fix: after code review

nomyo/SecureMemory.py

@@ -24,6 +24,7 @@ Python's immutable bytes objects cannot be securely zeroed in place.
 import ctypes
 import logging
 import sys
+import threading
 from contextlib import contextmanager
 from enum import Enum
 from typing import Optional, Union
@@ -230,7 +231,7 @@ class SecureMemory:
     def _init_windows(self):
         """Initialize Windows-specific functions (VirtualLock + RtlZeroMemory)"""
         try:
-            kernel32 = ctypes.windll.kernel32
+            kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)
 
             # Get page size
             class SYSTEM_INFO(ctypes.Structure):
@@ -429,8 +430,6 @@ class SecureMemory:
             logger.debug(f"Memory lock failed: {e}")
             return False
 
-        return False
-
     def _unlock_memory_at(self, addr: int, size: int) -> bool:
         """
         Unlock memory at a specific address.
@@ -472,8 +471,6 @@ class SecureMemory:
             logger.debug(f"Memory unlock failed: {e}")
             return False
 
-        return False
-
     def _zero_memory_at(self, addr: int, size: int) -> None:
         """
         Securely zero memory at a specific address.
@@ -655,13 +652,16 @@ class SecureMemory:
 
 # Global secure memory instance
 _secure_memory: Optional[SecureMemory] = None
+_secure_memory_lock = threading.Lock()
 
 
 def _get_secure_memory() -> SecureMemory:
     """Get or create the global SecureMemory instance."""
     global _secure_memory
     if _secure_memory is None:
-        _secure_memory = SecureMemory()
+        with _secure_memory_lock:
+            if _secure_memory is None:
+                _secure_memory = SecureMemory()
     return _secure_memory
 
 
@@ -763,7 +763,8 @@ def disable_secure_memory() -> None:
     This is useful for testing or when security is not required.
     """
     global _secure_memory
-    _secure_memory = SecureMemory(enable=False)
+    with _secure_memory_lock:
+        _secure_memory = SecureMemory(enable=False)
     logger.info("Secure memory operations disabled globally")
 
 
@@ -774,5 +775,6 @@ def enable_secure_memory() -> None:
     This reinitializes the secure memory handler with security enabled.
     """
     global _secure_memory
-    _secure_memory = SecureMemory(enable=True)
+    with _secure_memory_lock:
+        _secure_memory = SecureMemory(enable=True)
     logger.info("Secure memory operations re-enabled globally")