offsetof

[Dag-Erling Smørgrav]

I noticed that our definition of offsetof (in <sys/cdefs.h>) is as
follows:

#define __offsetof(type, field) ((size_t)(&((type *)0)->field))

This definition is gratuitously unportable (it assumes that a null
pointer is all-bits-zero).  A better definition would be the
following:

#define __offsetof(type, field) \
        ((size_t)((char *)&((type *)0)->field - (char *)(type *)0))

DES
-- 
Dag-Erling Smørgrav - des at des.no