@staticmethod
def gen_file_header(file_path, inode_str_struct):
    """Generate file header for rsync binary data file

        :param file_path: file path
        :param inode_str_struct: file binary string including inode data
        :return: chunk of binary data to be processed on the next iteration
        """
    start_of_block = b'\x00{}\x00'.format(file_path)
    header_size = len(start_of_block) + len(inode_str_struct)
    header_size += len(str(header_size))
    file_header = b'{}{}{}'.format(header_size, start_of_block,
        inode_str_struct)
    len_file_header = len(file_header)
    if header_size != len_file_header:
        file_header_list = file_header.split('\x00')
        file_header_list = file_header_list[1:]
        file_header_list.insert(0, str(len_file_header))
        file_header = '\x00'.join(file_header_list)
    return file_header
