have more than 10 environment variables defined in it. I added no bounds
checking or dynamic allocation, so if the file contained more than 10
environment variables (and it has since 2002), other stack memory in DOSXTRN
would get over-written (classic buffer overflow).

When I recently experimented with adding another environment variable (PCBDIR),
all dosxtrn NTVDM instances would crash with a familiar but mysterious error
dialog. This bug may have been causing other dosxtrn instances to crash for a
long tmie.
I also had an arbitrary limit on the number of command-line arguments, 16, with
no bounds-checking, so passing a long list of space-separated arguments could
also crash DOSXTRN.

So I've increased both limits to 32 and added bounds checking. I had to break
out the old 16-bit MSVC (v1.52) and an NT2K DDK (and remove the 64-bit int
stuff from gen_defs.h) to get this thing to build. But here it is. Updated
again after all these years. Who'd a thunk.