From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Matthew Leach Newsgroups: gmane.emacs.bugs Subject: bug#37564: [PATCH] don't export LINES and COLUMNS env vars in term to fix ncurses applications Date: Tue, 01 Oct 2019 19:33:39 +0100 Message-ID: <87sgocfh8c.fsf@mattleach.net> References: <87y2y5lfnb.fsf@1e0.co.uk> <83eezxatsv.fsf@gnu.org> <87tv8slb6w.fsf@mattleach.net> <83a7aka1q5.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="44736"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) Cc: 37564@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Tue Oct 01 20:34:24 2019 Return-path: Envelope-to: geb-bug-gnu-emacs@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 1iFMyd-000BTM-CU for geb-bug-gnu-emacs@m.gmane.org; Tue, 01 Oct 2019 20:34:23 +0200 Original-Received: from localhost ([::1]:46488 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFMya-0008KI-R9 for geb-bug-gnu-emacs@m.gmane.org; Tue, 01 Oct 2019 14:34:20 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:41407) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFMyJ-0008Jq-0x for bug-gnu-emacs@gnu.org; Tue, 01 Oct 2019 14:34:04 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iFMyH-0002hS-U4 for bug-gnu-emacs@gnu.org; Tue, 01 Oct 2019 14:34:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:54161) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1iFMyH-0002hK-Qu for bug-gnu-emacs@gnu.org; Tue, 01 Oct 2019 14:34:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1iFMyH-0002N4-Mj for bug-gnu-emacs@gnu.org; Tue, 01 Oct 2019 14:34:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Matthew Leach Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 01 Oct 2019 18:34:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 37564 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 37564-submit@debbugs.gnu.org id=B37564.15699548219084 (code B ref 37564); Tue, 01 Oct 2019 18:34:01 +0000 Original-Received: (at 37564) by debbugs.gnu.org; 1 Oct 2019 18:33:41 +0000 Original-Received: from localhost ([127.0.0.1]:34749 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1iFMxx-0002MS-0n for submit@debbugs.gnu.org; Tue, 01 Oct 2019 14:33:41 -0400 Original-Received: from mx0.mattleach.net ([176.58.118.143]:52748) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1iFMxu-0002MJ-Bw for 37564@debbugs.gnu.org; Tue, 01 Oct 2019 14:33:39 -0400 Original-Received: by mx0.mattleach.net (Postfix, from userid 99) id 6C2C161C5D; Tue, 1 Oct 2019 19:33:37 +0100 (BST) Original-Received: from hopton.mattleach.net (92.40.249.172.threembb.co.uk [92.40.249.172]) by mx0.mattleach.net (Postfix) with ESMTPSA id 8F4CD61C21; Tue, 1 Oct 2019 19:33:36 +0100 (BST) In-Reply-To: <83a7aka1q5.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 01 Oct 2019 19:07:30 +0300") 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: 209.51.188.43 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:168067 Archived-At: Eli Zaretskii writes: >> From: Matthew Leach >> Cc: 37564@debbugs.gnu.org >> Date: Tue, 01 Oct 2019 16:47:35 +0100 >> >> > Thanks, but I don't think we can make this change unconditionally, >> > because not all applications that heed LINES and COLUMNS use ncurses. >> >> I'm curious as to which programs you are referring? AFAIK, if a program >> tries to read the LINES and COLUMNS environment variables, using >> `getenv()', they don't exist. > > What makes you say that? If I run the C program in my previous post in an xterm and resize I get: getenv: (null) (null) ioctl: 24 80 getenv: (null) (null) ioctl: 42 169 You can see that doing getenv() on LINES and COLUMNS returns a null pointer. I've tested this same behaviour on gnome-terminal and numerous other terminal emulators. > Emacs exports these variables into the environment that is passed to > child subprocesses, so those subprocesses will definitely see them > using getenv. I'm no expert on how these things work but it doesn't appear to be the way that it's done, on my machine anyway. Perhaps there are programs that uses these variables on MacOS or Windows? >> Nevertheless, if a program does read the LINES and COLUMNS variables, >> these values will be wrong if the window has been resized (try and >> compile the attached C snippet and run in term mode while resizing the >> window). Should that be considered as a separate bug? > > We nowadays have window-adjust-process-window-size-function to support > that, and term.el is using that. So why isn't it working for you? > Maybe you are running a version of Emacs that's too old (AFAICT, you > didn't say which one)? I'm testing this on the latest Emacs Git version. I can see that window-adjust-process-window-size-function is used in term.el however, this doesn't appear to update the environment variables exported to the terminal process. If I run the same program with term on Emacs git and resize I get: getenv: 31 80 ioctl: 30 89 getenv: 31 80 ioctl: 30 90 getenv: 31 80 ioctl: 30 91 getenv: 31 80 ioctl: 31 92 getenv: 31 80 ioctl: 31 93 getenv: 31 80 ioctl: 31 94 ... Notice that the values returned by getenv don't change. Given that this functionality is broken, I'm suggesting that we don't export the variables. This will make ncurses fall back to using ioctls for window size inspection. Another way to fix this would be to somehow update the environment variables that are exported to the process. What are your thoughts? Thanks, -- Matt