bpo-43356: Allow passing a signal number to interrupt_main() (GH-24755)
Also introduce a new C API ``PyErr_SetInterruptEx(int signum)``.
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index f6217e6..0613dfd 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -9,6 +9,10 @@
#include <stddef.h> // offsetof()
#include "structmember.h" // PyMemberDef
+#ifdef HAVE_SIGNAL_H
+# include <signal.h> // SIGINT
+#endif
+
// ThreadError is just an alias to PyExc_RuntimeError
#define ThreadError PyExc_RuntimeError
@@ -1173,17 +1177,29 @@ This is synonymous to ``raise SystemExit''. It will cause the current\n\
thread to exit silently unless the exception is caught.");
static PyObject *
-thread_PyThread_interrupt_main(PyObject * self, PyObject *Py_UNUSED(ignored))
+thread_PyThread_interrupt_main(PyObject *self, PyObject *args)
{
- PyErr_SetInterrupt();
+ int signum = SIGINT;
+ if (!PyArg_ParseTuple(args, "|i:signum", &signum)) {
+ return NULL;
+ }
+
+ if (PyErr_SetInterruptEx(signum)) {
+ PyErr_SetString(PyExc_ValueError, "signal number out of range");
+ return NULL;
+ }
Py_RETURN_NONE;
}
PyDoc_STRVAR(interrupt_doc,
-"interrupt_main()\n\
+"interrupt_main(signum=signal.SIGINT, /)\n\
\n\
-Raise a KeyboardInterrupt in the main thread.\n\
-A subthread can use this function to interrupt the main thread."
+Simulate the arrival of the given signal in the main thread,\n\
+where the corresponding signal handler will be executed.\n\
+If *signum* is omitted, SIGINT is assumed.\n\
+A subthread can use this function to interrupt the main thread.\n\
+\n\
+Note: the default signal hander for SIGINT raises ``KeyboardInterrupt``."
);
static lockobject *newlockobject(PyObject *module);
@@ -1527,8 +1543,8 @@ static PyMethodDef thread_methods[] = {
METH_NOARGS, exit_doc},
{"exit", thread_PyThread_exit_thread,
METH_NOARGS, exit_doc},
- {"interrupt_main", thread_PyThread_interrupt_main,
- METH_NOARGS, interrupt_doc},
+ {"interrupt_main", (PyCFunction)thread_PyThread_interrupt_main,
+ METH_VARARGS, interrupt_doc},
{"get_ident", thread_get_ident,
METH_NOARGS, get_ident_doc},
#ifdef PY_HAVE_THREAD_NATIVE_ID
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index c6564be..98a938f 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -8,6 +8,7 @@
#include "pycore_call.h"
#include "pycore_ceval.h"
#include "pycore_pyerrors.h"
+#include "pycore_pylifecycle.h"
#include "pycore_pystate.h" // _PyThreadState_GET()
#ifndef MS_WINDOWS
@@ -49,18 +50,6 @@
#define SIG_ERR ((PyOS_sighandler_t)(-1))
#endif
-#ifndef NSIG
-# if defined(_NSIG)
-# define NSIG _NSIG /* For BSD/SysV */
-# elif defined(_SIGMAX)
-# define NSIG (_SIGMAX + 1) /* For QNX */
-# elif defined(SIGMAX)
-# define NSIG (SIGMAX + 1) /* For djgpp */
-# else
-# define NSIG 64 /* Use a reasonable default value */
-# endif
-#endif
-
#include "clinic/signalmodule.c.h"
/*[clinic input]
@@ -106,7 +95,10 @@ class sigset_t_converter(CConverter):
static volatile struct {
_Py_atomic_int tripped;
- PyObject *func;
+ /* func is atomic to ensure that PyErr_SetInterrupt is async-signal-safe
+ * (even though it would probably be otherwise, anyway).
