dbus/proxies.py

   1 # Copyright (C) 2003, 2004, 2005, 2006, 2007 Red Hat Inc. <http://www.redhat.com/>
   2 # Copyright (C) 2003 David Zeuthen
   3 # Copyright (C) 2004 Rob Taylor
   4 # Copyright (C) 2005, 2006, 2007 Collabora Ltd. <http://www.collabora.co.uk/>
   5 #
   6 # Licensed under the Academic Free License version 2.1
   7 #
   8 # This program is free software; you can redistribute it and/or modify
   9 # it under the terms of the GNU General Public License as published by
  10 # the Free Software Foundation; either version 2 of the License, or
  11 # (at your option) any later version.
  12 #
  13 # This program is distributed in the hope that it will be useful,
  14 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 # GNU General Public License for more details.
  17 #
  18 # You should have received a copy of the GNU General Public License
  19 # along with this program; if not, write to the Free Software
  20 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21
  22 import sys
  23 import logging
  24
  25 try:
  26     from threading import RLock
  27 except ImportError:
  28     from dummy_threading import RLock
  29
  30 import _dbus_bindings
  31 from dbus._expat_introspect_parser import process_introspection_data
  32 from dbus.exceptions import MissingReplyHandlerException, MissingErrorHandlerException, IntrospectionParserException, DBusException
  33
  34 __docformat__ = 'restructuredtext'
  35
  36
  37 _logger = logging.getLogger('dbus.proxies')
  38
  39
  40 BUS_DAEMON_NAME = 'org.freedesktop.DBus'
  41 BUS_DAEMON_PATH = '/org/freedesktop/DBus'
  42 BUS_DAEMON_IFACE = BUS_DAEMON_NAME
  43
  44 # This is special in libdbus - the bus daemon will kick us off if we try to
  45 # send any message to it :-/
  46 LOCAL_PATH = '/org/freedesktop/DBus/Local'
  47
  48
  49 class _ReplyHandler(object):
  50     __slots__ = ('_on_error', '_on_reply', '_get_args_options')
  51     def __init__(self, on_reply, on_error, **get_args_options):
  52         self._on_error = on_error
  53         self._on_reply = on_reply
  54         self._get_args_options = get_args_options
  55
  56     def __call__(self, message):
  57         if isinstance(message, _dbus_bindings.MethodReturnMessage):
  58             self._on_reply(*message.get_args_list(**self._get_args_options))
  59         elif isinstance(message, _dbus_bindings.ErrorMessage):
  60             args = message.get_args_list()
  61             if len(args) > 0:
  62                 self._on_error(DBusException(args[0]))
  63             else:
  64                 self._on_error(DBusException())
  65         else:
  66             self._on_error(DBusException('Unexpected reply message type: %s'
  67                                         % message))
  68
  69
  70 class _DeferredMethod:
  71     """A proxy method which will only get called once we have its
  72     introspection reply.
  73     """
  74     def __init__(self, proxy_method, append, block):
  75         self._proxy_method = proxy_method
  76         # the test suite relies on the existence of this property
  77         self._method_name = proxy_method._method_name
  78         self._append = append
  79         self._block = block
  80
  81     def __call__(self, *args, **keywords):
  82         if keywords.has_key('reply_handler'):
  83             # defer the async call til introspection finishes
  84             self._append(self._proxy_method, args, keywords)
  85             return None
  86         else:
  87             # we're being synchronous, so block
  88             self._block()
  89             return self._proxy_method(*args, **keywords)
  90
  91
  92 class _ProxyMethod:
  93     """A proxy method.
  94
  95     Typically a member of a ProxyObject. Calls to the
  96     method produce messages that travel over the Bus and are routed
  97     to a specific named Service.
