined with <constant>SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE</constant>, and will
default (e.g. <command>busctl introspect</command>). This corresponds to the not be shown in property listings by default (e.g. <command>busctl introspect</command>).
<constant>org.freedesktop.systemd1.Explicit</constant> annotation in introspection data.</para> This corresponds to the <constant>org.freedesktop.systemd1.Explicit</constant> annotation
</listitem> in introspection data.</para></listitem>
</varlistentry> </varlistentry>
</variablelist> </variablelist>
</refsect2> </refsect2>
@ -395,9 +463,9 @@
<programlisting><xi:include href="vtable-example.c" parse="text" /></programlisting> <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). <para>This creates a simple client on the bus (the user bus, when run as normal user). We may
We may use the D-Bus <constant>org.freedesktop.DBus.Introspectable.Introspect</constant> use the D-Bus <constant>org.freedesktop.DBus.Introspectable.Introspect</constant> call to
call to acquire the XML description of the interface:</para> acquire the XML description of the interface:</para>
<programlisting><xi:include href="vtable-example.xml" parse="text" /></programlisting> <programlisting><xi:include href="vtable-example.xml" parse="text" /></programlisting>
</example> </example>
@ -407,8 +475,8 @@
<title>Return Value</title> <title>Return Value</title>
<para>On success, <function>sd_bus_add_object_vtable</function> and <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 <function>sd_bus_add_fallback_vtable</function> calls return 0 or a positive integer. On
return a negative errno-style error code.</para> failure, they return a negative errno-style error code.</para>
<refsect2> <refsect2>
<title>Errors</title> <title>Errors</title>
@ -419,8 +487,9 @@
<varlistentry> <varlistentry>
<term><constant>-EINVAL</constant></term> <term><constant>-EINVAL</constant></term>
<listitem><para>One of the required parameters is <constant>NULL</constant> or invalid. A reserved <listitem><para>One of the required parameters is <constant>NULL</constant> or invalid. A
D-Bus interface was passed as the <replaceable>interface</replaceable> parameter.</para></listitem> reserved D-Bus interface was passed as the <replaceable>interface</replaceable> parameter.
</para></listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
@ -445,8 +514,8 @@
<term><constant>-EPROTOTYPE</constant></term> <term><constant>-EPROTOTYPE</constant></term>
<listitem><para><function>sd_bus_add_object_vtable</function> and <listitem><para><function>sd_bus_add_object_vtable</function> and
<function>sd_bus_add_fallback_vtable</function> have been both called <function>sd_bus_add_fallback_vtable</function> have been both called for the same bus
for the same bus object path, which is not allowed.</para></listitem> object path, which is not allowed.</para></listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>