constant_time_is_zero_8
good &= ~constant_time_is_zero_8(from[i]);
good &= constant_time_is_zero_8(from[flen - SSL_MAX_MASTER_KEY_LENGTH - 1]);
static ossl_inline unsigned char constant_time_is_zero_8(unsigned int a);
if (a == 0 && !TEST_uint_eq(constant_time_is_zero_8(a), CONSTTIME_TRUE_8))
if (a != 0 && !TEST_uint_eq(constant_time_is_zero_8(a), CONSTTIME_FALSE_8))