Refactor inTotoMaterials to skip directories

Author: aledbf

pkg/leeway/provenance.go

@@ -297,7 +297,13 @@ func (p *Package) inTotoMaterials() ([]in_toto.ProvenanceMaterial, error) {
 	for _, src := range p.Sources {
 		if stat, err := os.Lstat(src); err != nil {
 			return nil, err
-		} else if !stat.Mode().IsRegular() {
+		}
+
+		if stat.Mode().IsDir() {
+			continue
+		}
+
+		if !stat.Mode().IsRegular() {
 			continue
 		}
 
@@ -326,12 +332,14 @@ func sha256Hash(fn string) (res string, err error) {
 		return "", xerrors.Errorf("cannot compute hash of %s: %w", fn, err)
 	}
 
+	defer f.Close()
+
 	hash := sha256.New()
 	_, err = io.Copy(hash, f)
 	if err != nil {
 		return "", xerrors.Errorf("cannot compute hash of %s: %w", fn, err)
 	}
-	f.Close()
+
 
 	return fmt.Sprintf("%x", hash.Sum(nil)), nil
 }