The just-released 0.12.0 , in #79, made tar-split/archive/tar private.

The callback to asm.IterateHeaders requires the caller to refer to tar-split/archive/tar.Header. (The callback we use, I think, doesn’t need any special feature of tar-split/archive/tar, but the implementation of asm.IterateHeaders does depend on .ExpectedPadding; so IterateHeaders would need to tediously convert a tar-split/archive/tar.Header into a standard-library archive/tar.Header if it wanted to remove the former from the API.

More directly, both containers/storage and containerd/stargz-snapshotter call tar-split/archive/tar.Reader.RawBytes.