Encode special characters in a plain-text string for display as HTML.

Also validates strings as UTF-8 to prevent cross site scripting attacks on Internet Explorer 6.

Parameters

$text: The text to be checked or processed.

Return value

An HTML safe version of $text, or an empty string if $text is not valid UTF-8.

See also

drupal_validate_utf8().

File

drupal-6.x/includes/bootstrap.inc, line 845

Functions that need to be loaded on every Drupal request.

Code

function check_plain($text) {
  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') : '';
}