--- libaitio/src/bpf.c	2013/06/26 13:33:55	1.1.2.16
+++ libaitio/src/bpf.c	2013/06/26 15:31:17	1.1.2.18
@@ -219,35 +219,35 @@ io_etherSend(int eth, const void *buf, size_t buflen)
 
 #ifdef __FreeBSD__
 static inline void
-ackZCbuf(struct bpf_zbuf_header * __restrict bzh)
+ackZCbuf(struct bpf_zbuf_header *bzh)
 {
 	atomic_store_rel_int(&bzh->bzh_user_gen, bzh->bzh_kernel_gen);
 }
 
 static inline int
-chkZCbuf(struct bpf_zbuf_header * __restrict bzh)
+chkZCbuf(struct bpf_zbuf_header *bzh)
 {
 	/* return true if userspace owns buffer, and false otherwise. */
 	return (bzh->bzh_user_gen != atomic_load_acq_int(&bzh->bzh_kernel_gen));
 }
 
-static inline size_t
-nextZCbuf(void ** __restrict zcache, struct bpf_zbuf * __restrict zbuf)
+static inline ssize_t
+nextZCbuf(int eth, void ** __restrict zcache, struct bpf_zbuf * __restrict zbuf)
 {
-	size_t rlen = 0;
+	ssize_t rlen = 0;
 	struct bpf_zbuf_header *bzh;
 
 	if (!*zcache || *zcache == zbuf->bz_bufb) {
 		bzh = (struct bpf_zbuf_header *) zbuf->bz_bufa;
 		if (chkZCbuf(bzh)) {
-			rlen = atomic_load_acq_int(&bzh->bzh_kernel_len);
 			*zcache = zbuf->bz_bufa;
+			rlen = atomic_load_acq_int(&bzh->bzh_kernel_len);
 		}
 	} else if (*zcache == zbuf->bz_bufa) {
 		bzh = (struct bpf_zbuf_header *) zbuf->bz_bufb;
 		if (chkZCbuf(bzh)) {
-			rlen = atomic_load_acq_int(&bzh->bzh_kernel_len);
 			*zcache = zbuf->bz_bufb;
+			rlen = atomic_load_acq_int(&bzh->bzh_kernel_len);
 		}
 	}
 
@@ -270,7 +270,13 @@ io_etherRecv(int eth, void * __restrict buf, size_t bu
 	ssize_t rlen = 0;
 	void *zcache = NULL;
 #ifdef __FreeBSD__
+	struct bpf_zbuf bz;
 	struct bpf_zbuf_header *bzh;
+#else
+	if (zcbuf) {
+		io_SetErr(ENOTSUP, "bpf zero copy buffer mode is not supported");
+		return -1;
+	}
 #endif
 
 	if (!buf || !buflen) {
@@ -284,12 +290,16 @@ io_etherRecv(int eth, void * __restrict buf, size_t bu
 			LOGERR;
 	} else {
 #ifdef __FreeBSD__
-		rlen = (ssize_t) nextZCbuf(&zcache, (struct bpf_zbuf*) zcbuf);
-		if (rlen > 0) {
-			bzh = (struct bpf_zbuf_header*) zcache;
-			memcpy(buf, zcache + sizeof(struct bpf_zbuf_header), buflen);
-			ackZCbuf(bzh);
-		}
+		do {
+			rlen = nextZCbuf(eth, &zcache, (struct bpf_zbuf*) zcbuf);
+			if (rlen > 0) {
+				bzh = (struct bpf_zbuf_header*) zcache;
+				memcpy(buf, zcache + sizeof(struct bpf_zbuf_header), 
+						MIN(buflen, rlen));
+			}
+			if (!rlen && !ioctl(eth, BIOCROTZBUF, &bz))
+				continue;
+		} while (0);
 #else
 		rlen = -1;
 		io_SetErr(ENOTSUP, "bpf zero copy buffer mode is not supported");