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dbus/python/dbus.py
John (J5) Palmieri 38dad64ace * python/dbus.py (class Sender): added to support dbus signals better 
(Bus::add_signal_receiver): added expand_args parameter which defaults
to True.  When expand args is True the signal handler will pass the
message arguments as parameters to the signal handler.  If False
revert to previous behavior where the signal handler must get the
argument list from the message.  This is to help port applications
like HAL that have a tendancy to send variable length argument lists.
self._match_rule_to_receivers is now a dict of dicts.
(Bus::remove_signal_receiver): pop handler off the dict intead of
removing it from a list
(Bus::_signal_func): change signal handlers so that interface,
signal_name, service, path and message are packed into a Sender
object and that is passed to the handler.  If expand_args is True
extract the args list from the message and append it to the parameter
list

* python/dbus_bindings.pyx.in (class Signature): added to support
signiature types
(MessageIter::__init__): changed iteration limit to match D-BUS
(MessageIter::get*): added INT16, UINT16, SIGNATURE, DICT_ENTRY,
STRUCT and VARIENT type support
(MessageIter::python_value_to_dbus_sig): made recursive to support
recursive types
(MessageIter::append*): added Signature, dict, tuple
support

* python/examples/example-client.py: added examples of getting tuples
and dicts

* python/examples/example-service.py: added examples of sending tuples
and dicts

* python/examples/example-signal-recipient.py: Fixed to handle new
signal callback format
2005-02-11 19:51:18 +00:00

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"""Module for high-level communication over the FreeDesktop.org Bus (DBus)
DBus allows you to share and access remote objects between processes
running on the desktop, and also to access system services (such as
the print spool).
To use DBus, first get a Bus object, which provides a connection to one
of a few standard dbus-daemon instances that might be running. From the
Bus you can get a RemoteService. A service is provided by an application or
process connected to the Bus, and represents a set of objects. Once you
have a RemoteService you can get a RemoteObject that implements a specific interface
(an interface is just a standard group of member functions). Then you can call
those member functions directly.
You can think of a complete method call as looking something like:
Bus:SESSION -> Service:org.gnome.Evolution -> Object:/org/gnome/Evolution/Inbox -> Interface: org.gnome.Evolution.MailFolder -> Method: Forward('message1', 'seth@gnome.org')
This communicates over the SESSION Bus to the org.gnome.Evolution process to call the
Forward method of the /org/gnome/Evolution/Inbox object (which provides the
org.gnome.Evolution.MailFolder interface) with two string arguments.
For example, the dbus-daemon itself provides a service and some objects:
# Get a connection to the desktop-wide SESSION bus
bus = dbus.Bus(dbus.Bus.TYPE_SESSION)
# Get the service provided by the dbus-daemon named org.freedesktop.DBus
dbus_service = bus.get_service('org.freedesktop.DBus')
# Get a reference to the desktop bus' standard object, denoted
# by the path /org/freedesktop/DBus. The object /org/freedesktop/DBus
# implements the 'org.freedesktop.DBus' interface
dbus_object = dbus_service.get_object('/org/freedesktop/DBus',
'org.freedesktop.DBus')
# One of the member functions in the org.freedesktop.DBus interface
# is ListServices(), which provides a list of all the other services
# registered on this bus. Call it, and print the list.
print(dbus_object.ListServices())
"""
import dbus_bindings
_threads_initialized = 0
def init_gthreads ():
global _threads_initialized
if not _threads_initialized:
dbus_bindings.init_gthreads ()
_threads_initialized = 1
class Sender:
def __init__(self, interface, signal_name, service, path, message):
self.interface = interface
self.signal_name = signal_name
self.service = service
self.path = path
self.message = message
class Bus:
"""A connection to a DBus daemon.
