[foreign] Handling pointers with special (negative) values

[Jorn Vernee]

Florian Weimer schreef op 2018-10-25 13:06:
> Isn't the check simply incorrect?  I was under the impression that
> Solaris has userspace pointers in the upper region of the address space
> on x86-64 (i.e, where the 17 or so most significant bits are set).

I think it is incorrect, but I'm not sure how to proceed. We use `long` 
to model pointers everywhere, but as far as I can tell the size of a 
pointer is an implementation detail, and all the C standard says about 
them is that the size must be sufficient to cover anything you might 
want to get a pointer to.

The value is used in several places to calculate a memory offset to pass 
to `Unsafe` routines. I'm not sure if removing the check will break 
anything, it's hard to test on my machine (Windows) since I'm not 
running all the tests currently, and it's hard to check manually since 
afaik you can't just ask the OS for a dereferenceable pointer with it's 
high-order bit set.

Jorn

> Thanks,
> Florian