dbus/bus.py

   1 # Copyright (C) 2007 Collabora Ltd. <http://www.collabora.co.uk/>
   2 #
   3 # Licensed under the Academic Free License version 2.1
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU Lesser General Public License as published
   7 # by the Free Software Foundation; either version 2.1 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program; if not, write to the Free Software
  17 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18
  19 __all__ = ('BusConnection',)
  20 __docformat__ = 'reStructuredText'
  21
  22 import logging
  23 import weakref
  24
  25 from _dbus_bindings import validate_interface_name, validate_member_name,\
  26                            validate_bus_name, validate_object_path,\
  27                            validate_error_name,\
  28                            BUS_SESSION, BUS_STARTER, BUS_SYSTEM, \
  29                            DBUS_START_REPLY_SUCCESS, \
  30                            DBUS_START_REPLY_ALREADY_RUNNING, \
  31                            BUS_DAEMON_NAME, BUS_DAEMON_PATH, BUS_DAEMON_IFACE,\
  32                            NAME_FLAG_ALLOW_REPLACEMENT, \
  33                            NAME_FLAG_DO_NOT_QUEUE, \
  34                            NAME_FLAG_REPLACE_EXISTING, \
  35                            RELEASE_NAME_REPLY_NON_EXISTENT, \
  36                            RELEASE_NAME_REPLY_NOT_OWNER, \
  37                            RELEASE_NAME_REPLY_RELEASED, \
  38                            REQUEST_NAME_REPLY_ALREADY_OWNER, \
  39                            REQUEST_NAME_REPLY_EXISTS, \
  40                            REQUEST_NAME_REPLY_IN_QUEUE, \
  41                            REQUEST_NAME_REPLY_PRIMARY_OWNER
  42 from dbus.connection import Connection
  43 from dbus.exceptions import DBusException
  44 from dbus.lowlevel import HANDLER_RESULT_NOT_YET_HANDLED
  45
  46
  47 _NAME_OWNER_CHANGE_MATCH = ("type='signal',sender='%s',"
  48                             "interface='%s',member='NameOwnerChanged',"
  49                             "path='%s',arg0='%%s'"
  50                             % (BUS_DAEMON_NAME, BUS_DAEMON_IFACE,
  51                                BUS_DAEMON_PATH))
  52 """(_NAME_OWNER_CHANGE_MATCH % sender) matches relevant NameOwnerChange
  53 messages"""
  54
  55 _NAME_HAS_NO_OWNER = 'org.freedesktop.DBus.Error.NameHasNoOwner'
  56
  57 _logger = logging.getLogger('dbus.bus')
  58
  59
  60 class NameOwnerWatch(object):
  61     __slots__ = ('_match', '_pending_call')
  62
  63     def __init__(self, bus_conn, bus_name, callback):
  64         validate_bus_name(bus_name)
  65
  66         def signal_cb(owned, old_owner, new_owner):
  67             callback(new_owner)
  68
  69         def error_cb(e):
  70             if e.get_dbus_name() == _NAME_HAS_NO_OWNER:
  71                 callback('')
  72             else:
  73                 logging.basicConfig()
  74                 _logger.debug('GetNameOwner(%s) failed:', bus_name,
  75                               exc_info=(e.__class__, e, None))
  76
  77         self._match = bus_conn.add_signal_receiver(signal_cb,
  78                                                    'NameOwnerChanged',
  79                                                    BUS_DAEMON_IFACE,
  80                                                    BUS_DAEMON_NAME,
  81                                                    BUS_DAEMON_PATH,
  82                                                    arg0=bus_name)
  83         self._pending_call = bus_conn.call_async(BUS_DAEMON_NAME,
  84                                                  BUS_DAEMON_PATH,
  85                                                  BUS_DAEMON_IFACE,
  86                                                  'GetNameOwner',
  87                                                  's', (bus_name,),
  88                                                  callback, error_cb,
  89                                                  utf8_strings=True)
  90
  91     def cancel(self):
  92         if self._match is not None:
  93             self._match.remove()
  94         if self._pending_call is not None:
  95             self._pending_call.cancel()
  96         self._match = None
  97         self._pending_call = None
  98
  99
 100 class BusConnection(Connection):
 101     """A connection to a D-Bus daemon that implements the
 102     ``org.freedesktop.DBus`` pseudo-service.
