netdev-bsd: Fix sign extension bug in ifr_flags on FreeBSD.

FreeBSD fills the int return value with ifr_flagshigh in the high
16 bits and ifr_flags in the low 16 bits rather than blindly promoting
ifr_flags to an int, which will preserve the sign.
This commit makes sure the flags returned isn't negative and apply mask
0xffff to flags.

Signed-off-by: Kevin Lo <kevlo@FreeBSD.org>
Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/lib/netdev-bsd.c b/lib/netdev-bsd.c
index 85f3b21..671de37 100644 (file)
--- a/lib/netdev-bsd.c
+++ b/lib/netdev-bsd.c
@@ -1771,7 +1771,7 @@ static int
 ifr_get_flags(const struct ifreq *ifr)
 {
 #ifdef HAVE_STRUCT_IFREQ_IFR_FLAGSHIGH
-    return (ifr->ifr_flagshigh << 16) | ifr->ifr_flags;
+    return (ifr->ifr_flagshigh << 16) | (ifr->ifr_flags & 0xffff);
 #else
     return ifr->ifr_flags;
 #endif
@@ -1780,9 +1780,11 @@ ifr_get_flags(const struct ifreq *ifr)
 static void
 ifr_set_flags(struct ifreq *ifr, int flags)
 {
-    ifr->ifr_flags = flags;
 #ifdef HAVE_STRUCT_IFREQ_IFR_FLAGSHIGH
+    ifr->ifr_flags = flags & 0xffff;
     ifr->ifr_flagshigh = flags >> 16;
+#else
+    ifr->ifr_flags = flags;
 #endif
 }