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Date:      Sun, 22 May 2016 16:02:02 -0700
From:      Matthew Macy <mmacy@nextbsd.org>
To:        "Joerg Sonnenberger" <joerg@bec.de>
Cc:        "<freebsd-hackers@freebsd.org>" <freebsd-hackers@freebsd.org>
Subject:   Re: read(2) and thus bsdiff is limited to 2^31 bytes
Message-ID:  <154dab43060.11208cdfd132112.2616144627831899155@nextbsd.org>
In-Reply-To: <20160522225414.GB24398@britannica.bec.de>
References:  <b2515cae-b75d-66e9-4207-3cf100ab3ab0@erdgeist.org> <20160522225414.GB24398@britannica.bec.de>

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 ---- On Sun, 22 May 2016 15:54:14 -0700 Joerg Sonnenberger <joerg@bec.de> wrote ---- 
 > On Sun, May 22, 2016 at 10:54:30PM +0200, Dirk Engling wrote: 
 > > When trying to bsdiff two DVD images, I noticed it failing due to 
 > > read(2) returning EINVAL to the tool. man 2 read says, this would only 
 > > happen for a negative value for fildes, which clearly was not true. 
 >  
 > I would classify that as implementation bug. It seems perfectly sensible 
 > to turn overly large requests into a short read/write, even for blocking 
 > files. But erroring out seems to be quite wrong to me. 
 >  

read(2) takes a size_t so this is clearly an internal bug where it's an int and treating it as a negative value.

-M




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