Subject: Re: mkisofs file size limit
To: None <firstname.lastname@example.org>
From: Frederick Bruckman <email@example.com>
Date: 03/13/2005 01:37:31
In article <Pine.NEB.firstname.lastname@example.org>,
Todd Vierling <email@example.com> writes:
> On Wed, 9 Mar 2005, Dieter Baron wrote:
>> : Is there any way I can get round the file size limit of 0x7FFFFFFF?
>> : What determines this limit?
>> It's the largest size that can be represented as a signed 32 bit
>> value, and some people seem to think the size field in ISO 9660 file
>> systems is a signed value; playing it save, I guess.
> Many ISO9660 client implementations still use a signed 32-bit int, so 2GB is
> indeed the practical limit for a file in such a filesystem. There's a
> reason that DVD video discs limit VOBs to 1GB each; the splitting was deemed
> necessary to keep them well within the ISO9660 safety limits.
Make that 2GB - 1. 2GB would be interpreted as negative by
implementations that represent file sizes with signed 32-bit ints,
so 1GB is indeed the largest "round number" that would fit.
> Above 2GB, UDF is the only truly compatible choice, and ISO9660 is out the
> window altogether.
I've composed a patch to write files of arbitrary size (greater than 4GB)
using multiple extents, conditionally on giving "-iso-level 3". The only
guaranteed method to extract them is using "isoinfo" as patched by the patch,
although my DVD Video (hardware) player happens to be able to play them.