#33 different error message under "strace"

[Greg Ward]

I'm trying to run cdrdao as a regular user. Not
surprisingly, it's failing -- presumably
permissions problems on /dev/sg?. I also forgot
the --device argument -- again, my fault.
However, when I ran it under strace (to see which
/dev/sg? was the problem), I got completely
different output.

Here's what I get running cdrdao on its own
(device 1,0,0 is correct, but I forgot --driver):
$ cdrdao read-cd --device 1,0,0 --fast-toc toc
Cdrdao version 1.1.5 - (C) Andreas Mueller <andreas@daneb.de>
SCSI interface library - (C) Joerg Schilling
L-EC encoding library - (C) Heiko Eissfeldt
Paranoia DAE library - (C) Monty

Check http://cdrdao.sourceforge.net/drives.html#dt for current driver tables.

Using libscg version 'schily-0.5'

1,0,0: CREATIVE CD5220E-F 0225 Rev: 5.06
ERROR: No driver found for 'CREATIVE CD5220E-F 0225', available drivers:
cdd2600
generic-mmc
generic-mmc-raw
plextor
plextor-scan
ricoh-mp6200
sony-cdu920
sony-cdu948
taiyo-yuden
teac-cdr55
toshiba
yamaha-cdr10x
ERROR: Cannot setup device 1,0,0.

This error message is reasonable; if I had a clue
I would have actually read it and realized I
forgot --driver. But I'm stupid, I assumed it was
a permissions problem, so I ran strace to see
which /dev/sg? was the problem:

$ strace -otrace cdrdao read-cd --device 1,0,0 --fast-toc toc
Cdrdao version 1.1.5 - (C) Andreas Mueller <andreas@daneb.de>
SCSI interface library - (C) Joerg Schilling
L-EC encoding library - (C) Heiko Eissfeldt
Paranoia DAE library - (C) Monty

Check http://cdrdao.sourceforge.net/drives.html#dt for current driver tables.

ERROR: Cannot open SCSI device '1,0,0': Cannot open '/dev/sg1'
ERROR: Please use option '--device bus,id,lun', e.g. --device 0,6,0
ERROR: Cannot setup device 1,0,0.

Note that cdrdao no longer notices I forgot
--driver, or tells me the list of available
drivers. Strange.

This is Linux 2.4.10 (Debian woody), strace 4.2,
cdrdao 1.1.5. strace and cdrdao both from Debian
packages, the kernel I built myself.

I have verified that this is not a shell quoting
problem by running
system "cdrdao","read-cd","--device", ...
system "strace","-otrace","cdrdao","read-cd",...
in Perl, which guarantees that no shell is
involved when you do it like that. Same results.

I'll upload the trace file produced by strace along with this bug report.