mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-07-24 19:54:21 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

In PySlice_IndicesEx, clip the step to [-PY_SSIZE_T_MAX, PY_SSIZE_T_MAX] rather than [PY_SSIZE_T_MIN, PY_SSIZE_T_MAX].

Browse source
This commit is contained in:
Mark Dickinson 2010-08-06 18:55:26 +00:00
parent af5ac3974b
commit e6fc7401a9
2 changed files with 13 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

10
Objects/sliceobject.c
View file

@ -131,7 +131,8 @@ PySlice_GetIndices(PySliceObject *r, Py_ssize_t length,
int
PySlice_GetIndicesEx(PySliceObject *r, Py_ssize_t length,
Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step, Py_ssize_t *slicelength)
Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step,
Py_ssize_t *slicelength)
{
/* this is harder to get right than you might think */
@ -147,6 +148,13 @@ PySlice_GetIndicesEx(PySliceObject *r, Py_ssize_t length,
"slice step cannot be zero");
return -1;
}
/* Here *step might be -PY_SSIZE_T_MAX-1; in this case we replace it
* with -PY_SSIZE_T_MAX. This doesn't affect the semantics, and it
* guards against later undefined behaviour resulting from code that
* does "step = -step" as part of a slice reversal.
*/
if (*step < -PY_SSIZE_T_MAX)
*step = -PY_SSIZE_T_MAX;
}
defstart = *step < 0 ? length-1 : 0;