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From: Szabolcs Nagy <nsz@port70.net>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Rich Felker <dalias@libc.org>, Jeff King <peff@peff.net>,
	git@vger.kernel.org, musl@lists.openwall.com
Subject: Re: [musl] Re: Regression: git no longer works with musl libc's regex impl
Date: Wed, 5 Oct 2016 15:01:31 +0200	[thread overview]
Message-ID: <20161005130130.GM1280@port70.net> (raw)
In-Reply-To: <alpine.DEB.2.20.1610051250080.35196@virtualbox>

* Johannes Schindelin <Johannes.Schindelin@gmx.de> [2016-10-05 13:17:49 +0200]:
> I had a brief look at the source code (you use backtracking... hopefully
> nobody uses musl to parse regular expressions from untrusted, or
> inexperienced, sources [*1*]), and it seems that the regex code might

does git use BRE?

a conforming BRE implementation has to use back tracking
if the pattern has back references.

usually ERE implementations may also use back tracking
since they support back references as an extension.

musl does not support this extension (and many others) so
it never uses back tracking for ERE matches, note however
that match complexity and memory usage of a conforming
ERE implementation is still exponential in pattern
length because of repetition counts.

  reply	other threads:[~2016-10-05 13:07 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-04 15:08 Rich Felker
2016-10-04 15:27 ` Jeff King
2016-10-04 15:40   ` Rich Felker
2016-10-04 16:08     ` Johannes Schindelin
2016-10-04 16:11       ` Rich Felker
2016-10-04 17:16         ` Johannes Schindelin
2016-10-04 18:00           ` Ray Donnelly
2016-10-04 17:39       ` [musl] " Rich Felker
2016-10-05 11:17         ` Johannes Schindelin
2016-10-05 13:01           ` Szabolcs Nagy [this message]
2016-10-05 13:15           ` Rich Felker
2016-10-04 22:06       ` James B
2016-10-04 22:33         ` Rich Felker
2016-10-04 22:48           ` Junio C Hamano
2016-10-05 13:11           ` Jakub Narębski
2016-10-05 16:15             ` [musl] " Rich Felker
2016-10-05 10:41         ` Johannes Schindelin
2016-10-05 11:59           ` James B
2016-10-05 16:11             ` Jeff King
2016-10-05 16:27               ` Rich Felker
2016-10-06 10:44             ` Johannes Schindelin
2016-10-06 19:18       ` Ævar Arnfjörð Bjarmason
2016-10-06 19:23         ` Jeff King
2016-10-06 19:25           ` Rich Felker
2016-10-06 19:28             ` Jeff King
2016-10-06 22:42         ` Ramsay Jones
2016-10-07 11:30           ` Jakub Narębski
2016-10-04 16:01   ` Johannes Schindelin
2016-10-05  3:00 [musl] " writeonce
2016-10-05 10:49 ` Johannes Schindelin
2016-10-05 16:37 writeonce

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