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To: "Arnaud Le Blanc" <arnaud.lb@gmail.com>,
	<internals@lists.php.net>
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Date: Thu, 7 Aug 2008 13:35:12 +0100
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Subject: Re: [PHP-DEV] PCRE and recursion: NO_RECURSE flag
From: nlopess@php.net ("Nuno Lopes")

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