ntdll/cdrom : implement CDROM_Verify to work on Mac Os

[Ken Thomases]

On Dec 31, 2010, at 1:38 PM, Ken Thomases wrote:

> Why does that matter?  The question is, under what circumstances does it end up in CDROM_Verify()?  What is the right behavior of CDROM_Verify() and how would that be implemented on Mac OS X?

I should add that this patch seem correct to me.  It couldn't hurt to get Charles Davis's input, of course.

CDROM_Verify() is called when CDROM_DeviceIoControl() gets a IOCTL_*_CHECK_VERIFY request.  CDROM_DeviceIoControl() is only called (from NtDeviceIoControlFile()) for the appropriate type of device and that's further verified (on Mac OS X) by the call to get_parent_device().

MSDN documents that the purpose of IOCTL_*_CHECK_VERIFY is to check if the media has changed.  The Linux and FreeBSD implementations basically just check if there's media in the drive.  On Mac OS X, the BSD device file just plain doesn't exist unless and until there's media mounted.  There's no permanent BSD device file for the drive itself.  So, if CDROM_Verify() is called, which requires that the BSD device file is opened and thus is present, that by itself implies that there's media in the drive.  Therefore, CDROM_Verify() should just return success.

Which is basically what Loïc said.  :)

-Ken