Mounting & detecting DVD ROM

This is a discussion on Mounting & detecting DVD ROM within the Linux Programming forums, part of the Platform Specific Boards category; Hi, my boss wanted my application to be able to check whether the DVD ROM drive of the machine is ...

  1. #1
    In the Land of Diddly-Doo g4j31a5's Avatar
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    Mounting & detecting DVD ROM

    Hi, my boss wanted my application to be able to check whether the DVD ROM drive of the machine is faulty or not. So the user has to only click a button in the GUI, and if there's a DVD inside the drive and the it can read the disk, it will return a success value. Likewise, if it can't read the disk (ie. cannot mount disk, the drive's head is faulty, etc), it will return a failure value.

    The questions is:
    1. How do I mount from inside the application? Do I have to call:
    Code:
    system("mount ...");
    ??

    2. After the drive is successfully mounted, and then what? I don't have any clue as to what to do to check whether it can read any file on the disk. Or maybe I just call the "opendir()" function to see if it returned the directory pointer of the mounted DVD. But if a directory is successfully opened in the application, does that mean the drive itself is not faulty?

    Thanks in advance.
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    Frequently Quite Prolix dwks's Avatar
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    Since you seem to be using Linux or a compatible system, you could use exec*() instead of system(). But basically, if you need to launch the mount program, that's what you'd have to do. The nice thing about exec*() is that you'd be able to check the return value of mount and thus be able to tell if it succeeded or not.

    Supplying the path to mount (if it's the same between distros) would reduce the security risk involved in calling an external program. I don't think it's a constant, though.

    I think that mount will detect some errors related to the disk. For example, if it's unformatted or just plain not in the drive. So I wouldn't worry about that. If it's mounted, it's probably readable.

    Of course, it might not be the right disk. But that's another story. You could check the disk label, or perhaps some of the layout on the disk, to see if it's acceptable. Unless any disk's okay.
    dwk

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  3. #3
    In the Land of Diddly-Doo g4j31a5's Avatar
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    Quote Originally Posted by dwks View Post
    Since you seem to be using Linux or a compatible system, you could use exec*() instead of system(). But basically, if you need to launch the mount program, that's what you'd have to do. The nice thing about exec*() is that you'd be able to check the return value of mount and thus be able to tell if it succeeded or not.

    Supplying the path to mount (if it's the same between distros) would reduce the security risk involved in calling an external program. I don't think it's a constant, though.

    I think that mount will detect some errors related to the disk. For example, if it's unformatted or just plain not in the drive. So I wouldn't worry about that. If it's mounted, it's probably readable.

    Of course, it might not be the right disk. But that's another story. You could check the disk label, or perhaps some of the layout on the disk, to see if it's acceptable. Unless any disk's okay.
    But does that mean if the disk can be mounted, the DVD ROM always in a good condition? I don't know in Linux, but in Windows Explorer, even if the disk can recognize the label of the disk, it doesn't mean that the drive can always read the disk. For example, if the motor or the sensor is already weak, it probably can still read the label, but can't read the file within (in Windows Explorer). So how do I trace that kind of hardware error?
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