False control structure for structs (#342)

Co-authored-by: rihi <[email protected]> Co-authored-by: rihi <[email protected]> Co-authored-by: Steffen Enders <[email protected]>
fkie-cad · Oct 9, 2023 · 9663023 · 9663023
1 parent 83b07e6
commit 9663023
Showing 1 changed file with 8 additions and 5 deletions.
diff --git a/decompiler/frontend/binaryninja/handlers/assignments.py b/decompiler/frontend/binaryninja/handlers/assignments.py
@@ -95,18 +95,21 @@ def lift_get_field(self, instruction: mediumlevelil.MediumLevelILVarField, is_al
         case 1: struct member read access e.g. (x = )book.title
                 lift as (x = ) struct_member(book, title)
         case 2: accessing register portion e.g. (x = )eax.ah
-                lift as (x = ) eax & 0x0000ff00
+                lift as (x = ) (uint8_t)(eax >> 8)
         (x = ) <- for the sake of example, only rhs expression is lifted here.
         """
         source = self._lifter.lift(instruction.src, is_aliased=is_aliased, parent=instruction)
         if isinstance(source.type, Struct) or isinstance(source.type, Union):
             return self._get_field_as_member_access(instruction, source, **kwargs)
         cast_type = source.type.resize(instruction.size * self.BYTE_SIZE)
         if instruction.offset:
-            return BinaryOperation(
-                OperationType.bitwise_and,
-                [source, Constant(self._get_all_ones_mask_for_type(instruction.size) << instruction.offset)],
-                vartype=cast_type,
+            return UnaryOperation(
+                OperationType.cast,
+                [BinaryOperation(
+                    OperationType.right_shift_us,
+                    [source, Constant(instruction.offset, Integer.int32_t())]
+                )],
+                cast_type
             )
         return UnaryOperation(OperationType.cast, [source], vartype=cast_type, contraction=True)