+/* Given OBJECT of type pointer-to-structure, expands to the offset of MEMBER
+ * within an instance of the structure.
+ *
+ * The GCC-specific version avoids the technicality of undefined behavior if
+ * OBJECT is null, invalid, or not yet initialized. This makes some static
+ * checkers (like Coverity) happier. But the non-GCC version does not actually
+ * dereference any pointer, so it would be surprising for it to cause any
+ * problems in practice.
+ */
+#ifdef __GNUC__
+#define OBJECT_OFFSETOF(OBJECT, MEMBER) offsetof(typeof(*(OBJECT)), MEMBER)
+#else
+#define OBJECT_OFFSETOF(OBJECT, MEMBER) \
+ ((char *) &(OBJECT)->MEMBER - (char *) (OBJECT))
+#endif
+