From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Message's text-properties in *Messages* Date: Wed, 23 May 2018 13:41:36 -0400 Message-ID: References: <20180521171019.GA5750@ACM> <83a7sqcmnw.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1527097192 24314 195.159.176.226 (23 May 2018 17:39:52 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 23 May 2018 17:39:52 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed May 23 19:39:48 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fLXjn-0006CA-Ac for ged-emacs-devel@m.gmane.org; Wed, 23 May 2018 19:39:47 +0200 Original-Received: from localhost ([::1]:34776 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fLXls-0000tx-NT for ged-emacs-devel@m.gmane.org; Wed, 23 May 2018 13:41:56 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:46303) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fLXll-0000sd-Ql for emacs-devel@gnu.org; Wed, 23 May 2018 13:41:50 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fLXlh-0000Bm-Tx for emacs-devel@gnu.org; Wed, 23 May 2018 13:41:49 -0400 Original-Received: from [195.159.176.226] (port=37243 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fLXlh-0000BW-9V for emacs-devel@gnu.org; Wed, 23 May 2018 13:41:45 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1fLXjY-0005yD-1B for emacs-devel@gnu.org; Wed, 23 May 2018 19:39:32 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 33 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:/BR+UdMbYrFXbK3EqIEFEiIBFX4= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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:225619 Archived-At: >> - Why would arbitrary Lisp code be dangerous (I understand that message_dolog >> can be called from within redisplay, but redisplay runs Elisp code >> at several places, so "from redisplay" doesn't inherently imply you >> can't run Elisp code). > When Lisp code is called from redisplay, we always do that via > safe_call. Anything else is not safe, AFAIR. I see. This doesn't answer all the questions, tho: - The current code still does call0 (intern ("messages-buffer-mode")); hence doesn't use safe_call here. This is likely a bug (introduced when we added messages-buffer-mode) and it hasn't bitten us simply because it's run rarely enough (only after you kill the *Messages* buffer) and by default it probably doesn't do anything dangerous, so to trigger this bug, we'd need a "perfect storm" (i.e. set a nasty messages-buffer-mode-hook, then kill *Messages*, then arrange for the next message to come from within the redisplay code). - AFAICT message_dolog avoids running before/after change functions, so the comment about the GC being sometimes called because we run before/after change hooks seems odd. - If after/before change functions do end up called, are they really called via safe_call? I don't see any trace of that. - Would let-binding inhibit-foo-hooks good enough to avoid running Elisp code unsafely? Stefan