[Xen-devel] [PULL 2/3] tap-bsd: implement a FreeBSD only version of tap_open

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

The current behaviour of tap_open for BSD systems differ greatly from
it's Linux counterpart. Since FreeBSD supports interface renaming and
tap device cloning by opening /dev/tap, implement a FreeBSD specific
version of tap_open that behaves like it's Linux counterpart.

This is specially important for toolstacks that use Qemu (like Xen
libxl), in order to have a unified behaviour across suported
platforms.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
---
 net/tap-bsd.c |   70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 69 insertions(+), 1 deletion(-)

diff --git a/net/tap-bsd.c b/net/tap-bsd.c
index 90f8a02..bf91bd0 100644
--- a/net/tap-bsd.c
+++ b/net/tap-bsd.c
@@ -27,12 +27,13 @@
 #include "sysemu/sysemu.h"
 #include "qemu/error-report.h"
 
-#ifdef __NetBSD__
+#if defined(__NetBSD__) || defined(__FreeBSD__)
 #include <sys/ioctl.h>
 #include <net/if.h>
 #include <net/if_tap.h>
 #endif
 
+#ifndef __FreeBSD__
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
              int vnet_hdr_required, int mq_required)
 {
@@ -108,6 +109,73 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
     return fd;
 }
 
+#else /* __FreeBSD__ */
+
+#define PATH_NET_TAP "/dev/tap"
+
+int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
+             int vnet_hdr_required, int mq_required)
+{
+    int fd, s, ret;
+    struct ifreq ifr;
+
+    TFR(fd = open(PATH_NET_TAP, O_RDWR));
+    if (fd < 0) {
+        error_report("could not open %s: %s", PATH_NET_TAP, strerror(errno));
+        return -1;
+    }
+
+    memset(&ifr, 0, sizeof(ifr));
+
+    ret = ioctl(fd, TAPGIFNAME, (void *)&ifr);
+    if (ret < 0) {
+        error_report("could not get tap interface name");
+        goto error;
+    }
+
+    if (ifname[0] != '\0') {
+        /* User requested the interface to have a specific name */
+        s = socket(AF_LOCAL, SOCK_DGRAM, 0);
+        if (s < 0) {
+            error_report("could not open socket to set interface name");
+            goto error;
+        }
+        ifr.ifr_data = ifname;
+        ret = ioctl(s, SIOCSIFNAME, (void *)&ifr);
+        close(s);
+        if (ret < 0) {
+            error_report("could not set tap interface name");
+            goto error;
+        }
+    } else {
+        pstrcpy(ifname, ifname_size, ifr.ifr_name);
+    }
+
+    if (*vnet_hdr) {
+        /* BSD doesn't have IFF_VNET_HDR */
+        *vnet_hdr = 0;
+
+        if (vnet_hdr_required && !*vnet_hdr) {
+            error_report("vnet_hdr=1 requested, but no kernel "
+                         "support for IFF_VNET_HDR available");
+            goto error;
+        }
+    }
+    if (mq_required) {
+        error_report("mq_required requested, but not kernel support"
+                     "for IFF_MULTI_QUEUE available");
+        goto error;
+    }
+
+    fcntl(fd, F_SETFL, O_NONBLOCK);
+    return fd;
+
+error:
+    close(fd);
+    return -1;
+}
+#endif /* __FreeBSD__ */
+
 int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
 {
     return 0;
-- 
1.7.10.4


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