sys.setrecursionlimit() now raises RecursionError
Issue #25274: sys.setrecursionlimit() now raises a RecursionError if the new
recursion limit is too low depending at the current recursion depth. Modify
also the "lower-water mark" formula to make it monotonic. This mark is used to
decide when the overflowed flag of the thread state is reset.
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index f600baf..334f5d0 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -632,14 +632,37 @@
static PyObject *
sys_setrecursionlimit(PyObject *self, PyObject *args)
{
- int new_limit;
+ int new_limit, mark;
+ PyThreadState *tstate;
+
if (!PyArg_ParseTuple(args, "i:setrecursionlimit", &new_limit))
return NULL;
- if (new_limit <= 0) {
+
+ if (new_limit < 1) {
PyErr_SetString(PyExc_ValueError,
- "recursion limit must be positive");
+ "recursion limit must be greater or equal than 1");
return NULL;
}
+
+ /* Issue #25274: When the recursion depth hits the recursion limit in
+ _Py_CheckRecursiveCall(), the overflowed flag of the thread state is
+ set to 1 and a RecursionError is raised. The overflowed flag is reset
+ to 0 when the recursion depth goes below the low-water mark: see
+ Py_LeaveRecursiveCall().
+
+ Reject too low new limit if the current recursion depth is higher than
+ the new low-water mark. Otherwise it may not be possible anymore to
+ reset the overflowed flag to 0. */
+ mark = _Py_RecursionLimitLowerWaterMark(new_limit);
+ tstate = PyThreadState_GET();
+ if (tstate->recursion_depth >= mark) {
+ PyErr_Format(PyExc_RecursionError,
+ "cannot set the recursion limit to %i at "
+ "the recursion depth %i: the limit is too low",
+ new_limit, tstate->recursion_depth);
+ return NULL;
+ }
+
Py_SetRecursionLimit(new_limit);
Py_INCREF(Py_None);
return Py_None;