Added some extra error checks with libnl calls

Signed-off-by: David Sommerseth <davids@redhat.com>

Author: David Sommerseth

python-ethtool/etherinfo.c

@@ -185,7 +185,9 @@ int get_etherinfo_link(PyEtherInfo *self)
                 return 0;
         }
         link = rtnl_link_alloc();
-        /* FIXME: Error handling? */
+        if( !link ) {
+                return 0;
+        }
         rtnl_link_set_ifindex(link, self->index);
         nl_cache_foreach_filter(link_cache, OBJ_CAST(link), callback_nl_link, self);
         rtnl_link_put(link);
@@ -236,7 +238,9 @@ PyObject * get_etherinfo_address(PyEtherInfo *self, nlQuery query)
                 return NULL;
         }
         addr = rtnl_addr_alloc();
-        /* FIXME: Error handling? */
+        if( !addr ) {
+                return NULL;
+        }
         rtnl_addr_set_ifindex(addr, self->index);
 
 	switch( query ) {

python-ethtool/netlink.c

@@ -57,8 +57,8 @@ int open_netlink(PyEtherInfo *ethi)
 
 	/* No earlier connections exists, establish a new one */
 	nlconnection = nl_socket_alloc();
-	nl_connect(nlconnection, NETLINK_ROUTE);
-	if( (nlconnection != NULL) ) {
+	if( nlconnection != NULL ) {
+		nl_connect(nlconnection, NETLINK_ROUTE);
 		/* Force O_CLOEXEC flag on the NETLINK socket */
 		if( fcntl(nl_socket_get_fd(nlconnection), F_SETFD, FD_CLOEXEC) == -1 ) {
 			fprintf(stderr,