From adf7cfd851c3d9d6f1ad74653cbd2fecce8c3ba9 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Mon, 19 Jul 2010 13:46:52 -0700 Subject: [PATCH] util: New macro OBJECT_CONTAINING. This macro is a variant on CONTAINER_OF that takes an object pointer instead of a type name as its second argument. In the following commit this will simplify many users of CONTAINER_OF. --- lib/util.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/lib/util.h b/lib/util.h index 9eca8ec9..5147ffc5 100644 --- a/lib/util.h +++ b/lib/util.h @@ -82,6 +82,16 @@ extern const char *program_name; #define CONTAINER_OF(POINTER, STRUCT, MEMBER) \ ((STRUCT *) (void *) ((char *) (POINTER) - offsetof (STRUCT, MEMBER))) +/* Given POINTER, the address of the given MEMBER within an object of the type + * that that OBJECT points to, returns OBJECT as a "void *" pointer. OBJECT + * must be an lvalue. + * + * This is the same as CONTAINER_OF except that it infers the structure type + * from the type of '*OBJECT'. */ +#define OBJECT_CONTAINING(POINTER, OBJECT, MEMBER) \ + ((void *) ((char *) (POINTER) \ + - ((char *) &(OBJECT)->MEMBER - (char *) (OBJECT)))) + #ifdef __cplusplus extern "C" { #endif -- 2.30.2