From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Lars Ingebrigtsen Newsgroups: gmane.emacs.bugs Subject: bug#8035: Processing of .. in a file path after going thru symlink Date: Thu, 26 Aug 2021 18:29:54 +0200 Message-ID: <877dg8yxrx.fsf@gnus.org> References: <30918394.post@talk.nabble.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="11853"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: 8035@debbugs.gnu.org To: spucci Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu Aug 26 18:31:12 2021 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mJIHY-0002uR-KX for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 26 Aug 2021 18:31:12 +0200 Original-Received: from localhost ([::1]:42098 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJIHX-0003jc-EY for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 26 Aug 2021 12:31:11 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:37820) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJIHO-0003fq-1c for bug-gnu-emacs@gnu.org; Thu, 26 Aug 2021 12:31:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:38696) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mJIHN-0002lX-PU for bug-gnu-emacs@gnu.org; Thu, 26 Aug 2021 12:31:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1mJIHN-0005gr-Hs for bug-gnu-emacs@gnu.org; Thu, 26 Aug 2021 12:31:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Lars Ingebrigtsen Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 26 Aug 2021 16:31:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 8035 X-GNU-PR-Package: emacs Original-Received: via spool by 8035-submit@debbugs.gnu.org id=B8035.162999541121792 (code B ref 8035); Thu, 26 Aug 2021 16:31:01 +0000 Original-Received: (at 8035) by debbugs.gnu.org; 26 Aug 2021 16:30:11 +0000 Original-Received: from localhost ([127.0.0.1]:50239 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mJIGZ-0005fP-HF for submit@debbugs.gnu.org; Thu, 26 Aug 2021 12:30:11 -0400 Original-Received: from quimby.gnus.org ([95.216.78.240]:48946) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mJIGY-0005e6-0e for 8035@debbugs.gnu.org; Thu, 26 Aug 2021 12:30:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnus.org; s=20200322; h=Content-Type:MIME-Version:Message-ID:In-Reply-To:Date: References:Subject:Cc:To:From:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=6MCg+dIBhdWXOvEo5cZc1/XpQshvgENM0JuBMQAe3R8=; b=qF3PtyeZYwk/YE2+y3vvxFAXiu WUB3+1KlZZA2r+Ic4vRktE0CatNIPpBe+5DB/8bbw32kU3rl/iW5QsxTSr80HQDdiyvdOUaosUjRz G/oLz8FGOt9us6mt7Kx1SqVFF2gOLmU2OlJqzkyv2bi4yltQGGURfRLUzPtyaut4l99s=; Original-Received: from [84.212.220.105] (helo=elva) by quimby.gnus.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mJIGM-0002vx-8k; Thu, 26 Aug 2021 18:30:02 +0200 In-Reply-To: <30918394.post@talk.nabble.com> (spucci's message of "Sun, 13 Feb 2011 19:05:40 -0800 (PST)") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list 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-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:212727 Archived-At: spucci writes: > When emacs attempts to find a file with "../" as a path component, it > appears to be "smart" about it and simply remove the previous directory path > (e.g., "foo/bar/../x" gets converted to "foo/x"). But if bar is a symlink, > then it doesn't properly find the file. So in compiler output, which > references such files, the next-error function fails to find the file with > the given name. > > mkdir dest > mkdir dest/subdir > mkdir src > ln -s ../dest/subdir src/subdir > echo "#error This is an error" > dest/foo.c > > Now M-x compile, and give it cc -c src/subdir/../foo.c > > *compilation* buffer has: > cc -c src/subdir/../foo.c > src/subdir/../foo.c:1:2: error: #error This is an error > > and do a next-error: Emacs complains it can't find the file. This is an even more foundational problem: (file-exists-p "/tmp/comp/src/subdir/../foo.c") => nil (file-truename "/tmp/comp/src/subdir/../foo.c") => "/tmp/comp/dest/foo.c" (file-exists-p (file-truename "/tmp/comp/src/subdir/../foo.c")) => t And this is because: static Lisp_Object check_file_access (Lisp_Object file, Lisp_Object operation, int amode) { file = Fexpand_file_name (file, Qnil); I'm guessing it's calling expand-file-name here to resolve "~"? It's also a micro-optimisation, I guess -- collapsing "parent/.." textually without checking the file system is very cheap. But... this does mean that `file-exists-p' and friends are unreliable in the presence of symlinks, which is pretty depressing. I think that `expand-file-name' call in check_file_access should be changed to something that just does the "~" expansion. Any opinions? -- (domestic pets only, the antidote for overdose, milk.) bloggy blog: http://lars.ingebrigtsen.no