[gPXE] ptr_to_struct->member != ptr_to_struct + offsetof(struct, member)

[sobtwmxt]

1. Why the following asserion fail?  How to correct it?

        struct person {
                struct refcnt refcnt;
                const char *givenName;
                const char *fatherName;
        };

        fatherName = zalloc( 10 );

        static void person_free_fatherName ( struct refcnt *refcnt ) {
                struct person *person =
                        container_of ( refcnt, struct person, refcnt );

                assert ( (void *) person->fatherName ==
                            (void *) uri +
                                offsetof(struct person, fatherName) );
                free ( uri + offsetof(struct uri, decoded_user) );
        };


2. I think I have the following 2 options in order to add a
   decoded_[user:password] fields to struct uri:

   1. Keep what is already there, and add aditional 2 fields,
      namely decoded_user and decoded_password.
   2. Replace the contents of the existing user and password
      fields with the decoded information.

   Although I traced only net/tcp/http.c and usr/imgmgmt.c that are
   currently using it, initialy the replacment option seem to me more
   likely to break things.  Therefore, as of this writing, I coded 
   2 additional fields.

   In order to add those decoded_[user:password], I think I must use
   dynamic memory allocation.  I can:

   1. Create a
        strcut decoded_info {
                struct refcnt refcnt;
                const char *user;
                const char *password;
        };

        or

   2. Add 2 plain pointers,
        const char *decoded_user;
        const char *decoded_password;


   Is strcut decoded_info better then 2 plain char *ptr, or vice
   versa?

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