return io.Copy(struct{ io.Writer }{sw}, r)
	}

	var readLastByte bool
	pos0 := sw.pos
	for sw.logicalRemaining() > 0 && !readLastByte && err == nil {
		var nf int64 // Size of fragment
		dataStart, dataEnd := sw.sp[0].Offset, sw.sp[0].endOffset()
		if sw.pos < dataStart { // In a hole fragment
			nf = dataStart - sw.pos
			if sw.physicalRemaining() == 0 {
				readLastByte = true
				nf--
			}