return err
				}
				if st, err := f.Stat(); err == nil {
					sz = st.Size()
				}
				defer f.Close()
				r = f
			}
			if strings.HasSuffix(file, ".zip") {
				zr, err := zip.NewReader(r.(io.ReaderAt), sz)
				if err != nil {
					return err
				}
				for _, file := range zr.File {
					if !file.FileInfo().IsDir() && strings.HasSuffix(file.Name, "xl.meta") {
						r, err := file.Open()