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bpo-43963: Fix import _signal in subinterpreters (GH-25674)

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Importing the _signal module in a subinterpreter has no longer side
effects.

signal_module_exec() no longer modifies Handlers and no longer attempts
to set SIGINT signal handler in subinterpreters.
This commit is contained in:
Victor Stinner 2021-04-28 01:50:04 +02:00 • committed by GitHub
parent 6bd9288b80
commit a09766deab
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 45 additions and 29 deletions
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2
Misc/NEWS.d/next/Core and Builtins/2021-04-28-01-23-38.bpo-43963.u5Y6bS.rst Normal file
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@ -0,0 +1,2 @@
Importing the :mod:`_signal` module in a subinterpreter has no longer side
effects.

72
Modules/signalmodule.c
View file

@ -1543,6 +1543,46 @@ signal_add_constants(PyObject *module)
} }
static int
signal_get_set_handlers(PyObject *mod_dict)
{
// Get signal handlers
for (int signum = 1; signum < NSIG; signum++) {
void (*c_handler)(int) = PyOS_getsig(signum);
PyObject *func;
if (c_handler == SIG_DFL) {
func = DefaultHandler;
}
else if (c_handler == SIG_IGN) {
func = IgnoreHandler;
}
else {
func = Py_None; // None of our business
}
// If signal_module_exec() is called more than one, we must
// clear the strong reference to the previous function.
PyObject* old_func = get_handler(signum);
SetHandler(signum, Py_NewRef(func));
Py_XDECREF(old_func);
}
// Instal Python SIGINT handler which raises KeyboardInterrupt
PyObject* sigint_func = get_handler(SIGINT);
if (sigint_func == DefaultHandler) {
PyObject *int_handler = PyMapping_GetItemString(mod_dict,
"default_int_handler");
if (!int_handler) {
return -1;
}
SetHandler(SIGINT, int_handler);
Py_DECREF(sigint_func);
PyOS_setsig(SIGINT, signal_handler);
}
return 0;
}
static int static int
signal_module_exec(PyObject *m) signal_module_exec(PyObject *m)
{ {
@ -1571,37 +1611,11 @@ signal_module_exec(PyObject *m)
} }
#endif #endif
// Get signal handlers PyThreadState *tstate = _PyThreadState_GET();
for (int signum = 1; signum < NSIG; signum++) { if (_Py_IsMainInterpreter(tstate->interp)) {
void (*c_handler)(int) = PyOS_getsig(signum); if (signal_get_set_handlers(d) < 0) {
PyObject *func;
if (c_handler == SIG_DFL) {
func = DefaultHandler;
}
else if (c_handler == SIG_IGN) {
func = IgnoreHandler;
}
else {
func = Py_None; // None of our business
}
// If signal_module_exec() is called more than one, we must
// clear the strong reference to the previous function.
PyObject* old_func = get_handler(signum);
SetHandler(signum, Py_NewRef(func));
Py_XDECREF(old_func);
}
// Instal Python SIGINT handler which raises KeyboardInterrupt
PyObject* sigint_func = get_handler(SIGINT);
if (sigint_func == DefaultHandler) {
PyObject *int_handler = PyMapping_GetItemString(d, "default_int_handler");
if (!int_handler) {
return -1; return -1;
} }
SetHandler(SIGINT, int_handler);
Py_DECREF(sigint_func);
PyOS_setsig(SIGINT, signal_handler);
} }
assert(!PyErr_Occurred()); assert(!PyErr_Occurred());