From: zimoun <zimon.toutoune@gmail.com>
To: Mathieu Othacehe <othacehe@gnu.org>, 46796@debbugs.gnu.org
Subject: bug#46796: Cuirass & pointer finalization.
Date: Fri, 26 Feb 2021 21:12:56 +0100 [thread overview]
Message-ID: <86im6e1tbr.fsf@gmail.com> (raw)
In-Reply-To: <8735xihq60.fsf@gnu.org>
Hi Mathieu,
I know nothing about the topic and I probably out-of-scope.
On Fri, 26 Feb 2021 at 15:14, Mathieu Othacehe <othacehe@gnu.org> wrote:
> I'm trying to fix a memory corruption in the remote-server process of
> Cuirass since a few days. Even though I don't have a usable core dump
> file yet, I'm pretty sure the error comes from the "zmq-msg-init"
> procedure of Guile-Simple-ZMQ.
>
> This procedure creates a bytevector, call the C function zmq_msg_init to
> initialize it, adds zmq_msg_close as pointer finalizer and returns a
> wrapped pointer.
>
> My understanding is that the wrapped pointer that is passed around in
> Cuirass ensures that the underlying bytevector is not garbage collected
> until the pointer goes out of scope. However, some assertions failures
> such as this one:
>
> --8<---------------cut here---------------start------------->8---
> Assertion failed: check () (src/msg.cpp:394)
> --8<---------------cut here---------------end--------------->8---
>
> let me think that the bytevector is garbage collected, while ZMQ is
> still using it. Some help would be much appreciated here :).
From ’zmq-msg-init’ defined here:
<https://github.com/jerry40/guile-simple-zmq/blob/master/simple-zmq.scm.in#L543>
and why is ’zmq-message-content’ used for? Since ’message’ is
initialized with zero, I guess. Well, I am confused by:
--8<---------------cut here---------------start------------->8---
(let ((content-ptr (zmq_msg_data (message->pointer message)))
[...]
(pointer->bytevector content-ptr size))))
…
(let ((msg (pointer->message! msg-pointer)))
(when content-bv
(let ((target (zmq-message-content msg)))
(bytevector-copy! content-bv 0 target 0 len)))
msg))))
--8<---------------cut here---------------end--------------->8---
Is ’target’ at the same address than ’msg’? Maybe ’target’ creates
somehow a dangling pointer.
Cheers,
simon
next prev parent reply other threads:[~2021-02-26 20:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 14:14 bug#46796: Cuirass & pointer finalization Mathieu Othacehe
2021-02-26 20:12 ` zimoun [this message]
2021-02-27 12:59 ` Mathieu Othacehe
2021-02-27 12:50 ` Mathieu Othacehe
2021-03-01 9:37 ` Ludovic Courtès
2021-03-02 8:08 ` Mathieu Othacehe
2021-03-02 13:50 ` Ludovic Courtès
2021-03-02 17:02 ` Mathieu Othacehe
2021-03-08 13:45 ` Ludovic Courtès
2023-11-23 11:39 ` Ludovic Courtès
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