Minor changes to AllowListImporter

restrictedpython_code_eval.py

@@ -401,35 +401,32 @@ def _check_correctness(check_program, timeout, task_id, completion_id,
     return out_dict
 
 
-class LimitedSysModule:
-    def __init__(self):
-        self.maxsize = sys.maxsize
+ALLOWED_SYS_NAMES = ['maxsize']
 
 
 class AllowListImporter:
     def __init__(self, allowed_imports: List[str]):
         self.allowed_imports = allowed_imports
-
+        inner_sys = importlib.__import__('sys')
+        for key in list(dir(inner_sys)):
+            if key not in ALLOWED_SYS_NAMES:
+                delattr(inner_sys, key)
+        self.inner_sys = inner_sys
+        
     def __call__(self, name, globals=None, locals=None, fromlist=(), level=0):
         if name.startswith('.'):
             raise ImportError("Relative imports are not allowed.")
         
         if '.' in name:
-            package_name, _ = name.split('.', 1)
+            package_name, sub_name = name.split('.', 1)
 
         else:
             package_name = name
+            sub_name = None
 
         if package_name == 'sys':
-            limited_sys = LimitedSysModule()
-            if name is None:
-                return limited_sys
-            
-            if hasattr(limited_sys, name):
-                return getattr(limited_sys, name)
-
-            raise ImportError(f"Cannot import {name} from limited sys implementation.")
-
+            return self.inner_sys
+        
         if package_name in self.allowed_imports:
             return importlib.__import__(name, globals, locals, fromlist, level)