From: Gaetan Rivet <[email protected]> Implicit padding bytes in a struct are not necessarily initialized. Comparing such struct with memcmp might be wrong. To verify correctness of such comparison, add a macro to statically assert whether a structure contains padding.
Signed-off-by: Gaetan Rivet <[email protected]> Co-authored-by: Eli Britstein <[email protected]> Signed-off-by: Eli Britstein <[email protected]> --- include/openvswitch/compiler.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/openvswitch/compiler.h b/include/openvswitch/compiler.h index 7dee9ec7a..961339944 100644 --- a/include/openvswitch/compiler.h +++ b/include/openvswitch/compiler.h @@ -218,6 +218,18 @@ #define OVS_PACKED(DECL) __pragma(pack(push, 1)) DECL __pragma(pack(pop)) #endif +/* Define a type with this macro to enforce during + * compilation that it has no padding, i.e. packed. + * It *DOES NOT* pack the type, only statically check + * that it is already. Either the layout must be + * made to fit, or explicit padding must be used. + */ +#define OVS_ASSERT_PACKED(TYPE, MEMBERS) \ + TYPE { \ + MEMBERS \ + }; \ + BUILD_ASSERT_DECL(sizeof(TYPE) == sizeof(OVS_PACKED(struct { MEMBERS }))) + /* OVS_ALIGNED_STRUCT may be used to define a structure whose instances should * aligned on an N-byte boundary. This: * OVS_ALIGNED_STRUCT(64, mystruct) { ... }; -- 2.34.1 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
