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From: Eli Zaretskii <eliz@gnu.org>
Newsgroups: gmane.emacs.devel
Subject: Re: valid_pointer_p
Date: Sun, 06 Aug 2006 06:29:11 +0300
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> Cc: emacs-devel@gnu.org
> From: storm@cua.dk (Kim F. Storm)
> Date: Sun, 06 Aug 2006 00:11:30 +0200
> 
> > Btw, you always try to validate a 16-byte region starting at the
> > address P, which might give a false positive if the object is actually
> > smaller and happens to be at the end of an allocated page which is
> > followed by a page that we cannot access.  Am I missing something?
> 
> I validate a 16 area since the pointer is typically something
> "vector-like" where the code that access/print that object will look
> at data following the immedate byte/word that the pointer addresses.

Well, I figured that much.  But we do know the length of each object,
so we could validate exactly what is needed, right?  Just add another
argument to valid_pointer_p that tells it how many bytes to validate.