Before locking the device, the caller must open it in read/write access mode. If the device is already locked, the class driver returns the identification string of the current owner of the device.
The class driver uses this string to identify the application that has exclusive access.Īpplications should query for the current state of the device before attempting to lock it. When the caller makes this request, the caller must provide an identification string in the CallerName member of CDROM_EXCLUSIVE_LOCK. To use the exclusive access mechanism, applications must send an IOCTL_CDROM_EXCLUSIVE_ACCESS request to the CD-ROM class driver at PASSIVE_LEVEL IRQL. You should not use filter drivers to obtain exclusive access to CD-ROM devices. Without the exclusive access mechanism, the only way for vendors to give these two types of applications exclusive access would be to install a custom filter driver that fails I/O requests from other applications and components, and this approach causes system instability. If an application sends a command to the device during a firmware update, it might make the device unusable. Many manufacturers of CD-ROM devices provide a firmware update utility. Otherwise, data might be written incorrectly, causing data corruption. Some optical authoring software requires exclusive access to a CD-ROM device to write data without any interruption from other applications.
Applications that require exclusive access to CD-ROM devices include the following examples: The CD-ROM exclusive access mechanism (also known as exclusive access mode) enables applications and system components to obtain exclusive access to a CD-ROM device.
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