From owner-freebsd-emulation@FreeBSD.ORG Wed Sep 19 11:16:01 2007 Return-Path: Delivered-To: freebsd-emulation@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7234316A417 for ; Wed, 19 Sep 2007 11:16:01 +0000 (UTC) (envelope-from rdivacky@vlk.vlakno.cz) Received: from vlakno.cz (vlk.vlakno.cz [62.168.28.247]) by mx1.freebsd.org (Postfix) with ESMTP id 2862113C4CA for ; Wed, 19 Sep 2007 11:16:00 +0000 (UTC) (envelope-from rdivacky@vlk.vlakno.cz) Received: from localhost (localhost [127.0.0.1]) by vlakno.cz (Postfix) with ESMTP id 414026679C5; Wed, 19 Sep 2007 13:15:59 +0200 (CEST) X-Virus-Scanned: amavisd-new at vlakno.cz Received: from vlakno.cz ([127.0.0.1]) by localhost (vlk.vlakno.cz [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id OuyBQSO6sZCF; Wed, 19 Sep 2007 13:15:58 +0200 (CEST) Received: from vlk.vlakno.cz (localhost [127.0.0.1]) by vlakno.cz (Postfix) with ESMTP id 3BEF866766A; Wed, 19 Sep 2007 13:15:58 +0200 (CEST) Received: (from rdivacky@localhost) by vlk.vlakno.cz (8.13.8/8.13.8/Submit) id l8JBFvIp029151; Wed, 19 Sep 2007 13:15:57 +0200 (CEST) (envelope-from rdivacky) Date: Wed, 19 Sep 2007 13:15:57 +0200 From: Roman Divacky To: Boris Samorodov Message-ID: <20070919111557.GA28377@freebsd.org> References: <46EF62C5.5090704@gmail.com> <00483937@srv.sem.ipt.ru> <46EF7E05.5040405@gmail.com> <20070918074332.GA30053@freebsd.org> <88000019@srv.sem.ipt.ru> <20070918082119.GA30932@freebsd.org> <89768331@srv.sem.ipt.ru> <41596338@srv.sem.ipt.ru> <20070919085405.GA24442@freebsd.org> <18395962@srv.sem.ipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18395962@srv.sem.ipt.ru> User-Agent: Mutt/1.4.2.3i Cc: freebsd-emulation@freebsd.org, sam Subject: Re: linuxolator problem on i386 X-BeenThere: freebsd-emulation@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Development of Emulators of other operating systems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Sep 2007 11:16:01 -0000 > There is nothing wrong with 4084. The magic 4096 is the > answer. I.e. the first case (when a buffer is equal to that > has been really read) is wrongly processed. > > Ex. in C strings ends with 0x0. If a buffer 4096 bytes long was > assigned a string 4096 bytes long then the 0x0 will become a 4097 > byte. And this string will cause a fault of the program. > > PS. I don't say that I gave a strict example of the case. Of cause it > may be something else. But definitely there is a bug in processing of > 4096 bytes log strings by our linuxulator code (somewhere at the > linux_getdents area, linux_getdents64 used by linux_base-fc4 is not > affected by _at least_ 4096 bytes long strings). 1) what makes you think the 4096 buffer is wrongly processed? I still dont see it 2) the getdents64 and getdents use exactly the same code :) the fact is that the structures copied out are of different size so there might be a corner case for th getdents 3) you seem to be confused.. getdents does NOT return strings it returns structures "somehow" fitted in a buffer anyway... I looked at the sources and I found a strange thing so here's a patch... @@ -442,8 +443,7 @@ off = fp->f_offset; - buflen = max(LINUX_DIRBLKSIZ, nbytes); - buflen = min(buflen, MAXBSIZE); + buflen = max(buflen, MAXBSIZE); buf = malloc(buflen, M_TEMP, M_WAITOK); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); I am quite interested if this changes anything because the code is imho obviously wrong. it first limits buflen < 512 and then to buflen = 64K. I dont see how this could affect only 4096 bytes long buffers but its worth a try. thnx, roman