bpo-27660: remove unnecessary overflow checks in list_resize (GH-189)
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3e8d6cb189
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4cee049f5b
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@ -26,7 +26,7 @@ static int
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list_resize(PyListObject *self, Py_ssize_t newsize)
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{
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PyObject **items;
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size_t new_allocated;
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size_t new_allocated, num_allocated_bytes;
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Py_ssize_t allocated = self->allocated;
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/* Bypass realloc() when a previous overallocation is large enough
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@ -45,24 +45,19 @@ list_resize(PyListObject *self, Py_ssize_t newsize)
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* sequence of appends() in the presence of a poorly-performing
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* system realloc().
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* The growth pattern is: 0, 4, 8, 16, 25, 35, 46, 58, 72, 88, ...
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* Note: new_allocated won't overflow because the largest possible value
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* is PY_SSIZE_T_MAX * (9 / 8) + 6 which always fits in a size_t.
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*/
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new_allocated = (newsize >> 3) + (newsize < 9 ? 3 : 6);
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/* check for integer overflow */
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if (new_allocated > SIZE_MAX - newsize) {
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new_allocated = (size_t)newsize + (newsize >> 3) + (newsize < 9 ? 3 : 6);
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if (new_allocated > (size_t)PY_SSIZE_T_MAX / sizeof(PyObject *)) {
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PyErr_NoMemory();
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return -1;
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} else {
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new_allocated += newsize;
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}
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if (newsize == 0)
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new_allocated = 0;
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items = self->ob_item;
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if (new_allocated <= (SIZE_MAX / sizeof(PyObject *)))
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PyMem_RESIZE(items, PyObject *, new_allocated);
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else
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items = NULL;
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num_allocated_bytes = new_allocated * sizeof(PyObject *);
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items = (PyObject **)PyMem_Realloc(self->ob_item, num_allocated_bytes);
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if (items == NULL) {
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PyErr_NoMemory();
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return -1;
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