[Python-Dev] PyErr_Format security note

[Jim Fulton]

"Andrew M. Kuchling" wrote:
> 
> Guido van Rossum writes:
> >Assuming that Linux and Solaris have vsnprintf(), can't we just use
> >the configure script to detect it, and issue a warning blaming the
> >platform for those platforms that don't have it?  That seems much
> 
> But people using an already-installed Python binary won't see any such
> configure-time warning, and won't find out about the potential
> problem.  Plus, how do people fix the problem on platforms that don't
> have vsnprintf() -- switch to Solaris or Linux?  Not much of a
> solution.  (vsnprintf() isn't ANSI C, though it's a common extension,
> so platforms that lack it aren't really deficient.)
> 
> Hmm... could we maybe use Python's existing (string % vars) machinery?
> <think think> No, that seems to be hard, because it would want
> PyObjects, and we can't know what Python types to convert the varargs
> to, unless we parse the format string (at which point we may as well
> get a vsnprintf() implementation.

It's easy. You use two format strings. One a Python string format, 
and the other a Py_BuildValue format. See my other note.

Jim


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