[Python-Dev] Preventing recursion core dumps

[Vladimir Marangozov]

I'm looking at preventing core dumps due to recursive calls. With
simple nested call counters for every function in object.c, limited to
500 levels deep recursions, I think this works okay for repr, str and
print. It solves most of the complaints, like:

class Crasher:
	def __str__(self): print self

print Crasher()

With such protection, instead of a core dump, we'll get an exception:

RuntimeError: Recursion too deep


So far, so good. 500 nested calls to repr, str or print are likely
to be programming bugs. Now I wonder whether it's a good idea to do
the same thing for getattr and setattr, to avoid crashes like:

class Crasher:
	def __getattr__(self, x): return self.x 

Crasher().bonk

Solving this the same way is likely to slow things down a bit, but
would prevent the crash. OTOH, in a complex object hierarchy with
tons of delegation and/or lookup dispatching, 500 nested calls is
probably not enough. Or am I wondering too much? Opinions?

-- 
       Vladimir MARANGOZOV          | Vladimir.Marangozov@inrialpes.fr
http://sirac.inrialpes.fr/~marangoz | tel:(+33-4)76615277 fax:76615252