If no snapshotter is specified and `os.features` contains "erofs",
unpacking should use the EROFS snapshotter and differ.
This enhances the usability of native EROFS container images.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
The EROFS differ only applies to EROFS layers which are marked by
a special file `.erofslayer` generated by the EROFS snapshotter.
Why it's needed? Since we'd like to parse []mount.Mount directly
without actual mounting and convert OCI layers into EROFS blobs,
`.erofslayer` gives a hint that the active snapshotter supports
the output blob generated by the EROFS differ.
I'd suggest it could be read together with the next commit.
Signed-off-by: cardy.tang <zuniorone@gmail.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
