Before commit c2d936a44fa6 (ofp-actions: Centralize all OpenFlow action
code for maintainability.), struct ofpact was 4 bytes with GCC and Clang,
and 12 bytes with other compilers. That commit changed struct ofpact so
that it remained 4 bytes with GCC and Clang but shrank to 8 bytes on other
compilers. An unexpected side effect of that change was that the size
of the pad[] array in struct ofpact_nest shrank to 0 bytes, because that
array padded to a multiple of 8 bytes. MSVC does not support 0-element
arrays, so this caused a build failure.
This commit fixes the problem by changing struct ofpact so that it is 4
bytes with every compiler.
Reported-by: Alin Serdean <aserd...@cloudbasesolutions.com>
Signed-off-by: Ben Pfaff <b...@nicira.com>
---
lib/compiler.h | 1 +
lib/ofp-actions.h | 12 ++++++++----
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/lib/compiler.h b/lib/compiler.h
index cfe9066..e8bf119 100644
--- a/lib/compiler.h
+++ b/lib/compiler.h
@@ -169,6 +169,7 @@
* or otherwise exposed outside of a single process. */
#if __GNUC__ && !__CHECKER__
#define OVS_PACKED_ENUM __attribute__((__packed__))
+#define HAVE_PACKED_ENUM
#else
#define OVS_PACKED_ENUM
#endif
diff --git a/lib/ofp-actions.h b/lib/ofp-actions.h
index 0f1ea3f..5436f24 100644
--- a/lib/ofp-actions.h
+++ b/lib/ofp-actions.h
@@ -157,16 +157,20 @@ enum {
* code to translate the ofpact to OpenFlow must tolerate this case.)
*/
struct ofpact {
+ /* We want the space advantage of an 8-bit type here on every
+ * implementation, without giving up the advantage of having a useful type
+ * on implementations that support packed enums. */
+#ifdef HAVE_PACKED_ENUM
enum ofpact_type type; /* OFPACT_*. */
+#else
+ uint8_t type; /* OFPACT_* */
+#endif
+
uint8_t raw; /* Original type when added, if any. */
uint16_t len; /* Length of the action, in bytes, including
* struct ofpact, excluding padding. */
};
-
-#ifdef __GNUC__
-/* Make sure that OVS_PACKED_ENUM really worked. */
BUILD_ASSERT_DECL(sizeof(struct ofpact) == 4);
-#endif
/* Alignment. */
#define OFPACT_ALIGNTO 8
--
1.7.10.4
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