Add init support for structure variable members being written, identi…

…fied occasional recursion problem by struct members.

decompiler/backend/cexpressiongenerator.py

@@ -7,7 +7,7 @@
 from decompiler.structures.pseudo import Float, Integer, OperationType, Pointer, StringSymbol
 from decompiler.structures.pseudo import instructions as instructions
 from decompiler.structures.pseudo import operations as operations
-from decompiler.structures.pseudo.operations import StructMember
+from decompiler.structures.pseudo.operations import StructMemberAccess
 from decompiler.structures.pseudo.typing import StructureType
 from decompiler.structures.visitors.interfaces import DataflowObjectVisitorInterface
 

decompiler/frontend/binaryninja/handlers/assignments.py

@@ -1,4 +1,5 @@
 """Module implementing the AssignmentHandler for binaryninja."""
+import logging
 from functools import partial
 from typing import Union
 
@@ -16,6 +17,7 @@
     RegisterPair,
     UnaryOperation,
 )
+from decompiler.structures.pseudo.operations import StructMemberAccess
 
 
 class AssignmentHandler(Handler):
@@ -170,21 +172,14 @@ def lift_split_assignment(self, assignment: mediumlevelil.MediumLevelILSetVarSpl
     def _lift_store_struct(self, instruction: mediumlevelil.MediumLevelILStoreStruct, **kwargs) -> Assignment:
         """Lift a MLIL_STORE_STRUCT_SSA instruction to pseudo (e.g. object->field = x)."""
         vartype = self._lifter.lift(instruction.dest.expr_type)
-        return Assignment(
-            UnaryOperation(
-                OperationType.dereference,
-                [
-                    BinaryOperation(
-                        OperationType.plus,
-                        [
-                            UnaryOperation(OperationType.cast, [self._lifter.lift(instruction.dest)], vartype=Pointer(Integer.char())),
-                            Constant(instruction.offset),
-                        ],
-                        vartype=vartype,
-                    ),
-                ],
-                vartype=Pointer(vartype),
-                writes_memory=instruction.dest_memory
-            ),
-            self._lifter.lift(instruction.src),
+        struct_variable = self._lifter.lift(instruction.dest)
+        struct_member_access = StructMemberAccess(
+            src=struct_variable,
+            member_name=vartype.type.members.get(instruction.offset),
+            offset=instruction.offset,
+            operands=[struct_variable],
+            vartype=vartype,
+            writes_memory=instruction.dest_memory,
         )
+        src = self._lifter.lift(instruction.src)
+        return Assignment(struct_member_access, src)

decompiler/frontend/binaryninja/handlers/types.py

@@ -71,6 +71,9 @@ def lift_struct(self, struct: StructureType, **kwargs) -> PseudoStructureType:
         return PseudoStructureType(tag_name=struct_name, members=members_dict, size=0)
 
     def lift_struct_member(self, member: StructureMember) -> PseudoStructureMember:
+        # TODO handle the case when struct member is a pointer on the same struct
+        if isinstance(member.type, PointerType) and (isinstance(member.type.target, StructureType) or isinstance(member.type.target, NamedTypeReferenceType)):
+            return CustomType("SomeStructTemp", size=0)
         return PseudoStructureMember(name=member.name, offset=member.offset, type=self._lifter.lift(member.type), size=0)
 
     def lift_void(self, _, **kwargs) -> CustomType:

decompiler/frontend/binaryninja/handlers/unary.py

@@ -15,7 +15,7 @@
     Pointer,
     UnaryOperation,
 )
-from decompiler.structures.pseudo.operations import StructMember
+from decompiler.structures.pseudo.operations import StructMemberAccess
 from decompiler.structures.pseudo.typing import StructureType
 
 
@@ -94,17 +94,16 @@ def _lift_zx_operation(self, instruction: MediumLevelILInstruction, **kwargs) ->
             )
         return self.lift_cast(instruction, **kwargs)
 
-    def _lift_load_struct(self, instruction: mediumlevelil.MediumLevelILLoadStruct, **kwargs) -> StructMember:
+    def _lift_load_struct(self, instruction: mediumlevelil.MediumLevelILLoadStruct, **kwargs) -> StructMemberAccess:
         """Lift a MLIL_LOAD_STRUCT_SSA (struct member access e.g. var#n->x) instruction."""
         # TODO type of struct variable should be either ptr on struct or struct
         # TODO type of the member hm actually we want member instance to know the struct type.
         # TODO But it is not the same as vartype
-        # TODO check what happens if members values are changed
         struct_variable = self._lifter.lift(instruction.src)
         struct_ptr: Pointer = self._lifter.lift(instruction.src.expr_type)
         struct_type: StructureType = struct_ptr.type
         struct_member_name = struct_type.members.get(instruction.offset).name
-        return StructMember(src=struct_variable,  vartype=struct_ptr, operands=[struct_variable], offset=instruction.offset, member_name=struct_member_name)
+        return StructMemberAccess(src=struct_variable, vartype=struct_ptr, operands=[struct_variable], offset=instruction.offset, member_name=struct_member_name)
 
     def _lift_ftrunc(self, instruction: mediumlevelil.MediumLevelILFtrunc, **kwargs) -> UnaryOperation:
         """Lift a MLIL_FTRUNC operation."""

decompiler/structures/pseudo/operations.py

@@ -378,7 +378,7 @@ def accept(self, visitor: DataflowObjectVisitorInterface[T]) -> T:
         return visitor.visit_unary_operation(self)
 
 
-class StructMember(Operation):
+class StructMemberAccess(Operation):
     def __init__(
         self,
         src: Expression,
@@ -388,10 +388,11 @@ def __init__(
         vartype: Type = UnknownType(),
         writes_memory: Optional[int] = None,
     ):
-        super().__init__(OperationType.struct_member, operands, vartype, writes_memory)
+        super().__init__(OperationType.struct_member, operands, vartype)
         self.struct_variable = src
         self.member_offset = offset
         self.member_name = member_name
+        self.writes_memory = writes_memory
 
     def __str__(self):
         return f"{self.struct_variable}->{self.member_name}"
@@ -404,21 +405,27 @@ def substitute(self, replacee: Expression, replacement: Expression) -> None:
             self.struct_variable = replacement
             self.operands[:] = [replacement]
 
-    def copy(self) -> StructMember:
+    def copy(self) -> StructMemberAccess:
         """Copy the current UnaryOperation, copying all operands and the type."""
-        return StructMember(
+        return StructMemberAccess(
             self.struct_variable,
             self.member_offset,
             self.member_name,
             [operand.copy() for operand in self._operands],
             self._type.copy(),
-            # writes_memory=self._writes_memory,
+            writes_memory=self.writes_memory,
         )
 
     def accept(self, visitor: DataflowObjectVisitorInterface[T]) -> T:
         """Invoke the appropriate visitor for this Operation."""
         return str(self)
 
+    def is_read_access(self):
+        return self.writes_memory is None
+
+    def is_write_access(self):
+        return self.writes_memory is not None
+
 
 class BinaryOperation(Operation):
     """Class representing operations with two operands."""