Función php tamaño de una carpeta o archivo

function size($path, $formated = true, $retstring = null){
 if(!is_dir($path) || !is_readable($path)){
 if(is_file($path) || file_exists($path)){
 $size = filesize($path);
 } else {
 return false;
 }
 } else {
 $path_stack[] = $path;
 $size = 0;

 do {
 $path   = array_shift($path_stack);
 $handle = opendir($path);
 while(false !== ($file = readdir($handle))) {
 if($file != '.' && $file != '..' && is_readable($path . DIRECTORY_SEPARATOR . $file)) {
 if(is_dir($path . DIRECTORY_SEPARATOR . $file)){ $path_stack[] = $path . DIRECTORY_SEPARATOR . $file; }
 $size += filesize($path . DIRECTORY_SEPARATOR . $file);
 }
 }
 closedir($handle);
 } while (count($path_stack)> 0);
 }
 if($formated){
 $sizes = array('B', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB');
 if($retstring == null) { $retstring = '%01.2f %s'; }
 $lastsizestring = end($sizes);
 foreach($sizes as $sizestring){
 if($size <1024){ break; }
 if($sizestring != $lastsizestring){ $size /= 1024; }
 }
 if($sizestring == $sizes[0]){ $retstring = '%01d %s'; } // los Bytes normalmente no son fraccionales
 $size = sprintf($retstring, $size, $sizestring);
 }
 return $size;
 }