| /* CC0 (Public domain) - see LICENSE file for details */ |
| #ifndef CCAN_CONTAINER_OF_H |
| #define CCAN_CONTAINER_OF_H |
| #include <stddef.h> |
| |
| #include "config.h" |
| #include <ccan/check_type/check_type.h> |
| |
| /** |
| * container_of - get pointer to enclosing structure |
| * @member_ptr: pointer to the structure member |
| * @containing_type: the type this member is within |
| * @member: the name of this member within the structure. |
| * |
| * Given a pointer to a member of a structure, this macro does pointer |
| * subtraction to return the pointer to the enclosing type. |
| * |
| * Example: |
| * struct foo { |
| * int fielda, fieldb; |
| * // ... |
| * }; |
| * struct info { |
| * int some_other_field; |
| * struct foo my_foo; |
| * }; |
| * |
| * static struct info *foo_to_info(struct foo *foo) |
| * { |
| * return container_of(foo, struct info, my_foo); |
| * } |
| */ |
| #define container_of(member_ptr, containing_type, member) \ |
| ((containing_type *) \ |
| ((char *)(member_ptr) \ |
| - container_off(containing_type, member)) \ |
| + check_types_match(*(member_ptr), ((containing_type *)0)->member)) |
| |
| |
| /** |
| * container_of_or_null - get pointer to enclosing structure, or NULL |
| * @member_ptr: pointer to the structure member |
| * @containing_type: the type this member is within |
| * @member: the name of this member within the structure. |
| * |
| * Given a pointer to a member of a structure, this macro does pointer |
| * subtraction to return the pointer to the enclosing type, unless it |
| * is given NULL, in which case it also returns NULL. |
| * |
| * Example: |
| * struct foo { |
| * int fielda, fieldb; |
| * // ... |
| * }; |
| * struct info { |
| * int some_other_field; |
| * struct foo my_foo; |
| * }; |
| * |
| * static struct info *foo_to_info_allowing_null(struct foo *foo) |
| * { |
| * return container_of_or_null(foo, struct info, my_foo); |
| * } |
| */ |
| static inline char *container_of_or_null_(void *member_ptr, size_t offset) |
| { |
| return member_ptr ? (char *)member_ptr - offset : NULL; |
| } |
| #define container_of_or_null(member_ptr, containing_type, member) \ |
| ((containing_type *) \ |
| container_of_or_null_(member_ptr, \ |
| container_off(containing_type, member)) \ |
| + check_types_match(*(member_ptr), ((containing_type *)0)->member)) |
| |
| /** |
| * container_off - get offset to enclosing structure |
| * @containing_type: the type this member is within |
| * @member: the name of this member within the structure. |
| * |
| * Given a pointer to a member of a structure, this macro does |
| * typechecking and figures out the offset to the enclosing type. |
| * |
| * Example: |
| * struct foo { |
| * int fielda, fieldb; |
| * // ... |
| * }; |
| * struct info { |
| * int some_other_field; |
| * struct foo my_foo; |
| * }; |
| * |
| * static struct info *foo_to_info(struct foo *foo) |
| * { |
| * size_t off = container_off(struct info, my_foo); |
| * return (void *)((char *)foo - off); |
| * } |
| */ |
| #define container_off(containing_type, member) \ |
| offsetof(containing_type, member) |
| |
| /** |
| * container_of_var - get pointer to enclosing structure using a variable |
| * @member_ptr: pointer to the structure member |
| * @container_var: a pointer of same type as this member's container |
| * @member: the name of this member within the structure. |
| * |
| * Given a pointer to a member of a structure, this macro does pointer |
| * subtraction to return the pointer to the enclosing type. |
| * |
| * Example: |
| * static struct info *foo_to_i(struct foo *foo) |
| * { |
| * struct info *i = container_of_var(foo, i, my_foo); |
| * return i; |
| * } |
| */ |
| #if HAVE_TYPEOF |
| #define container_of_var(member_ptr, container_var, member) \ |
| container_of(member_ptr, typeof(*container_var), member) |
| #else |
| #define container_of_var(member_ptr, container_var, member) \ |
| ((void *)((char *)(member_ptr) - \ |
| container_off_var(container_var, member))) |
| #endif |
| |
| /** |
| * container_off_var - get offset of a field in enclosing structure |
| * @container_var: a pointer to a container structure |
| * @member: the name of a member within the structure. |
| * |
| * Given (any) pointer to a structure and a its member name, this |
| * macro does pointer subtraction to return offset of member in a |
| * structure memory layout. |
| * |
| */ |
| #if HAVE_TYPEOF |
| #define container_off_var(var, member) \ |
| container_off(typeof(*var), member) |
| #else |
| #define container_off_var(var, member) \ |
| ((const char *)&(var)->member - (const char *)(var)) |
| #endif |
| |
| #endif /* CCAN_CONTAINER_OF_H */ |