PHP中的权限被拒绝

My script generates a directory for photos that user uploads but permissions for that generated directory shows as r----x--t even though i specify 777 in php

if (!is_dir($dir.$new_id)) {
    $new_dir = $dir.$new_id.'/';
    mkdir($new_dir, 777, true);
    $thumbnail_dir = $new_dir.'thumbnail/';
    if (!is_dir($thumbnail_dir)) {
        mkdir($thumbnail_dir, 777, true);   
    }
}

I should mention that i'm on hostinger free account that is running centos OS.

set your umask temporarily to zero, the umask acts as a set of permissions that applications cannot set on files. Source : http://php.net/manual/en/function.umask.php

  $old = umask(0);
  if (!is_dir($dir.$new_id)) {
      $new_dir = $dir.$new_id.'/';
      mkdir($new_dir, 0777, true);
      $thumbnail_dir = $new_dir.'thumbnail/';
      if (!is_dir($thumbnail_dir)) {
          mkdir($thumbnail_dir, 0777, true);   
      }
  }
  umask($old);
  if ($old != umask()) {
     die('An error occurred while changing back the umask');
  }