[PATCH] random_int: Fix power of two check.

On Sun, May 10, 2015 at 12:40 PM, Lauri Kenttä lauri.kentta@gmail.com
wrote:

(x & ~x) is always 0.
((x & (~x + 1)) != x) works.
((x & (x - 1)) != 0) works too.

ext/standard/random.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ext/standard/random.c b/ext/standard/random.c
index 12c2503..4a1adbf 100644
--- a/ext/standard/random.c
+++ b/ext/standard/random.c
@@ -182,7 +182,7 @@ PHP_FUNCTION(random_int)
umax++;

    /* Powers of two are not biased */

•   if ((umax & ~umax) != umax) {
  

•   if ((umax & (umax - 1)) != 0) {
            /* Ceiling under which ZEND_LONG_MAX % max == 0 */
            zend_ulong limit = ZEND_ULONG_MAX - (ZEND_ULONG_MAX %
  

umax) - 1;

--
2.4.0

Good catch, thanks! Applied via
https://github.com/php/php-src/commit/cf7e5357a46afe1dca978f4887bbd83a7507ce69
.

Nikita