diff options
Diffstat (limited to 'git-compat-util.h')
| -rw-r--r-- | git-compat-util.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/git-compat-util.h b/git-compat-util.h index 4a23b90..8605cb4 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -1337,4 +1337,17 @@ static inline void *container_of_or_null_offset(void *ptr, size_t offset) #define container_of_or_null(ptr, type, member) \ (type *)container_of_or_null_offset(ptr, offsetof(type, member)) +/* + * like offsetof(), but takes a pointer to a a variable of type which + * contains @member, instead of a specified type. + * @ptr is subject to multiple evaluation since we can't rely on __typeof__ + * everywhere. + */ +#if defined(__GNUC__) /* clang sets this, too */ +#define OFFSETOF_VAR(ptr, member) offsetof(__typeof__(*ptr), member) +#else /* !__GNUC__ */ +#define OFFSETOF_VAR(ptr, member) \ + ((uintptr_t)&(ptr)->member - (uintptr_t)(ptr)) +#endif /* !__GNUC__ */ + #endif |