One of three possible standard buses, the SESSION, SYSTEM,
or STARTER bus
"""
TYPE_SESSION = dbus_bindings.BUS_SESSION
TYPE_SYSTEM = dbus_bindings.BUS_SYSTEM
TYPE_STARTER = dbus_bindings.BUS_STARTER
"""bus_type=[Bus.TYPE_SESSION | Bus.TYPE_SYSTEM | Bus.TYPE_STARTER]
"""
START_REPLY_SUCCESS = dbus_bindings.DBUS_START_REPLY_SUCCESS
START_REPLY_ALREADY_RUNNING = dbus_bindings.DBUS_START_REPLY_ALREADY_RUNNING
def __init__(self, bus_type=TYPE_SESSION, glib_mainloop=True):
self._connection = dbus_bindings.bus_get(bus_type)
self._connection.add_filter(self._signal_func)
self._match_rule_to_receivers = { }
if (glib_mainloop):
self._connection.setup_with_g_main()
def get_connection(self):
return self._connection
def get_service(self, service_name="org.freedesktop.Broadcast"):
"""Get one of the RemoteServices connected to this Bus. service_name
is just a string of the form 'com.widgetcorp.MyService'
"""
return RemoteService(self, service_name)
def add_signal_receiver(self, handler_function, signal_name=None, interface=None, service=None, path=None, expand_args=True):
match_rule = self._get_match_rule(signal_name, interface, service, path)
if (not self._match_rule_to_receivers.has_key(match_rule)):
self._match_rule_to_receivers[match_rule] = {handler_function: True}
self._match_rule_to_receivers[match_rule][handler_function] = expand_args
dbus_bindings.bus_add_match(self._connection, match_rule)
def remove_signal_receiver(self, handler_function, signal_name=None, interface=None, service=None, path=None):
match_rule = self._get_match_rule(signal_name, interface, service, path)
if self._match_rule_to_receivers.has_key(match_rule):
if self._match_rule_to_receivers[match_rule].__contains__(handler_function):
self._match_rule_to_receivers[match_rule].pop(handler_function)
dbus_bindings.bus_remove_match(self._connection, match_rule)
def get_connection(self):
"""Get the dbus_bindings.Connection object associated with this Bus"""
return self._connection
def get_unix_user(self, service_name):
"""Get the unix user for the given service_name on this Bus"""
return dbus_bindings.bus_get_unix_user(self._connection, service_name)
def _get_match_rule(self, signal_name, interface, service, path):
match_rule = "type='signal'"
if (interface):
match_rule = match_rule + ",interface='%s'" % (interface)
if (service):
if (service[0] != ':' and service != "org.freedesktop.DBus"):
bus_service = self.get_service("org.freedesktop.DBus")
bus_object = bus_service.get_object('/org/freedesktop/DBus',
'org.freedesktop.DBus')
service = bus_object.GetNameOwner(service)
match_rule = match_rule + ",sender='%s'" % (service)
if (path):
match_rule = match_rule + ",path='%s'" % (path)
if (signal_name):
match_rule = match_rule + ",member='%s'" % (signal_name)
return match_rule
def _signal_func(self, connection, message):
if (message.get_type() != dbus_bindings.MESSAGE_TYPE_SIGNAL):
return dbus_bindings.HANDLER_RESULT_NOT_YET_HANDLED
interface = message.get_interface()
service = message.get_sender()
path = message.get_path()
signal_name = message.get_member()
match_rule = self._get_match_rule(signal_name, interface, service, path)
if (self._match_rule_to_receivers.has_key(match_rule)):
receivers = self._match_rule_to_receivers[match_rule]
sender = Sender(interface, signal_name, service, path, message)
arg = [sender]
for receiver in receivers.iterkeys():
if receivers[receiver]:
args = [sender]
args.extend(message.get_args_list())
receiver(*args)
else:
receiver(*arg)
def start_service_by_name(self, service):
return dbus_bindings.bus_start_service_by_name(self._connection, service)
class SystemBus(Bus):
"""The system-wide message bus
"""
def __init__(self):
Bus.__init__(self, Bus.TYPE_SYSTEM)
class SessionBus(Bus):
"""The session (current login) message bus
"""
def __init__(self):
Bus.__init__(self, Bus.TYPE_SESSION)
class StarterBus(Bus):
"""The bus that activated this process (if
this process was launched by DBus activation)
"""
def __init__(self):
Bus.__init__(self, Bus.TYPE_STARTER)
class RemoteObject:
"""A remote Object.