+ */
+ _Py_atomic_address func;
} Handlers[NSIG];
#ifdef MS_WINDOWS
@@ -143,6 +135,16 @@ static HANDLE sigint_event = NULL;
static PyObject *ItimerError;
#endif
+Py_LOCAL_INLINE(PyObject *)
+get_handler(int i) {
+ return (PyObject *)_Py_atomic_load(&Handlers[i].func);
+}
+
+Py_LOCAL_INLINE(void)
+SetHandler(int i, PyObject* func) {
+ _Py_atomic_store(&Handlers[i].func, (uintptr_t)func);
+}
+
#ifdef HAVE_GETITIMER
/* auxiliary functions for setitimer */
static int
@@ -516,8 +518,8 @@ signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
return NULL;
}
- old_handler = Handlers[signalnum].func;
- Handlers[signalnum].func = Py_NewRef(handler);
+ old_handler = get_handler(signalnum);
+ SetHandler(signalnum, Py_NewRef(handler));
if (old_handler != NULL) {
return old_handler;
@@ -553,7 +555,7 @@ signal_getsignal_impl(PyObject *module, int signalnum)
"signal number out of range");
return NULL;
}
- old_handler = Handlers[signalnum].func;
+ old_handler = get_handler(signalnum);
if (old_handler != NULL) {
return Py_NewRef(old_handler);
}
@@ -1584,17 +1586,21 @@ signal_module_exec(PyObject *m)
}
// If signal_module_exec() is called more than one, we must
// clear the strong reference to the previous function.
- Py_XSETREF(Handlers[signum].func, Py_NewRef(func));
+ PyObject* old_func = get_handler(signum);
+ SetHandler(signum, Py_NewRef(func));
+ Py_XDECREF(old_func);
}
// Instal Python SIGINT handler which raises KeyboardInterrupt
- if (Handlers[SIGINT].func == DefaultHandler) {
+ PyObject* sigint_func = get_handler(SIGINT);
+ if (sigint_func == DefaultHandler) {
PyObject *int_handler = PyMapping_GetItemString(d, "default_int_handler");
if (!int_handler) {
return -1;
}
- Py_SETREF(Handlers[SIGINT].func, int_handler);
+ SetHandler(SIGINT, int_handler);
+ Py_DECREF(sigint_func);
PyOS_setsig(SIGINT, signal_handler);
}
@@ -1630,9 +1636,9 @@ _PySignal_Fini(void)
{
// Restore default signals and clear handlers
for (int signum = 1; signum < NSIG; signum++) {
- PyObject *func = Handlers[signum].func;
+ PyObject *func = get_handler(signum);
_Py_atomic_store_relaxed(&Handlers[signum].tripped, 0);
- Handlers[signum].func = NULL;
+ SetHandler(signum, NULL);
if (func != NULL
&& func != Py_None
&& func != DefaultHandler
@@ -1712,7 +1718,7 @@ _PyErr_CheckSignalsTstate(PyThreadState *tstate)
* signal handler for it by the time PyErr_CheckSignals() is called
* (see bpo-43406).
*/
- PyObject *func = Handlers[i].func;
+ PyObject *func = get_handler(i);
if (func == NULL || func == Py_None || func == IgnoreHandler ||
func == DefaultHandler) {
/* No Python signal handler due to aforementioned race condition.
@@ -1761,18 +1767,27 @@ _PyErr_CheckSignals(void)
}
-/* Simulate the effect of a signal.SIGINT signal arriving. The next time
- PyErr_CheckSignals is called, the Python SIGINT signal handler will be
- raised.
+/* Simulate the effect of a signal arriving. The next time PyErr_CheckSignals
+ is called, the corresponding Python signal handler will be raised.
- Missing signal handler for the SIGINT signal is silently ignored. */
+ Missing signal handler for the given signal number is silently ignored. */
+int
+PyErr_SetInterruptEx(int signum)
+{
+ if (signum < 1 || signum >= NSIG) {
+ return -1;
+ }
+ PyObject* func = get_handler(signum);
+ if (func != IgnoreHandler && func != DefaultHandler) {
+ trip_signal(signum);
+ }
+ return 0;
+}
+
void
PyErr_SetInterrupt(void)
{
- if ((Handlers[SIGINT].func != IgnoreHandler) &&
- (Handlers[SIGINT].func != DefaultHandler)) {
- trip_signal(SIGINT);
- }
+ (void) PyErr_SetInterruptEx(SIGINT);
}
static int