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 from _dbus_bindings import LOCAL_PATH, \
  40                            BUS_DAEMON_NAME, BUS_DAEMON_PATH, BUS_DAEMON_IFACE,\
  41                            INTROSPECTABLE_IFACE
  42
  43
  44 class _DeferredMethod:
  45     """A proxy method which will only get called once we have its
  46     introspection reply.
  47     """
  48     def __init__(self, proxy_method, append, block):
  49         self._proxy_method = proxy_method
  50         # the test suite relies on the existence of this property
  51         self._method_name = proxy_method._method_name
  52         self._append = append
  53         self._block = block
  54
  55     def __call__(self, *args, **keywords):
  56         if keywords.has_key('reply_handler'):
  57             # defer the async call til introspection finishes
  58             self._append(self._proxy_method, args, keywords)
  59             return None
  60         else:
  61             # we're being synchronous, so block
  62             self._block()
  63             return self._proxy_method(*args, **keywords)
  64
  65     def call_async(self, *args, **keywords):
  66         self._append(self._proxy_method, args, keywords)
  67
  68
  69 class _ProxyMethod:
  70     """A proxy method.
  71
  72     Typically a member of a ProxyObject. Calls to the
  73     method produce messages that travel over the Bus and are routed
  74     to a specific named Service.
  75     """
  76     def __init__(self, proxy, connection, named_service, object_path, method_name, iface):
  77         if object_path == LOCAL_PATH:
  78             raise DBusException('Methods may not be called on the reserved '
  79                                 'path %s' % LOCAL_PATH)
  80
  81         # trust that the proxy, and the properties it had, are OK
  82         self._proxy          = proxy
  83         self._connection     = connection
  84         self._named_service  = named_service
  85         self._object_path    = object_path
  86         # fail early if the method name is bad
  87         _dbus_bindings.validate_member_name(method_name)
  88         # the test suite relies on the existence of this property
  89         self._method_name    = method_name
  90         # fail early if the interface name is bad
  91         if iface is not None:
  92             _dbus_bindings.validate_interface_name(iface)
  93         self._dbus_interface = iface
  94
  95     def __call__(self, *args, **keywords):
  96         reply_handler = keywords.pop('reply_handler', None)
  97         error_handler = keywords.pop('error_handler', None)
  98         ignore_reply = keywords.pop('ignore_reply', False)
  99
 100         if reply_handler is not None or error_handler is not None:
 101             if reply_handler is None:
 102                 raise MissingErrorHandlerException()
 103             elif error_handler is None:
 104                 raise MissingReplyHandlerException()
 105             elif ignore_reply:
 106                 raise TypeError('ignore_reply and reply_handler cannot be '
 107                                 'used together')
 108
 109         dbus_interface = keywords.pop('dbus_interface', self._dbus_interface)
 110
 111         if dbus_interface is None:
 112             key = self._method_name
 113         else:
 114             key = dbus_interface + '.' + self._method_name
 115         introspect_sig = self._proxy._introspect_method_map.get(key, None)
 116
 117         if ignore_reply or reply_handler is not None:
 118             self._connection.call_async(self._named_service,
 119                                         self._object_path,
 120                                         dbus_interface,
 121                                         self._method_name,
 122                                         introspect_sig,
 123                                         args,
 124                                         reply_handler,
 125                                         error_handler,
 126                                         **keywords)
 127         else:
 128             return self._connection.call_blocking(self._named_service,
 129                                                   self._object_path,
 130                                                   dbus_interface,
 131                                                   self._method_name,
 132                                                   introspect_sig,
 133                                                   args,
 134                                                   **keywords)
 135
 136     def call_async(self, *args, **keywords):
 137         reply_handler = keywords.pop('reply_handler', None)
 138         error_handler = keywords.pop('error_handler', None)
 139
 140         dbus_interface = keywords.pop('dbus_interface', self._dbus_interface)
 141
 142         if dbus_interface:
 143             key = dbus_interface + '.' + self._method_name
 144         else:
 145             key = self._method_name
 146         introspect_sig = self._proxy._introspect_method_map.get(key, None)
 147
 148         self._connection.call_async(self._named_service,
 149                                     self._object_path,
 150                                     dbus_interface,
 151                                     self._method_name,
 152                                     introspect_sig,
 153                                     args,
 154                                     reply_handler,
 155                                     error_handler,
 156                                     **keywords)
 157
 158
 159 class ProxyObject(object):
 160     """A proxy to the remote Object.
 161
 162     A ProxyObject is provided by the Bus. ProxyObjects
 163     have member functions, and can be called like normal Python objects.