A RemoteObject is provided by a RemoteService on a particular Bus. RemoteObjects
have member functions, and can be called like normal Python objects.
"""
def __init__(self, service, object_path, interface):
self._service = service
self._object_path = object_path
self._interface = interface
def connect_to_signal(self, signal_name, handler_function):
self._service.get_bus().add_signal_receiver(handler_function,
signal_name=signal_name,
interface=self._interface,
service=self._service.get_service_name(),
path=self._object_path)
def __getattr__(self, member):
if member == '__call__':
return object.__call__
else:
return RemoteMethod(self._service.get_bus().get_connection(),
self._service.get_service_name(),
self._object_path, self._interface, member)
class RemoteMethod:
"""A remote Method.
Typically a member of a RemoteObject. Calls to the
method produce messages that travel over the Bus and are routed
to a specific Service.
"""
def __init__(self, connection, service_name, object_path, interface, method_name):
self._connection = connection
self._service_name = service_name
self._object_path = object_path
self._interface = interface
self._method_name = method_name
def __call__(self, *args):
message = dbus_bindings.MethodCall(self._object_path, self._interface, self._method_name)
message.set_destination(self._service_name)
# Add the arguments to the function
iter = message.get_iter(True)
for arg in args:
iter.append(arg)
reply_message = self._connection.send_with_reply_and_block(message, 5000)
args_tuple = reply_message.get_args_list()
if len(args_tuple) == 0:
return
elif len(args_tuple) == 1:
return args_tuple[0]
else:
return args_tuple
class Service:
"""A base class for exporting your own Services across the Bus
Just inherit from Service, providing the name of your service
(e.g. org.designfu.SampleService).
"""
def __init__(self, service_name, bus=None):
self._service_name = service_name
if bus == None:
# Get the default bus
self._bus = Bus()
else:
self._bus = bus
dbus_bindings.bus_request_name(self._bus.get_connection(), service_name)
def get_bus(self):
"""Get the Bus this Service is on"""
return self._bus
def get_service_name(self):
"""Get the name of this service"""
return self._service_name
def _dispatch_dbus_method_call(target_method, argument_list, message):
"""Calls method_to_call using argument_list, but handles
exceptions, etc, and generates a reply to the DBus Message message
"""
try:
retval = target_method(message, *argument_list)
except Exception, e:
if e.__module__ == '__main__':
# FIXME: is it right to use .__name__ here?
error_name = e.__class__.__name__
else:
error_name = e.__module__ + '.' + str(e.__class__.__name__)
error_contents = str(e)
reply = dbus_bindings.Error(message, error_name, error_contents)
else:
reply = dbus_bindings.MethodReturn(message)
if retval != None:
iter = reply.get_iter(append=True)
iter.append(retval)
return reply
def _build_method_dictionary(methods):
method_dict = {}
for method in methods:
if method_dict.has_key(method.__name__):
print ('WARNING: registering DBus Object methods, already have a method named %s' % (method.__name__))
method_dict[method.__name__] = method
return method_dict
class Object:
"""A base class for exporting your own Objects across the Bus.
Just inherit from Object and provide a list of methods to share
across the Bus. These will appear as member functions of your
ServiceObject.
