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Use the | trick to save a comparison in our calloc check.

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This commit is contained in:
Nick Mathewson 2014-11-02 11:48:08 -05:00
parent 0d8abf5365
commit ded33cb2c7
1 changed files with 9 additions and 2 deletions
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11
src/common/util.c
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@ -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