 164     """
 165     ProxyMethodClass = _ProxyMethod
 166     DeferredMethodClass = _DeferredMethod
 167
 168     INTROSPECT_STATE_DONT_INTROSPECT = 0
 169     INTROSPECT_STATE_INTROSPECT_IN_PROGRESS = 1
 170     INTROSPECT_STATE_INTROSPECT_DONE = 2
 171
 172     def __init__(self, bus, named_service, object_path, introspect=True,
 173                  follow_name_owner_changes=False):
 174         """Initialize the proxy object.
 175
 176         :Parameters:
 177             `bus` : `dbus.Bus`
 178                 The bus on which to find this object
 179             `named_service` : str
 180                 A bus name for the endpoint owning the object (need not
 181                 actually be a service name)
 182             `object_path` : str
 183                 The object path at which the endpoint exports the object
 184             `introspect` : bool
 185                 If true (default), attempt to introspect the remote
 186                 object to find out supported methods and their signatures
 187             `follow_name_owner_changes` : bool
 188                 If true (default is false) and the `named_service` is a
 189                 well-known name, follow ownership changes for that name
 190         """
 191         if follow_name_owner_changes:
 192             # we don't get the signals unless the Bus has a main loop
 193             # XXX: using Bus internals
 194             bus._require_main_loop()
 195
 196         self._bus           = bus
 197
 198         if named_service is not None:
 199             _dbus_bindings.validate_bus_name(named_service)
 200         self._named_service = self._requested_bus_name = named_service
 201
 202         _dbus_bindings.validate_object_path(object_path)
 203         self.__dbus_object_path__ = object_path
 204
 205         if not follow_name_owner_changes:
 206             self._named_service = bus.activate_name_owner(named_service)
 207
 208         #PendingCall object for Introspect call
 209         self._pending_introspect = None
 210         #queue of async calls waiting on the Introspect to return
 211         self._pending_introspect_queue = []
 212         #dictionary mapping method names to their input signatures
 213         self._introspect_method_map = {}
 214
 215         # must be a recursive lock because block() is called while locked,
 216         # and calls the callback which re-takes the lock
 217         self._introspect_lock = RLock()
 218
 219         if not introspect or self.__dbus_object_path__ == LOCAL_PATH:
 220             self._introspect_state = self.INTROSPECT_STATE_DONT_INTROSPECT
 221         else:
 222             self._introspect_state = self.INTROSPECT_STATE_INTROSPECT_IN_PROGRESS
 223
 224             self._pending_introspect = self._Introspect()
 225
 226     bus_name = property(lambda self: self._named_service, None, None,
 227             """The bus name to which this proxy is bound. (Read-only,
 228             may change.)
 229
 230             If the proxy was instantiated using a unique name, this property
 231             is that unique name.
 232
 233             If the proxy was instantiated with a well-known name and with
 234             `follow_name_owner_changes` set false (the default), this
 235             property is the unique name of the connection that owned that
 236             well-known name when the proxy was instantiated, which might
 237             not actually own the requested well-known name any more.
 238
 239             If the proxy was instantiated with a well-known name and with
 240             `follow_name_owner_changes` set true, this property is that
 241             well-known name.
 242             """)
 243
 244     requested_bus_name = property(lambda self: self._requested_bus_name,
 245             None, None,
 246             """The bus name which was requested when this proxy was
 247             instantiated.
 248             """)
 249
 250     object_path = property(lambda self: self.__dbus_object_path__,
 251             None, None,
 252             """The object-path of this proxy.""")
 253
 254     # XXX: We don't currently support this because it's the signal receiver
 255     # that's responsible for tracking name owner changes, but it
 256     # seems a natural thing to add in future.
 257     #unique_bus_name = property(lambda self: something, None, None,
 258     #        """The unique name of the connection to which this proxy is
 259     #        currently bound. (Read-only, may change.)
 260     #        """)
 261
 262     def connect_to_signal(self, signal_name, handler_function, dbus_interface=None, **keywords):
 263         """Arrange for the given function to be called when the given signal
 264         is received.
 265
 266         :Parameters:
 267             `signal_name` : str
 268                 The name of the signal
 269             `handler_function` : callable
 270                 A function to be called when the signal is emitted by
 271                 the remote object. Its positional arguments will be the
 272                 arguments of the signal; optionally, it may be given
 273                 keyword arguments as described below.
 274             `dbus_interface` : str
 275                 Optional interface with which to qualify the signal name.
 276                 If None (the default) the handler will be called whenever a
 277                 signal of the given member name is received, whatever
 278                 its interface.
 279         :Keywords:
 280             `utf8_strings` : bool
 281                 If True, the handler function will receive any string
 282                 arguments as dbus.UTF8String objects (a subclass of str
 283                 guaranteed to be UTF-8). If False (default) it will receive
 284                 any string arguments as dbus.String objects (a subclass of
 285                 unicode).
