Function sliceForAppend

conn.go:474–483

sliceForAppend extends the input slice by n bytes. head is the full extended slice, while tail is the appended part. If the original slice has sufficient capacity no allocation is performed.

(in []byte, n int)

// slice, while tail is the appended part. If the original slice has sufficient
// capacity no allocation is performed.
func sliceForAppend(in []byte, n int) (head, tail []byte) {
	if total := len(in) + n; cap(in) >= total {
		head = in[:total]
	} else {
		head = make([]byte, total)
		copy(head, in)
	}
	tail = head[len(in):]
	return
}

// encrypt encrypts payload, adding the appropriate nonce and/or MAC, and
// appends it to record, which must already contain the record header.