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Mail Archives: djgpp-workers/2002/05/17/13:26:09

From: sandmann AT clio DOT rice DOT edu (Charles Sandmann)
Message-Id: <10205171727.AA21975@clio.rice.edu>
Subject: Re: emacs under w2k and malloc effects
To: djgpp-workers AT delorie DOT com
Date: Fri, 17 May 2002 12:27:24 -0500 (CDT)
In-Reply-To: <3CE517CD.AD3D0617@yahoo.com> from "CBFalconer" at May 17, 2002 10:46:37 AM
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> However if something else effectively calls sbrk with a negative
> value, nmalloc may later think it has a new noncontiguous block,
> and may then very well allocate the same space twice!.  This would
> NOT be good.

If someone calls sbrk() with a negative value, they are deallocating
memory.  This isn't any different than doing
Yes, you can do stupid things to kill your program.  

feeding sbrk() negative values has valid uses, but it's a rare thing
that would only be used carefully.

> It cannot be protected by insisting on monatonic increasing, since
> I found that the startup code does some wierd things and leaves
> things fragmented before the application starts.

DPMI may also return memory blocks without being monatonic increasing.

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