From 50856d5ae745d1c9f691afbd78572bf073c941cf Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Tue, 13 Oct 2015 00:11:21 +0200 Subject: 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. --- Python/sysmodule.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) (limited to 'Python/sysmodule.c') diff --git a/Python/sysmodule.c b/Python/sysmodule.c index f600baf10e..334f5d0c8e 100644 --- a/Python/sysmodule.c +++ b/Python/sysmodule.c @@ -632,14 +632,37 @@ processor's time-stamp counter." 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; -- cgit v1.2.1