Mercurial > cpython-lru_cache-weakref
diff Modules/_bisectmodule.c @ 76325:709af2d0e862 2.7
Issue 13496: Fix bisect.bisect overflow bug for large collections.
| author | Mark Dickinson <mdickinson@enthought.com> |
|---|---|
| date | Sun, 15 Apr 2012 16:43:19 +0100 |
| parents | b36cb4602e21 |
| children | bfe2d1acc09d |
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--- a/Modules/_bisectmodule.c Sun Apr 15 15:19:06 2012 +0100 +++ b/Modules/_bisectmodule.c Sun Apr 15 16:43:19 2012 +0100 @@ -21,7 +21,13 @@ return -1; } while (lo < hi) { - mid = (lo + hi) / 2; + /* The (size_t)cast ensures that the addition and subsequent division + are performed as unsigned operations, avoiding difficulties from + signed overflow. (See issue 13496.) */ + printf("lo: %d\n", lo); + printf("hi: %d\n", hi); + printf("mid: %d\n", mid); + mid = ((size_t)lo + hi) / 2; litem = PySequence_GetItem(list, mid); if (litem == NULL) return -1; @@ -122,7 +128,10 @@ return -1; } while (lo < hi) { - mid = (lo + hi) / 2; + /* The (size_t)cast ensures that the addition and subsequent division + are performed as unsigned operations, avoiding difficulties from + signed overflow. (See issue 13496.) */ + mid = ((size_t)lo + hi) / 2; litem = PySequence_GetItem(list, mid); if (litem == NULL) return -1;