commit ded33cb2c73151e2f02a8a1d520b54e4f1c14072 Author: Nick Mathewson <nickm@torproject.org> Date: Sun Nov 2 11:48:08 2014 -0500 Use the | trick to save a comparison in our calloc check. --- src/common/util.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/src/common/util.c b/src/common/util.c index 006fd80..3d81f2b 100644 --- a/src/common/util.c +++ b/src/common/util.c @@ -206,8 +206,15 @@ tor_malloc_zero_(size_t size DMALLOC_PARAMS) static INLINE int size_mul_check(const size_t x, const size_t y) { - return ((x < SQRT_SIZE_MAX_P1 && y < SQRT_SIZE_MAX_P1) || - y == 0 || x <= SIZE_MAX / y); + /* This first check is equivalent to + (x < SQRT_SIZE_MAX_P1 && y < SQRT_SIZE_MAX_P1) + + Rationale: if either one of x or y is >= SQRT_SIZE_MAX_P1, then it + will have some bit set in its most significant half. + */ + return ((x|y) < SQRT_SIZE_MAX_P1 || + y == 0 || + x <= SIZE_MAX / y); } /** Allocate a chunk of <b>nmemb</b>*<b>size</b> bytes of memory, fill