From 361f3ea9ee577c5a3e2fed687a0b417b257c31de Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 22 Feb 2012 14:59:32 +1030 Subject: lib/ccan: import failtest and required ccan modules for TDB2 unit tests. New modules: failtest, list, time, read_write_all and tlist. Signed-off-by: Rusty Russell --- lib/ccan/container_of/container_of.h | 108 +++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 lib/ccan/container_of/container_of.h (limited to 'lib/ccan/container_of/container_of.h') diff --git a/lib/ccan/container_of/container_of.h b/lib/ccan/container_of/container_of.h new file mode 100644 index 0000000000..1c9d147ae0 --- /dev/null +++ b/lib/ccan/container_of/container_of.h @@ -0,0 +1,108 @@ +#ifndef CCAN_CONTAINER_OF_H +#define CCAN_CONTAINER_OF_H +#include + +#include "config.h" +#include + +/** + * 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_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) \ + ((char *)&(var)->member - (char *)(var)) +#endif + +#endif /* CCAN_CONTAINER_OF_H */ -- cgit