New submission from Christian Heimes <li...@cheimes.de>:
The signal.signal() function directly compares PyObject *handler with PyObject
*modstate->ignore_handler. This works on most platforms because they are both
small ints and Python uses singletons for cached small ints.
The assumption breaks when Python is built without small int cache or a
platform has SIG_IGN / SIG_DFL that is outside the range of small int cache.
The wasm32-emscripten platform uses "((void (*)(int))-2)" (4294967294) for
SIG_IGN. The wrong comparison breaks several tests on WASM32. The function
should use PyObject_RichCompareBool(handler, modstate->ignore_handler, Py_EQ)
instead.
if (handler == modstate->ignore_handler) {
func = SIG_IGN;
}
else if (handler == modstate->default_handler) {
func = SIG_DFL;
}
https://github.com/python/cpython/blob/7f4b69b9076bdbcea31f6ad16eb125ee99cf0175/Modules/signalmodule.c#L530-L534
----------
components: Extension Modules
messages: 410747
nosy: christian.heimes
priority: normal
severity: normal
status: open
title: signal module wrongly relies on small int singletons
type: behavior
versions: Python 3.10, Python 3.11, Python 3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue46408>
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