From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: master 9dc306b1: Improve reporting of I/O, access errors Date: Thu, 19 Sep 2019 17:21:09 -0700 Organization: UCLA Computer Science Department Message-ID: <585476bd-e9f4-f622-a114-d7db6a36b06a@cs.ucla.edu> References: <20190918022442.11082.40975@vcs0.savannah.gnu.org> <20190918022444.103AC207F5@vcs0.savannah.gnu.org> <875zlqgiga.fsf@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="146056"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 Cc: emacs-devel@gnu.org To: Michael Albinus Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Sep 20 02:22:18 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iB6gj-000bp1-8e for ged-emacs-devel@m.gmane.org; Fri, 20 Sep 2019 02:22:17 +0200 Original-Received: from localhost ([::1]:50034 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iB6gh-0002Nj-Tu for ged-emacs-devel@m.gmane.org; Thu, 19 Sep 2019 20:22:15 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:44787) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iB6fh-0002Lf-5H for emacs-devel@gnu.org; Thu, 19 Sep 2019 20:21:14 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iB6ff-0007G3-Sq for emacs-devel@gnu.org; Thu, 19 Sep 2019 20:21:12 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:47768) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iB6ff-0007Fh-Mj for emacs-devel@gnu.org; Thu, 19 Sep 2019 20:21:11 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 01D6C1600A0; Thu, 19 Sep 2019 17:21:11 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 13GwuJBF_KQU; Thu, 19 Sep 2019 17:21:10 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 363841600B0; Thu, 19 Sep 2019 17:21:10 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id LSuMXxfuMJxS; Thu, 19 Sep 2019 17:21:10 -0700 (PDT) Original-Received: from Penguin.CS.UCLA.EDU (Penguin.CS.UCLA.EDU [131.179.64.200]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 1D1E41600A0; Thu, 19 Sep 2019 17:21:10 -0700 (PDT) In-Reply-To: <875zlqgiga.fsf@gmx.de> Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:240174 Archived-At: On 9/18/19 12:41 AM, Michael Albinus wrote: > Tramp trusts on file-attributes returning nil, when a > file does not exist or is not accessible for whatever reason. This is > true also for local files. Could you give an example of where Tramp does this? That is, suppose there is a serious local-file error (I/O error, ancestor-directory permissions failure, etc.) when one uses Tramp to access a file - when would it be wrong for Tramp to signal such an error? You suggested that there might be such an example in Bug#37202; I didn't quite understand that suggestion, and have followed up there. > Furthermore, Tramp does not report anything but nil if a remote file is > not accessible due to I/O errors. So the promise of this change cannot > be kept for all situations. It would be nicer if serious errors were also signaled for remote files, but that's not essential; such a feature can be delayed until a later version (if ever). Although the jury might still be out on the ancestor-directory-permissions aspect of the change (certainly on MS-Windows, which reports EACCES for missing directories), surely Emacs should not simply ignore I/O errors and the like. And the permissions change has been helpful for testing, as it's uncovered a configuration bug in how Emacs starts up (Bug#37445, still being investigated). As that bug is possibly security-relevant, I'd like to shake it out (along with any similar bugs that crop up) before deciding any withdrawal of the ancestor-directory permissions aspect of the change.