 286             `byte_arrays` : bool
 287                 If True, the handler function will receive any byte-array
 288                 arguments as dbus.ByteArray objects (a subclass of str).
 289                 If False (default) it will receive any byte-array
 290                 arguments as a dbus.Array of dbus.Byte (subclasses of:
 291                 a list of ints).
 292             `sender_keyword` : str
 293                 If not None (the default), the handler function will receive
 294                 the unique name of the sending endpoint as a keyword
 295                 argument with this name
 296             `destination_keyword` : str
 297                 If not None (the default), the handler function will receive
 298                 the bus name of the destination (or None if the signal is a
 299                 broadcast, as is usual) as a keyword argument with this name.
 300             `interface_keyword` : str
 301                 If not None (the default), the handler function will receive
 302                 the signal interface as a keyword argument with this name.
 303             `member_keyword` : str
 304                 If not None (the default), the handler function will receive
 305                 the signal name as a keyword argument with this name.
 306             `path_keyword` : str
 307                 If not None (the default), the handler function will receive
 308                 the object-path of the sending object as a keyword argument
 309                 with this name
 310             `message_keyword` : str
 311                 If not None (the default), the handler function will receive
 312                 the `dbus.lowlevel.SignalMessage` as a keyword argument with
 313                 this name.
 314             `arg...` : unicode or UTF-8 str
 315                 If there are additional keyword parameters of the form
 316                 ``arg``\ *n*, match only signals where the *n*\ th argument
 317                 is the value given for that keyword parameter. As of this time
 318                 only string arguments can be matched (in particular,
 319                 object paths and signatures can't).
 320         """
 321         return \
 322         self._bus.add_signal_receiver(handler_function,
 323                                       signal_name=signal_name,
 324                                       dbus_interface=dbus_interface,
 325                                       named_service=self._named_service,
 326                                       path=self.__dbus_object_path__,
 327                                       **keywords)
 328
 329     def _Introspect(self):
 330         return self._bus.call_async(self._named_service,
 331                                     self.__dbus_object_path__,
 332                                     INTROSPECTABLE_IFACE, 'Introspect', '', (),
 333                                     self._introspect_reply_handler,
 334                                     self._introspect_error_handler,
 335                                     utf8_strings=True,
 336                                     require_main_loop=False)
 337
 338     def _introspect_execute_queue(self):
 339         # FIXME: potential to flood the bus
 340         # We should make sure mainloops all have idle handlers
 341         # and do one message per idle
 342         for (proxy_method, args, keywords) in self._pending_introspect_queue:
 343             proxy_method(*args, **keywords)
 344
 345     def _introspect_reply_handler(self, data):
 346         self._introspect_lock.acquire()
 347         try:
 348             try:
 349                 self._introspect_method_map = process_introspection_data(data)
 350             except IntrospectionParserException, e:
 351                 self._introspect_error_handler(e)
 352                 return
 353
 354             self._introspect_state = self.INTROSPECT_STATE_INTROSPECT_DONE
 355             self._pending_introspect = None
 356             self._introspect_execute_queue()
 357         finally:
 358             self._introspect_lock.release()
 359
 360     def _introspect_error_handler(self, error):
 361         self._introspect_lock.acquire()
 362         try:
 363             self._introspect_state = self.INTROSPECT_STATE_DONT_INTROSPECT
 364             self._pending_introspect = None
 365             self._introspect_execute_queue()
 366             sys.stderr.write("Introspect error: " + str(error) + "\n")
 367         finally:
 368             self._introspect_lock.release()
 369
 370     def _introspect_block(self):
 371         self._introspect_lock.acquire()
 372         try:
 373             if self._pending_introspect is not None:
 374                 self._pending_introspect.block()
 375             # else someone still has a _DeferredMethod from before we
 376             # finished introspection: no need to do anything special any more
 377         finally:
 378             self._introspect_lock.release()
 379
 380     def _introspect_add_to_queue(self, callback, args, kwargs):
 381         self._introspect_lock.acquire()
 382         try:
 383             if self._introspect_state == self.INTROSPECT_STATE_INTROSPECT_IN_PROGRESS:
 384                 self._pending_introspect_queue.append((callback, args, kwargs))
 385             else:
 386                 # someone still has a _DeferredMethod from before we
 387                 # finished introspection
 388                 callback(*args, **kwargs)
 389         finally:
 390             self._introspect_lock.release()
 391
 392     def __getattr__(self, member):
 393         if member.startswith('__') and member.endswith('__'):
 394             raise AttributeError(member)
 395         else:
 396             return self.get_dbus_method(member)
 397
 398     def get_dbus_method(self, member, dbus_interface=None):
 399         """Return a proxy method representing the given D-Bus method. The
 400         returned proxy method can be called in the usual way. For instance, ::
 401
 402             proxy.get_dbus_method("Foo", dbus_interface='com.example.Bar')(123)
 403
 404         is equivalent to::
 405
 406             proxy.Foo(123, dbus_interface='com.example.Bar')
 407
 408         or even::
 409
 410             getattr(proxy, "Foo")(123, dbus_interface='com.example.Bar')
 411
 412         However, using `get_dbus_method` is the only way to call D-Bus
 413         methods with certain awkward names - if the author of a service
 414         implements a method called ``connect_to_signal`` or even
 415         ``__getattr__``, you'll need to use `get_dbus_method` to call them.
