[Python-Dev] Proper initialization of structs

Guido van Rossum guido at python.org
Thu Oct 30 18:00:03 CET 2008

Yes, that's what __new__ / tp_new is for! Thanks for finding this.

On Thu, Oct 30, 2008 at 7:20 AM, Christian Heimes <lists at cheimes.de> wrote:
> I like to raise attention for a problem revealed by
> http://bugs.python.org/issue4237
> ---
> The bug was caused by a design flaw -- which was partly my fault. Some
> elements of the PyFileIOObject struct were initialized in __new__ while
> other parts were initialized in __init__. I've moved the initialization
> to __new__.
> We should add a rule that all struct members must be properly
> initialized in __new__. In the past Victor's fuzzying tool has revealed
> several crashers related to similar design flaws.
> I'm raising the severity of the bug to release blocker because I can't
> predict if the problem can be abused to crash the interpreter. We should
> also review all __new__ and __init__ methods of objects and extension
> modules for similar issues.
> ---
> The same design flaw was responsible for bugs like the pickle crasher
> http://bugs.python.org/issue3664. I like to establish a rule that *all*
> struct members must be initialized properly in the type's tp_new function.
> Comments?
> Christian
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--Guido van Rossum (home page: http://www.python.org/~guido/)

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