X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fstructeq%2Fstructeq.h;h=81799539c51e45f9c2f1b9c23a1b3949b47564c1;hp=6b90754c73a92fe3d203644ba9b075c8b0f5fcbd;hb=8e6c2fecfd633171250b7f09ef4aa0328bd5b698;hpb=92be2eff52133138e4975308f6e731c46b53ace1

diff --git a/ccan/structeq/structeq.h b/ccan/structeq/structeq.h
index 6b90754c..81799539 100644
--- a/ccan/structeq/structeq.h
+++ b/ccan/structeq/structeq.h
@@ -9,14 +9,15 @@
 /**
  * STRUCTEQ_DEF - define an ..._eq function to compare two structures.
  * @sname: name of the structure, and function (<sname>_eq) to define.
- * @padbytes: number of bytes of expected padding, or -1 if unknown.
+ * @padbytes: number of bytes of expected padding, or negative "max".
  * @...: name of every member of the structure.
  *
  * This generates a single memcmp() call in the common case where the
  * structure contains no padding.  Since it can't tell the difference between
  * padding and a missing member, @padbytes can be used to assert that
- * there isn't any, or how many we expect.  -1 means "expect some", since
- * it can be platform dependent.
+ * there isn't any, or how many we expect.  A negative number means
+ * "up to or equal to that amount of padding", as padding can be
+ * platform dependent.
  */
 #define STRUCTEQ_DEF(sname, padbytes, ...)				\
 static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \
@@ -25,7 +26,7 @@ static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \
 	BUILD_ASSERT(((padbytes) < 0 &&					\
 		      CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \
 						    __VA_ARGS__))	\
-		      > sizeof(*_a))					\
+		      - (padbytes) >= sizeof(*_a))			\
 		     || CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \
 						      __VA_ARGS__))	\
 		     + (padbytes) == sizeof(*_a));			\