Post-merge cleanup after erofs feature merge

[rchincha]

#25

^ intended to:

1. add erofs support
2. achieve functional parity with squashfs

This issue tracks some cleanup that needs to happen right after.

[ ] add tighter/better "mkfs" checks for compression for both squashfs and erofs

[rchincha]

func ExtractSingleErofs(erofsFile string, extractDir string) error {
exPolInfo.once.Do(func() {
const envName = "STACKER_EROFS_EXTRACT_POLICY"
const defPolicy = "kmount erofsfuse fsc.erofs"
Member
@raharper raharper 4 days ago
default policy should probably be exported variable so callers can use it.
Individual policies should be const export variables.

[rchincha]

// Ignore errs here as mkerofs --help exit status code is 1
_ = cmd.Run()

	if strings.Contains(stdoutBuffer.String(), "zstd") ||

Member
@raharper raharper 4 days ago
Probably should check for the the Available compressors prefix:

% mkfs.erofs --help 2>&1 | grep compressors
Available compressors are: lz4hc, lz4
Also, why do we care about the compression used? won't kernel or fuse erofs mount handle the decompression?

[rchincha]

pkg/erofs/mediatype.go
BaseMediaTypeLayerErofs = "application/vnd.stacker.image.layer.erofs"

LZ4HCCompression ErofsCompression = "lz4hc"
LZ4Compression   ErofsCompression = "lz4"

Member
@raharper raharper 4 days ago
You list the other types here, but we don;t check for them in the the mkfs.erofs output

Member
Author
@rchincha rchincha 4 days ago •
These are the original default ones. mkfs.erofs skipping these would be a major breakage. Both tools released by same group and yes, making assumptions here but probably ok.

Member
@raharper raharper 4 days ago
Any mkfs.erofs may not have those enabled; it seems strange to check for other flags, but not the "default" ones when the command itself indicates whether it's enabled or not. Either drop the "check for features" function and use "original default ones", or check for all of them.

[rchincha]

Increase code coverage post merge.