bug#57804: An infinite loop in a `fontify-region' function causes Emacs to hang indefinitely

[Paul Pogonyshev <pogonyshev@gmail.com>]

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I give up. Do as you like.

Paul

On Fri, 16 Sept 2022 at 08:40, Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Paul Pogonyshev <pogonyshev@gmail.com>
> > Date: Fri, 16 Sep 2022 00:53:37 +0200
> > Cc: Eli Zaretskii <eliz@gnu.org>, 57804@debbugs.gnu.org, Lars
> Ingebrigtsen <larsi@gnus.org>
> >
> > > It is for example possible to parse the buffer outside of
> > > fontification-functions
> >
> > You are ignoring that this is not only about fontification. It can
> > happen anywhere, because I may need full access to the buffer at any
> > time.
>
> Your mode is requested to be able to run in some kind of "simplified
> mode" when long-line-threshold is exceeded, in a way that doesn't
> require such full access.
>
> > > Yet another method would be to use a simpler fontification method in
> > > buffers with too long lines.  Yet another method would be to turn
> > > font locking off in buffers with too long lines.
> >
> > I don't want to lose fontification in a 10 MB buffer because one line
> > somewhere there is over 10000 characters.
>
> The locked restriction leaves accessible a region of the buffer that
> is quite large.  So if you are fontifying a line that is not very long
> in such a buffer, you should still be able to access enough text
> before and after the window to be able to fontify.  It is expected
> that modes which need to access more than that will be amended to
> perform, perhaps sub-optimally, in such cases.  In extreme cases, you
> can simply not fontify if there's no reasonable way of fontifying even
> approximately.  (I don't believe such extreme measures should be
> necessary, but they are a possibility.)
>
> IOW, we fully expect that in some cases and with some features, there
> will be partial loss of functionality in these cases.  We consider
> that still much better than a locked-up Emacs that can only be killed.
>
> > Security against what, for fuck's sake?
>
> Language!
>

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