diff mbox

batman-adv: Check type of x and y in seq_(before|after)

Message ID 1305834188-15514-1-git-send-email-sven@narfation.org (mailing list archive)
State Accepted, archived
Commit 288421eda7806d1dbbecd0893e07611b6c75b485
Headers

Commit Message

Sven Eckelmann May 19, 2011, 7:43 p.m. UTC 
  seq_before and seq_after depend on the fact that both sequence numbers
have the same type and thus the same bitwidth. We can ensure that by
compile time checking using a compare between the pointer to the
temporary buffers which were created using the typeof of both
parameters. For example gcc would create a warning like
"warning: comparison of distinct pointer types lacks a cast".

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 main.h |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

Comments

Marek Lindner May 22, 2011, 9:14 a.m. UTC | #1 
On Thursday 19 May 2011 21:43:08 Sven Eckelmann wrote:
> seq_before and seq_after depend on the fact that both sequence numbers
> have the same type and thus the same bitwidth. We can ensure that by
> compile time checking using a compare between the pointer to the
> temporary buffers which were created using the typeof of both
> parameters. For example gcc would create a warning like
> "warning: comparison of distinct pointer types lacks a cast".

Applied in revision 288421e.

Thanks,
Marek
diff mbox

Patch

diff --git a/main.h b/main.h
index db29444..3395bf9 100644
--- a/main.h
+++ b/main.h
@@ -196,8 +196,11 @@  static inline int compare_eth(const void *data1, const void *data2)
  *  - before adding more than 127 to the starting value - it is a predecessor,
  *  - when adding 128 - it is neither a predecessor nor a successor,
  *  - after adding more than 127 to the starting value - it is a successor */
-#define seq_before(x, y) ({typeof(x) _dummy = (x - y); \
-			_dummy > smallest_signed_int(_dummy); })
+#define seq_before(x, y) ({typeof(x) _d1 = (x); \
+			  typeof(y) _d2 = (y); \
+			  typeof(x) _dummy = (_d1 - _d2); \
+			  (void) (&_d1 == &_d2); \
+			  _dummy > smallest_signed_int(_dummy); })
 #define seq_after(x, y) seq_before(y, x)
 
 #endif /* _NET_BATMAN_ADV_MAIN_H_ */