X-Recipient: archive-cygwin AT delorie DOT com DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:subject:message-id:reply-to :references:mime-version:content-type:in-reply-to; q=dns; s= default; b=JPwwa8MsiH7ONXmE/wHr0b7Dk7nZQSCcMvTotAOVm7ufBrXc/lH6h 1E1OAxsGkcz+wGcGLY1zosIedcbkvc1azEXpOk1ycTo3LzwSoPQPcOuO4aXI1Wto 5oeTJvcogI+3dq1fldCxI50HLWolk1h/bLHi1nBYdSJlzMwxc5JlJM= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:subject:message-id:reply-to :references:mime-version:content-type:in-reply-to; s=default; bh=+BS3raVhqi/3aEs4wDTHGb5eO4g=; b=Y6UZBjTtuStsAAqKfxiTinL8xyQE t/+LMe6YSWJ2soRXGZcdvYcG8rbkEveKF41G2KQbfssZ2JPdNeBrI83NlKP/7AlY lqNsrqB4a0FseaR0i8GDDeiHlNT9t4cU9f8FpYsvTaELz0aUjLNsq0stysTiBUcJ qu/zUQAihiCGFXw= Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com X-Spam-SWARE-Status: No, score=-1.8 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.3.1 Date: Tue, 11 Jun 2013 17:26:24 +0200 From: Corinna Vinschen To: cygwin AT cygwin DOT com Subject: Re: [PATCH] Check for existence of the path before processing '..' Message-ID: <20130611152624.GE9484@calimero.vinschen.de> Reply-To: cygwin AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com References: <001401ce66a4$bb9029a0$32b07ce0$%fedin AT samsung DOT com> <20130611142002 DOT GA1927 AT ednor DOT casa DOT cgf DOT cx> <20130611150446 DOT GB9484 AT calimero DOT vinschen DOT de> <20130611151708 DOT GB2235 AT ednor DOT casa DOT cgf DOT cx> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20130611151708.GB2235@ednor.casa.cgf.cx> User-Agent: Mutt/1.5.21 (2010-09-15) On Jun 11 11:17, Christopher Faylor wrote: > On Tue, Jun 11, 2013 at 05:04:46PM +0200, Corinna Vinschen wrote: > >I don't see how do this without calling path_conv, though. You have to > >perform the full conversion on the parent path, with symlinks and > >everything to get the right result. > > Yes, but it is a HUGE stack hit to call path_conv recursively here. Shouldn't that be much reduced by the fact that the temporary buffers used by path_conv are tmp_pathbuf buffers? Originally, when we started with 1.7, we had all those 64K buffers on the stack and thus a lot of spurious crashes due to stack overflow. But since using tmp_pathbuf buffers we got rid of those. Maybe we should contemplate the idea to raise the maximum number of tmp_pathbuf buffers to accommodate situations we're not aware of at this point in time. > >However, I'm rather impressed by the low impact of this change. I moved > >the check_parent setting so it's only set when a slash occurs, and then > >I made a couple of runs building coreutils. As you know, GCC uses .. > >paths a lot. The performance hit is almost unnoticable: 72.3 seconds > >without, 73.4 seconds with the patch. > > If we are considering doing this, then couldn't we somehow just avoid > eliminating "/.." until after the path is fully parsed and then collapse > all of them in one final loop? Also, don't we have the same problem for > foo/./bar? We change that to foo/bar but foo may not exist. The problem with .. is that a path component disappears while normalizing the path, without checking it's existence. Therefore foo/./bar is no problem here, because the final patch still contains foo and thus it's existence will be checked anyway. I may be missing something, but if we don't remove .. and . from the path right at the start of path_conv, then we have exactly the problem which so far kept us from doing the check: A . or .. component spoils the mount_table->conv_to_win32_path path, and it might (I'm *not* sure) break the sym.check call as well. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple