code: public function stream_seek($offset, $whence = SEEK_SET)
      {
          if (!$this->handle) {
              return false;
          }
          self::restorePrev();
          $result = \fseek($this->handle, $offset, $whence);
          $success = $result !== -1;
          self::register();
          return $success;
      }
docs: Seek to specific location in a stream
  
  @param integer $offset The stream offset to seek to
  @param integer $whence [SEEK_SET] | SEEK_CUR | SEEK_END
  
  @return boolean
  
  @see http://php.net/manual/en/streamwrapper.stream-seek.php