From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Finalizing 'inhibit-automatic-native-compilation' Date: Mon, 20 Feb 2023 07:48:29 -0500 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="4313"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Tatsuya Kinoshita , emacs-devel@gnu.org, spwhitton@spwhitton.name, 1021842@bugs.debian.org, Eli Zaretskii To: Andrea Corallo Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Feb 20 13:49:30 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 1pU5bl-0000uN-1K for ged-emacs-devel@m.gmane-mx.org; Mon, 20 Feb 2023 13:49:29 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pU5b0-0003YE-BF; Mon, 20 Feb 2023 07:48:42 -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 1pU5ay-0003Y2-7N for emacs-devel@gnu.org; Mon, 20 Feb 2023 07:48:40 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pU5av-0007sO-NT; Mon, 20 Feb 2023 07:48:39 -0500 Original-Received: from pmg3.iro.umontreal.ca (localhost [127.0.0.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 931364407E0; Mon, 20 Feb 2023 07:48:33 -0500 (EST) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 13E004406FC; Mon, 20 Feb 2023 07:48:32 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1676897312; bh=BFTWDkb/RpT6UzgOp52PNTMslCZgW354VxAXzqcz9MI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=MdOKITivjZIW68Qe6z3Blu62dpunrCqPO4XcTIloe8uJgsckbtt/3CFKBZTu1YyDh /ZhDj446g98+H4AfcJKhEx72Wpwg++t+QBDV9NS0amkV3SBBcOP66Qj/p8fuR+UlaJ c25us8DDffiBMbymFqj4uDJTQ5cnEUI4+r7Q6UlAe+9g+2THsvT+u4AIkqbGMNlEIB N3tp0FBCshYqGqSVcLRrXvxTPryt9HAnYWCxXq/GhPtmvU2nK5wNYhx6KhpUqHLdJg 2LHS8WKRC4P+MgnkLAYgvPHR/c+C6qK8DrjFJgePykOSTy4W3lJd96QSY99zkf+f79 JyEAsKRYWSYjQ== Original-Received: from pastel (unknown [216.154.34.24]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id CEC4212126E; Mon, 20 Feb 2023 07:48:31 -0500 (EST) In-Reply-To: (Andrea Corallo's message of "Mon, 20 Feb 2023 09:03:34 +0000") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URI_DOTEDU=1.999 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:303605 Archived-At: >> `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). > 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. If you tell it to write to a pre-existing file, does it fail with an error? If not, then I think it can't be used safely unless *you* pre-create the file (e.g. with `make-temp-file`). Stefan