From owner-freebsd-hackers@FreeBSD.ORG Thu Dec 30 14:20:30 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BC4DC16A4CE for ; Thu, 30 Dec 2004 14:20:30 +0000 (GMT) Received: from www.portaone.com (web.portaone.com [195.70.151.35]) by mx1.FreeBSD.org (Postfix) with ESMTP id CE5CF43D49 for ; Thu, 30 Dec 2004 14:20:29 +0000 (GMT) (envelope-from sobomax@portaone.com) Received: from [192.168.0.73] (portacare.portaone.com [195.140.247.242]) (authenticated bits=0) by www.portaone.com (8.12.11/8.12.11) with ESMTP id iBUEKOn7021787 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 30 Dec 2004 15:20:26 +0100 (CET) (envelope-from sobomax@portaone.com) Message-ID: <41D40EA0.2060009@portaone.com> Date: Thu, 30 Dec 2004 16:20:16 +0200 From: Maxim Sobolev Organization: Porta Software Ltd User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Peter Pentchev References: <1104358540.2895.10.camel@kaiser.sig11.org> <20041230103433.GB830@straylight.m.ringlet.net> <1104409708.6657.1.camel@kaiser.sig11.org> <20041230123116.GE830@straylight.m.ringlet.net> <41D4036B.1060600@portaone.com> <20041230140007.GH830@straylight.m.ringlet.net> In-Reply-To: <20041230140007.GH830@straylight.m.ringlet.net> Content-Type: text/plain; charset=KOI8-U; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV 0.80/589/Wed Nov 17 13:38:41 2004 clamav-milter version 0.80j on www.portaone.com X-Virus-Status: Clean X-Mailman-Approved-At: Thu, 30 Dec 2004 16:05:45 +0000 cc: freebsd-hackers@FreeBSD.ORG cc: Matteo Riondato Subject: Re: Creating Compressed Loop FS from stdin X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Dec 2004 14:20:31 -0000 You don't check return code of the second lseek - I bet it fails. This probably leads to creation of seemingly valid loop fs (i.e. with valid header), but filled with zeroes or some random junk. -Maxim Peter Pentchev wrote: > On Thu, Dec 30, 2004 at 03:32:27PM +0200, Maxim Sobolev wrote: > >>Peter Pentchev wrote: >> >>>On Thu, Dec 30, 2004 at 01:28:28PM +0100, Matteo Riondato wrote: >>> >>> >>>>Il giorno Gio, 30-12-2004 alle 12:34 +0200, Peter Pentchev ha scritto: >>>> >>>> >>>>>This could be fixed by the following patch. I'm CC'ing Maxim Sobolev, >>>>>the author of mkuzip(8); Maxim, do you have any objections to this patch? >>>> >>>>Thank you for the answer and fo the patch! I hope Maxim will commit it >>>>soon. >>> >>> >>>Actually, if Maxim has no objections, I could commit it myself. >>>However, it would be totally understandable if he doesn't answer in >>>the next day or three, what with the calendar moving ahead and all :) >> >>It will not help, since AFAIK you can't seek stdin anyway, or even if I >>am wrong and you can seek it to the end you will be unable to seek it >>backward. > > > I tested the patch before posting it, fully expecting to find that stdin > really cannot be seeked (sought? :), and surprisingly it worked, at least > on RELENG_5 as of today! > > >>I've already replied to this message, but Matteo has some very strange >>settings of his smtp relay so that neither my original message nor my >>follow-up in which I had forwarded mail delivery error message got through. >> >>-Maxim >> >>-------- Original Message -------- >>Subject: Re: Creating Compressed Loop FS from stdin >>Date: Fri, 17 Dec 2004 17:14:48 +0200 >>From: Maxim Sobolev >>Organization: Porta Software Ltd >>To: Matteo Riondato >>References: <1103290915.8516.9.camel@kaiser.sig11.org> >> >>This is not going to work by design unfortunately. cloop format has >>serious design flaw: it contains variable-lengh header at the beginning >>of the compressed image, so that before doing compression mkuzip(1) uses >>stat(2) call at the original file to get its size and reserve necessary >>space, which doesn't work with /dev/stdin as you may guess. Original GNU >>utility either keeps the whole compressed image in memory or uses some >>form of temporary storage (I don't quite remember) to work around this >>problem. > > > Well, another solution would be to make mkuzip use a temporary file > (obviously, keeping the whole thing in memory would be a bad idea for > big ISO filesystems ;). However, as I noted above, my lseek patch > works at least for RELENG_5. Can somebody test it on -CURRENT? > > G'luck, > Peter >