--- libaitio/src/bpf.c	2013/06/25 09:29:34	1.1.2.10
+++ libaitio/src/bpf.c	2013/06/25 10:58:22	1.1.2.11
@@ -97,11 +97,19 @@ allocZCbuf(u_int len)
 int
 io_etherOpen(const char *csIface, int flags, int whdr, u_int *buflen, void **zcbuf)
 {
-	int n = 1, eth = -1;
+	int eth = -1;
 	register int i;
 	char szStr[STRSIZ];
 	struct ifreq ifr;
+	u_int n = 1;
 
+#ifndef __FreeBSD__
+	if (zcbuf) {
+		io_SetErr(ENOTSUP, "bpf zero copy buffer mode is not supported");
+		return -1;
+	}
+#endif
+
 	for (i = 0; i < BPF_DEV_MAX; i++) {
 		memset(szStr, 0, sizeof szStr);
 		snprintf(szStr, sizeof szStr, "/dev/bpf%d", i);
@@ -124,39 +132,49 @@ io_etherOpen(const char *csIface, int flags, int whdr,
 		close(eth);
 		return -1;
 	}
-	if (buflen && *buflen) {
-		if (!zcbuf) {
-			if (ioctl(eth, BIOCSBLEN, buflen) == -1) {
-				LOGERR;
-				close(eth);
-				return -1;
-			}
-		} else {
+
+	if (!zcbuf) {
+		if (ioctl(eth, BIOCGBLEN, &n) == -1) {
+			LOGERR;
+			close(eth);
+			return -1;
+		} else
+			n = (buflen && *buflen) ? MIN(n, *buflen) : n;
+		if (ioctl(eth, BIOCSBLEN, &n) == -1) {
+			LOGERR;
+			close(eth);
+			return -1;
+		}
+		if (buflen && *buflen)
+			*buflen = n;
+	} else {
 #ifdef __FreeBSD__
-			n = BPF_BUFMODE_ZBUF;
-			if (ioctl(eth, BIOCSETBUFMODE, &n) == -1) {
-				LOGERR;
-				close(eth);
-				return -1;
-			}
-			if (ioctl(eth, BIOCGETZMAX, &n) == -1) {
-				LOGERR;
-				close(eth);
-				return -1;
-			} else
-				*buflen = MIN(n, *buflen);
-			if (!(*zcbuf = allocZCbuf(*buflen))) {
-				close(eth);
-				return -1;
-			}
-			if (ioctl(eth, BIOCSETZBUF, (struct bpf_zbuf*) *zcbuf) == -1) {
-				LOGERR;
-				io_etherClose(eth, zcbuf);
-				return -1;
-			}
-#endif
+		n = BPF_BUFMODE_ZBUF;
+		if (ioctl(eth, BIOCSETBUFMODE, &n) == -1) {
+			LOGERR;
+			close(eth);
+			return -1;
 		}
+		if (ioctl(eth, BIOCGETZMAX, &n) == -1) {
+			LOGERR;
+			close(eth);
+			return -1;
+		} else
+			n = (buflen && *buflen) ? MIN(n, *buflen) : n;
+		if (!(*zcbuf = allocZCbuf(n))) {
+			close(eth);
+			return -1;
+		}
+		if (ioctl(eth, BIOCSETZBUF, (struct bpf_zbuf*) *zcbuf) == -1) {
+			LOGERR;
+			io_etherClose(eth, zcbuf);
+			return -1;
+		}
+		if (buflen && *buflen)
+			*buflen = n;
+#endif
 	}
+
 	if (csIface)
 		strlcpy(szStr, csIface, sizeof szStr);
 	else if (io_get1stiface(szStr, sizeof szStr) == -1) {