[ltp] Detecting CDs (is there a disc in the cdrom drive ?)

[Richard Neill]

Dear All,

I'm trying to write an acpi script for an X22 ultrabase.
I need to know whether there is a CD or DVD in the drive at the time.
Is there any easy way to find out?

I can't see anything helpful in /proc, or from hdparm. Unfortunately, 
mount only tells me if there is a mounted data CD present. I want to 
know whether there is any disc, eg (audio cd or dvd) present.

The purpose of the script is thus:

1)User presses the "I want to eject the ultrabase" button

2)Script responds to the acpi event by shutting down the drive if 
possible, then unregistering the IDE interface. Or it complains loudly 
if you have a mounted filesystem.

3)User then physically removes the ultrabase.


Thanks for your help.

Richard


P.S. my current script is below, and uses a truly horrid hack with 
cddb-id. There *must* be a better way!



/etc/acpi/actions/ultrabase_eject.sh
------------------------------------------
#!/bin/bash
echo "syncing disks for safety"
sync

echo "Unregistering IDE interface for CDROM and preparing to eject."

#What if there is a disk in the drive?
#Case 1: there is an umounted CDROM, or an AudioCD/DVD which is
#NOT playing.
#OK to proceed.

#Case 2: there is a mounted CDROM. We mustn't proceed.
#Actually, we could *sometimes* unmount it (using eject), but safer to
#leave it for the user.
if grep hdc /proc/mounts >/dev/null; then
         echo "There is a mounted filesystem on /dev/hdc. Cannot eject
               it."
         echo 9 > /proc/acpi/ibm/beep
         exit 1
fi

#Case 3: there is a AudioCD/DVD which is currently playing.
#How do we detect this? It could be just using cdp (which has
#no process)
#Assuming that we have already ruled out a mounted filesystem, then...
if cddb-id /dev/hdc >/dev/null 2>&1; then
         echo "There is a CD in the drive. Ejecting it"
         eject /dev/hdc
fi
#This has the bug that we don't really want to eject the disk; we merely 
#want to stop it playing.


#Unregister IDE interface 1. This WILL cause a kernel panic if there
#is anything in the drive!
idectl 1 off

#Tell the thinkpad the bay is to be ejected
echo eject > /proc/acpi/ibm/bay

#Beep happily
echo 6 > /proc/acpi/ibm/beep

echo "OK to undock"