diff options
Diffstat (limited to 'include/linux/stddef.h')
| -rw-r--r-- | include/linux/stddef.h | 42 |
1 files changed, 37 insertions, 5 deletions
diff --git a/include/linux/stddef.h b/include/linux/stddef.h index ca507bd5f808..80b6bfb944f0 100644 --- a/include/linux/stddef.h +++ b/include/linux/stddef.h @@ -13,11 +13,7 @@ enum { }; #undef offsetof -#ifdef __compiler_offsetof -#define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER) -#else -#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) -#endif +#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER) /** * sizeof_field() - Report the size of a struct field in bytes @@ -97,4 +93,40 @@ enum { #define DECLARE_FLEX_ARRAY(TYPE, NAME) \ __DECLARE_FLEX_ARRAY(TYPE, NAME) +/** + * __TRAILING_OVERLAP() - Overlap a flexible-array member with trailing + * members. + * + * Creates a union between a flexible-array member (FAM) in a struct and a set + * of additional members that would otherwise follow it. + * + * @TYPE: Flexible structure type name, including "struct" keyword. + * @NAME: Name for a variable to define. + * @FAM: The flexible-array member within @TYPE + * @ATTRS: Any struct attributes (usually empty) + * @MEMBERS: Trailing overlapping members. + */ +#define __TRAILING_OVERLAP(TYPE, NAME, FAM, ATTRS, MEMBERS) \ + union { \ + TYPE NAME; \ + struct { \ + unsigned char __offset_to_FAM[offsetof(TYPE, FAM)]; \ + MEMBERS \ + } ATTRS; \ + } + +/** + * TRAILING_OVERLAP() - Overlap a flexible-array member with trailing members. + * + * Creates a union between a flexible-array member (FAM) in a struct and a set + * of additional members that would otherwise follow it. + * + * @TYPE: Flexible structure type name, including "struct" keyword. + * @NAME: Name for a variable to define. + * @FAM: The flexible-array member within @TYPE + * @MEMBERS: Trailing overlapping members. + */ +#define TRAILING_OVERLAP(TYPE, NAME, FAM, MEMBERS) \ + __TRAILING_OVERLAP(TYPE, NAME, FAM, /* no attrs */, MEMBERS) + #endif |