code: func ReadPageSize(path string) (int, error) {
  	// Open database file.
  	f, err := os.Open(path)
  	if err != nil {
  		return 0, err
  	}
  	defer f.Close()
  
  	// Read 4KB chunk.
  	buf := make([]byte, 4096)
  	if _, err := io.ReadFull(f, buf); err != nil {
  		return 0, err
  	}
  
  	// Read page size from metadata.
  	m := (*meta)(unsafe.Pointer(&buf[PageHeaderSize]))
  	return int(m.pageSize), nil
  }
docs: // ReadPageSize reads page size a path.
  // This is not transactionally safe.