Function getB5DigestForBucketAndDepDigests

private/bufpkg/bufmodule/digest.go:331–370

getB5Digest computes a b5 Digest for the given set of module files and dependencies. A Digest is a composite digest of all Module Files, and all Module dependencies. All Files are added to a cas.Manifest, which is then turned into a cas.Digest. The file cas.Digest, along with all Digests of the de

(
	ctx context.Context,
	bucketWithStorageMatcherApplied storage.ReadBucket,
	depDigests []Digest,
)

//
// Note that the order of the depDigests does not matter - they are sorted within this function.
func getB5DigestForBucketAndDepDigests(
	ctx context.Context,
	bucketWithStorageMatcherApplied storage.ReadBucket,
	depDigests []Digest,
) (Digest, error) {
	// First, compute the shake256 cas.Digest of the files. This will include a
	// sorted list of file names and their digests.
	filesDigest, err := getFilesDigestForB5Digest(ctx, bucketWithStorageMatcherApplied)
	if err != nil {
		return nil, err
	}
	if filesDigest.Type() != cas.DigestTypeShake256 {
		return nil, syserror.Newf("trying to compute b5 Digest with files digest of type %v", filesDigest.Type())
	}
	// Next, we get the b5 digests of all the dependencies and sort their string representations.
	depDigestStrings, err := xslices.MapError(
		depDigests,
		func(digest Digest) (string, error) {
			if digest.Type() != DigestTypeB5 {
				// Even if the buf.lock file had a b4 digest, we should still end up retrieving the b5
				// digest from the BSR, we should never have a b5 digest here.
				return "", syserror.Newf("trying to compute b5 Digest with dependency digest of type %v", digest.Type())
			}
			return digest.String(), nil
		},
	)
	if err != nil {
		return nil, err
	}
	sort.Strings(depDigestStrings)
	// Now, place the file digest first, then the sorted dependency digests afterwards.
	digestStrings := append([]string{filesDigest.String()}, depDigestStrings...)
	// Join these strings together with newlines, and make a new shake256 digest.
	digestOfDigests, err := cas.NewDigestForContent(cas.DigestTypeShake256, strings.NewReader(strings.Join(digestStrings, "\n")))
	if err != nil {
		return nil, err
	}
	// The resulting digest is a b5 digest.
	return NewDigest(DigestTypeB5, digestOfDigests)
}

// The bucket should have already been filtered to just module files.
func getFilesDigestForB5Digest(