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sd-bus: Add sd_bus_add_object and callback docs

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Daan De Meyer 2020-03-30 20:53:24 +02:00
parent 6ba8071ca1
commit fc91667d77
3 changed files with 66 additions and 3 deletions
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4
man/rules/meson.build
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@ -134,7 +134,9 @@ manpages = [
'SD_BUS_VTABLE_END',
'SD_BUS_VTABLE_START',
'SD_BUS_WRITABLE_PROPERTY',
'sd_bus_add_fallback_vtable'],
'sd_bus_add_fallback',
'sd_bus_add_fallback_vtable',
'sd_bus_add_object'],
''],
['sd_bus_attach_event', '3', ['sd_bus_detach_event', 'sd_bus_get_event'], ''],
['sd_bus_call', '3', ['sd_bus_call_async'], ''],

3
man/sd-bus.xml
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@ -41,7 +41,10 @@
<para>See
<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_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_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_call_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

62
man/sd_bus_add_object_vtable.xml
View file

@ -19,6 +19,8 @@
<refnamediv>
<refname>sd_bus_add_object_vtable</refname>
<refname>sd_bus_add_fallback_vtable</refname>
<refname>sd_bus_add_object</refname>
<refname>sd_bus_add_fallback</refname>
<refname>SD_BUS_VTABLE_START</refname>
<refname>SD_BUS_VTABLE_END</refname>
<refname>SD_BUS_METHOD_WITH_NAMES_OFFSET</refname>
@ -97,6 +99,24 @@
<paramdef>void *<parameter>userdata</parameter></paramdef>
</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>
<para>
<constant>SD_BUS_VTABLE_START(<replaceable>flags</replaceable>)</constant>
</para>
@ -200,7 +220,7 @@
<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>
necessary. An interface can have any number of vtables attached to it.</para>
<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.
@ -220,7 +240,45 @@
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
<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 defer handling of the
request to the next callback. 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 timeout 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>.