CDs.
With audio CDs, you can't just do a READ(10) call on most drives without
first setting the blocksize with a mode select command. The disklabel code
does a read of the first sector of the media to find a label if it exists.
This caused drives to return an error when an audio CD was in the drive,
due to the problem described above.
The solution is to read the table of contents on the CD, and only attempt
to read the disklabel if the first track is a data track.
This works on all the various CD and DVD media I have tried, but further
testing (especially with Video CDs and other mode 2 media) will be
needed to determine if this is a universal solution.
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