Utilities: Avoid warnings if unable to open /dev/urandom

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@2820 44740490-163a-0410-bde0-09ae8108e29a

lib/SimpleSAML/Utilities.php

@@ -972,8 +972,8 @@ class SimpleSAML_Utilities {
 		assert('is_int($length)');
 
 		if($fp === NULL) {
-			if (file_exists('/dev/urandom')) {
-				$fp = fopen('/dev/urandom', 'rb');
+			if (@file_exists('/dev/urandom')) {
+				$fp = @fopen('/dev/urandom', 'rb');
 			} else {
 				$fp = FALSE;
 			}