  98     """
  99     def __init__(self, proxy, connection, named_service, object_path, method_name, iface):
 100         if object_path == LOCAL_PATH:
 101             raise DBusException('Methods may not be called on the reserved '
 102                                 'path %s' % LOCAL_PATH)
 103
 104         # trust that the proxy, and the properties it had, are OK
 105         self._proxy          = proxy
 106         self._connection     = connection
 107         self._named_service  = named_service
 108         self._object_path    = object_path
 109         # fail early if the method name is bad
 110         _dbus_bindings.validate_member_name(method_name)
 111         # the test suite relies on the existence of this property
 112         self._method_name    = method_name
 113         # fail early if the interface name is bad
 114         if iface is not None:
 115             _dbus_bindings.validate_interface_name(iface)
 116         self._dbus_interface = iface
 117
 118     def __call__(self, *args, **keywords):
 119         timeout = -1
 120         if keywords.has_key('timeout'):
 121             timeout = keywords['timeout']
 122
 123         reply_handler = None
 124         if keywords.has_key('reply_handler'):
 125             reply_handler = keywords['reply_handler']
 126
 127         error_handler = None
 128         if keywords.has_key('error_handler'):
 129             error_handler = keywords['error_handler']
 130
 131         ignore_reply = False
 132         if keywords.has_key('ignore_reply'):
 133             ignore_reply = keywords['ignore_reply']
 134
 135         get_args_options = {}
 136         if keywords.has_key('utf8_strings'):
 137             get_args_options['utf8_strings'] = keywords['utf8_strings']
 138         if keywords.has_key('byte_arrays'):
 139             get_args_options['byte_arrays'] = keywords['byte_arrays']
 140
 141         if not(reply_handler and error_handler):
 142             if reply_handler:
 143                 raise MissingErrorHandlerException()
 144             elif error_handler:
 145                 raise MissingReplyHandlerException()
 146
 147         dbus_interface = self._dbus_interface
 148         if keywords.has_key('dbus_interface'):
 149             dbus_interface = keywords['dbus_interface']
 150
 151         tmp_iface = ''
 152         if dbus_interface:
 153             tmp_iface = dbus_interface + '.'
 154
 155         key = tmp_iface + self._method_name
 156
 157         introspect_sig = None
 158         if self._proxy._introspect_method_map.has_key (key):
 159             introspect_sig = self._proxy._introspect_method_map[key]
 160
 161         message = _dbus_bindings.MethodCallMessage(destination=None,
 162                                                    path=self._object_path,
 163                                                    interface=dbus_interface,
 164                                                    method=self._method_name)
 165         message.set_destination(self._named_service)
 166
 167         # Add the arguments to the function
 168         try:
 169             message.append(signature=introspect_sig, *args)
 170         except Exception, e:
 171             _logger.error('Unable to set arguments %r according to '
 172                           'introspected signature %r: %s: %s',
 173                           args, introspect_sig, e.__class__, e)
 174             raise
 175
 176         if ignore_reply:
 177             self._connection.send_message(message)
 178             return None
 179         elif reply_handler:
 180             self._connection.send_message_with_reply(message, _ReplyHandler(reply_handler, error_handler, **get_args_options), timeout/1000.0, require_main_loop=1)
 181             return None
 182         else:
 183             reply_message = self._connection.send_message_with_reply_and_block(message, timeout)
 184             args_list = reply_message.get_args_list(**get_args_options)
 185             if len(args_list) == 0:
 186                 return None
 187             elif len(args_list) == 1:
 188                 return args_list[0]
 189             else:
 190                 return tuple(args_list)
 191
 192
 193 class ProxyObject:
 194     """A proxy to the remote Object.
 195
 196     A ProxyObject is provided by the Bus. ProxyObjects
 197     have member functions, and can be called like normal Python objects.
 198     """
 199     ProxyMethodClass = _ProxyMethod
 200     DeferredMethodClass = _DeferredMethod
 201
 202     INTROSPECT_STATE_DONT_INTROSPECT = 0
 203     INTROSPECT_STATE_INTROSPECT_IN_PROGRESS = 1
 204     INTROSPECT_STATE_INTROSPECT_DONE = 2
 205
 206     def __init__(self, bus, named_service, object_path, introspect=True,
 207                  follow_name_owner_changes=False):
 208         """Initialize the proxy object.
