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Re: thread cancellation, take 2

From: Ludovic Courtès
Subject: Re: thread cancellation, take 2
Date: Wed, 26 Sep 2007 06:03:15 +0200
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux)


"Julian Graham" <address@hidden> writes:

> Fair enough, re: closures.  But why should callers outside the current
> thread be able to access that thread's cleanup handler procedure?
> Maybe this isn't a realistic issue, but you could use this to "inject"
> arbitrary code into a separate thread by setting the cleanup procedure
> and immediately canceling the thread.  Why not treat the handler as
> thread-specific data?

Anyway, as long as you have a reference to an object (including a thread
object), you can use the relevant procedures to mutate it.  For
instance, if my code passes a list to yours, I have no guarantee that
your code won't call `set-car!' on it.

Just to say that hiding the data doesn't solve this authorization
problem, it just makes it less visible.

Beside, it may be useful in some cases to assign a thread finalizer from
outside the thread itself.


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