[PATCH 13/16] batman-adv: add build check macros for packet member offset

[Antonio Quartulli <antonio@meshcoding.com>]

From: Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>

Since we removed the __packed from most of the packets, we should
make sure that the offset generated by the compiler are correct for
sent/received data.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
---
 net/batman-adv/main.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 43dc92e..b22368e 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -393,6 +393,14 @@ static void batadv_recv_handler_init(void)
 	for (i = 0; i < ARRAY_SIZE(batadv_rx_handler); i++)
 		batadv_rx_handler[i] = batadv_recv_unhandled_packet;
 
+	/* compile time checks for struct member offsets */
+	BUILD_BUG_ON(offsetof(struct batadv_unicast_4addr_packet, src) != 10);
+	BUILD_BUG_ON(offsetof(struct batadv_unicast_packet, dest) != 4);
+	BUILD_BUG_ON(offsetof(struct batadv_unicast_frag_packet, dest) != 4);
+	BUILD_BUG_ON(offsetof(struct batadv_unicast_tvlv_packet, dst) != 4);
+	BUILD_BUG_ON(offsetof(struct batadv_icmp_packet, dst) != 4);
+	BUILD_BUG_ON(offsetof(struct batadv_icmp_packet_rr, dst) != 4);
+
 	/* batman icmp packet */
 	batadv_rx_handler[BATADV_ICMP] = batadv_recv_icmp_packet;
 	/* unicast with 4 addresses packet */
-- 
1.8.3.2