On 23May2017 1212, Victor Stinner wrote:
2017-05-22 13:17 GMT-05:00 Steve Dower <steve.do...@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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