Date: Tue, 19 Oct 1999 07:43:54 -0500 (CDT)
From: Dave Dribin <drib AT enteract DOT com>
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
cc: djgpp AT delorie DOT com, Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Subject: Re: spawnvpe hanging and bash GPF after running non-DJGPP exe
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On Tue, 19 Oct 1999, Eli Zaretskii wrote:
> I think some older version of DOS4GW was tested with CWSDPMI and
> worked.  Charles, do you remember what version was that?

BTW, I think I tried 1.95 with no success as well.

> Would PMODE/DJ help here?  I mean stubediting Bash to use PMODE/DJ 
> instead of CWDSDPMI.

Hmm... interesting idea.  I will try this.

> > > Sadly, no.  Since restoring an interrupt vector requires a call to
> > > another function of Int 31h, this is a catch-22.
> > 
> > Darn!  Well how does this program trample Int 31h?  If they can
> > trample it, can't I restore it?
> 
> A program that hooks Int 31h usually saves the old Int 31h handler in
> some variable.  It then can call that old handler directly, e.g. to
> restore the old handler.  But once it exits without restoring the old
> handler, an external program has no way of doing this, because the
> variable holding the old handler is gone.

Ok, here's a silly idea which may show my lack of DOS environment
understanding.  What if my program saved the old handler before
launching the program?  Then right after the program exits, my program
could call the old handler to essentially restore itself, just as the
other program should have done?

> Why do you need to launch the game from a DJGPP program?  Perhaps the
> problem you are trying to solve can be solved in a different way?

I don't really need to use DJGPP.  I just figured it would be the
easiest thing 'cause I'm not very familiar with the DOS programming
environment.  Plus, I was planning on using Allegro to spice things
up.

I don't have any other compiler, and I think $70 for Turbo C++ for DOS
is a bit too expensive for what I want it for.  If you know of any
other alternatives, I'd be more than willing to investigate them.

Thanx,

-Dave