Re: Why would a valid DVD show zero files on Linux?

From: Bryce Nesbitt (bryce@obviously.com)
Date: Sat Jan 05 2002 - 11:14:16 EST


Here is the table of contents mounted three ways. First udf, then
iso9660, then iso9660 nojoliet. Only the udf version works with the
application. Note that the huge udf filesizes are not a mistake -
this DVD is also offered as 7 CD set.

/mnt/cdrom1/:
total 14
dr-xr-xr-x 3 4294967295 4294967295 184 Feb 28 2001 .
drwxr-xr-x 24 root root 4096 Jan 5 10:27 ..
-r--r--r-- 1 4294967295 4294967295 2763 Feb 28 2001 CD.TXT
dr-xr-xr-x 2 4294967295 4294967295 380 Feb 28 2001 DATA
-r--r--r-- 1 4294967295 4294967295 196 Feb 28 2001 PDATASET.TXT

/mnt/cdrom1/DATA:
total 3266832
dr-xr-xr-x 2 4294967295 4294967295 380 Feb 28 2001 .
dr-xr-xr-x 3 4294967295 4294967295 184 Feb 28 2001 ..
-r--r--r-- 1 4294967295 4294967295 34735660 Feb 28 2001 GRIDAK.DAT
-r--r--r-- 1 4294967295 4294967295 1921298 Feb 28 2001 GRIDAK.IND
-r--r--r-- 1 4294967295 4294967295 1832319997 Feb 28 2001 GRID.DAT
-r--r--r-- 1 4294967295 4294967295 51128921 Feb 28 2001 GRID.IND
-r--r--r-- 1 4294967295 4294967295 34839 Feb 28 2001 VEC.COV
-r--r--r-- 1 4294967295 4294967295 1424439251 Feb 28 2001 VEC.V
-r--r--r-- 1 4294967295 4294967295 643405 Feb 28 2001 VEC.VI

/mnt/cdrom1/:
total 1
dr-xr-xr-x 1 root root 1 Feb 28 2001 .

/mnt/cdrom1/:
total 12
dr-xr-xr-x 1 root root 2048 Feb 28 2001 .
drwxr-xr-x 24 root root 4096 Jan 5 10:27 ..
-r-xr-xr-x 1 root root 2763 Feb 28 2001 cd.txt
dr-xr-xr-x 1 root root 2048 Feb 28 2001 data
-r-xr-xr-x 1 root root 196 Feb 28 2001 pdataset.txt

/mnt/cdrom1/data:
total 22849
dr-xr-xr-x 1 root root 2048 Feb 28 2001 .
dr-xr-xr-x 1 root root 2048 Feb 28 2001 ..
-r-xr-xr-x 1 root root 1181228 Feb 28 2001 gridak.dat
-r-xr-xr-x 1 root root 1921298 Feb 28 2001 gridak.ind
-r-xr-xr-x 1 root root 3603453 Feb 28 2001 grid.dat
-r-xr-xr-x 1 root root 797273 Feb 28 2001 grid.ind
-r-xr-xr-x 1 root root 34839 Feb 28 2001 vec.cov
-r-xr-xr-x 1 root root 15153107 Feb 28 2001 vec.v
-r-xr-xr-x 1 root root 643405 Feb 28 2001 vec.vi

As this is one clear example of differing iso9660 and udf views
of the same disc, I propose to change mount(8) and fstab(5) to warn the
two can be different (either intentionally, accidentally, or because
of iso9660 limitations).

I also propose to change "mount -t auto" to try udf first, and fall back to
iso9660. This, of course, requires more discussion first. But based
on serching other lists, reading the udf "iso9660 bridge" spec,
and email conversations, it seems to be the right long term answer.
Since udf is used on CD's, I propose that udf be tried first for
all meda, not just DVD's.

The kernel, of course, remains unchanged, and because you're using Linux,
you would still be able force mount anything you want.

                        -Bryce

Andries.Brouwer@cwi.nl wrote:
>
> > Here are the first 2048 1024 byte blocks.
>
> Hmm. I am a bit slow, but just looked at this image.
> It looks fine in iso9660 style, provided you give the
> nojoliet option. I get:
>
> # mount DeLorme_TopoUSA_DVD.head /mnt -t iso9660 -o loop,nojoliet
> # ls -l /mnt
> total 12
> dr-xr-xr-x 1 root root 2048 Feb 28 2001 .
> drwxr-xr-x 31 root root 4096 Jan 3 02:11 ..
> -r-xr-xr-x 1 root root 2763 Feb 28 2001 cd.txt
> dr-xr-xr-x 1 root root 2048 Feb 28 2001 data
> -r-xr-xr-x 1 root root 196 Feb 28 2001 pdataset.txt
>
> and
>
> # mount DeLorme_TopoUSA_DVD.head /mnt -t udf -o loop
> # ls -l /mnt
> total 14
> dr-xr-xr-x 3 4294967295 4294967295 184 Feb 28 2001 .
> drwxr-xr-x 31 root root 4096 Jan 3 02:11 ..
> -r--r--r-- 1 4294967295 4294967295 2763 Feb 28 2001 CD.TXT
> dr-xr-xr-x 2 4294967295 4294967295 380 Feb 28 2001 DATA
> -r--r--r-- 1 4294967295 4294967295 196 Feb 28 2001 PDATASET.TXT
>
> so the iso9660 version looks a bit better than the udf version.
> (But I cannot look at the actual contents because the initial
> fragment is not large enough. You can check for yourself
> whether the nojoliet mount is OK.)
>
> Thus, there do not seem reasons to change mount(2) or mount(8)
> in the way you suggested. There is no "empty iso9660 filesystem" here.
>
> Andries
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This archive was generated by hypermail 2b29 : Mon Jan 07 2002 - 21:00:28 EST