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Date: Fri, 24 Jul 2015 19:58:05 +0700
Message-ID: <CAEZPtU5NfTCpR9AoRkWD8hRbLJg3o-1qgd6wzrQsyetLWMvbMg@mail.gmail.com>
To: David Zuelke <dz@heroku.com>
Cc: Christoph Becker <cmbecker69@gmx.de>, Adam Harvey <aharvey@php.net>, 
	PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c11776120255051b9e8eee
Subject: Re: [PHP-DEV] PCRE JIT stack size limit
From: pierre.php@gmail.com (Pierre Joye)

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On Jul 24, 2015 3:32 PM, "David Zuelke" <dz@heroku.com> wrote:
>
> On 24.07.2015, at 09:33, Adam Harvey <aharvey@php.net> wrote:
> >
> > On 23 July 2015 at 11:47, Christoph Becker <cmbecker69@gmx.de> wrote:
> > <snip great explanation, thanks>
> >> Therefore I tend to prefer a new ini setting (say,
pcre.jitstack_limit).
> >> That would mean, however, to add yet another ini setting, of which
> >> there are already so many.
> >
> > I'm not a big fan of that, although it's at least in the spirit of
> > what configuration settings are meant to be used for.
> >
> > What if we added the PCRE_ERROR_JIT_STACKLIMIT error constant to those
> > exposed to userland so that it's more easily noticed via
> > preg_last_error(), and adding a modifier that can be used to disable
> > the JIT on a per-pattern basis (by setting PCRE_NO_START_OPTIMIZE,
> > which admittedly disables other stuff too, but at least the regex will
> > run)? At least then users could check the error when the regex fails
> > and re-run the regex without the JIT if they chose to.
>
> But this might mean that patterns which previously worked, because no JIT
was used, suddenly fail in existing code with a new error constant. Which I
guess is a BC break.

Such things happened in the past with normal updates, both ways. Simple
code  changes, fixes etc may have led to changes in the stack usage. I can
remember issues with some specific updates.

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