[Python-Dev] what can we do to hide the 'file' type? (original) (raw)

Michael Chermside mcherm at mcherm.com
Thu Jul 6 17:31:27 CEST 2006

Armin Rigo writes:

I don't think I can "sign off" [on hiding the file type]. Really hiding Python objects is quite hard IMHO.

I agree. But we don't have to give up yet. How about instead of hiding file, we cripple it. Completely. Modify the file type so that when executing on a sandboxed interpreter, all of the dangerous methods and attributes of file throw exceptions.

Then we create a separate thing (in C) called a "SecureFileWrapper". It has methods that are passed a reference to a file object and can invoke the methods without error. We provide a means for obtaining a SecureFileWrapper bound to a given file (perhaps open()).

Essentially, we give up on hiding file, which is a frequently-used type, and very hard to hide, and instead we rely on our ability to write a reliably secure "SecureFileWrapper" class (in C).

-- Michael Chermside

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