Will nested scoping break restricted execution ??

Tim Peters tim.one at home.com
Sun Feb 4 05:20:02 CET 2001


[Martin von Loewis]
> ...
> I believe there isn't a way to prevent restricted code from accessing
> a specific __builtin__, either - instead, you have to provide
> alternative or missing versions of the builtins in advance.

RExec.nok_builtin_names is a tuple of the builtin names to be rendered
invisible.  A subclass can define its own tuple of forbidden builtins.
Attempts to reference one of these names in restricted code just raises a
NameError, because it's plain missing:

>>> from rexec import RExec
>>> class NoIntRExec(RExec):
...     nok_builtin_names = RExec.nok_builtin_names + ("int",)
...
>>> def int_abuser():
...     print int(44.4)
...
>>> RExec().r_exec(int_abuser.func_code)  # fine by regular RExec
44
>>> NoIntRExec().r_exec(int_abuser.func_code) # but not mine
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  ... [lotsa rexec stuff] ...
  File "c:\code\python\dist\src\lib\ihooks.py", line 326, in load_module
    exec code in m.__dict__
  File "c:\code\python\dist\src\lib\string.py", line 189, in ?
    _int = int
NameError: name 'int' is not defined
>>>

simple-and-effective-is-a-delightful-combo-ly y'rs  - tim





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