diff options
Diffstat (limited to 'xorg-server/include/list.h')
| -rw-r--r-- | xorg-server/include/list.h | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/xorg-server/include/list.h b/xorg-server/include/list.h index d04f65745..61b10bd2a 100644 --- a/xorg-server/include/list.h +++ b/xorg-server/include/list.h @@ -26,6 +26,8 @@ #ifndef _XORG_LIST_H_ #define _XORG_LIST_H_ +#include <stddef.h> /* offsetof() */ + /** * @file Classic doubly-link circular list implementation. * For real usage examples of the linked list, see the file test/list.c @@ -232,7 +234,7 @@ xorg_list_is_empty(struct xorg_list *head) */ #ifndef container_of #define container_of(ptr, type, member) \ - (type *)((char *)(ptr) - (char *) &((type *)0)->member) + (type *)((char *)(ptr) - offsetof(type, member)) #endif /** @@ -271,9 +273,20 @@ xorg_list_is_empty(struct xorg_list *head) #define xorg_list_last_entry(ptr, type, member) \ xorg_list_entry((ptr)->prev, type, member) -#define __container_of(ptr, sample, member) \ - (void *)((char *)(ptr) \ - - ((char *)&(sample)->member - (char *)(sample))) +#ifdef HAVE_TYPEOF +#define __container_of(ptr, sample, member) \ + container_of(ptr, typeof(*sample), member) +#else +/* This implementation of __container_of has undefined behavior according + * to the C standard, but it works in many cases. If your compiler doesn't + * support typeof() and fails with this implementation, please try a newer + * compiler. + */ +#define __container_of(ptr, sample, member) \ + (void *)((char *)(ptr) \ + - ((char *)&(sample)->member - (char *)(sample))) +#endif + /** * Loop through the list given by head and set pos to struct in the list. * |