From 05469fa1c05acf55bdca05db21822ecdd7f6487a Mon Sep 17 00:00:00 2001 From: Xiang Zhang Date: Wed, 10 May 2017 19:20:28 +0800 Subject: [PATCH] bpo-30281: Fix the default value for stop in PySlice_Unpack() (#1531) (#1480) --- Objects/sliceobject.c | 8 +++++--- Python/ceval.c | 2 +- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c index 64be9270386..c66e057cdb3 100644 --- a/Objects/sliceobject.c +++ b/Objects/sliceobject.c @@ -137,6 +137,8 @@ _PySlice_Unpack(PyObject *_r, PySliceObject *r = (PySliceObject *)_r; /* this is harder to get right than you might think */ + assert(PY_SSIZE_T_MIN + 1 <= -PY_SSIZE_T_MAX); + if (r->step == Py_None) { *step = 1; } @@ -157,14 +159,14 @@ _PySlice_Unpack(PyObject *_r, } if (r->start == Py_None) { - *start = *step < 0 ? PY_SSIZE_T_MAX-1 : 0;; + *start = *step < 0 ? PY_SSIZE_T_MAX : 0; } else { if (!_PyEval_SliceIndex(r->start, start)) return -1; } 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 { if (!_PyEval_SliceIndex(r->stop, stop)) return -1; @@ -198,7 +200,7 @@ _PySlice_AdjustIndices(Py_ssize_t length, *stop = (step < 0) ? -1 : 0; } } - else if (*stop >= length) { + else if (*stop >= length) { *stop = (step < 0) ? length - 1 : length; } diff --git a/Python/ceval.c b/Python/ceval.c index cea503e56fa..4e4adc2d63d 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -4679,7 +4679,7 @@ ext_call_fail: /* Extract a slice index from a PyInt or PyLong or an object with the nb_index slot defined, and store in *pi. 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. */ /* Note: If v is NULL, return success without storing into *pi. This