if b.r > 0 {
		copy(b.buf, b.buf[b.r:b.w])
		b.w -= b.r
		b.r = 0
	}

	if b.w >= len(b.buf) {
		panic("bufio: tried to fill full buffer")
	}

	// Read new data: try a limited number of times.
	for i := maxConsecutiveEmptyReads; i > 0; i-- {
		n, err := b.rd.Read(b.buf[b.w:])
		if n < 0 {
			panic(errNegativeRead)
		}
		b.w += n
		if err != nil {
			b.err = err
			return