Return the uncompressed raw CPIO data of the RPM archive.

def data_file(self):
        """Return the uncompressed raw CPIO data of the RPM archive."""

        if self._data_file is None:
            fileobj = _SubFile(self._fileobj, self.data_offset)

            if self.headers["archive_compression"] == b"xz":
                if not getattr(sys.modules[__name__], 'lzma', False):
                    raise NoLZMAModuleError('lzma module not present')
                self._data_file = lzma.LZMAFile(fileobj)
            else:
                self._data_file = gzip.GzipFile(fileobj=fileobj)

        return self._data_file