From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#35179: [PATCH] Plug memory leak in GTK x-display-monitor-attributes-list Date: Sun, 07 Apr 2019 19:32:49 +0300 Message-ID: <83wok593ny.fsf@gnu.org> References: <87a7h2z96i.fsf@gmail.com> <871s2dvpgf.fsf@gmail.com> Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="164582"; mail-complaints-to="usenet@blaine.gmane.org" Cc: 35179@debbugs.gnu.org To: Alex Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Sun Apr 07 18:34:12 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 (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hDAkF-000ghm-H4 for geb-bug-gnu-emacs@m.gmane.org; Sun, 07 Apr 2019 18:34:11 +0200 Original-Received: from localhost ([127.0.0.1]:41142 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hDAkE-0008Vy-Bp for geb-bug-gnu-emacs@m.gmane.org; Sun, 07 Apr 2019 12:34:10 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:55524) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hDAk7-0008Ve-Ou for bug-gnu-emacs@gnu.org; Sun, 07 Apr 2019 12:34:04 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hDAk6-0001YJ-Pz for bug-gnu-emacs@gnu.org; Sun, 07 Apr 2019 12:34:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:35095) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1hDAk6-0001YA-1I for bug-gnu-emacs@gnu.org; Sun, 07 Apr 2019 12:34:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1hDAk5-0007nL-TS for bug-gnu-emacs@gnu.org; Sun, 07 Apr 2019 12:34:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sun, 07 Apr 2019 16:34:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 35179 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 35179-submit@debbugs.gnu.org id=B35179.155465478529897 (code B ref 35179); Sun, 07 Apr 2019 16:34:01 +0000 Original-Received: (at 35179) by debbugs.gnu.org; 7 Apr 2019 16:33:05 +0000 Original-Received: from localhost ([127.0.0.1]:48639 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1hDAjA-0007m9-V5 for submit@debbugs.gnu.org; Sun, 07 Apr 2019 12:33:05 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:41023) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1hDAj9-0007lg-6P for 35179@debbugs.gnu.org; Sun, 07 Apr 2019 12:33:03 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:56713) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hDAj3-00011Z-FT; Sun, 07 Apr 2019 12:32:57 -0400 Original-Received: from [176.228.60.248] (port=4127 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1hDAj2-0003nm-TT; Sun, 07 Apr 2019 12:32:57 -0400 In-reply-to: <871s2dvpgf.fsf@gmail.com> (message from Alex on Sun, 07 Apr 2019 08:51:12 -0600) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] 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:157313 Archived-At: > From: Alex > Cc: bug-gnu-emacs@gnu.org, 35179@debbugs.gnu.org > Date: Sun, 07 Apr 2019 08:51:12 -0600 > > > I'd prefer to leave g_strdup intact, and instead explicitly release the storage of previous value. IOW, plug the leak in our own code, not rely on undocumented features which can easily go away some day. > > The documentation of gdk_monitor_get_model[1] specifies that the return > value is "[transfer none]", which has the description "Don't free data > after code is done". That could mean anything. The only thing it tells us not to call 'free' on the result, but it could be, for example, that the result is a pointer to a static buffer that can be changed by a subsequent call to the function. > The main memory leak, though, was that the MonitorList array wasn't > being freed. Does your patch change that? If not, why not? > I considered using the free_monitors procedure like the non-GTK > versions do, but I saw no reason to call g_strdup for each name and > free each name almost right after. I don't see how the short lifetime of the array changes anything here. As long as we aren't sure the pointer returned by gdk_monitor_get_model is a copy that cannot be changed by another thread, we should ourselves make a copy. Otherwise, who can ensure us that some other GTK thread doesn't call this same function during the short life time of the array? > Since make_monitor_attribute_list uses make_string on each name, I don't > see any issues that this removal would cause. The issue I see is that between the time we call gdk_monitor_get_model and the time we use the string something could change the string to which the pointer points. If you can spot something in the GDK docs that guarantees this couldn't happen, please point me to that piece of docs.