From: John Carr <jfc@mit.edu>
To: "Richard W.M. Jones" <rich@annexia.org>
Cc: Caml List <caml-list@inria.fr>
Subject: Re: [Caml-list] Interfacing with C: bad practice
Date: Tue, 16 Aug 2011 12:06:58 -0400 [thread overview]
Message-ID: <201108161606.p7GG6wR9029895@outgoing.mit.edu> (raw)
In-Reply-To: <20110816152550.GA21081@annexia.org>
Richard W.M. Jones <rich@annexia.org> wrote:
> On Tue, Aug 16, 2011 at 11:37:03AM +0400, Dmitry Bely wrote:
> > C compiler first puts "list" pointer on stack and then calls
> > caml_copy_string(*s), potentially invalidating "list". Of course, the
> > stack copy of "list" is not registered as a global root so wrp_ml_cons
> > gets an invalid value.
>
> I think this must be a bug in your C compiler. The address of list is
> stashed in the roots struct, so the C compiler should know that list
> can be changed by the call to caml_copy_string.
The call
f(g(), x)
can behave as either
temp1 = g()
temp2 = x
f(temp1, temp2)
or
temp1 = x
temp2 = g()
f(temp2, temp1)
The order does not need to be deterministic.
If the call to g() changes x, the second order results in the
function f() receiving the "wrong" value.
--John Carr (jfc@mit.edu)
next prev parent reply other threads:[~2011-08-16 16:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-16 7:37 Dmitry Bely
2011-08-16 8:04 ` Török Edwin
2011-08-16 8:25 ` Dmitry Bely
2011-08-16 8:43 ` Török Edwin
2011-08-16 9:46 ` rixed
2011-08-16 9:53 ` Dmitry Bely
2011-08-16 10:17 ` Török Edwin
2011-08-16 11:04 ` rixed
[not found] ` <20110816.105738.246515733851238101.Christophe.Troestler@umons.ac.be>
2011-08-16 9:21 ` Dmitry Bely
2011-08-16 10:39 ` Mauricio Fernandez
2011-08-16 14:27 ` John Carr
2011-08-16 12:28 ` [Caml-list] " Dmitry Bely
2011-08-16 15:25 ` [Caml-list] " Richard W.M. Jones
2011-08-16 15:51 ` rixed
2011-08-16 16:00 ` Will M. Farr
2011-08-16 16:10 ` Richard W.M. Jones
2011-08-16 16:17 ` Richard W.M. Jones
2011-08-16 16:18 ` Dmitry Bely
2011-08-16 16:22 ` Richard W.M. Jones
2011-08-16 16:27 ` Richard W.M. Jones
2011-08-16 16:30 ` malc
2011-08-16 16:34 ` Török Edwin
2011-08-16 16:47 ` Richard W.M. Jones
2011-08-16 16:55 ` [Caml-list] " Jeffrey Scofield
2011-08-16 17:08 ` Will M. Farr
2011-08-16 19:46 ` Gerd Stolpmann
2011-08-16 20:18 ` Jeffrey Scofield
2011-08-16 17:08 ` [Caml-list] " rixed
2011-08-16 16:06 ` John Carr [this message]
2011-08-16 16:14 ` Wojciech Meyer
2011-08-16 16:13 ` Dmitry Bely
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