Function bpf_zerocopy_canwritebuf

freebsd/net/bpf_zerocopy.c:449–463

* Query from the BPF framework as to whether or not the buffer current in * the store position can actually be written to. This may return false if * the store buffer is assigned to userspace before the hold buffer is * acknowledged. */

 * acknowledged.
 */
int
bpf_zerocopy_canwritebuf(struct bpf_d *d)
{
	struct zbuf *zb;

	KASSERT(d->bd_bufmode == BPF_BUFMODE_ZBUF,
	    ("bpf_zerocopy_canwritebuf: not in zbuf mode"));

	zb = (struct zbuf *)d->bd_sbuf;
	KASSERT(zb != NULL, ("bpf_zerocopy_canwritebuf: bd_sbuf NULL"));

	if (zb->zb_flags & ZBUF_FLAG_ASSIGNED)
		return (0);
	return (1);
}

/*
 * Free zero copy buffers at request of descriptor.