Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!orstcs!curt3028@oce.orst.edu
From: curt3028@oce.orst.edu (Curt Vandetta)
Newsgroups: comp.sys.hp
Subject: re:  removable r/w optical disk
Message-ID: <16205@orstcs.CS.ORST.EDU>
Date: 23 Feb 90 23:01:41 GMT
Sender: usenet@orstcs.CS.ORST.EDU
Reply-To: curt3028@oce.orst.edu (Curt Vandetta)
Organization: College of Oceanography, Oregon State Univ., Corvallis, Or.
Lines: 52


 Hello folks,

 I've written some C-code that we user here on an HP 9000 series 370,
 that runs setuid to root, so it allows normal users to mount and 
 unmount the optical disk.  I worked in some SCSI commands that HP
 provide to disable/enable the ejection button on the drive as well,
 so it helps to prevent the removal of mounted media.  Basically
 the programs work as follows:

   odmount - Mounts the optical to the directory /optical (This is 
			 hard coded for security reasons but can be changed to
			 any directory you see fit, and with some work it could
			 probably even pick a directory under the users homedir.
			 But I had problems with this i.e. ../../etc) 
			 And changes the ownership of /optical to the user.

		   - Then it disables the ejection button on drive to prevent
			 someone from ejecting the mounted disk.

		   - Then it uses a file /usr/local/etc/odlock_file to record
			 who has the optical mounted and when they mounted it.

 odumount - Unmounts the optical from /optical, but only if it is 
			invoked by the same user that mounted it or root.

		  - Enables the ejection button so that you can take the disk
		    out.
		 
		  - Clears the /usr/local/etc/odlock_file.


  I would be happy to send copies to anyone who wishes to try the code.
  We've been using it for about 3 months now and have only found one
  real problem (discribed later).  Infact my SE has requested a copy and
  I just sent it to him, so I still have a shar file all ready for
  mailing.  

  The one problem is that the odmount program tries to mount the disk
  read-write, and it really hoses the drive (i.e. reboot) when you
  try to mount a disk that is write protected.  But I'm sure if enough
  people get there hands on the code someone will figure out the
  SCSI command (if it exists) to check the disk first, then mount it
  apropriately.  

  If your interested send me mail: curt@oce.orst.edu, if I get a flood
  of requests check this group I might post it here or get an anonymous
  ftp area set up for it.  Also, I'm leaving town until March 2nd so
  only send me one message until then :-)

  Thanks
  Curt