 103
 104     :Since: 0.81.0
 105     """
 106
 107     TYPE_SESSION    = BUS_SESSION
 108     """Represents a session bus (same as the global dbus.BUS_SESSION)"""
 109
 110     TYPE_SYSTEM     = BUS_SYSTEM
 111     """Represents the system bus (same as the global dbus.BUS_SYSTEM)"""
 112
 113     TYPE_STARTER = BUS_STARTER
 114     """Represents the bus that started this service by activation (same as
 115     the global dbus.BUS_STARTER)"""
 116
 117     START_REPLY_SUCCESS = DBUS_START_REPLY_SUCCESS
 118     START_REPLY_ALREADY_RUNNING = DBUS_START_REPLY_ALREADY_RUNNING
 119
 120     def __new__(cls, address_or_type=TYPE_SESSION, mainloop=None):
 121         bus = cls._new_for_bus(address_or_type, mainloop=mainloop)
 122
 123         # _bus_names is used by dbus.service.BusName!
 124         bus._bus_names = weakref.WeakValueDictionary()
 125
 126         bus._signal_sender_matches = {}
 127         """Map from SignalMatch to NameOwnerWatch."""
 128
 129         return bus
 130
 131     def add_signal_receiver(self, handler_function, signal_name=None,
 132                             dbus_interface=None, bus_name=None,
 133                             path=None, **keywords):
 134         named_service = keywords.pop('named_service', None)
 135         if named_service is not None:
 136             if bus_name is not None:
 137                 raise TypeError('bus_name and named_service cannot both be '
 138                                 'specified')
 139             bus_name = named_service
 140             from warnings import warn
 141             warn('Passing the named_service parameter to add_signal_receiver '
 142                  'by name is deprecated: please use positional parameters',
 143                  DeprecationWarning, stacklevel=2)
 144
 145         match = super(BusConnection, self).add_signal_receiver(
 146                 handler_function, signal_name, dbus_interface, bus_name,
 147                 path, **keywords)
 148
 149         if (bus_name is not None and bus_name != BUS_DAEMON_NAME):
 150             if bus_name[:1] == ':':
 151                 def callback(new_owner):
 152                     if new_owner == '':
 153                         match.remove()
 154             else:
 155                 callback = match.set_sender_name_owner
 156             watch = self.watch_name_owner(bus_name, callback)
 157             self._signal_sender_matches[match] = watch
 158
 159         self.add_match_string(str(match))
 160
 161         return match
 162
 163     def _clean_up_signal_match(self, match):
 164         # The signals lock is no longer held here (it was in <= 0.81.0)
 165         self.remove_match_string_non_blocking(str(match))
 166         watch = self._signal_sender_matches.pop(match, None)
 167         if watch is not None:
 168             watch.cancel()
 169
 170     def activate_name_owner(self, bus_name):
 171         if (bus_name is not None and bus_name[:1] != ':'
 172             and bus_name != BUS_DAEMON_NAME):
 173             try:
 174                 return self.get_name_owner(bus_name)
 175             except DBusException, e:
 176                 if e.get_dbus_name() != _NAME_HAS_NO_OWNER:
 177                     raise
 178                 # else it doesn't exist: try to start it
 179                 self.start_service_by_name(bus_name)
 180                 return self.get_name_owner(bus_name)
 181         else:
 182             # already unique
 183             return bus_name
 184
 185     def get_object(self, bus_name, object_path, introspect=True,
 186                    follow_name_owner_changes=False, **kwargs):
 187         """Return a local proxy for the given remote object.
 188
 189         Method calls on the proxy are translated into method calls on the
 190         remote object.
 191
 192         :Parameters:
 193             `bus_name` : str
 194                 A bus name (either the unique name or a well-known name)
 195                 of the application owning the object. The keyword argument
 196                 named_service is a deprecated alias for this.
 197             `object_path` : str
 198                 The object path of the desired object
 199             `introspect` : bool
 200                 If true (default), attempt to introspect the remote
 201                 object to find out supported methods and their signatures
 202             `follow_name_owner_changes` : bool
 203                 If the object path is a well-known name and this parameter
 204                 is false (default), resolve the well-known name to the unique
 205                 name of its current owner and bind to that instead; if the
 206                 ownership of the well-known name changes in future,
 207                 keep communicating with the original owner.
