allow file metadata digests to be optional + add link destination

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

syft/file/digest_cataloger_test.go

@@ -7,6 +7,10 @@ import (
 	"os"
 	"testing"
 
+	"github.com/anchore/stereoscope/pkg/file"
+
+	"github.com/anchore/stereoscope/pkg/imagetest"
+
 	"github.com/stretchr/testify/assert"
 
 	"github.com/anchore/syft/syft/source"
@@ -38,12 +42,13 @@ func testDigests(t testing.TB, files []string, hashes ...crypto.Hash) map[source
 	return digests
 }
 
-func TestDigestsCataloger(t *testing.T) {
-	files := []string{"test-fixtures/last/path.txt", "test-fixtures/another-path.txt", "test-fixtures/a-path.txt"}
+func TestDigestsCataloger_SimpleContents(t *testing.T) {
+	regularFiles := []string{"test-fixtures/last/path.txt", "test-fixtures/another-path.txt", "test-fixtures/a-path.txt"}
 
 	tests := []struct {
 		name           string
 		algorithms     []string
+		files          []string
 		expected       map[source.Location][]Digest
 		constructorErr bool
 		catalogErr     bool
@@ -51,22 +56,32 @@ func TestDigestsCataloger(t *testing.T) {
 		{
 			name:           "bad algorithm",
 			algorithms:     []string{"sha-nothing"},
+			files:          regularFiles,
 			constructorErr: true,
 		},
 		{
 			name:           "unsupported algorithm",
 			algorithms:     []string{"sha512"},
+			files:          regularFiles,
 			constructorErr: true,
 		},
 		{
-			name:       "md5-sha1-sha256",
+			name:       "md5",
 			algorithms: []string{"md5"},
-			expected:   testDigests(t, files, crypto.MD5),
+			files:      regularFiles,
+			expected:   testDigests(t, regularFiles, crypto.MD5),
 		},
 		{
 			name:       "md5-sha1-sha256",
 			algorithms: []string{"md5", "sha1", "sha256"},
-			expected:   testDigests(t, files, crypto.MD5, crypto.SHA1, crypto.SHA256),
+			files:      regularFiles,
+			expected:   testDigests(t, regularFiles, crypto.MD5, crypto.SHA1, crypto.SHA256),
+		},
+		{
+			name:       "directory returns error",
+			algorithms: []string{"md5"},
+			files:      []string{"test-fixtures/last"},
+			catalogErr: true,
 		},
 	}
 
@@ -81,7 +96,7 @@ func TestDigestsCataloger(t *testing.T) {
 				return
 			}
 
-			resolver := source.NewMockResolverForPaths(files...)
+			resolver := source.NewMockResolverForPaths(test.files...)
 			actual, err := c.Catalog(resolver)
 			if err != nil && !test.catalogErr {
 				t.Fatalf("could not catalog (but should have been able to): %+v", err)
@@ -96,3 +111,80 @@ func TestDigestsCataloger(t *testing.T) {
 		})
 	}
 }
+
+func TestDigestsCataloger_MixFileTypes(t *testing.T) {
+	testImage := "image-file-type-mix"
+
+	if *updateImageGoldenFiles {
+		imagetest.UpdateGoldenFixtureImage(t, testImage)
+	}
+
+	img := imagetest.GetGoldenFixtureImage(t, testImage)
+
+	src, err := source.NewFromImage(img, "---")
+	if err != nil {
+		t.Fatalf("could not create source: %+v", err)
+	}
+
+	resolver, err := src.FileResolver(source.SquashedScope)
+	if err != nil {
+		t.Fatalf("could not create resolver: %+v", err)
+	}
+
+	tests := []struct {
+		path     string
+		expected string
+	}{
+		{
+			path:     "/file-1.txt",
+			expected: "888c139e550867814eb7c33b84d76e4d",
+		},
+		{
+			path: "/hardlink-1",
+		},
+		{
+			path: "/symlink-1",
+		},
+		{
+			path: "/char-device-1",
+		},
+		{
+			path: "/block-device-1",
+		},
+		{
+			path: "/fifo-1",
+		},
+		{
+			path: "/bin",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.path, func(t *testing.T) {
+			c, err := NewDigestsCataloger([]string{"md5"})
+			if err != nil {
+				t.Fatalf("unable to get cataloger: %+v", err)
+			}
+
+			actual, err := c.Catalog(resolver)
+			if err != nil {
+				t.Fatalf("could not catalog: %+v", err)
+			}
+
+			_, ref, err := img.SquashedTree().File(file.Path(test.path))
+			if err != nil {
+				t.Fatalf("unable to get file=%q : %+v", test.path, err)
+			}
+			l := source.NewLocationFromImage(test.path, *ref, img)
+
+			if len(actual[l]) == 0 {
+				if test.expected != "" {
+					t.Fatalf("no digest found, but expected one")
+				}
+
+			} else {
+				assert.Equal(t, actual[l][0].Value, test.expected, "mismatched digests")
+			}
+		})
+	}
+}