// Check non existent directory.
	if _, err := readDir("/tmp/non-existent-directory"); err != errFileNotFound {
		t.Fatalf("expected = %s, got: %s", errFileNotFound, err)
	}

	file := path.Join(os.TempDir(), "issue")
	if err := os.WriteFile(file, []byte(""), 0o644); err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(file)

	// Check if file is given.
	if _, err := readDir(path.Join(file, "mydir")); err != errFileNotFound {

		// slow, not worth repeating in -check
		t.Skip("skipping with -check set")
	}

	testenv.MustHaveGoBuild(t)

	td, err := os.Open("testdata/src/pkg")
	if err != nil {
		t.Fatal(err)
	}
	fis, err := td.Readdir(0)
	if err != nil {
		t.Fatal(err)
	}
	for _, fi := range fis {
		if !fi.IsDir() {
			continue
		}

		// TODO(gri) remove extra pkg directory eventually

func (d *openDir) Read([]byte) (int, error) {
	return 0, &fs.PathError{Op: "read", Path: d.e.name, Err: errors.New("is a directory")}
}

func (d *openDir) ReadDir(count int) ([]fs.DirEntry, error) {
	n := len(d.files) - d.offset
	if count > 0 && n > count {
		n = count
	}
	if n == 0 {
		if count <= 0 {
			return nil, nil
		}
		return nil, io.EOF
	}

	// Limit the number of returned objects if > 0.
	Limit int

	// DiskID contains the disk ID of the disk.
	// Leave empty to not check disk ID.
	DiskID string
}

// supported FS for Nlink optimization in readdir.
const (
	xfs  = "XFS"
	ext4 = "EXT4"
)

// WalkDir will traverse a directory and return all entries found.
// On success a sorted meta cache stream will be returned.
// Metadata has data stripped, if any.

	// If so, we try to add it to certificate manager.
	root, err := Open(globalCertsDir.Get())
	if err != nil {
		return nil, nil, false, err
	}
	defer root.Close()

	files, err := root.Readdir(-1)
	if err != nil {
		return nil, nil, false, err
	}
	for _, file := range files {
		// Ignore all
		// - regular files
		// - "CAs" directory
		// - any directory which starts with ".."

			objSize, err = gr.ObjInfo.DecryptedSize()
			if err != nil {
				return nil, ObjectInfo{}, err
			}
		} else {
			objSize = gr.ObjInfo.Size
		}

		files, err := zipindex.ReadDir(b[len(b)-size:], objSize, nil)
		if err == nil {
			return files, gr.ObjInfo, nil
		}
		var terr zipindex.ErrNeedMoreData
		if errors.As(err, &terr) {
			size = int(terr.FromEnd)

		// to verify for legacy version.
		if formatLegacy {
			// We only need this code if we are moving
			// from `xl.json` to `xl.meta`, we can avoid
			// one extra readdir operation here for all
			// new deployments.
			entries, err := readDir(currentDataPath)
			if err != nil && err != errFileNotFound {
				return res, osErrToFileErr(err)
			}
			for _, entry := range entries {

		t.Errorf("Opening %q with fs.FS API succeeded", "")
	}
	if _, err := r.Open("test.txt"); err != nil {
		t.Errorf("Error opening %q with fs.FS API: %v", "test.txt", err)
	}
	dirEntries, err := fs.ReadDir(r, ".")
	if err != nil {
		t.Fatalf("Error reading the root directory: %v", err)
	}
	if len(dirEntries) != 1 || dirEntries[0].Name() != "test.txt" {
		t.Errorf("Unexpected directory entries")