add file source digest support (#1914)

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

syft/file/cataloger/filedigest/cataloger.go

@@ -10,10 +10,11 @@ import (
 	stereoscopeFile "github.com/anchore/stereoscope/pkg/file"
 	"github.com/anchore/syft/internal"
 	"github.com/anchore/syft/internal/bus"
+	intFile "github.com/anchore/syft/internal/file"
 	"github.com/anchore/syft/internal/log"
 	"github.com/anchore/syft/syft/event"
 	"github.com/anchore/syft/syft/file"
-	internal2 "github.com/anchore/syft/syft/file/cataloger/internal"
+	intCataloger "github.com/anchore/syft/syft/file/cataloger/internal"
 )
 
 var ErrUndigestableFile = errors.New("undigestable file")
@@ -33,7 +34,7 @@ func (i *Cataloger) Catalog(resolver file.Resolver, coordinates ...file.Coordina
 	var locations []file.Location
 
 	if len(coordinates) == 0 {
-		locations = internal2.AllRegularFiles(resolver)
+		locations = intCataloger.AllRegularFiles(resolver)
 	} else {
 		for _, c := range coordinates {
 			locations = append(locations, file.NewLocationFromCoordinates(c))
@@ -82,7 +83,7 @@ func (i *Cataloger) catalogLocation(resolver file.Resolver, location file.Locati
 	}
 	defer internal.CloseAndLogError(contentReader, location.VirtualPath)
 
-	digests, err := file.NewDigestsFromFile(contentReader, i.hashes)
+	digests, err := intFile.NewDigestsFromFile(contentReader, i.hashes)
 	if err != nil {
 		return nil, internal.ErrPath{Context: "digests-cataloger", Path: location.RealPath, Err: err}
 	}

syft/file/cataloger/filedigest/cataloger_test.go

@@ -13,6 +13,7 @@ import (
 
 	stereoscopeFile "github.com/anchore/stereoscope/pkg/file"
 	"github.com/anchore/stereoscope/pkg/imagetest"
+	intFile "github.com/anchore/syft/internal/file"
 	"github.com/anchore/syft/syft/file"
 	"github.com/anchore/syft/syft/source"
 )
@@ -40,7 +41,7 @@ func testDigests(t testing.TB, root string, files []string, hashes ...crypto.Has
 			h := hash.New()
 			h.Write(b)
 			digests[file.NewLocation(f).Coordinates] = append(digests[file.NewLocation(f).Coordinates], file.Digest{
-				Algorithm: file.CleanDigestAlgorithmName(hash.String()),
+				Algorithm: intFile.CleanDigestAlgorithmName(hash.String()),
 				Value:     fmt.Sprintf("%x", h.Sum(nil)),
 			})
 		}

syft/file/digest.go

@@ -1,76 +1,6 @@
 package file
 
-import (
-	"crypto"
-	"fmt"
-	"hash"
-	"io"
-	"strings"
-)
-
 type Digest struct {
 	Algorithm string `json:"algorithm"`
 	Value     string `json:"value"`
 }
-
-func NewDigestsFromFile(closer io.ReadCloser, hashes []crypto.Hash) ([]Digest, error) {
-	// create a set of hasher objects tied together with a single writer to feed content into
-	hashers := make([]hash.Hash, len(hashes))
-	writers := make([]io.Writer, len(hashes))
-	for idx, hashObj := range hashes {
-		hashers[idx] = hashObj.New()
-		writers[idx] = hashers[idx]
-	}
-
-	size, err := io.Copy(io.MultiWriter(writers...), closer)
-	if err != nil {
-		return nil, err
-	}
-
-	if size == 0 {
-		return make([]Digest, 0), nil
-	}
-
-	result := make([]Digest, len(hashes))
-	// only capture digests when there is content. It is important to do this based on SIZE and not
-	// FILE TYPE. The reasoning is that it is possible for a tar to be crafted with a header-only
-	// file type but a body is still allowed.
-	for idx, hasher := range hashers {
-		result[idx] = Digest{
-			Algorithm: DigestAlgorithmName(hashes[idx]),
-			Value:     fmt.Sprintf("%+x", hasher.Sum(nil)),
-		}
-	}
-
-	return result, nil
-}
-
-func Hashers(names ...string) ([]crypto.Hash, error) {
-	supportedHashAlgorithms := make(map[string]crypto.Hash)
-	for _, h := range []crypto.Hash{
-		crypto.MD5,
-		crypto.SHA1,
-		crypto.SHA256,
-	} {
-		supportedHashAlgorithms[DigestAlgorithmName(h)] = h
-	}
-
-	var hashers []crypto.Hash
-	for _, hashStr := range names {
-		hashObj, ok := supportedHashAlgorithms[CleanDigestAlgorithmName(hashStr)]
-		if !ok {
-			return nil, fmt.Errorf("unsupported hash algorithm: %s", hashStr)
-		}
-		hashers = append(hashers, hashObj)
-	}
-	return hashers, nil
-}
-
-func DigestAlgorithmName(hash crypto.Hash) string {
-	return CleanDigestAlgorithmName(hash.String())
-}
-
-func CleanDigestAlgorithmName(name string) string {
-	lower := strings.ToLower(name)
-	return strings.ReplaceAll(lower, "-", "")
-}