container_of: add container_off() helper.

[ccan] / ccan / container_of / test / run.c

diff --git a/ccan/container_of/test/run.c b/ccan/container_of/test/run.c
index f28d9998503dc63e482355927fe66ebfbe445b9d..8f86bc8da3a4db10eb53c32e9d6ee6590b8b9dcb 100644 (file)
--- a/ccan/container_of/test/run.c
+++ b/ccan/container_of/test/run.c
@@ -12,10 +12,13 @@ int main(int argc, char *argv[])
        int *intp = &foo.a;
        char *charp = &foo.b;
 
-       plan_tests(4);
+       plan_tests(6);
        ok1(container_of(intp, struct foo, a) == &foo);
        ok1(container_of(charp, struct foo, b) == &foo);
        ok1(container_of_var(intp, &foo, a) == &foo);
        ok1(container_of_var(charp, &foo, b) == &foo);
+
+       ok1(container_off(intp, struct foo, a) == 0);
+       ok1(container_off(charp, struct foo, b) == offsetof(struct foo, b));
        return exit_status();
 }