"""
def __init__(self, object_path, service, dbus_methods=[]):
# Reversed constructor argument order. Add a temporary
# check to help people get things straightened out with minimal pain.
if type(service) == list:
raise TypeError, "dbus.Object.__init__(): the order of the 'service' and 'dbus_methods' arguments has been reversed (for consistency with dbus.ObjectTree)."
self._object_path = object_path
self._service = service
self._bus = service.get_bus()
self._connection = self._bus.get_connection()
self._method_name_to_method = _build_method_dictionary(dbus_methods)
self._connection.register_object_path(object_path, self._unregister_cb, self._message_cb)
def emit_signal(self, interface, signal_name, *args):
message = dbus_bindings.Signal(self._object_path, interface, signal_name)
iter = message.get_iter(True)
for arg in args:
iter.append(arg)
self._connection.send(message)
def _unregister_cb(self, connection):
print ("Unregister")
def _message_cb(self, connection, message):
target_method_name = message.get_member()
target_method = self._method_name_to_method[target_method_name]
args = message.get_args_list()
reply = _dispatch_dbus_method_call(target_method, args, message)
self._connection.send(reply)
class ObjectTree:
"""An object tree allows you to register a handler for a tree of object paths.
This means that literal Python objects do not need to be created for each object
over the bus, but you can have a virtual tree of objects handled by a single
Python object. There are two ways to handle method calls on virtual objects:
1) Pass a list of dbus_methods in to __init__. This works just like dbus.Object,
except an object_path is passed as the first argument to each method, denoting which
virtual object the call was made on. If all the objects in the tree support the same
methods, this is the best approach.
2) Override object_method_called. This allows you to define the valid methods dynamically
on an object by object basis. For example, if providing an object tree that represented
a filesystem heirarchy, you'd only want an ls method on directory objects, not file objects.
"""
def __init__(self, base_path, service, dbus_methods=[]):
self._base_path = base_path
self._service = service
self._bus = service.get_bus()
self._connection = self._bus.get_connection()
self._method_name_to_method = _build_method_dictionary(dbus_methods)
self._connection.register_fallback(base_path, self._unregister_cb, self._message_cb)
def relative_path_to_object_path(self, relative_path):
return ObjectPath(self._base_path + relative_path)
def broadcast_signal(self, interface, signal_name, relative_path):
object_path = self.relative_path_to_object_path(relative_path)
message = dbus_bindings.Signal(object_path, interface, signal_name)
self._connection.send(message)
def object_method_called(self, message, relative_path, method_name, argument_list):
"""Override this method. Called with, object_path, the relative path of the object
under the base_path, the name of the method invoked, and a list of arguments
"""
raise NotImplementedException, "object_method_called() must be overriden"
def _unregister_cb(self, connection):
print ("Unregister")
def _message_cb(self, connection, message):
target_object_full_path = message.get_path()
assert(self._base_path == target_object_full_path[:len(self._base_path)])
target_object_path = target_object_full_path[len(self._base_path):]
target_method_name = message.get_member()
message_args = message.get_args_list()
try:
target_method = self._method_name_to_method[target_method_name]
args = [target_object_path] + message_args
except KeyError:
target_method = self.object_method_called
args = [target_object_path, target_method_name, message_args]
reply = _dispatch_dbus_method_call(target_method, args, message)
self._connection.send(reply)
class RemoteService:
"""A remote service providing objects.
A service is typically a process or application that provides
remote objects, but can also be the broadcast service that
receives signals from all applications on the Bus.
"""
def __init__(self, bus, service_name):
self._bus = bus
self._service_name = service_name
def get_bus(self):
return self._bus
def get_service_name(self):
return self._service_name
def get_object(self, object_path, interface):
"""Get an object provided by this Service that implements a
particular interface. object_path is a string of the form
'/com/widgetcorp/MyService/MyObject1'. interface looks a lot
like a service_name (they're often the same) and is of the form,
'com.widgetcorp.MyInterface', and mostly just defines the
set of member functions that will be present in the object.
"""
return RemoteObject(self, object_path, interface)
ObjectPath = dbus_bindings.ObjectPath
ByteArray = dbus_bindings.ByteArray
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