Re: [openpgp] Possible ambiguity in description of regular expressions: [^][]
"Neal H. Walfield" <neal@walfield.org> Sun, 27 December 2020 10:57 UTC
Return-Path: <neal@walfield.org>
X-Original-To: openpgp@ietfa.amsl.com
Delivered-To: openpgp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 32AC23A03F4 for <openpgp@ietfa.amsl.com>; Sun, 27 Dec 2020 02:57:38 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.899
X-Spam-Level:
X-Spam-Status: No, score=-1.899 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_NONE=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id tCGmjIbMrmkK for <openpgp@ietfa.amsl.com>; Sun, 27 Dec 2020 02:57:36 -0800 (PST)
Received: from mail.dasr.de (mail.dasr.de [217.69.77.164]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 517B63A03EC for <openpgp@ietf.org>; Sun, 27 Dec 2020 02:57:35 -0800 (PST)
Received: from pd9e79cc0.dip0.t-ipconnect.de ([217.231.156.192] helo=forster.huenfield.org) by mail.dasr.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.86_2) (envelope-from <neal@walfield.org>) id 1ktTjw-0004Qi-JA; Sun, 27 Dec 2020 10:57:32 +0000
Received: from grit.huenfield.org ([192.168.20.9] helo=grit.walfield.org) by forster.huenfield.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from <neal@walfield.org>) id 1ktTjw-0000p7-Bp; Sun, 27 Dec 2020 11:57:32 +0100
Date: Sun, 27 Dec 2020 11:57:32 +0100
Message-ID: <87mtxzv7mr.wl-neal@walfield.org>
From: "Neal H. Walfield" <neal@walfield.org>
To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
Cc: openpgp@ietf.org
In-Reply-To: <87tusbuwzp.fsf@fifthhorseman.net>
References: <87r1nguquq.wl-neal@walfield.org> <87tusbuwzp.fsf@fifthhorseman.net>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM/1.14.9 (Gojō) APEL/10.8 EasyPG/1.0.0 Emacs/26 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset="US-ASCII"
X-SA-Exim-Connect-IP: 192.168.20.9
X-SA-Exim-Mail-From: neal@walfield.org
X-SA-Exim-Scanned: No (on forster.huenfield.org); SAEximRunCond expanded to false
Archived-At: <https://mailarchive.ietf.org/arch/msg/openpgp/AUs1nsssfsN41DqszQWjBCfZZro>
Subject: Re: [openpgp] Possible ambiguity in description of regular expressions: [^][]
X-BeenThere: openpgp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Ongoing discussion of OpenPGP issues." <openpgp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/openpgp>, <mailto:openpgp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/openpgp/>
List-Post: <mailto:openpgp@ietf.org>
List-Help: <mailto:openpgp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/openpgp>, <mailto:openpgp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 27 Dec 2020 10:57:38 -0000
Hi Daniel, Thanks for following up. On Thu, 24 Dec 2020 14:58:18 +0100, Daniel Kahn Gillmor wrote: > nice find! it's rather ugly, though. Thanks for confirming my suspicions. > the most straightforward way to resolve it seems to be to say that > sequences in a [] must be non-empty. Indeed. > This means we don't get to say "[]", but that's ok because we already > have ".", which will handily replace it with the same semantics. We > also don't get to say "[^]". While i don't know how to replicate the > "no match" semantics, i'm also unclear where it could possibly be > useful. For a non-empty regex, you can use an anchor where it doesn't belong. So, 'a^' won't match anything. Likewise, '$a' won't match anything. This is obviously context sensitive, so it is not a perfect replacement, but I don't think "no match" is that useful in practice. > Seems like a sufficient clarification would be: > > -A range is a sequence of characters enclosed in '[]'. > +A range is a non-empty sequence of characters enclosed in '[]'. We need to exclude [^] as well. Perhaps: +A range is a non-empty sequence of characters excluding the optional leading ^ enclosed in '[]'. > Neal, perhaps you want to formally file this as an erratum on rfc4880? I'll do that. Thanks, Neal
- [openpgp] Possible ambiguity in description of re… Neal H. Walfield
- Re: [openpgp] Possible ambiguity in description o… Daniel Kahn Gillmor
- Re: [openpgp] Possible ambiguity in description o… Neal H. Walfield
- Re: [openpgp] Possible ambiguity in description o… Daniel Kahn Gillmor
- Re: [openpgp] Possible ambiguity in description o… Andrew Gallagher
- Re: [openpgp] Possible ambiguity in description o… Ángel
- Re: [openpgp] Possible ambiguity in description o… Ángel
- Re: [openpgp] Possible ambiguity in description o… Andrew Gallagher
- Re: [openpgp] Possible ambiguity in description o… Ángel
- Re: [openpgp] Possible ambiguity in description o… Daniel Kahn Gillmor
- Re: [openpgp] Possible ambiguity in description o… Ángel
- Re: [openpgp] Possible ambiguity in description o… Daniel Kahn Gillmor
- Re: [openpgp] Possible ambiguity in description o… Ángel
- Re: [openpgp] Possible ambiguity in description o… Wiktor Kwapisiewicz