kread() and NULL pointers

[Stone, Joshua I]

Mike Mason wrote:
> So should the following generate an error?  It doesn't.  It just prints 
> "ptr = 0" and exits.
> 
> function test_addr:long () %{
>        void *nullptr = NULL;
>        THIS->__retvalue = (long) kread(&(nullptr));
-----------------------------------------^

You're reading the address *of* your pointer, not the address in the 
pointer.  Thus kread() is dereferencing an address on the stack, and the 
value there is NULL.  Drop the '&', and change nullptr to a type that's 
meaningful to dereference (e.g., long*), and you'll get your error.

The "&(xxx)" pattern you see everywhere is because usually the "xxx" is 
a struct value, and so you pass kread() a pointer to that value.


Josh