 209
 210         :Parameters:
 211             `bus` : `dbus.Bus`
 212                 The bus on which to find this object
 213             `named_service` : str
 214                 A bus name for the endpoint owning the object (need not
 215                 actually be a service name)
 216             `object_path` : str
 217                 The object path at which the endpoint exports the object
 218             `introspect` : bool
 219                 If true (default), attempt to introspect the remote
 220                 object to find out supported methods and their signatures
 221             `follow_name_owner_changes` : bool
 222                 If true (default is false) and the `named_service` is a
 223                 well-known name, follow ownership changes for that name
 224         """
 225         if follow_name_owner_changes:
 226             bus._require_main_loop()   # we don't get the signals otherwise
 227
 228         self._bus           = bus
 229
 230         if named_service is not None:
 231             _dbus_bindings.validate_bus_name(named_service)
 232         self._named_service = named_service
 233
 234         _dbus_bindings.validate_object_path(object_path)
 235         self.__dbus_object_path__ = object_path
 236
 237         if (named_service is not None and named_service[:1] != ':'
 238             and named_service != BUS_DAEMON_NAME
 239             and not follow_name_owner_changes):
 240             bus_object = bus.get_object(BUS_DAEMON_NAME, BUS_DAEMON_PATH)
 241             try:
 242                 self._named_service = bus_object.GetNameOwner(named_service,
 243                         dbus_interface=BUS_DAEMON_IFACE)
 244             except DBusException, e:
 245                 # FIXME: detect whether it's NameHasNoOwner, but properly
 246                 #if not str(e).startswith('org.freedesktop.DBus.Error.NameHasNoOwner:'):
 247                 #    raise
 248                 # it might not exist: try to start it
 249                 bus_object.StartServiceByName(named_service,
 250                                               _dbus_bindings.UInt32(0))
 251                 self._named_service = bus_object.GetNameOwner(named_service,
 252                         dbus_interface=BUS_DAEMON_IFACE)
 253
 254         #PendingCall object for Introspect call
 255         self._pending_introspect = None
 256         #queue of async calls waiting on the Introspect to return
 257         self._pending_introspect_queue = []
 258         #dictionary mapping method names to their input signatures
 259         self._introspect_method_map = {}
 260
 261         # must be a recursive lock because block() is called while locked,
 262         # and calls the callback which re-takes the lock
 263         self._introspect_lock = RLock()
 264
 265         if not introspect or self.__dbus_object_path__ == LOCAL_PATH:
 266             self._introspect_state = self.INTROSPECT_STATE_DONT_INTROSPECT
 267         else:
 268             self._introspect_state = self.INTROSPECT_STATE_INTROSPECT_IN_PROGRESS
 269
 270             self._pending_introspect = self._Introspect()
 271
 272     def connect_to_signal(self, signal_name, handler_function, dbus_interface=None, **keywords):
 273         """Arrange for the given function to be called when the given signal
 274         is received.
 275
 276         :Parameters:
 277             `signal_name` : str
 278                 The name of the signal
 279             `handler_function` : callable
 280                 A function to be called when the signal is emitted by
 281                 the remote object. Its positional arguments will be the
 282                 arguments of the signal; optionally, it may be given
 283                 keyword arguments as described below.
 284             `dbus_interface` : str
 285                 Optional interface with which to qualify the signal name.
 286                 If None (the default) the handler will be called whenever a
 287                 signal of the given member name is received, whatever
 288                 its interface.
 289         :Keywords:
 290             `utf8_strings` : bool
 291                 If True, the handler function will receive any string
 292                 arguments as dbus.UTF8String objects (a subclass of str
 293                 guaranteed to be UTF-8). If False (default) it will receive
 294                 any string arguments as dbus.String objects (a subclass of
 295                 unicode).
 296             `byte_arrays` : bool
 297                 If True, the handler function will receive any byte-array
 298                 arguments as dbus.ByteArray objects (a subclass of str).
 299                 If False (default) it will receive any byte-array
 300                 arguments as a dbus.Array of dbus.Byte (subclasses of:
 301                 a list of ints).
 302             `sender_keyword` : str
 303                 If not None (the default), the handler function will receive
 304                 the unique name of the sending endpoint as a keyword
 305                 argument with this name
 306             `destination_keyword` : str
 307                 If not None (the default), the handler function will receive
 308                 the bus name of the destination (or None if the signal is a
 309                 broadcast, as is usual) as a keyword argument with this name.
 310             `interface_keyword` : str
 311                 If not None (the default), the handler function will receive
 312                 the signal interface as a keyword argument with this name.
 313             `member_keyword` : str
 314                 If not None (the default), the handler function will receive
 315                 the signal name as a keyword argument with this name.
 316             `path_keyword` : str
 317                 If not None (the default), the handler function will receive
 318                 the object-path of the sending object as a keyword argument
 319                 with this name
 320             `message_keyword` : str
 321                 If not None (the default), the handler function will receive
 322                 the `dbus.lowlevel.SignalMessage` as a keyword argument with
 323                 this name.
 324             `arg...` : unicode or UTF-8 str
 325                 If there are additional keyword parameters of the form
 326                 ``arg``\ *n*, match only signals where the *n*\ th argument
 327                 is the value given for that keyword parameter. As of this time
 328                 only string arguments can be matched (in particular,
 329                 object paths and signatures can't).
