Bugtraq mailing list archives

Re: Object tag crashes Internet Explorer 4.0


From: paulle () MICROSOFT COM (Paul Leach)
Date: Tue, 4 Aug 1998 14:42:41 -0700


I meant the variant of HTML that includes object tags and J-Script/VB-Script
that has conditional statements and recursion -- which is enough to make it
Turing complete. If the precise name of that is DHTML, it's not relevant --
as far as users are concerened it's stuff in web pages that nearly all
browsers know how to and will execute and will throw it into a
non-terminating computation -- which makes it "HTML" as far as they are
concerned.

-----Original Message-----
From: kragen () pobox com [mailto:kragen () pobox com]
Sent: Tuesday, August 04, 1998 2:37 PM
To: Paul Leach
Cc: BUGTRAQ () netspace org
Subject: Re: Object tag crashes Internet Explorer 4.0


On Tue, 4 Aug 1998, Paul Leach wrote:
The possibility of infinite loops and infinite recursion in
HTML has been
discussed on the lists before. Trying to detect and prevent
them is an
instance of the "Turing machine halting" problem, and it is
well known among
computer scientists to be impossible.

Certainly not.  HTML is not Turing-complete.  In fact, detecting and
preventing infinite loops and recursion in HTML simply requires
traversing a directed acyclic graph and determining that it is, in
fact, acyclic.  This is simple.

Perhaps you're thinking of DHTML.  Or perhaps you're thinking of some
kind of evil, twisted web server that serves up the same page under an
infinite number of different names, each modified to include a frame
reference to that page under a different name.

Kragen




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