 208                 This is necessary if the D-Bus API used is stateful.
 209
 210                 If the object path is a well-known name and this parameter
 211                 is true, whenever the well-known name changes ownership in
 212                 future, bind to the new owner, if any.
 213
 214                 If the given object path is a unique name, this parameter
 215                 has no effect.
 216
 217         :Returns: a `dbus.proxies.ProxyObject`
 218         :Raises `DBusException`: if resolving the well-known name to a
 219             unique name fails
 220         """
 221         if follow_name_owner_changes:
 222             self._require_main_loop()   # we don't get the signals otherwise
 223
 224         named_service = kwargs.pop('named_service', None)
 225         if named_service is not None:
 226             if bus_name is not None:
 227                 raise TypeError('bus_name and named_service cannot both '
 228                                 'be specified')
 229             from warnings import warn
 230             warn('Passing the named_service parameter to get_object by name '
 231                  'is deprecated: please use positional parameters',
 232                  DeprecationWarning, stacklevel=2)
 233             bus_name = named_service
 234         if kwargs:
 235             raise TypeError('get_object does not take these keyword '
 236                             'arguments: %s' % ', '.join(kwargs.iterkeys()))
 237
 238         return self.ProxyObjectClass(self, bus_name, object_path,
 239                                      introspect=introspect,
 240                                      follow_name_owner_changes=follow_name_owner_changes)
 241
 242     def get_unix_user(self, bus_name):
 243         """Get the numeric uid of the process owning the given bus name.
 244
 245         :Parameters:
 246             `bus_name` : str
 247                 A bus name, either unique or well-known
 248         :Returns: a `dbus.UInt32`
 249         :Since: 0.80.0
 250         """
 251         validate_bus_name(bus_name)
 252         return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 253                                   BUS_DAEMON_IFACE, 'GetConnectionUnixUser',
 254                                   's', (bus_name,))
 255
 256     def start_service_by_name(self, bus_name, flags=0):
 257         """Start a service which will implement the given bus name on this Bus.
 258
 259         :Parameters:
 260             `bus_name` : str
 261                 The well-known bus name to be activated.
 262             `flags` : dbus.UInt32
 263                 Flags to pass to StartServiceByName (currently none are
 264                 defined)
 265
 266         :Returns: A tuple of 2 elements. The first is always True, the
 267             second is either START_REPLY_SUCCESS or
 268             START_REPLY_ALREADY_RUNNING.
 269
 270         :Raises `DBusException`: if the service could not be started.
 271         :Since: 0.80.0
 272         """
 273         validate_bus_name(bus_name)
 274         return (True, self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 275                                          BUS_DAEMON_IFACE,
 276                                          'StartServiceByName',
 277                                          'su', (bus_name, flags)))
 278
 279     # XXX: it might be nice to signal IN_QUEUE, EXISTS by exception,
 280     # but this would not be backwards-compatible
 281     def request_name(self, name, flags=0):
 282         """Request a bus name.
 283
 284         :Parameters:
 285             `name` : str
 286                 The well-known name to be requested
 287             `flags` : dbus.UInt32
 288                 A bitwise-OR of 0 or more of the flags
 289                 `NAME_FLAG_ALLOW_REPLACEMENT`,
 290                 `NAME_FLAG_REPLACE_EXISTING`
 291                 and `NAME_FLAG_DO_NOT_QUEUE`
 292         :Returns: `REQUEST_NAME_REPLY_PRIMARY_OWNER`,
 293             `REQUEST_NAME_REPLY_IN_QUEUE`,
 294             `REQUEST_NAME_REPLY_EXISTS` or
 295             `REQUEST_NAME_REPLY_ALREADY_OWNER`
 296         :Raises `DBusException`: if the bus daemon cannot be contacted or
 297             returns an error.
 298         """
 299         validate_bus_name(name, allow_unique=False)
 300         return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 301                                   BUS_DAEMON_IFACE, 'RequestName',
 302                                   'su', (name, flags))
 303
 304     def release_name(self, name):
 305         """Release a bus name.
 306
 307         :Parameters:
 308             `name` : str
 309                 The well-known name to be released
 310         :Returns: `RELEASE_NAME_REPLY_RELEASED`,
 311             `RELEASE_NAME_REPLY_NON_EXISTENT`
 312             or `RELEASE_NAME_REPLY_NOT_OWNER`
 313         :Raises `DBusException`: if the bus daemon cannot be contacted or
 314             returns an error.
