Re: Avoiding an Infinite Loop in Arbitrary eval(user_code)

Bill Mill wrote:
I want to have a user able to eval code in a text box. However, if he
accidentally types "while(1) { i=0; }" and hits "run", I also want him
to be able to hit a stop button such that his browser does not go into
an infinite, soul-crushing, interface-locking loop. The stop button
would not need to be instantly responsive, but of course the more
responsive the better.

Short of writing a javascript-in-javascript interpreter, is there any
way to do so?

No. ECMAScript implementations so far are single-threaded, and there is yet
an algorithm to be written for a universal solution of the Halting Problem.

http://en.wikipedia.org/wiki/Halting_problem

You will have to rely on the user's user agent to recognize a not-responding
script, and provide the user with such a dialog window, as Gecko-based UAs
(e.g. Mozilla Firefox) do.

Does Caja make this sort of thing possible?

I don't think so:

http://code.google.com/p/google-caja/wiki/AttackVectors

Please be more verbose next time.

Will I need to restrict myself to Gears+threads to do this?

Never heard of those.


PointedEars
--
realism: HTML 4.01 Strict
evangelism: XHTML 1.0 Strict
madness: XHTML 1.1 as application/xhtml+xml
-- Bjoern Hoehrmann
.

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