Function bpf_setif

freebsd/net/bpf.c:2053–2088

* Detach a file from its current interface (if attached at all) and attach * to the interface indicated by the name stored in ifr. * Return an errno or 0. */

 * Return an errno or 0.
 */
static int
bpf_setif(struct bpf_d *d, struct ifreq *ifr)
{
	struct bpf_if *bp;
	struct ifnet *theywant;

	BPF_LOCK_ASSERT();

	theywant = ifunit(ifr->ifr_name);
	if (theywant == NULL || theywant->if_bpf == NULL)
		return (ENXIO);

	bp = theywant->if_bpf;
	/*
	 * At this point, we expect the buffer is already allocated.  If not,
	 * return an error.
	 */
	switch (d->bd_bufmode) {
	case BPF_BUFMODE_BUFFER:
	case BPF_BUFMODE_ZBUF:
		if (d->bd_sbuf == NULL)
			return (EINVAL);
		break;

	default:
		panic("bpf_setif: bufmode %d", d->bd_bufmode);
	}
	if (bp != d->bd_bif)
		bpf_attachd(d, bp);
	else {
		BPFD_LOCK(d);
		reset_d(d);
		BPFD_UNLOCK(d);
	}
	return (0);
}

/*
 * Support for select() and poll() system calls