[Python-Dev] Challenge: Please break this! (was: Reviving restricted mode)

tav tav at espians.com
Tue Feb 24 01:33:35 CET 2009

Hey all,

  victor> Could you keep all versions of safelite.py?

I took Steven D'Aprano's advice and added a VERSION attribute and
state the latest version on

Is that okay?

  antoine> I guess Tav should open a restaurant :-)

Hehe!! Thankfully I only offered to it to the first person *phew!*

  farshid> It seems like some code in safelite passes
  farshid> a file object to isinstance. By overriding the
  farshid> builtin isinstance function I can get access to
  frashid> the original file object and create a new one.

Farshid, this is beautiful!!!

Thank you -- it's very nicely done!!

Do you have a website I could link to from the blog article?

  guido> I think in the next version Tav will have to stop
  guido> the sharing of __builtins__ between the supervisor
  guido> and the sandboxed code. There are too many
  guido> tricks you can play with this.


The common pattern that arised out of the various
builtins-overriding-hacks is that "safe" code should *never* make
assumptions about the state of the globals. The use of closures seems
to fix this problem with an easily-auditable design pattern.

love, tav

plex:espians/tav | tav at espians.com | +44 (0) 7809 569 369
http://tav.espians.com | http://twitter.com/tav | skype:tavespian

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