 330         """
 331         return \
 332         self._bus.add_signal_receiver(handler_function,
 333                                       signal_name=signal_name,
 334                                       dbus_interface=dbus_interface,
 335                                       named_service=self._named_service,
 336                                       path=self.__dbus_object_path__,
 337                                       **keywords)
 338
 339     def _Introspect(self):
 340         message = _dbus_bindings.MethodCallMessage(None, self.__dbus_object_path__, 'org.freedesktop.DBus.Introspectable', 'Introspect')
 341         message.set_destination(self._named_service)
 342
 343         result = self._bus.get_connection().send_message_with_reply(message, _ReplyHandler(self._introspect_reply_handler, self._introspect_error_handler, utf8_strings=True), -1)
 344         return result
 345
 346     def _introspect_execute_queue(self):
 347         # FIXME: potential to flood the bus
 348         # We should make sure mainloops all have idle handlers
 349         # and do one message per idle
 350         for (proxy_method, args, keywords) in self._pending_introspect_queue:
 351             proxy_method(*args, **keywords)
 352
 353     def _introspect_reply_handler(self, data):
 354         self._introspect_lock.acquire()
 355         try:
 356             try:
 357                 self._introspect_method_map = process_introspection_data(data)
 358             except IntrospectionParserException, e:
 359                 self._introspect_error_handler(e)
 360                 return
 361
 362             self._introspect_state = self.INTROSPECT_STATE_INTROSPECT_DONE
 363             self._pending_introspect = None
 364             self._introspect_execute_queue()
 365         finally:
 366             self._introspect_lock.release()
 367
 368     def _introspect_error_handler(self, error):
 369         self._introspect_lock.acquire()
 370         try:
 371             self._introspect_state = self.INTROSPECT_STATE_DONT_INTROSPECT
 372             self._pending_introspect = None
 373             self._introspect_execute_queue()
 374             sys.stderr.write("Introspect error: " + str(error) + "\n")
 375         finally:
 376             self._introspect_lock.release()
 377
 378     def _introspect_block(self):
 379         self._introspect_lock.acquire()
 380         try:
 381             if self._pending_introspect is not None:
 382                 self._pending_introspect.block()
 383             # else someone still has a _DeferredMethod from before we
 384             # finished introspection: no need to do anything special any more
 385         finally:
 386             self._introspect_lock.release()
 387
 388     def _introspect_add_to_queue(self, callback, args, kwargs):
 389         self._introspect_lock.acquire()
 390         try:
 391             if self._introspect_state == self.INTROSPECT_STATE_INTROSPECT_IN_PROGRESS:
 392                 self._pending_introspect_queue.append((callback, args, kwargs))
 393             else:
 394                 # someone still has a _DeferredMethod from before we
 395                 # finished introspection
 396                 callback(*args, **kwargs)
 397         finally:
 398             self._introspect_lock.release()
 399
 400     def __getattr__(self, member, dbus_interface=None):
 401         if member == '__call__':
 402             return object.__call__
 403         elif member.startswith('__') and member.endswith('__'):
 404             raise AttributeError(member)
 405         else:
 406             return self.get_dbus_method(member, dbus_interface)
 407
 408     def get_dbus_method(self, member, dbus_interface=None):
 409         """Return a proxy method representing the given D-Bus method. The
 410         returned proxy method can be called in the usual way. For instance, ::
 411
 412             proxy.get_dbus_method("Foo", dbus_interface='com.example.Bar')(123)
 413
 414         is equivalent to::
 415
 416             proxy.Foo(123, dbus_interface='com.example.Bar')
 417
 418         or even::
 419
 420             getattr(proxy, "Foo")(123, dbus_interface='com.example.Bar')
 421
 422         However, using `get_dbus_method` is the only way to call D-Bus
 423         methods with certain awkward names - if the author of a service
 424         implements a method called ``connect_to_signal`` or even
 425         ``__getattr__``, you'll need to use `get_dbus_method` to call them.
 426
 427         For services which follow the D-Bus convention of CamelCaseMethodNames
 428         this won't be a problem.
 429         """
 430
 431         ret = self.ProxyMethodClass(self, self._bus.get_connection(),
 432                                     self._named_service,
 433                                     self.__dbus_object_path__, member,
 434                                     dbus_interface)
 435
 436         # this can be done without taking the lock - the worst that can
 437         # happen is that we accidentally return a _DeferredMethod just after
 438         # finishing introspection, in which case _introspect_add_to_queue and
 439         # _introspect_block will do the right thing anyway
 440         if self._introspect_state == self.INTROSPECT_STATE_INTROSPECT_IN_PROGRESS:
 441             ret = self.DeferredMethodClass(ret, self._introspect_add_to_queue,
 442                                            self._introspect_block)
 443
 444         return ret
 445
 446     def __repr__(self):
 447         return '<ProxyObject wrapping %s %s %s at %#x>'%(
 448             self._bus, self._named_service, self.__dbus_object_path__, id(self))
 449     __str__ = __repr__
 450