From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.bugs Subject: bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack allocation. Date: Fri, 05 Sep 2014 11:44:25 -0400 Message-ID: References: <5409536B.5090201@cs.ucla.edu> <54097827.1020508@yandex.ru> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1409931932 588 80.91.229.3 (5 Sep 2014 15:45:32 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 5 Sep 2014 15:45:32 +0000 (UTC) Cc: Paul Eggert , 18410@debbugs.gnu.org To: Dmitry Antipov Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Fri Sep 05 17:45:22 2014 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XPvhS-0001z2-Gb for geb-bug-gnu-emacs@m.gmane.org; Fri, 05 Sep 2014 17:45:22 +0200 Original-Received: from localhost ([::1]:58597 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPvhS-0001l8-4G for geb-bug-gnu-emacs@m.gmane.org; Fri, 05 Sep 2014 11:45:22 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:39514) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPvhG-0001hl-SN for bug-gnu-emacs@gnu.org; Fri, 05 Sep 2014 11:45:19 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XPvh8-0004Rw-KG for bug-gnu-emacs@gnu.org; Fri, 05 Sep 2014 11:45:10 -0400 Original-Received: from debbugs.gnu.org ([140.186.70.43]:40181) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPvh8-0004R7-Hk for bug-gnu-emacs@gnu.org; Fri, 05 Sep 2014 11:45:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.80) (envelope-from ) id 1XPvh7-0000nK-Qx for bug-gnu-emacs@gnu.org; Fri, 05 Sep 2014 11:45:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Stefan Monnier Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 05 Sep 2014 15:45:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 18410 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 18410-submit@debbugs.gnu.org id=B18410.14099318933025 (code B ref 18410); Fri, 05 Sep 2014 15:45:01 +0000 Original-Received: (at 18410) by debbugs.gnu.org; 5 Sep 2014 15:44:53 +0000 Original-Received: from localhost ([127.0.0.1]:59978 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XPvgy-0000mi-JU for submit@debbugs.gnu.org; Fri, 05 Sep 2014 11:44:52 -0400 Original-Received: from mercure.iro.umontreal.ca ([132.204.24.67]:46991) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XPvgw-0000ma-Of for 18410@debbugs.gnu.org; Fri, 05 Sep 2014 11:44:51 -0400 Original-Received: from hidalgo.iro.umontreal.ca (hidalgo.iro.umontreal.ca [132.204.27.50]) by mercure.iro.umontreal.ca (Postfix) with ESMTP id 13FC584F4C; Fri, 5 Sep 2014 11:44:50 -0400 (EDT) Original-Received: from lechon.iro.umontreal.ca (lechon.iro.umontreal.ca [132.204.27.242]) by hidalgo.iro.umontreal.ca (Postfix) with ESMTP id E273A1E5B8A; Fri, 5 Sep 2014 11:44:25 -0400 (EDT) Original-Received: by lechon.iro.umontreal.ca (Postfix, from userid 20848) id BFC16B4171; Fri, 5 Sep 2014 11:44:25 -0400 (EDT) In-Reply-To: <54097827.1020508@yandex.ru> (Dmitry Antipov's message of "Fri, 05 Sep 2014 12:45:27 +0400") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) X-DIRO-MailScanner-Information: Please contact the ISP for more information X-DIRO-MailScanner: Found to be clean X-DIRO-MailScanner-SpamCheck: n'est pas un polluriel, SpamAssassin (score=-2.82, requis 5, autolearn=not spam, ALL_TRUSTED -2.82, MC_TSTLAST 0.00) X-DIRO-MailScanner-From: monnier@iro.umontreal.ca X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.15 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 140.186.70.43 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-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:93068 Archived-At: > USE_SAFE_ALLOCA; |- > ptrdiff_t count = SPECPDL_INDEX (); |- | > ... | inner bind | outer bind > Lisp_Object result = unbind_to (count, Fsome_func ()); |- | > SAFE_FREE (); |- > return result; > > looks suboptimal because it calls unbind_to twice. Only if the object is "too large" and requires heap allocation. BTW, AFAIK Lisp_Object result = unbind_to (count, Fsome_func ()); can always be written Lisp_Object result = Fsome_func (); unbind_to (count, Qnil); which I find more readable (if it were me, unbind_to would take a single arg and return void). Stefan