Date:	Thu, 24 May 2001 09:42:44 +0300 (IDT)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
cc:	djgpp-workers AT delorie DOT com
Subject:	Re: Crashes due to selector depletion
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On Wed, 23 May 2001, Charles Sandmann wrote:

> > (I originally considered to use the PSP selector, since the transfer
> > buffer follows the PSP, but that selector seems to have a 100h-byte
> > limit, or at least could be like that according to the DPMI spec.)
> 
> You could use the 128 bytes of the command line area, overwriting it
> with the message string, since you are getting ready to exit.  This
> should be guaranteed to be enough for a message, and fit in the limit.
> 
> > Question: is it safe to overwrite the program's environment by using
> > the environment block as the transfer buffer?  Note that I don't want
> > to modify the selector itself -- this is verboten by the DPMI rules --
> > only to write over the environment strings accessing them via the
> > selector stuffed by the DPMI host at offset 2Ch in the PSP.
> 
> This would probably work also, since I don't think the environment will
> be needed anymore.  But what if the environment is very short?  Probably
> unlikely (especially if you are in an environment which runs out of 
> selectors), but the possibility of dos memory block corruption.

Thanks for all the ideas, everybody.  I think I have enough to solve this 
in some reasonable way.

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