From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 2DDF31F466 for ; Tue, 21 Jan 2020 01:15:53 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:cc:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; q=dns; s=default; b=BabIqGWSEj6velK9 T6UcV0JVN/eBfe67Qcas61JqOJe9Xxtv5ecg2pIuGQH1Ng7Y6qDe1oMt7M4pNDOV Ibcd+2ZDO85LKurE+ZqEAd8bAhpp2h2JDE1JmlA6qt7XDLyQV75KKwz4n//CyMoO 4NuVM4sQGJrCI7vFERzyjD0/beY= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:cc:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; s=default; bh=TPBroGUai61Xjt8bgxsGSa +6V28=; b=FMWG57I0TUdZMPxoArlATh4G99taclz9w5lz/+3ckebCgo3LjGZqu8 XTKkfjI5MIEAgR5YlXR1Br0EV2QjDH4RSZMXZraPZOz4GBx2MjOvpARZPRPjX0yJ 2uSuk6ouKCdnuFTrU0yM+WAtN0SJgHYkxYlbpYp4ORl5qdc2Ia5oI= Received: (qmail 119544 invoked by alias); 21 Jan 2020 01:15:50 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 119529 invoked by uid 89); 21 Jan 2020 01:15:49 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: huawei.com Subject: Re: question about regex To: Paul Eggert , =?UTF-8?Q?Tim_R=c3=bchsen?= CC: , Florian Weimer , "Carlos O'Donell" , Hushiyuan , Liusirui References: <05dfac46-6cf3-1f5d-14e7-3c8b07b2093e@cs.ucla.edu> <377311fb-fdf3-6467-3b48-28404d8c3326@huawei.com> <034194cc-908b-d29f-5ee7-9cf273868ff0@cs.ucla.edu> From: liqingqing Message-ID: <10479390-8a29-07f3-2d80-ebc7c340fe64@huawei.com> Date: Tue, 21 Jan 2020 09:15:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <034194cc-908b-d29f-5ee7-9cf273868ff0@cs.ucla.edu> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit On 2020/1/21 3:25, Paul Eggert wrote: > On 1/20/20 2:41 AM, liqingqing wrote: >> it's not a easy work to fix bug#24269 by modify the regex algorithm. >> a possible way is that add a backtrack limit to avoid infinite loop. > > If there's an arbitrary backtrack limit, won't that cause the code to mishandle some regular expressions? That is, wouldn't an arbitrary limit cause the code to incorrectly fail to match in some cases? In some sense that would be worse than looping. > > Perhaps I am misunderstanding what you're proposing. If so, could you give more details about the proposal? > > . Hello Paul, thanks for your explanation. yes you are right and I totally agree with your opinion. The proposal is that I want to find a way to fix the bug#24269(infinite loop bugs). and I think it's very hard for me to totally fix it. So, I send this email and ask for all your suggestions.