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Mail Archives: djgpp-workers/2003/04/22/08:44:03

Message-ID: <3EA53744.383B819C@yahoo.com>
Date: Tue, 22 Apr 2003 08:36:20 -0400
From: CBFalconer <cbfalconer AT yahoo DOT com>
Organization: Ched Research
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To: djgpp-workers AT delorie DOT com
Subject: Re: nmalloc revisited
References: <10304211942 DOT AA12379 AT clio DOT rice DOT edu> <3277-Tue22Apr2003105749+0300-eliz AT elta DOT co DOT il>
Reply-To: djgpp-workers AT delorie DOT com

Eli Zaretskii wrote:
> From: sandmann AT clio DOT rice DOT edu (Charles Sandmann)
> >
> > > What about my new method of installing hooks?
> >
> > I will defer to Eli and other developers on that call.
> 
> As I said before, I don't mind.  However, in the interests of bringing
> more people into this decision-making process, could you please post a
> short tutorial about what you suggest, i.e. a few examples of how
> hooks will be installed and uninstalled?
> 
> Yes, I know it's probably buried somewhere in your zip file, but I,
> for one, don't have time to glean this information from there, and
> others might not have it as well.  Posting that information in a
> concise form will allow more developers to make up their minds and
> perhaps even suggest improvements.

It's on my to-do list.  In general, though, DJGPP is not Unix and
can never be Unix.  In particular it doesn't have the memory
protections that Unix does, so I think extra care in providing
sensitive interfaces is needed.  A unix hook would trap if set to
point to non-executable memory.  Imagine someone writing:

   gets((char *)&somehookptr);

or something equally bizaare.

BTW, the hook documentation says they are specific to DJGPP.  My
proposal is not compliant with POSIX in the extra argument and
macros to malloc_debug only, all other variations are in things
marked as !posix and possibly "available on many unices".

Maybe, for compatibility, the malloc_debug should be as previously
documented, and I should add a function "FILE
*setmalloc_debug_dump(FILE *fp)".  My gut tells me this is going
to be invaluable for holding before and after snapshots, etc.

For now the malloc_debug levels are going to remain as originally
documented.

-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT worldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!

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