(Really addressing inside struct)Re: get size of malloc'd object

[john at anasazi.UUCP]

A related problem that we have found with C alignment is this:
We have a structure with a number of structures contained within it. 
Because of linked list processing, we have a pointer to one of the
structures within, and we want to derive a pointer to the top of
the structure without LINT complaining, and in a truly portable way.
How can this be done? Many things have been tried without success
here at Anasazi. Example:

struct links {
   struct links *forward;
   struct links *backward;
};

struct foo {
   char bar;
   struct links snake;
   struct whocares junk;
   struct links lizard;
};

struct links *reptile;

Assume that reptile points to the lizard structure of a "foo" structure.
What construct allows one to do the following:

struct foo *iwish = (mystery function of reptile);

Example of a wrong solution:
struct foo *iwish = (struct foo *)((char *)reptile + (char *)0->lizard);

Any help would be appreciated.

-- 
John Moore (NJ7E)
{decvax|ihnp4|hao}!noao!mot!anasazi!john
{hao!noao|decvax|ihnp4|seismo}!mot!anasazi!john
mot!anasazi!john at SEISMO.CSS.GOV
(602) 861-7607 (day or evening)
7525 Clearwater Pkwy, Paradise Valley, AZ, 85253 (Home Address)

The opinions expressed here are obviously not mine, so they must be
someone else's.