problem using ioctl , CDROM_DRIVE_STATUS

Hi,
I'm using the ubuntu version of Linux and C++.  I'm trying to use ioctl to detect the status of the cdrom drive.  according to the documentation http://www.mjmwired.net/kernel/Documentation/ioctl/cdrom.txt (line 682) CDROM_DRIVE_STATUS should return one of 5 states:

CDS_NO_INFO      
CDS_NO_DISC
CDS_TRAY_OPEN
CDS_DRIVE_NOT_READY
CDS_DISC_OK

I have only been able to detect two states: CDS_DISC_OK and CDS_TRAY_OPEN.  I'm getting CDS_TRAY_OPEN when there is no disc in the drive, even when the tray is closed.  I need to know if the tray is closed but there is no disc in the drive.  Is there something I'm doing wrong (my code is below)?


Thanks,
Nick



#include <sys/ioctl.h>
#include <iostream>
#include <fstream>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/cdrom.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>


using std::cout;
using std::endl;





int main(char** argv)
{

    int fd;
    int ret,d;


    while(1)
    {
    if ((fd = open("/dev/cdrom",O_RDONLY | O_NONBLOCK)) < 0) {
        perror("open");
        exit(1);
    }
   
   
      ret = ioctl(fd,CDROM_DRIVE_STATUS,0);

      cout<<ret<<endl;

      switch(ret) {
      case CDS_NO_INFO:
          cout<<"CDS_NO_INFO"<<endl;
          break;
      case CDS_NO_DISC:
          cout<<"CDS_NO_DISC"<<endl;
          break;
      case CDS_TRAY_OPEN:
          cout<<"CDS_TRAY_OPEN"<<endl;
          d = ioctl(fd,CDROM_DISC_STATUS,0);
          cout<<d<<endl;
          break;
      case CDS_DRIVE_NOT_READY:
          cout<<"CDS_DRIVE_NOT_READY"<<endl;
          break;
      case CDS_DISC_OK:
          cout<<"CDS_DISC_OK"<<endl;
          d = ioctl(fd,CDROM_DISC_STATUS,0);
          cout<<d<<endl;
          switch(d){
          case CDS_NO_INFO:
            cout<<"CDS_NO_INFO"<<endl;
            break;
          case CDS_AUDIO:
            cout<<"CDS_AUDIO"<<endl;
            break;
          case CDS_XA_2_2:
            cout<<"CDS_XA_2_2"<<endl;
            break;
          case CDS_XA_2_1:
            cout<<"CDS_XA_2_1"<<endl;
            break;
          case CDS_DATA_1:
            cout<<"CDS_DATA_1"<<endl;
            break;
          case CDS_MIXED:
            cout<<"CDS_MIXED"<<endl;
            break;
          default:
            cout<<"SUPER ERROR 2"<<endl;
          }
          break;
      case -1:
          cout<<"ERROR"<<endl;
          cout<<errno<<endl;
          switch(errno) {
          case ENOSYS:
            cout<<"ENOSYS"<<endl;
            break;
          case EINVAL:
            cout<<"EINVAL"<<endl;
            break;
          case ENOMEM:
            cout<<"ENOMEM"<<endl;
            break;
          default:
            cout<<"ERRNO ERROR"<<endl;
          }
          break;
      default:
          cout<<"SUPER ERROR"<<endl;
      }
      usleep(100);
    }
    return 0;

}


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