Move the masking code into the data layer.

volatility/framework/interfaces/layers.py

@@ -5,6 +5,7 @@ Created on 4 May 2013
 """
 import collections
 import collections.abc
+import math
 from abc import ABCMeta, abstractmethod, abstractproperty
 
 from volatility.framework import exceptions, validity
@@ -85,6 +86,11 @@ class DataLayerInterface(configuration.ConfigurableInterface, validity.ValidityR
     def minimum_address(self):
         """Returns the minimum valid address of the space"""
 
+    @property
+    def address_mask(self):
+        """Returns a mask which encapsulates all the actives bit of an address for this layer"""
+        return (1 << int(math.ceil(math.log2(self.maximum_address)))) - 1
+
     @abstractmethod
     def is_valid(self, offset, length = 1):
         """Returns a boolean based on whether the offset is valid or not"""

volatility/framework/interfaces/objects.py

@@ -6,7 +6,6 @@ Created on 6 May 2013
 
 import collections
 import collections.abc
-import math
 from abc import ABCMeta, abstractmethod
 
 from volatility.framework import validity
@@ -69,7 +68,7 @@ class ObjectInterface(validity.ValidityRoutines, metaclass = ABCMeta):
         #
 
         # Normalize offsets
-        mask = (1 << int(math.ceil(math.log2(context.memory[object_info.layer_name].maximum_address)))) - 1
+        mask = context.memory[object_info.layer_name].address_mask
         normalized_offset = object_info.offset & mask
 
         self._vol = collections.ChainMap({}, object_info, {'type_name': type_name}, {'offset': normalized_offset},

volatility/framework/objects/__init__.py

@@ -5,7 +5,6 @@ Created on 17 Feb 2013
 """
 
 import collections
-import math
 import struct
 
 from volatility.framework import interfaces
@@ -164,7 +163,7 @@ class Pointer(Integer):
         """
         if layer_name is None:
             layer_name = self.vol.layer_name
-        mask = (1 << int(math.ceil(math.log2(self._context.memory[layer_name].maximum_address)))) - 1
+        mask = self._context.memory[layer_name].address_mask
         offset = self & mask
         return self.vol.subtype(context = self._context,
                                 object_info = interfaces.objects.ObjectInformation(
@@ -276,7 +275,7 @@ class Array(interfaces.objects.ObjectInterface, collections.Sequence):
     def __getitem__(self, i):
         """Returns the i-th item from the array"""
         result = []
-        mask = (1 << int(math.ceil(math.log2(self._context.memory[self.vol.layer_name].maximum_address)))) - 1
+        mask = self._context.memory[self.vol.layer_name].address_mask
         if isinstance(i, slice):
             if i.step:
                 series = range(i.start, i.stop, i.step)
@@ -371,7 +370,7 @@ class Struct(interfaces.objects.ObjectInterface):
         if attr in self._concrete_members:
             return self._concrete_members[attr]
         elif attr in self.vol.members:
-            mask = (1 << int(math.ceil(math.log2(self._context.memory[self.vol.layer_name].maximum_address)))) - 1
+            mask = self._context.memory[self.vol.layer_name].address_mask
             relative_offset, member = self.vol.members[attr]
             member = member(context = self._context,
                             object_info = interfaces.objects.ObjectInformation(layer_name = self.vol.layer_name,