From: Lars Ingebrigtsen <larsi@gnus.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: ARISAWA Akihiro <ari@mbf.ocn.ne.jp>, 7496@debbugs.gnu.org
Subject: bug#7496: 23.2; copy recursive keymap cause crash
Date: Sun, 13 Oct 2019 03:15:17 +0200 [thread overview]
Message-ID: <874l0dh2e2.fsf@gnus.org> (raw)
In-Reply-To: <jwvhbf3fpgj.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Fri, 26 Nov 2010 22:01:28 -0500")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> When I call `copy-keymap' with a keymap which contains recursive binding,
>> the emacs crashed.
>> I can reproduce it by following sexp.
>
>> (let ((map (make-sparse-keymap)))
>> (define-key map " " map)
>> (copy-keymap map))
>
> I'm not surprised. There are many ways to address it:
> - try and make sure we better handle the "using up all memory" case
> rather than crashing. This is very difficult. We already try to do
> it, but clearly it's not working that well.
> - try and detect such cycles and either signal an error or reproduce the
> same cycle in the copy. We have added such things in several other
> cases, so we should probably do that.
While this is a pretty obscure, Emacs shouldn't crash on stuff like
this. I first considered whether just to check for EQ in Fcopy_keymap,
but it's possible to have nested keymaps that are mutually recursive,
so that won't work.
So I just added a recursion counter and refuse to copy when we've
reached level 100.
It does not protect against the case where the keymap is a char table
where one of the entries is the same keymap, but I don't know whether
that's a thing.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2019-10-13 1:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-27 1:08 bug#7496: 23.2; copy recursive keymap cause crash ARISAWA Akihiro
2010-11-27 3:01 ` Stefan Monnier
2010-11-27 5:10 ` ARISAWA Akihiro
2019-10-13 1:15 ` Lars Ingebrigtsen [this message]
2019-10-13 6:58 ` Eli Zaretskii
2019-10-13 17:56 ` Lars Ingebrigtsen
2019-10-13 18:47 ` Eli Zaretskii
2019-10-13 20:24 ` Stefan Monnier
2019-10-13 20:34 ` Lars Ingebrigtsen
2019-10-13 21:26 ` Stefan Monnier
2019-10-13 21:38 ` Drew Adams
2019-10-14 6:09 ` Eli Zaretskii
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