libiptc/linux_stddef.h

   1 #ifndef _LINUX_STDDEF_H
   2 #define _LINUX_STDDEF_H
   3
   4 #undef NULL
   5 #if defined(__cplusplus)
   6 #define NULL 0
   7 #else
   8 #define NULL ((void *)0)
   9 #endif
  10
  11 #undef offsetof
  12 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
  13
  14
  15 /**
  16  * container_of - cast a member of a structure out to the containing structure
  17  *
  18  * @ptr:        the pointer to the member.
  19  * @type:       the type of the container struct this is embedded in.
  20  * @member:     the name of the member within the struct.
  21  *
  22  */
  23 #define container_of(ptr, type, member) ({                      \
  24         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
  25         (type *)( (char *)__mptr - offsetof(type,member) );})
  26
  27 /*
  28  * Check at compile time that something is of a particular type.
  29  * Always evaluates to 1 so you may use it easily in comparisons.
  30  */
  31 #define typecheck(type,x) \
  32 ({      type __dummy; \
  33         typeof(x) __dummy2; \
  34         (void)(&__dummy == &__dummy2); \
  35         1; \
  36 })
  37
  38
  39 #endif