Function ng_ppp_prepend

freebsd/netgraph/ng_ppp.c:2459–2467

* Prepend some bytes to an mbuf. */

 * Prepend some bytes to an mbuf.
 */
static struct mbuf *
ng_ppp_prepend(struct mbuf *m, const void *buf, int len)
{
	M_PREPEND(m, len, M_NOWAIT);
	if (m == NULL || (m->m_len < len && (m = m_pullup(m, len)) == NULL))
		return (NULL);
	bcopy(buf, mtod(m, uint8_t *), len);
	return (m);
}

/*
 * Update private information that is derived from other private information