Fix bug with very large ranges

gauravpadia · Jan 18, 2012 · e7265ff · e7265ff
1 parent 13c6046
commit e7265ff
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Showing 2 changed files with 23 additions and 4 deletions.
diff --git a/lib/CryptLib/Random/Generator.php b/lib/CryptLib/Random/Generator.php
@@ -94,14 +94,19 @@ public function generateInt($min = 0, $max = PHP_INT_MAX) {
         $range = $max - $min;
         if ($range == 0) {
             return $max;
-        } elseif ($range > PHP_INT_MAX) {
-            // This works, because PHP will auto-convert it to a float at this point
+        } elseif ($range > PHP_INT_MAX || is_float($range)) {
+            /**
+             * This works, because PHP will auto-convert it to a float at this point,
+             * But on 64 bit systems, the float won't have enough precision to
+             * actually store the difference, so we need to check if it's a float
+             * and hence auto-converted...
+             */
             throw new \RangeException(
                 'The supplied range is too great to generate'
             );
         }
-        $bits  = ceil(log($range, 2));
-        $bytes = max(ceil($bits / 8), 1);
+        $bits  = (int) ceil(log($range, 2));
+        $bytes = (int) max(ceil($bits / 8), 1);
         $mask  = (int) (pow(2, $bits) - 1);
         /**
          * The mask is a better way of dropping unused bits.  Basically what it does

diff --git a/test/Unit/Random/GeneratorTest.php b/test/Unit/Random/GeneratorTest.php
@@ -167,6 +167,20 @@ public function testGenerateIntFail() {
         $n = $this->generator->generateInt(-1, PHP_INT_MAX);
     }
 
+    /**
+     * @covers CryptLib\Random\Generator::generateInt
+     */
+    public function testGenerateIntLargeTest() {
+        $bits = 30;
+        $expected = 50529027;
+        if (PHP_INT_MAX > 4000000000) {
+            $bits = 56;
+            $expected = 1693273676973062;
+        }
+        $n = $this->generator->generateInt(0, pow(2, $bits));
+        $this->assertEquals($expected, $n);
+    }
+
     /**
      * @covers CryptLib\Random\Generator::generateString
      * @dataProvider provideGenerateStringTest