Support unlinking package subpaths

main.go

@@ -87,11 +87,33 @@ func parsePackageFlags(args []string) (packageFlags, string, error) {
 		pkg = arg
 	}
 	if pkg == "" {
-		return flags, "", errors.New("missing package name")
+		return flags, "", errors.New("missing package")
 	}
 	return flags, pkg, nil
 }
 
+func splitPackageSpec(spec string) (string, string, error) {
+	if spec == "" {
+		return "", "", errors.New("missing package")
+	}
+
+	parts := strings.SplitN(spec, ":", 2)
+	pkg := parts[0]
+	rel := ""
+	if len(parts) == 2 {
+		rel = parts[1]
+	}
+
+	pkg = strings.Trim(pkg, "/")
+	rel = strings.TrimPrefix(rel, "/")
+
+	if pkg == "" {
+		return "", "", errors.New("invalid package")
+	}
+
+	return pkg, rel, nil
+}
+
 func applyCmd(args []string) error {
 	prune := false
 	for _, arg := range args {
@@ -275,7 +297,12 @@ func addCmd(args []string) error {
 }
 
 func unlinkCmd(args []string) error {
-	flags, pkgName, err := parsePackageFlags(args)
+	flags, pkgSpec, err := parsePackageFlags(args)
+	if err != nil {
+		return err
+	}
+
+	pkgName, relPath, err := splitPackageSpec(pkgSpec)
 	if err != nil {
 		return err
 	}
@@ -302,7 +329,11 @@ func unlinkCmd(args []string) error {
 		return err
 	}
 
-	return restorePackage(filesDir, targetRoot, flags.dryRun)
+	if relPath == "" {
+		return restorePackage(filesDir, targetRoot, flags.dryRun)
+	}
+
+	return restorePath(filesDir, targetRoot, relPath, flags.dryRun)
 }
 
 func removeCmd(args []string) error {
@@ -708,44 +739,88 @@ func restorePackage(filesDir, targetRoot string, dryRun bool) error {
 			return err
 		}
 		targetPath := filepath.Join(targetRoot, rel)
-
-		info, err := os.Lstat(targetPath)
-		if errors.Is(err, os.ErrNotExist) {
-			return nil
-		}
-		if err != nil {
-			return err
-		}
-		if info.Mode()&os.ModeSymlink == 0 {
-			return nil
-		}
-
-		src, err := os.Readlink(targetPath)
-		if err != nil {
-			return err
-		}
-		if !filepath.IsAbs(src) {
-			src = filepath.Join(filepath.Dir(targetPath), src)
-		}
-		src = filepath.Clean(src)
-
-		if !strings.HasPrefix(src, filesAbs+string(os.PathSeparator)) && src != filesAbs {
-			return nil
-		}
-
-		if dryRun {
-			fmt.Printf("dry-run: restore %s\n", targetPath)
-			return nil
-		}
-
-		if err := os.Remove(targetPath); err != nil {
-			return err
-		}
-
-		return copyFile(path, targetPath)
+		return restoreOne(path, targetPath, filesAbs, dryRun)
 	})
 }
 
+func restorePath(filesDir, targetRoot, relPath string, dryRun bool) error {
+	filesAbs, err := filepath.Abs(filesDir)
+	if err != nil {
+		return err
+	}
+
+	relPath = filepath.Clean(relPath)
+	if strings.HasPrefix(relPath, "..") || filepath.IsAbs(relPath) {
+		return fmt.Errorf("invalid relative path %q", relPath)
+	}
+
+	sourcePath := filepath.Join(filesDir, relPath)
+	info, err := os.Lstat(sourcePath)
+	if err != nil {
+		return err
+	}
+
+	if info.IsDir() {
+		return filepath.WalkDir(sourcePath, func(path string, entry fs.DirEntry, err error) error {
+			if err != nil {
+				return err
+			}
+			if entry.IsDir() {
+				return nil
+			}
+			rel, err := filepath.Rel(filesDir, path)
+			if err != nil {
+				return err
+			}
+			targetPath := filepath.Join(targetRoot, rel)
+			return restoreOne(path, targetPath, filesAbs, dryRun)
+		})
+	}
+
+	rel, err := filepath.Rel(filesDir, sourcePath)
+	if err != nil {
+		return err
+	}
+	return restoreOne(sourcePath, filepath.Join(targetRoot, rel), filesAbs, dryRun)
+}
+
+func restoreOne(sourcePath, targetPath, filesAbs string, dryRun bool) error {
+	info, err := os.Lstat(targetPath)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	if info.Mode()&os.ModeSymlink == 0 {
+		return nil
+	}
+
+	src, err := os.Readlink(targetPath)
+	if err != nil {
+		return err
+	}
+	if !filepath.IsAbs(src) {
+		src = filepath.Join(filepath.Dir(targetPath), src)
+	}
+	src = filepath.Clean(src)
+
+	if !strings.HasPrefix(src, filesAbs+string(os.PathSeparator)) && src != filesAbs {
+		return nil
+	}
+
+	if dryRun {
+		fmt.Printf("dry-run: restore %s\n", targetPath)
+		return nil
+	}
+
+	if err := os.Remove(targetPath); err != nil {
+		return err
+	}
+
+	return copyFile(sourcePath, targetPath)
+}
+
 func copyFile(src, dst string) error {
 	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
 		return err