Function m_cat

freebsd/kern/uipc_mbuf.c:748–767

* Concatenate mbuf chain n to m. * Both chains must be of the same type (e.g. MT_DATA). * Any m_pkthdr is not updated. */

 * Any m_pkthdr is not updated.
 */
void
m_cat(struct mbuf *m, struct mbuf *n)
{
	while (m->m_next)
		m = m->m_next;
	while (n) {
		if (!M_WRITABLE(m) ||
		    (n->m_flags & M_EXTPG) != 0 ||
		    M_TRAILINGSPACE(m) < n->m_len) {
			/* just join the two chains */
			m->m_next = n;
			return;
		}
		/* splat the data from one into the other */
		bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
		    (u_int)n->m_len);
		m->m_len += n->m_len;
		n = m_free(n);
	}
}

/*
 * Concatenate two pkthdr mbuf chains.