[Python-Dev] Deprecate invalid ctypes call protection on Windows

[Victor Stinner]

Sure, make your change and then update libffi!

Victor

Le 23 mai 2017 18:19, "Steve Dower" <steve.dower at python.org> a écrit :

> On 23May2017 1212, Victor Stinner wrote:
>
>> 2017-05-22 13:17 GMT-05:00 Steve Dower <steve.dower at python.org>:
>>
>>> Once the special protection is removed, most of these cases will become
>>> OSError due to the general protection against segmentation faults.
>>>
>>
>> It didn't know that ctypes on Windows had a special protection against
>> programming errors. I'm not aware of such protection Linux. If you
>> call a function with the wrong number of arguments, it's likely to
>> crash or return random data.
>>
>> I guess that the point is to help debugging. But since Python 3.6,
>> faulthandler now registers a Windows exception handler and so it able
>> to dump the Python traceback on any Windows exception:
>> https://docs.python.org/dev/library/faulthandler.html#faulthandler.enable
>>
>> So I think that it's now fine to remove the ctypes protection. Just
>> advice (remind? ;-)) users to enable faulthandler: python3 -X
>> faulthandler, or call faulthandler.enable(). (You might want to use a
>> log file for that on Windows, depends on the use case.)
>>
>
> faulthandler is already recommended in the docs, and the existing SEH
> protection for access violations will remain (since that is independent of
> libffi).
>
> I'll be honest, I have appreciated the functionality in the past, but it
> really isn't good practice and getting rid of it will be an overall
> benefit. Technically even the segfault protection isn't a great idea, since
> you really do end up in an unknown state with regards to memory page
> allocations, but it's better than crashing all the way out.
>
> Cheers,
> Steve
>
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