code: func (h *fs) enrichFileInfo(path string, fi os.FileInfo) os.FileInfo {
  	h.m.Lock()
  	if mode, ok := h.fileModes[path]; ok {
  		fi = copyFileInfo(fi)
  		fi.(*FileInfo).FileMode = mode
  	}
  	h.m.Unlock()
  	return fi
  }
docs: // enrichFileInfo is used on Windows.  It takes an os.FileInfo object, e.g. as
  // returned by os.Stat, and enriches the OS-returned file mode with the "real"
  // UNIX file mode, if we know what it is.