+The "sequence of chunks" is:
+
+ length of chunk (not including length word itself)
+ struct guestfs_chunk (encoded as XDR)
+ length of chunk
+ struct guestfs_chunk (encoded as XDR)
+ ...
+ length of chunk
+ struct guestfs_chunk (with data.data_len == 0)
+
+The final chunk has the C<data_len> field set to zero. Additionally a