/* Copy len bytes from m, starting off bytes into n  */
int m_copy(struct mbuf *n, struct mbuf *m, int off, int len)
/* Copy len bytes from m, starting off bytes into n  */
int m_copy(struct mbuf *n, struct mbuf *m, int off, int len)
{
	if (len > M_FREEROOM(n))
		return -1;
	memcpy((n->m_data + n->m_len), (m->m_data + off), len);
	n->m_len += len;
	return 0;
}