[Whiteout] Simple refactoring of whiteout file handling.

PiperOrigin-RevId: 712416206
google · Feb 7, 2025 · 07bf513 · 07bf513
1 parent 620a293
commit 07bf513
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Showing 3 changed files with 153 additions and 7 deletions.
diff --git a/artifact/image/layerscanning/image/image.go b/artifact/image/layerscanning/image/image.go
@@ -325,10 +325,10 @@ func fillChainLayerWithFilesFromTar(img *Image, tarReader *tar.Reader, originLay
 			continue
 		}
 
-		tombstone := strings.HasPrefix(basename, whiteout.WhiteoutPrefix)
+		isWhiteout := whiteout.IsWhiteout(basename)
 		// TODO: b/379094217 - Handle Opaque Whiteouts
-		if tombstone {
-			basename = basename[len(whiteout.WhiteoutPrefix):]
+		if isWhiteout {
+			basename = whiteout.ToPath(basename)
 		}
 
 		// If we're checking a directory, don't filepath.Join names.
@@ -346,11 +346,11 @@ func fillChainLayerWithFilesFromTar(img *Image, tarReader *tar.Reader, originLay
 		var newNode *fileNode
 		switch header.Typeflag {
 		case tar.TypeDir:
-			newNode, err = img.handleDir(realFilePath, virtualPath, originLayerID, tarReader, header, tombstone)
+			newNode, err = img.handleDir(realFilePath, virtualPath, originLayerID, tarReader, header, isWhiteout)
 		case tar.TypeReg:
-			newNode, err = img.handleFile(realFilePath, virtualPath, originLayerID, tarReader, header, tombstone)
+			newNode, err = img.handleFile(realFilePath, virtualPath, originLayerID, tarReader, header, isWhiteout)
 		case tar.TypeSymlink, tar.TypeLink:
-			newNode, err = img.handleSymlink(realFilePath, virtualPath, originLayerID, tarReader, header, tombstone)
+			newNode, err = img.handleSymlink(realFilePath, virtualPath, originLayerID, tarReader, header, isWhiteout)
 		default:
 			log.Warnf("unsupported file type: %v, path: %s", header.Typeflag, header.Name)
 			continue

diff --git a/artifact/image/whiteout/whiteout.go b/artifact/image/whiteout/whiteout.go
@@ -19,6 +19,7 @@ package whiteout
 import (
 	"fmt"
 	"io/fs"
+	"path"
 	"path/filepath"
 	"strings"
 
@@ -39,7 +40,7 @@ func Files(scalibrfs scalibrfs.FS) (map[string]struct{}, error) {
 
 	err := fs.WalkDir(scalibrfs, ".", func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
-			//nolint:nilerr // continue walking if there is an error
+			//nolint:nilerr // Continue walking if there is an error.
 			return nil
 		}
 
@@ -60,3 +61,32 @@ func Files(scalibrfs scalibrfs.FS) (map[string]struct{}, error) {
 	}
 	return whiteouts, nil
 }
+
+// IsWhiteout returns true if a path is a whiteout path.
+func IsWhiteout(p string) bool {
+	_, file := path.Split(p)
+	return strings.HasPrefix(file, WhiteoutPrefix)
+}
+
+// ToWhiteout returns the whiteout version of a path.
+func ToWhiteout(p string) string {
+	dir, file := path.Split(p)
+	return filepath.Join(dir, fmt.Sprintf("%s%s", WhiteoutPrefix, file))
+}
+
+// ToPath returns the non whiteout version of a path.
+func ToPath(p string) string {
+	dir, file := path.Split(p)
+
+	if strings.HasPrefix(file, WhiteoutPrefix) {
+		file = strings.TrimPrefix(file, WhiteoutPrefix)
+	}
+
+	nonWhitoutPath := filepath.Join(dir, file)
+
+	if dir != "" && file == "" {
+		nonWhitoutPath = fmt.Sprintf("%s/", nonWhitoutPath)
+	}
+
+	return nonWhitoutPath
+}
diff --git a/artifact/image/whiteout/whiteout_test.go b/artifact/image/whiteout/whiteout_test.go
@@ -147,3 +147,119 @@ func TestWhiteout(t *testing.T) {
 		})
 	}
 }
+
+func TestIsWhiteout(t *testing.T) {
+	testCases := []struct {
+		desc string
+		path string
+		want bool
+	}{
+		{
+			desc: "Empty path",
+			path: "",
+			want: false,
+		},
+		{
+			desc: "Simple file path",
+			path: "file.txt",
+			want: false,
+		},
+		{
+			desc: "Path with directories",
+			path: "dir1/dir2/foo.txt",
+			want: false,
+		},
+		{
+			desc: "Simple whiteout path",
+			path: ".wh.file.txt",
+			want: true,
+		},
+		{
+			desc: "Whiteout path with directories",
+			path: "dir1/dir2/.wh.foo.txt",
+			want: true,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			got := whiteout.IsWhiteout(tc.path)
+			if got != tc.want {
+				t.Errorf("IsWhiteout(%q) = %v, want: %v", tc.path, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestToWhiteout(t *testing.T) {
+	testCases := []struct {
+		desc string
+		path string
+		want string
+	}{
+		{
+			desc: "Empty path",
+			path: "",
+			want: ".wh.",
+		},
+		{
+			desc: "Simple file path",
+			path: "file.txt",
+			want: ".wh.file.txt",
+		},
+		{
+			desc: "Path with directories",
+			path: "dir1/dir2/foo.txt",
+			want: "dir1/dir2/.wh.foo.txt",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			got := whiteout.ToWhiteout(tc.path)
+			if got != tc.want {
+				t.Errorf("ToWhiteout(%q) = %q, want: %q", tc.path, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestToPath(t *testing.T) {
+	testCases := []struct {
+		desc string
+		path string
+		want string
+	}{
+		{
+			desc: "Empty path",
+			path: "",
+			want: "",
+		},
+		{
+			desc: "Simple file path",
+			path: "file.txt",
+			want: "file.txt",
+		},
+		{
+			desc: "Path with directories",
+			path: "dir1/dir2/foo.txt",
+			want: "dir1/dir2/foo.txt",
+		},
+		{
+			desc: "Simple whiteout path",
+			path: ".wh.file.txt",
+			want: "file.txt",
+		},
+		{
+			desc: "Whiteout path with directories",
+			path: "dir1/dir2/.wh.foo.txt",
+			want: "dir1/dir2/foo.txt",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			got := whiteout.ToPath(tc.path)
+			if got != tc.want {
+				t.Errorf("ToPath(%q) = %q, want: %q", tc.path, got, tc.want)
+			}
+		})
+	}
+}