Legacy Document

Inside Macintosh: Devices /

Chapter 1 - Device Manager / Device Manager Reference

Device Manager Functions / Opening and Closing Device Drivers

CloseDriver

You can use the CloseDriver function to close an open device driver.

pascal OSErr CloseDriver(short refNum); 

refNum

The driver reference number returned by the driver-opening function.

DESCRIPTION

The CloseDriver function closes the device driver indicated by the refNum parameter. The Device Manager waits until the driver is inactive before calling the driver's close routine. When the driver indicates it has processed the close request, the Device Manager unlocks the driver resource if the dRAMBased flag is set, and unlocks the device control entry if the dNeedLock flag is not set. The Device Manager does not dispose of the device control entry or remove it from the unit table.

This function is a high-level version of the low-level PBClose function. Use the PBClose function when you want to specify a completion routine.

WARNING

You should not close drivers that other applications may be using, such as a disk driver, the AppleTalk drivers, and so on.

SPECIAL CONSIDERATIONS

The Device Manager does not queue close requests.

WARNING

Do not call the CloseDriver function at interrupt time because if the driver was processing a request when the interrupt occurred the Device Manager may loop indefinitely, waiting for the driver to complete the request.

RESULT CODES

noErr	0	No error
badUnitErr	-21	Driver reference number does not match unit table
unitEmptyErr	-22	Driver reference number specifies a nil handle in unit table
closErr	-24	Driver unable to complete close request
dRemovErr	-25	Attempt to remove an open driver

SEE ALSO

For information about the low-level function for closing device drivers, see the next section, which describes the PBClose function.