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| author | Ben Pfaff <blp@nicira.com> | 2010-07-19 13:46:52 -0700 |
|---|---|---|
| committer | Ben Pfaff <blp@nicira.com> | 2010-10-01 10:25:10 -0700 |
| commit | adf7cfd851c3d9d6f1ad74653cbd2fecce8c3ba9 (patch) | |
| tree | 9fef3d694e27290b71dd93cc0f395a93a12ecf0f | |
| parent | ca0f572cfe87f284018e14fa7f1de58fbaef4c87 (diff) | |
| download | openvswitch-adf7cfd851c3d9d6f1ad74653cbd2fecce8c3ba9.tar.gz | |
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.
| -rw-r--r-- | lib/util.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/lib/util.h b/lib/util.h index 9eca8ec9a..5147ffc55 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 |