[TUHS] reviving a bit of WWB

[John Cowan]

On Mon, Sep 21, 2020 at 1:55 AM Steve Nickolas <usotsuki at buric.co> wrote:


> I've never written anything that uses varargs, so I've never run into
> that.  But I've actually done quite a bit of work with an environment
> where this isn't true: MS-DOS using the large or huge model.  In this
> environment, sizeof(int)=2, and sizeof(void*) is 4. Of course, it's not
> conformant to pass an int variable as an argument where a pointer variable
> is expected.
>

If the compiler was ISO-conformant (which it almost certainly was not),
that would not matter.  0 in int context would be a 2-byte int with all
bits zero, and 0 in pointer context would be a 4-byte null pointer,
probably with all bits zero.

C doesn't require that the address represented by the null pointer (whether
or not it is all-bits-zero) is inaccessible, merely that there is no C
object or function there.  A simple shim of the appropriate size (1, 2, 4,
8 bytes depending on the CPU's alignment rules) will suffice.
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