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      1 # Copyright 2015 The Chromium OS Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be # found in the LICENSE file.
      3 
      4 import dbus
      5 import dbus.service
      6 import logging
      7 
      8 
      9 class ObjectManager(dbus.service.Object):
     10     """Exports the org.freedesktop.DBus.ObjectManager interface:
     11 
     12     GetManagedObjects(
     13             out DICT<OBJPATH,DICT<STRING,DICT<STRING,VARIANT>>>
     14                     objpath_interfaces_and_properties);
     15 
     16     The return value of this method is a dict whose keys are object
     17     paths. All returned object paths are children of the object path
     18     implementing this interface, i.e. their object paths start with
     19     the ObjectManager's object path plus '/'.
     20 
     21     Each value is a dict whose keys are interfaces names. Each value
     22     in this inner dict is the same dict that would be returned by the
     23     org.freedesktop.DBus.Properties.GetAll() method for that
     24     combination of object path and interface. If an interface has no
     25     properties, the empty dict is returned.
     26 
     27     Changes are emitted using the following two signals:
     28 
     29     InterfacesAdded(
     30             OBJPATH object_path,
     31             DICT<STRING,DICT<STRING,VARIANT>> interfaces_and_properties);
     32 
     33     InterfacesRemoved (OBJPATH object_path, ARRAY<STRING> interfaces);
     34 
     35     """
     36 
     37     OBJECT_MANAGER_INTERFACE = 'org.freedesktop.DBus.ObjectManager'
     38 
     39 
     40     def __init__(self, bus, path):
     41         super(ObjectManager, self).__init__(bus, path)
     42         self._paths = dict()
     43 
     44 
     45     def claim_interface(self, path, interface_name, property_getter):
     46         """Claim an interface for an object exposed under this ObjectManager.
     47 
     48         @param path: string object path of object exposed.
     49         @param interface_name: string DBus interface name of exposed object.
     50         @param property_getter: function that takes no objects and returns
     51                 a dictionary mapping from property name to property value.
     52                 Both property names and values must be DBus types.
     53 
     54         """
     55         logging.debug('claim_interface(%s, %s, ...)', path, interface_name)
     56         if path in self._paths:
     57             self._paths[path][interface_name] = property_getter
     58         else:
     59             self._paths[path] = {interface_name: property_getter}
     60         interface2properties = dbus.Dictionary(
     61                 {dbus.String(interface_name): property_getter()}, 'sa{sv}')
     62         self.InterfacesAdded(dbus.ObjectPath(path), interface2properties)
     63 
     64 
     65     def release_interface(self, path, interface_name):
     66         """Release an interface previously claimed for a particular |path|.
     67 
     68         You may call this method even if the interface has not been claimed.
     69         This is intended to simplify destruction patterns.
     70 
     71         @param path: string path exposed previously.
     72         @param interface_name: string DBus interface name previously claimed.
     73 
     74         """
     75         logging.debug('release_interface(%s, %s)', path, interface_name)
     76         if path not in self._paths or interface_name not in self._paths[path]:
     77             return
     78         self._paths[path].pop(interface_name)
     79         if not self._paths[path]:
     80             self._paths.pop(path)
     81         self.InterfacesRemoved(dbus.ObjectPath(path),
     82                                dbus.Array([dbus.String(interface_name)]))
     83 
     84 
     85     @dbus.service.method(dbus_interface=OBJECT_MANAGER_INTERFACE,
     86                          in_signature='', out_signature='a{oa{sa{sv}}}')
     87     def GetManagedObjects(self):
     88         """Implementation of DBus interface method of the same name.
     89 
     90         @return see class documentation.
     91 
     92         """
     93         logging.debug('Received call to GetManagedObjects()')
     94         result = dbus.Dictionary(dict(), 'oa{sa{sv}}')
     95         for path, interfaces in self._paths.iteritems():
     96             dbus_path = dbus.ObjectPath(path)
     97             result[dbus_path] = dbus.Dictionary(dict(), 'sa{sv}')
     98             for interface_name, property_getter in interfaces.iteritems():
     99                 dbus_if_name = dbus.String(interface_name)
    100                 result[dbus_path][dbus_if_name] = property_getter()
    101         return result
    102 
    103 
    104     @dbus.service.signal(dbus_interface=OBJECT_MANAGER_INTERFACE,
    105                          signature='oa{sa{sv}}')
    106     def InterfacesAdded(self, object_path, interfaces2properties):
    107         """Implementation of DBus interface signal.
    108 
    109         @param object_path: dbus.ObjectPath object.
    110         @param interfaces2properties: see class documentation.
    111 
    112         """
    113 
    114 
    115     @dbus.service.signal(dbus_interface=OBJECT_MANAGER_INTERFACE,
    116                          signature='oas')
    117     def InterfacesRemoved(self, object_path, interfaces):
    118         """Implementation of DBus interface signal.
    119 
    120         @param object_path: dbus.ObjectPath object.
    121         @param interfaces: see class documentation.
    122 
    123         """
    124