 315         """
 316         validate_bus_name(name, allow_unique=False)
 317         return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 318                                   BUS_DAEMON_IFACE, 'ReleaseName',
 319                                   's', (name,))
 320
 321     def list_names(self):
 322         """Return a list of all currently-owned names on the bus.
 323
 324         :Returns: a dbus.Array of dbus.UTF8String
 325         :Since: 0.81.0
 326         """
 327         return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 328                                   BUS_DAEMON_IFACE, 'ListNames',
 329                                   '', (), utf8_strings=True)
 330
 331     def list_activatable_names(self):
 332         """Return a list of all names that can be activated on the bus.
 333
 334         :Returns: a dbus.Array of dbus.UTF8String
 335         :Since: 0.81.0
 336         """
 337         return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 338                                   BUS_DAEMON_IFACE, 'ListNames',
 339                                   '', (), utf8_strings=True)
 340
 341     def get_name_owner(self, bus_name):
 342         """Return the unique connection name of the primary owner of the
 343         given name.
 344
 345         :Raises `DBusException`: if the `bus_name` has no owner
 346         :Since: 0.81.0
 347         """
 348         validate_bus_name(bus_name, allow_unique=False)
 349         return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 350                                   BUS_DAEMON_IFACE, 'GetNameOwner',
 351                                   's', (bus_name,), utf8_strings=True)
 352
 353     def watch_name_owner(self, bus_name, callback):
 354         """Watch the unique connection name of the primary owner of the
 355         given name.
 356
 357         `callback` will be called with one argument, which is either the
 358         unique connection name, or the empty string (meaning the name is
 359         not owned).
 360
 361         :Since: 0.81.0
 362         """
 363         return NameOwnerWatch(self, bus_name, callback)
 364
 365     def name_has_owner(self, bus_name):
 366         """Return True iff the given bus name has an owner on this bus.
 367
 368         :Parameters:
 369             `bus_name` : str
 370                 The bus name to look up
 371         :Returns: a `bool`
 372         """
 373         return bool(self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 374                                        BUS_DAEMON_IFACE, 'NameHasOwner',
 375                                        's', (bus_name,)))
 376
 377     def add_match_string(self, rule):
 378         """Arrange for this application to receive messages on the bus that
 379         match the given rule. This version will block.
 380
 381         :Parameters:
 382             `rule` : str
 383                 The match rule
 384         :Raises `DBusException`: on error.
 385         :Since: 0.80.0
 386         """
 387         self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 388                            BUS_DAEMON_IFACE, 'AddMatch', 's', (rule,))
 389
 390     # FIXME: add an async success/error handler capability?
 391     # (and the same for remove_...)
 392     def add_match_string_non_blocking(self, rule):
 393         """Arrange for this application to receive messages on the bus that
 394         match the given rule. This version will not block, but any errors
 395         will be ignored.
 396
 397
 398         :Parameters:
 399             `rule` : str
 400                 The match rule
 401         :Raises `DBusException`: on error.
 402         :Since: 0.80.0
 403         """
 404         self.call_async(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 405                         BUS_DAEMON_IFACE, 'AddMatch', 's', (rule,),
 406                         None, None)
 407
 408     def remove_match_string(self, rule):
 409         """Arrange for this application to receive messages on the bus that
 410         match the given rule. This version will block.
 411
 412         :Parameters:
 413             `rule` : str
 414                 The match rule
 415         :Raises `DBusException`: on error.
 416         :Since: 0.80.0
 417         """
 418         self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 419                            BUS_DAEMON_IFACE, 'RemoveMatch', 's', (rule,))
 420
 421     def remove_match_string_non_blocking(self, rule):
 422         """Arrange for this application to receive messages on the bus that
 423         match the given rule. This version will not block, but any errors
 424         will be ignored.
 425
 426
 427         :Parameters:
 428             `rule` : str
 429                 The match rule
 430         :Raises `DBusException`: on error.
 431         :Since: 0.80.0
 432         """
 433         self.call_async(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
 434                         BUS_DAEMON_IFACE, 'RemoveMatch', 's', (rule,),
 435                         None, None)