From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#23397: 25.0.92; assertion failure auto-reverting a file being overwritten Date: Sun, 17 Jun 2018 08:36:35 +0300 Message-ID: <83r2l6x9cs.fsf@gnu.org> References: <6epot9crti.fsf@just-testing.permabit.com> <83vb2wl83m.fsf@gnu.org> <6efuu0chsv.fsf@just-testing.permabit.com> <87zhzutngf.fsf@gmail.com> Reply-To: Eli Zaretskii NNTP-Posting-Host: blaine.gmane.org X-Trace: blaine.gmane.org 1529213783 13965 195.159.176.226 (17 Jun 2018 05:36:23 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 17 Jun 2018 05:36:23 +0000 (UTC) Cc: raeburn@permabit.com, 23397@debbugs.gnu.org To: Noam Postavsky Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Sun Jun 17 07:36:18 2018 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fUQMM-0003W8-KR for geb-bug-gnu-emacs@m.gmane.org; Sun, 17 Jun 2018 07:36:18 +0200 Original-Received: from localhost ([::1]:53891 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fUQOT-0006G5-N1 for geb-bug-gnu-emacs@m.gmane.org; Sun, 17 Jun 2018 01:38:29 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54424) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fUQN6-0005fz-GB for bug-gnu-emacs@gnu.org; Sun, 17 Jun 2018 01:37:09 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fUQN5-0006QJ-PO for bug-gnu-emacs@gnu.org; Sun, 17 Jun 2018 01:37:04 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:44591) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fUQN5-0006QE-Ky for bug-gnu-emacs@gnu.org; Sun, 17 Jun 2018 01:37:03 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1fUQN4-0002ZK-0G for bug-gnu-emacs@gnu.org; Sun, 17 Jun 2018 01:37:03 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sun, 17 Jun 2018 05:37:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 23397 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: confirmed Original-Received: via spool by 23397-submit@debbugs.gnu.org id=B23397.15292138159861 (code B ref 23397); Sun, 17 Jun 2018 05:37:01 +0000 Original-Received: (at 23397) by debbugs.gnu.org; 17 Jun 2018 05:36:55 +0000 Original-Received: from localhost ([127.0.0.1]:52488 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fUQMw-0002Yz-Ty for submit@debbugs.gnu.org; Sun, 17 Jun 2018 01:36:55 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:35168) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fUQMu-0002Ym-Ti for 23397@debbugs.gnu.org; Sun, 17 Jun 2018 01:36:53 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fUQMk-0006EC-Og for 23397@debbugs.gnu.org; Sun, 17 Jun 2018 01:36:47 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:45760) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fUQMk-0006Dr-HT; Sun, 17 Jun 2018 01:36:42 -0400 Original-Received: from [176.228.60.248] (port=4822 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1fUQMj-0006fP-Vh; Sun, 17 Jun 2018 01:36:42 -0400 In-reply-to: <87zhzutngf.fsf@gmail.com> (message from Noam Postavsky on Sat, 16 Jun 2018 17:45:36 -0400) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:147561 Archived-At: > From: Noam Postavsky > Cc: Eli Zaretskii , 23397@debbugs.gnu.org > Date: Sat, 16 Jun 2018 17:45:36 -0400 > > I don't quite understand what the overlap expression is trying to > compute though. It prevents us from re-using the same portion of buffer text for matching both at start and at end of the file. This could happen, e.g., with buffers whose contents is the same character, and a file whose contents is mostly the same, but larger, and with a few different characters in the middle. Then the "same_at_end" loop could inadvertently match a part of the buffer that was already matched by the "same_at_start" loop. The overlap expression computes the portion of the buffer that was matched by both "same_at_start" and "same_at_end" loops.