//
// If fs implements [ReadDirFS], ReadDir calls fs.ReadDir.
// Otherwise ReadDir calls fs.Open and uses ReadDir and Close
// on the returned file.
func ReadDir(fsys FS, name string) ([]DirEntry, error) {
	if fsys, ok := fsys.(ReadDirFS); ok {
		return fsys.ReadDir(name)
	}

	file, err := fsys.Open(name)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	dir, ok := file.(ReadDirFile)
	if !ok {

	}
	return ^FileMode(0)
}

// Implemented in syscall/syscall_darwin.go.

//go:linkname closedir syscall.closedir
func closedir(dir uintptr) (err error)

//go:linkname readdir_r syscall.readdir_r

func isDirEmpty(dirname string, legacy bool) bool {
	if legacy {
		// On filesystems such as btrfs, nfs this is not true, so fallback
		// to performing readdir() instead.
		entries, err := readDirN(dirname, 1)
		if err != nil {
			return false
		}
		return len(entries) == 0
	}
	var stat syscall.Stat_t
	if err := syscall.Stat(dirname, &stat); err != nil {
		return false
	}

			t.errorf("%s: third Open: ReadDir(%d) after %d: 0 entries but nil error", dir, n, len(list2))
			return
		}
	}
	t.checkDirList(dir, "first Open+ReadDir(-1) vs third Open+ReadDir(1,2) loop", list, list2)

	// If fsys has ReadDir, check that it matches and is sorted.
	if fsys, ok := t.fsys.(fs.ReadDirFS); ok {
		list2, err := fsys.ReadDir(dir)
		if err != nil {
			t.errorf("%s: fsys.ReadDir: %w", dir, err)
			return
		}

	if file == nil {
		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
	}
	if file.IsDir() {
		return &openDir{file, f.readDir(name), 0}, nil
	}
	return &openFile{file, 0}, nil
}

// ReadDir reads and returns the entire named directory.
func (f FS) ReadDir(name string) ([]fs.DirEntry, error) {
	file, err := f.Open(name)
	if err != nil {
		return nil, err
	}
	dir, ok := file.(*openDir)

func (f *File) Readdir(n int) ([]FileInfo, error) {
	if f == nil {
		return nil, ErrInvalid
	}
	_, _, infos, err := f.readdir(n, readdirFileInfo)
	if infos == nil {
		// Readdir has historically always returned a non-nil empty slice, never nil,
		// even on error (except misuse with nil receiver above).
		// Keep it that way to avoid breaking overly sensitive callers.
		infos = []FileInfo{}
	}
	return infos, err
}

			d.bufp, d.nbuf = 0, nb

			if err != nil {
				if err == io.EOF {
					break
				}
				return names, dirents, infos, &PathError{Op: "readdir", Path: file.name, Err: err}
			}
			if nb < syscall.STATFIXLEN {
				return names, dirents, infos, &PathError{Op: "readdir", Path: file.name, Err: syscall.ErrShortStat}
			}
		}

		// Get a record from the buffer.
		b := d.buf[d.bufp:]

	}
}

func TestReadDir(t *testing.T) {
	t.Parallel()

	dirname := "rumpelstilzchen"
	_, err := ReadDir(dirname)
	if err == nil {
		t.Fatalf("ReadDir %s: error expected, none found", dirname)
	}

	dirname = "."
	list, err := ReadDir(dirname)
	if err != nil {
		t.Fatalf("ReadDir %s: %v", dirname, err)
	}

	foundFile := false
	foundSubDir := false
	for _, dir := range list {
		switch {

	return os.WriteFile(filename, data, perm)
}

// ReadDir reads the directory named by dirname and returns
// a list of fs.FileInfo for the directory's contents,
// sorted by filename. If an error occurs reading the directory,
// ReadDir returns no directory entries along with the error.
//
// Deprecated: As of Go 1.16, [os.ReadDir] is a more efficient and correct choice:

	return syscall.Chdir(fd.Path)
}

// ReadDir wraps syscall.ReadDir.
// We treat this like an ordinary system call rather than a call
// that tries to fill the buffer.
func (fd *FD) ReadDir(buf []byte, cookie syscall.Dircookie) (int, error) {
	if err := fd.incref(); err != nil {
		return 0, err
	}
	defer fd.decref()
	for {
		n, err := syscall.ReadDir(fd.Sysfd, buf, cookie)
		if err != nil {
			n = 0