Re: CD writing in future Linux (stirring up a hornets' nest)

[Rob Landley <rob@landley.net>]

On Tuesday 14 February 2006 7:23 am, Matthias Andree wrote:
> > -	How to send non disturbing SCSI commands from another
> > 	cdrecord process in case one or more are already running?
>
> Open the device node you obtained and
> send non-disturbing commands through it.
>
> No special treatment required.

On a mostly unrelated note, I've pondered adding quick and dirty versions of 
mkisofs and cdrecord to busybox for a while.  (Low priority, back burner 
thing.)  I actually poked at the cdrecord source once or twice, but it's 
unintellgible and disgusting.*

With mkisofs I can just start from the spec, reverse engineer a few existing 
ISOs, or grab the really old code from before Joerg got ahold of it (back 
when it was still readable).  That's no problem.  But for cdrecord, I can't 
find documentation on what the kernel expects.

I'm only interested in supporting ATA cd burners under a 2.6 or newer kernel, 
using the DMA method.  (SCSI is dead, I honestly don't care.)  I was hoping I 
could just open the /dev/cdrom and call the appropriate ioctls on it, but 
reading the cdrecord source proved enough of an exercise in masochism that I 
always give up after the first hour and put it back on the todo list.

I suppose I should say "screw the source code" and just run the cdrecord 
binary under strace to see what it's doing, but I thought I'd ask: is there a 
good starting place, somewhere?  (Or is there already a simple "cdrecord 
file.iso /dev/cdrom" someplace?)  I expect I'll wind up buying a 50-pack of 
coasters anyway, and I doubt I'll damage my laptop's burner too badly...

Rob

* How bad?  Random example of ignoring how the rest of the world works is that 
it runs autoconf from within make, meaning there's no obvious way to specify 
"./configure --prefix=/mypath", so the last time I played with it (which was 
a while ago), I wound up doing this:

cd /sources &&
tar xvjf buildtools/cdrtools-2.00.3.tar.bz2 &&
cd cdrtools-2.00.3 &&
make &&
cp mkisofs/OBJ/*/mkisofs cdrecord/OBJ/*/cdrecord \ 
cdda2wav/OBJ/*/cdda2wav /usr/bin &&
cp mkisofs/mkisofs.8 /usr/man/man8 &&
cp cdrecord/cdrecord.1 cdda2wav/cdda2wav.1 /usr/man/man1 &&
cd .. &&
rm -rf cdrtools-2.00.3

if [ $? -ne 0 ]; then exit 1; fi

I could understand if it didn't use autoconf at all, but having autoconf but 
_not_ a configure step is deeply into control freak territory...

Rob
-- 
Never bet against the cheap plastic solution.
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