}
	if tw.err != nil {
		return tw.err
	}

	// Trailer: two zero blocks.
	err := tw.Flush()
	for i := 0; i < 2 && err == nil; i++ {
		_, err = tw.w.Write(zeroBlock[:])
	}

	// Ensure all future actions are invalid.
	tw.err = ErrWriteAfterClose
	return err // Report IO errors
}

// regFileWriter is a fileWriter for writing data to a regular file entry.
type regFileWriter struct {