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Subjectisofs: truncated files on volume 2 of CD set

I have created backup CD set. In respect to mkisofs manual, I have
numbered these volumes using -volset-seqno. I have been badly
surprised, that files with size >16MB on volume 2 were truncated.

I have looked at isofs source code and found reason:

For volume 2 and higher "cruft" option is auto activated. Does anybody
know the reason for this behavior? I am adding a patch. I didn't
looked at ISO9660 specification to see upper limit of volume sequence
number, I don't also know, whether CD set is numbered from 0 or 1, so
please fix me, if I am wrong.

Included fix tests oddity of this number by its negativity.

There are two other possible tests:

Stronger test for highest byte non-zero (does anybody have more than
16777216 CD's in set?)
- (volume_seq_no != 0) && (volume_seq_no != 1)) {
+ (volume_seq_no & 0xff000000)) {

Third posible test is checking, whether volume sequence number is <=
than volume set size (yet not included).

Please let me know, which test you consider as appropriate and I will
change the patch.

-volset-size #
Sets the volume set size to #. The volume set size
is the number of CD's that are in a CD set. The
-volset-size option may be used to create CD's that
are part of e.g. a Operation System installation
set of CD's. The option -volset-size must be spec-
ified before -volset-seqno on each command line.

-volset-seqno #
Sets the volume set sequence number to #. The vol-
ume set sequence number is the index number of the
current CD in a CD set. The option -volset-size
must be specified before -volset-seqno on each com-
mand line.

--- linux/fs/isofs/inode.c.orig Thu Oct 25 23:53:53 2001
+++ linux/fs/isofs/inode.c Sun Dec 2 16:38:59 2001
@@ -1284,13 +1284,13 @@
volume_seq_no = isonum_723 (de->volume_sequence_number) ;

- * Disable checking if we see any volume number other than 0 or 1.
+ * Disable checking if we see strange volume number.
* We could use the cruft option, but that has multiple purposes, one
* of which is limiting the file size to 16Mb. Thus we silently allow
* volume numbers of 0 to go through without complaining.
if (inode->i_sb->u.isofs_sb.s_cruft == 'n' &&
- (volume_seq_no != 0) && (volume_seq_no != 1)) {
+ (volume_seq_no < 0) && (volume_seq_no > 0x7FFFFFFE)) {
printk(KERN_WARNING "Warning: defective CD-ROM "
"(volume sequence number %d). "
"Enabling \"cruft\" mount option.\n", volume_seq_no);
Stanislav Brabec
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