From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Andrea Corallo Newsgroups: gmane.emacs.devel Subject: Re: Finalizing 'inhibit-automatic-native-compilation' Date: Mon, 20 Feb 2023 16:07:59 +0000 Message-ID: References: <20230218.061335.1468428093197134401.tats%nobody@tats.iris.ne.jp> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="10931"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) Cc: Tatsuya Kinoshita , emacs-devel@gnu.org, spwhitton@spwhitton.name, 1021842@bugs.debian.org, Eli Zaretskii To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Feb 20 17:08:26 2023 Return-path: Envelope-to: ged-emacs-devel@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 1pU8iI-0002bk-2e for ged-emacs-devel@m.gmane-mx.org; Mon, 20 Feb 2023 17:08:26 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pU8i1-0005zs-M0; Mon, 20 Feb 2023 11:08:09 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pU8i0-0005yn-7c for emacs-devel@gnu.org; Mon, 20 Feb 2023 11:08:08 -0500 Original-Received: from ma.sdf.org ([205.166.94.33]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pU8hy-0007Xg-7b; Mon, 20 Feb 2023 11:08:07 -0500 Original-Received: from akrl by ma.sdf.org with local (Exim 4.92) (envelope-from ) id 1pU8hr-0002dY-AZ; Mon, 20 Feb 2023 16:07:59 +0000 In-Reply-To: (Stefan Monnier's message of "Mon, 20 Feb 2023 07:48:29 -0500") Received-SPF: pass client-ip=205.166.94.33; envelope-from=akrl@sdf.org; helo=ma.sdf.org X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:303613 Archived-At: Stefan Monnier writes: >>> `make-temp-name` uses `O_EXCL | O_CREAT` so as to close the race >>> condition: if someone predicated the filename, we detect it atomically >>> and we try again. >>> >>> You might like to check >>> >>> https://wiki.sei.cmu.edu/confluence/display/c/FIO21-C.+Do+not+create+temporary+files+in+shared+directories >> >> Thanks for the pointer. >> >> I'm still not really convinced we have a problem here with trampolines. >> With `make-temp-file' we are really only choosing the filename and >> suggesting it to libgccjit, this last one will perform the file >> creation. > > The important part is the use of `O_EXCL | O_CREAT` when creating > the file. > *BUT* `O_EXCL | O_CREAT` will fail if the file already exists. Which is > why `make-temp-file` needs `make-temp-name` to generate new names until > we find one that really doesn't exist (not just at the time > `make-temp-name` is called but the fraction of a millisecond later when > we do try to create it). We can't use this loop, we tipically pass a filename to be used to libgccjit and we have no control after (also see my last comment). >> I'd be surprised if GCC does not handle this correctly, and >> in case shouldn't this be a GCC bug? > > I'd be surprised. Surprised if it does or does not? > If you tell it to write to a pre-existing file, does > it fail with an error? I believe it does not. > If not, then I think it can't be used safely unless > *you* pre-create the file (e.g. with `make-temp-file`). Are we sure? Also if I pre-create the file with make-temp-file can't someone just replace it even more easily with the infamous link before libgccjit comes in? Thanks Andrea