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bpo-23325: Fix SIG_IGN and SIG_DFL int comparison in signal module (GH-31759)

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Christian Heimes 2022-03-08 20:22:32 +02:00 • committed by GitHub
parent 5498a61c7c
commit c8a47e76a3
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2 changed files with 25 additions and 13 deletions
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2
Misc/NEWS.d/next/Library/2022-03-08-11-34-06.bpo-23325.3VQnfo.rst Normal file
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@ -0,0 +1,2 @@
The :mod:`signal` module no longer assumes that :const:`~signal.SIG_IGN` and
:const:`~signal.SIG_DFL` are small int singletons.

36
Modules/signalmodule.c
View file

@ -177,6 +177,17 @@ get_signal_state(PyObject *module)
} }
static inline int
compare_handler(PyObject *func, PyObject *dfl_ign_handler)
{
assert(PyLong_CheckExact(dfl_ign_handler));
if (!PyLong_CheckExact(func)) {
return 0;
}
// Assume that comparison of two PyLong objects will never fail.
return PyObject_RichCompareBool(func, dfl_ign_handler, Py_EQ) == 1;
}
#ifdef HAVE_GETITIMER #ifdef HAVE_GETITIMER
/* auxiliary functions for setitimer */ /* auxiliary functions for setitimer */
static int static int
@ -528,21 +539,18 @@ signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
"signal number out of range"); "signal number out of range");
return NULL; return NULL;
} }
if (handler == modstate->ignore_handler) { if (PyCallable_Check(handler)) {
func = signal_handler;
} else if (compare_handler(handler, modstate->ignore_handler)) {
func = SIG_IGN; func = SIG_IGN;
} } else if (compare_handler(handler, modstate->default_handler)) {
else if (handler == modstate->default_handler) {
func = SIG_DFL; func = SIG_DFL;
} } else {
else if (!PyCallable_Check(handler)) {
_PyErr_SetString(tstate, PyExc_TypeError, _PyErr_SetString(tstate, PyExc_TypeError,
"signal handler must be signal.SIG_IGN, " "signal handler must be signal.SIG_IGN, "
"signal.SIG_DFL, or a callable object"); "signal.SIG_DFL, or a callable object");
return NULL; return NULL;
} }
else {
func = signal_handler;
}
/* Check for pending signals before changing signal handler */ /* Check for pending signals before changing signal handler */
if (_PyErr_CheckSignalsTstate(tstate)) { if (_PyErr_CheckSignalsTstate(tstate)) {
@ -1752,8 +1760,8 @@ _PySignal_Fini(void)
set_handler(signum, NULL); set_handler(signum, NULL);
if (func != NULL if (func != NULL
&& func != Py_None && func != Py_None
&& func != state->default_handler && !compare_handler(func, state->default_handler)
&& func != state->ignore_handler) && !compare_handler(func, state->ignore_handler))
{ {
PyOS_setsig(signum, SIG_DFL); PyOS_setsig(signum, SIG_DFL);
} }
@ -1824,8 +1832,9 @@ _PyErr_CheckSignalsTstate(PyThreadState *tstate)
* (see bpo-43406). * (see bpo-43406).
*/ */
PyObject *func = get_handler(i); PyObject *func = get_handler(i);
if (func == NULL || func == Py_None || func == state->ignore_handler || if (func == NULL || func == Py_None ||
func == state->default_handler) { compare_handler(func, state->ignore_handler) ||
compare_handler(func, state->default_handler)) {
/* No Python signal handler due to aforementioned race condition. /* No Python signal handler due to aforementioned race condition.
* We can't call raise() as it would break the assumption * We can't call raise() as it would break the assumption
* that PyErr_SetInterrupt() only *simulates* an incoming * that PyErr_SetInterrupt() only *simulates* an incoming
@ -1893,7 +1902,8 @@ PyErr_SetInterruptEx(int signum)
signal_state_t *state = &signal_global_state; signal_state_t *state = &signal_global_state;
PyObject *func = get_handler(signum); PyObject *func = get_handler(signum);
if (func != state->ignore_handler && func != state->default_handler) { if (!compare_handler(func, state->ignore_handler)
&& !compare_handler(func, state->default_handler)) {
trip_signal(signum); trip_signal(signum);
} }
return 0; return 0;