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Re: question about regex

From: Paul Eggert <eggert at cs dot ucla dot edu>
To: liqingqing <liqingqing3 at huawei dot com>, Tim Rühsen <tim dot ruehsen at gmx dot de>
Cc: libc-alpha at sourceware dot org, Florian Weimer <fweimer at redhat dot com>, Carlos O'Donell <carlos at redhat dot com>, Hushiyuan <hushiyuan at huawei dot com>, Liusirui <liusirui at huawei dot com>
Date: Mon, 20 Jan 2020 11:25:01 -0800
Subject: Re: question about regex
References: <fe3eef9c-740e-9b83-c472-59f8e2353b86@huawei.com> <e92f791d-7448-17ce-2820-a968770791b6@huawei.com> <fe84ed3d-6bbc-ea87-4e50-93e11736b005@gmx.de> <05dfac46-6cf3-1f5d-14e7-3c8b07b2093e@cs.ucla.edu> <377311fb-fdf3-6467-3b48-28404d8c3326@huawei.com> <dbd2cdae-5a33-593e-83d8-6a3fd0f85afb@huawei.com>

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 mishandlesome regular expressions? That is, wouldn't an arbitrary limit cause the code toincorrectly fail to match in some cases? In some sense that would be worse thanlooping.

Perhaps I am misunderstanding what you're proposing. If so, could you give moredetails about the proposal?

Follow-Ups:
- Re: question about regex
  - From: liqingqing

References:
- question about regex
  - From: liqingqing
- Re: question about regex
  - From: Tim Rühsen
- Re: question about regex
  - From: Paul Eggert
- Re: question about regex
  - From: liqingqing
- Re: question about regex
  - From: liqingqing

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