Return the offset of the zip central directory.

Read a zip from a ReaderAt.

Read a zip from a stream, using a separate copy of the central directory.

Read a zip from a ReaderAt, with a separate copy of the central directory.

Read a tar stream produced by ZipToTar and return the zip directory.

Make a tar archive with two members: - the central directory of the zip file - the complete zip file This lets us process the zip in one pass, which normally isn't possible with the directory at the end.