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To: "Nuno Lopes" <nlopess@php.net>
Date: Thu, 7 Aug 2008 15:01:39 +0200
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Cc: internals@lists.php.net
References: <200808071424.04620.arnaud.lb@gmail.com> <44A6E3DD049940C089EC87E672C6C252@pc07654>
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Message-ID: <200808071501.39666.arnaud.lb@gmail.com>
Subject: Re: [PHP-DEV] PCRE and recursion: NO_RECURSE flag
From: arnaud.lb@gmail.com (Arnaud Le Blanc)


Sorry, I had not thought about that. I just checked with the example given in 
the bug report and it's effectively slower (~25% on this expression).

On Thursday 07 August 2008 14:35:12 Nuno Lopes wrote:
> No!
> Last time I benchmark it, it has about 100x slower, so I don't think so..
> If you need to match large amounts of data, just increase the stack size.
> ulimit is your friend :)
>
> Nuno
>
>
> ----- Original Message -----
> From: "Arnaud Le Blanc" <arnaud.lb@gmail.com>
> To: <internals@lists.php.net>
> Sent: Thursday, August 07, 2008 1:24 PM
> Subject: [PHP-DEV] PCRE and recursion: NO_RECURSE flag
>
> > Hi,
> >
> > PCRE can be highly recursive [1] and this can cause segmentation faults
> > [2].
> > This is a known problem and the pcre ini settings avoids the segfaults,
> > but
> > the execution of the expression will fail anyway.
> >
> > PCRE has a NO_RECURSE flag which makes the match() internal function no
> > recursive and avoids this problem. The configure switch for this option
> > is --
> > disable-stack-for-recursion. NO_RECURSE is documented in pcre_exec.c.
> >
> > This can be easily enabled [3] for the bundled PCRE. It seems to be safe
> > to
> > enable that. Actually the PCRE test suite pass with NO_RECURSE enabled,
> > and
> > segfaults without. Can this be enabled ?
> >
> > [1] http://manpages.courier-mta.org/htmlman3/pcrestack.3.html
> > [2] http://bugs.php.net/bug.php?id=45735
> > [3] http://arnaud.lb.s3.amazonaws.com/pcre_no_recurse.patch
> >
> > Regards,
> >
> > Arnaud