Previously, Windows layer diffs were written using a Windows-internal
format based on the BackupRead/BackupWrite Win32 APIs. This caused
problems with tar-split and tarsum and led to performance problems
in implementing methods such as DiffPath. It also was just an
unnecessary differentiation point between Windows and Linux.
With this change, Windows layer diffs look much more like their
Linux counterparts. They use AUFS-style whiteout files for files
that have been removed, and they encode all metadata directly in
the tar file.
This change only affects Windows post-TP4, since changes to the Windows
container storage APIs were necessary to make this possible.
Signed-off-by: John Starks <jostarks@microsoft.com>
Upstream-commit: 5649030e25bd87b4b0bbd200515b8c7317ae8ce1
Component: engine
209e95dee8