You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: armor.go
    path of file: ./repos/lazygit/vendor/golang.org/x/crypto/openpgp/armor
    
    the code of the file until where you have to start completion: // Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package armor implements OpenPGP ASCII Armor, see RFC 4880. OpenPGP Armor is
// very similar to PEM except that it has an additional CRC checksum.
//
// Deprecated: this package is unmaintained except for security fixes. New
// applications should consider a more focused, modern alternative
    
func (l *lineReader) Read(p []byte) (n int, err error) {
	if l.eof {
		return 0, io.EOF
	}

	if len(l.buf) > 0 {
		n = copy(p, l.buf)
		l.buf = l.buf[n:]
		return
	}

	line, isPrefix, err := l.in.ReadLine()
	if err != nil {
		return
	}
	if isPrefix {
		return 0, ArmorCorrupt
	}

	if bytes.HasPrefix(line, armorEnd) {
		l.eof = true
		return 0, io.EOF
	}

	if len(line) == 5 && line[0] == '=' {
		// This is the checksum line
		var expectedBytes [3]byte
		var m int
		m, err = base64.StdEncoding.Decode(expectedBytes[0:], line[1:])
		if m != 3 || err != nil {
			return
		}
		l.crc = uint32(expectedBytes[0])<<16 |
			uint32(expectedBytes[1])<<8 |
			uint32(expectedBytes[2])

		line, _, err = l.in.ReadLine()
		if err != nil && err != io.EOF {
			return
		}
		if !bytes.HasPrefix(line, armorEnd) {
			return 0, ArmorCorrupt
		}

		l.eof = true
		l.crcSet = true
		return 0, io.EOF
	}

	if len(line) > 96 {
		return 0, ArmorCorrupt
	}

	n = copy(p, line)
	bytesToSave := len(line) - n
	if bytesToSave > 0 {
		if cap(l.buf) < bytesToSave {
			l.buf = make([]byte, 0, bytesToSave)
		}
		l.buf = l.buf[0:bytesToSave]
		copy(l.buf, line[n:])
	}

	return
}