 416
 417         For services which follow the D-Bus convention of CamelCaseMethodNames
 418         this won't be a problem.
 419         """
 420
 421         ret = self.ProxyMethodClass(self, self._bus,
 422                                     self._named_service,
 423                                     self.__dbus_object_path__, member,
 424                                     dbus_interface)
 425
 426         # this can be done without taking the lock - the worst that can
 427         # happen is that we accidentally return a _DeferredMethod just after
 428         # finishing introspection, in which case _introspect_add_to_queue and
 429         # _introspect_block will do the right thing anyway
 430         if self._introspect_state == self.INTROSPECT_STATE_INTROSPECT_IN_PROGRESS:
 431             ret = self.DeferredMethodClass(ret, self._introspect_add_to_queue,
 432                                            self._introspect_block)
 433
 434         return ret
 435
 436     def __repr__(self):
 437         return '<ProxyObject wrapping %s %s %s at %#x>'%(
 438             self._bus, self._named_service, self.__dbus_object_path__, id(self))
 439     __str__ = __repr__
 440
 441
 442 class Interface(object):
 443     """An interface into a remote object.
 444
 445     An Interface can be used to wrap ProxyObjects
 446     so that calls can be routed to their correct
 447     D-Bus interface.
 448     """
 449
 450     def __init__(self, object, dbus_interface):
 451         """Construct a proxy for the given interface on the given object.
 452
 453         :Parameters:
 454             `object` : `dbus.proxies.ProxyObject` or `dbus.Interface`
 455                 The remote object or another of its interfaces
 456             `dbus_interface` : str
 457                 An interface the `object` implements
 458         """
 459         if isinstance(object, Interface):
 460             self._obj = object.proxy_object
 461         else:
 462             self._obj = object
 463         self._dbus_interface = dbus_interface
 464
 465     object_path = property (lambda self: self._obj.object_path, None, None,
 466                             "The D-Bus object path of the underlying object")
 467     __dbus_object_path__ = object_path
 468     bus_name = property (lambda self: self._obj.bus_name, None, None,
 469                          "The bus name to which the underlying proxy object "
 470                          "is bound")
 471     requested_bus_name = property (lambda self: self._obj.requested_bus_name,
 472                                    None, None,
 473                                    "The bus name which was requested when the "
 474                                    "underlying object was created")
 475     proxy_object = property (lambda self: self._obj, None, None,
 476                              """The underlying proxy object""")
 477     dbus_interface = property (lambda self: self._dbus_interface, None, None,
 478                                """The D-Bus interface represented""")
 479
 480     def connect_to_signal(self, signal_name, handler_function,
 481                           dbus_interface=None, **keywords):
 482         """Arrange for a function to be called when the given signal is
 483         emitted.
 484
 485         The parameters and keyword arguments are the same as for
 486         `dbus.proxies.ProxyObject.connect_to_signal`, except that if
 487         `dbus_interface` is None (the default), the D-Bus interface that
 488         was passed to the `Interface` constructor is used.
 489         """
 490         if not dbus_interface:
 491             dbus_interface = self._dbus_interface
 492
 493         return self._obj.connect_to_signal(signal_name, handler_function,
 494                                            dbus_interface, **keywords)
 495
 496     def __getattr__(self, member):
 497         if member.startswith('__') and member.endswith('__'):
 498             raise AttributeError(member)
 499         else:
 500             return self._obj.get_dbus_method(member, self._dbus_interface)
 501
 502     def get_dbus_method(self, member, dbus_interface=None):
 503         """Return a proxy method representing the given D-Bus method.
 504
 505         This is the same as `dbus.proxies.ProxyObject.get_dbus_method`
 506         except that if `dbus_interface` is None (the default),
 507         the D-Bus interface that was passed to the `Interface` constructor
 508         is used.
 509         """
 510         if dbus_interface is None:
 511             dbus_interface = self._dbus_interface
 512         return self._obj.get_dbus_method(member, dbus_interface)
 513
 514     def __repr__(self):
 515         return '<Interface %r implementing %r at %#x>'%(
 516         self._obj, self._dbus_interface, id(self))
 517     __str__ = __repr__