Issues #16029, #16030: Fix pickling and repr of large xranges.
diff --git a/Objects/rangeobject.c b/Objects/rangeobject.c
index 4e64dba..c602e7d 100644
--- a/Objects/rangeobject.c
+++ b/Objects/rangeobject.c
@@ -37,6 +37,30 @@
return 0UL;
}
+/* Return a stop value suitable for reconstructing the xrange from
+ * a (start, stop, step) triple. Used in range_repr and range_reduce.
+ * Computes start + len * step, clipped to the range [LONG_MIN, LONG_MAX].
+ */
+static long
+get_stop_for_range(rangeobject *r)
+{
+ long last;
+
+ if (r->len == 0)
+ return r->start;
+
+ /* The tricky bit is avoiding overflow. We first compute the last entry in
+ the xrange, start + (len - 1) * step, which is guaranteed to lie within
+ the range of a long, and then add step to it. See the range_reverse
+ comments for an explanation of the casts below.
+ */
+ last = (long)(r->start + (unsigned long)(r->len - 1) * r->step);
+ if (r->step > 0)
+ return last > LONG_MAX - r->step ? LONG_MAX : last + r->step;
+ else
+ return last < LONG_MIN - r->step ? LONG_MIN : last + r->step;
+}
+
static PyObject *
range_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
@@ -112,17 +136,17 @@
if (r->start == 0 && r->step == 1)
rtn = PyString_FromFormat("xrange(%ld)",
- r->start + r->len * r->step);
+ get_stop_for_range(r));
else if (r->step == 1)
rtn = PyString_FromFormat("xrange(%ld, %ld)",
r->start,
- r->start + r->len * r->step);
+ get_stop_for_range(r));
else
rtn = PyString_FromFormat("xrange(%ld, %ld, %ld)",
r->start,
- r->start + r->len * r->step,
+ get_stop_for_range(r),
r->step);
return rtn;
}
@@ -131,9 +155,9 @@
static PyObject *
range_reduce(rangeobject *r, PyObject *args)
{
- return Py_BuildValue("(O(iii))", Py_TYPE(r),
+ return Py_BuildValue("(O(lll))", Py_TYPE(r),
r->start,
- r->start + r->len * r->step,
+ get_stop_for_range(r),
r->step);
}