cd_eject (): ioctl (cd_desc, CDAUDIO_EJECT) always returning -1

Hello,

In src/compat.h we define:

#ifdef CDROMEJECT
#define CDAUDIO_EJECT CDROMEJECT
#endif

So we really use CDROMEJECT.

The error message comes from this function in src/cdaudio.c:

/* Eject the tray */
int
cd_eject(int cd_desc)
{
  int r = ioctl(cd_desc, CDAUDIO_EJECT);
  if(r) {
    printf("ioctl returned %d\n", r);
    return -1;
  }
  return 0;
}

What we could add here is an additional print of the errno (with e.g. perror()) to better understand the error. Note that libcdaudio and cdcd are currently in search for a maintainer; if you would like to improve it, please contact me.

The Linux kernel source says (in Documentation/ioctl/cdrom.txt):

CDROMEJECT          Ejects the cdrom media

    usage:

      ioctl(fd, CDROMEJECT, 0);

    inputs:     none

    outputs:    none

    error returns:
      ENOSYS    cd drive not capable of ejecting
      EBUSY     other processes are accessing drive, or door is locked

    notes:
      See CDROM_LOCKDOOR, below.

Probably your error is one of the errors above. For more information on what's going on, please search for information on the Linux kernel part (internet search, ask maintainers...) as I wouldn't be able to help here.

Thanks!

Best regards

Thank you for the hints. I have already decoded the errno: It gives me 5, which means "input output error" — so the error can be literally anywhere.

UPDATE: After another user's hint, I used strace to hunt down the cause of the error. Here is its output:

ioctl(3, CDROM_DISC_STATUS, 0)          = 100
ioctl(3, CDROMSUBCHNL, 0x7e93e308)      = 0
ioctl(3, CDROMEJECT, 0x1)               = -1 EIO (Input/output error)
write(1, "ioctl returned -1\n", 18)     = 18

For comparison, here is the strace output of the eject command-line utility, which works flawlessly:

geteuid32()                             = 1000
open("/dev/sr0", O_RDWR|O_NONBLOCK)     = 3
ioctl(3, CDROMEJECT, 0x1)               = 0
close(3)                                = 0
exit_group(0)                           = ?
+++ exited with 0 +++

The ioctl command is exactly the same, but the CD drive is opened in a slightly different manner, namely in RDWR mode, in contrast to what you are doing:

open("/dev/sr0", O_RDONLY|O_NONBLOCK)   = 3

UPDATE: Looking into the sourcecode of eject reveals that they first check for whether the drive is read-write, or not, and then open it read-write or read-only: eject.c, lines 686 thru 694

OK, I've adapted the cd_eject following the eject utility and recompiled the library as well as cdcd, but no use: Instead of the CD, I only get the ioctl error. See the file attached for a complete output of strace when invoking cdcd with the eject command directly from the shell.

UPDATE: After fiddling around with the eject utility, I found out that my drive (and many others as well, I suppose) apparently would only accept SCSI commands, so it's basically a SCSI-over-USB device:

pi@autoradio:/import/valen/autoradio $ eject -v /dev/sr0
eject: device name is `/dev/sr0'
eject: expanded name is `/dev/sr0'
eject: `/dev/sr0' is not mounted
eject: `/dev/sr0' is not a mount point
eject: `/dev/sr0' is not a multipartition device
eject: trying to eject `/dev/sr0' using CD-ROM eject command
eject: CD-ROM eject command failed
eject: trying to eject `/dev/sr0' using SCSI commands
eject: SCSI eject succeeded

cdaudio, on the other hand, seems to support CD-ROM commands only, so this way will never work. As you may see in the sourcecode of eject, it's a fairly complicated task. Who can implement this feature in cdaudio?

I've now got a solution based on the eject_scsi () method from the eject utility: If the old CDROMEJECT fails, just switch to a series of SCSI commands as a fallback. Continue here: Patch #7