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bpo-30281: Fix the default value for stop in PySlice_Unpack() (#1480)

This commit is contained in:
Xiang Zhang 2017-05-10 18:19:41 +08:00 committed by GitHub
parent 305ccbe27e
commit 2ddf5a19c3
3 changed files with 7 additions and 5 deletions
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2
Doc/c-api/slice.rst
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@ -75,7 +75,7 @@ Slice Objects
Extract the start, stop and step data members from a slice object as Extract the start, stop and step data members from a slice object as
C integers. Silently reduce values larger than ``PY_SSIZE_T_MAX`` to C integers. Silently reduce values larger than ``PY_SSIZE_T_MAX`` to
``PY_SSIZE_T_MAX``, silently boost the start and stop values less than ``PY_SSIZE_T_MAX``, silently boost the start and stop values less than
``-PY_SSIZE_T_MAX-1`` to ``-PY_SSIZE_T_MAX-1``, and silently boost the step ``PY_SSIZE_T_MIN`` to ``PY_SSIZE_T_MIN``, and silently boost the step
values less than ``-PY_SSIZE_T_MAX`` to ``-PY_SSIZE_T_MAX``. values less than ``-PY_SSIZE_T_MAX`` to ``-PY_SSIZE_T_MAX``.
Return ``-1`` on error, ``0`` on success. Return ``-1`` on error, ``0`` on success.

8
Objects/sliceobject.c
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@ -197,6 +197,8 @@ PySlice_Unpack(PyObject *_r,
PySliceObject *r = (PySliceObject*)_r; PySliceObject *r = (PySliceObject*)_r;
/* this is harder to get right than you might think */ /* this is harder to get right than you might think */
Py_BUILD_ASSERT(PY_SSIZE_T_MIN + 1 <= -PY_SSIZE_T_MAX);
if (r->step == Py_None) { if (r->step == Py_None) {
*step = 1; *step = 1;
} }
@ -217,14 +219,14 @@ PySlice_Unpack(PyObject *_r,
} }
if (r->start == Py_None) { if (r->start == Py_None) {
*start = *step < 0 ? PY_SSIZE_T_MAX-1 : 0;; *start = *step < 0 ? PY_SSIZE_T_MAX : 0;
} }
else { else {
if (!_PyEval_SliceIndex(r->start, start)) return -1; if (!_PyEval_SliceIndex(r->start, start)) return -1;
} }
if (r->stop == Py_None) { if (r->stop == Py_None) {
*stop = *step < 0 ? -PY_SSIZE_T_MAX : PY_SSIZE_T_MAX; *stop = *step < 0 ? PY_SSIZE_T_MIN : PY_SSIZE_T_MAX;
} }
else { else {
if (!_PyEval_SliceIndex(r->stop, stop)) return -1; if (!_PyEval_SliceIndex(r->stop, stop)) return -1;
@ -258,7 +260,7 @@ PySlice_AdjustIndices(Py_ssize_t length,
*stop = (step < 0) ? -1 : 0; *stop = (step < 0) ? -1 : 0;
} }
} }
else if (*stop >= length) { else if (*stop >= length) {
*stop = (step < 0) ? length - 1 : length; *stop = (step < 0) ? length - 1 : length;
} }

2
Python/ceval.c
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@ -4889,7 +4889,7 @@ do_call_core(PyObject *func, PyObject *callargs, PyObject *kwdict)
/* Extract a slice index from a PyLong or an object with the /* Extract a slice index from a PyLong or an object with the
nb_index slot defined, and store in *pi. nb_index slot defined, and store in *pi.
Silently reduce values larger than PY_SSIZE_T_MAX to PY_SSIZE_T_MAX, Silently reduce values larger than PY_SSIZE_T_MAX to PY_SSIZE_T_MAX,
and silently boost values less than -PY_SSIZE_T_MAX-1 to -PY_SSIZE_T_MAX-1. and silently boost values less than PY_SSIZE_T_MIN to PY_SSIZE_T_MIN.
Return 0 on error, 1 on success. Return 0 on error, 1 on success.
*/ */
int int