#523058 by catch, sun, c960657, smk-ka, pwolanin, andypost: optimize calls to...

#523058 by catch, sun, c960657, smk-ka, pwolanin, andypost: optimize calls to check_plain() by trying to use new PHP 5 features and inlining UTF-8 checking

includes/bootstrap.inc

@@ -734,11 +734,35 @@ function referer_uri() {
 /**
  * Encode special characters in a plain-text string for display as HTML.
  *
- * Uses drupal_validate_utf8 to prevent cross site scripting attacks on
+ * Also validates strings as UTF-8 to prevent cross site scripting attacks on
  * Internet Explorer 6.
+ *
+ * @param $text
+ *   The text to be checked or processed.
+ * @return
+ *   An HTML safe version of $text, or an empty string if $text is not
+ *   valid UTF-8.
+ *
+ * @see drupal_validate_utf8().
  */
 function check_plain($text) {
-  return drupal_validate_utf8($text) ? htmlspecialchars($text, ENT_QUOTES) : '';
+  static $php525;
+
+  if (!isset($php525)) {
+    $php525 = version_compare(PHP_VERSION, '5.2.5', '>=');
+  }
+  // We duplicate the preg_match() to validate strings as UTF-8 from
+  // drupal_validate_utf8() here. This avoids the overhead of an additional
+  // function call, since check_plain() may be called hundreds of times during
+  // a request. For PHP 5.2.5+, this check for valid UTF-8 should be handled
+  // internally by PHP in htmlspecialchars().
+  // @see http://www.php.net/releases/5_2_5.php
+  // @todo remove this when support for either IE6 or PHP < 5.2.5 is dropped.
+
+  if ($php525) {
+    return htmlspecialchars($text, ENT_QUOTES, 'UTF-8');
+  }
+  return (preg_match('/^./us', $text) == 1) ? htmlspecialchars($text, ENT_QUOTES, 'UTF-8') : '';
 }
 
 /**
@@ -774,6 +798,7 @@ function drupal_validate_utf8($text) {
   if (strlen($text) == 0) {
     return TRUE;
   }
+  // For performance reasons this logic is duplicated in check_plain().
   return (preg_match('/^./us', $text) == 1);
 }