Date: Thu, 30 Dec 2004 16:20:16 +0200 From: Maxim Sobolev <sobomax@portaone.com> To: Peter Pentchev <roam@ringlet.net> Cc: Matteo Riondato <rionda@gufi.org> Subject: Re: Creating Compressed Loop FS from stdin Message-ID: <41D40EA0.2060009@portaone.com> In-Reply-To: <20041230140007.GH830@straylight.m.ringlet.net> 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>
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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 <sobomax@portaone.com> >>Organization: Porta Software Ltd >>To: Matteo Riondato <rionda@freesbie.org> >>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 >
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