[Python-Dev] Deprecate invalid ctypes call protection on Windows (original) (raw)

Victor Stinner victor.stinner at gmail.com
Wed May 24 00:11:53 EDT 2017

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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20170523/5d61620e/attachment.html>

More information about the Python-Dev mailing list