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Bug 1003935: xrange overflows

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Added XXX comment about why the undocumented PyRange_New() API function
is too broken to be worth the considerable pain of repairing.

Changed range_new() to stop using PyRange_New().  This fixes a variety
of bogus errors.  Nothing in the core uses PyRange_New() now.

Documented that xrange() is intended to be simple and fast, and that
CPython restricts its arguments, and length of its result sequence, to
native C longs.

Added some tests that failed before the patch, and repaired a test that
relied on a bogus OverflowError getting raised.
This commit is contained in:
Tim Peters 2004-08-08 07:17:39 +00:00
parent d976ab7caf
commit feec4533e2
3 changed files with 37 additions and 11 deletions
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17
Objects/rangeobject.c
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@ -9,6 +9,13 @@ typedef struct {
long len;
} rangeobject;
/* XXX PyRange_New should be deprecated. It's not documented. It's not
* used in the core. Its error-checking is akin to Swiss cheese: accepts
* step == 0; accepts len < 0; ignores that (len - 1) * step may overflow;
* raises a baffling "integer addition" exception if it thinks the last
* item is "too big"; and doesn't compute whether "last item is too big"
* correctly even if the multiplication doesn't overflow.
*/
PyObject *
PyRange_New(long start, long len, long step, int reps)
{
@ -79,6 +86,7 @@ get_len_of_range(long lo, long hi, long step)
static PyObject *
range_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
rangeobject *obj;
long ilow = 0, ihigh = 0, istep = 1;
long n;
@ -107,7 +115,14 @@ range_new(PyTypeObject *type, PyObject *args, PyObject *kw)
"xrange() result has too many items");
return NULL;
}
return PyRange_New(ilow, n, istep, 1);
obj = PyObject_New(rangeobject, &PyRange_Type);
if (obj == NULL)
return NULL;
obj->start = ilow;
obj->len = n;
obj->step = istep;
return (PyObject *) obj;
}
PyDoc_STRVAR(range_doc,