Issue 28069: signalmodule.c does "is" comparisons for SIG_IGN and SIG_DFL (original) (raw)

Issue28069

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/72256

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process

Created on 2016-09-10 19:49 by mark.dickinson, last changed 2022-04-11 14:58 by admin.

Messages (3)
msg275687 - (view)	Author: Mark Dickinson (mark.dickinson) *	Date: 2016-09-10 19:49
Modules/signalmodule.c contains this code: if (handler == IgnoreHandler) func = SIG_IGN; else if (handler == DefaultHandler) func = SIG_DFL; ... Here IgnoreHandler and DefaultHandler are ints. The code above effectively does an "is" comparison with those ints, assuming that SIG_IGN and SIG_DFL are amongst the small interned ints.
msg275688 - (view)	Author: Mark Dickinson (mark.dickinson) *	Date: 2016-09-10 19:52
Also applies to 2.7, 3.5.
msg275696 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2016-09-10 20:54
This was not a problem before 3.5 since IgnoreHandler and DefaultHandler were singletons exposed in the signal module as SIG_DFL and SIG_IGN. But in they were converted to enums. This involves converting between enums and ints. All works only while SIG_DFL and SIG_IGN are small integers and there is small integer cache. I proposed either revert this change (signal_no_enum_handlers.patch in ) or even make SIG_DFL and SIG_IGN non-integer singletons ().