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Chapter 4 - SCSI Manager 4.3 / SCSI Manager 4.3 Reference

SCSI Manager 4.3 Functions / Client Functions

SCSIAbortCommand

You can use the SCSIAbortCommand function to cancel an I/O request.

OSErr SCSIAction(SCSIAbortCommandPB *scsiPB);

scsiPB

A pointer to a SCSI abort command parameter block, which is described on page 4-33.

-->	scsiPBLength	UInt16	The size of the parameter block.
-->	scsiFunctionCode	UInt8	The SCSIAbortCommand function selector code (0x10).
<--	scsiResult	OSErr	The returned result code.
-->	scsiDevice	DeviceIdent	The device identification record.
-->	scsiCompletion	CallbackProc	A pointer to a completion routine. If this field is set to nil, the function is executed synchronously.
-->	scsiDriverStorage	UInt8 *	Optional pointer to the device driver's private storage.
-->	scsiIOptr	SCSI_IO *	A pointer to the SCSI I/O parameter block to be canceled.

DESCRIPTION

The SCSIAbortCommand function cancels the SCSIExecIO request identified by the scsiIOptr field. If the request has not yet been delivered to the device, it is removed from the queue and its completion routine is called with a result code of scsiRequestAborted. If the request has already been started, the SIM attempts to send an ABORT message to the device, either by asserting the /ATN signal or by reselecting the device. The function returns the scsiUnableToAbort result code if the specified request has already been completed.

SPECIAL CONSIDERATIONS

Because the interrupt that calls the completion routine can pre-empt the SCSIAbortCommand request, this function can produce unexpected results if the completion routine for the canceled request reuses the parameter block.

RESULT CODES

noErr	0	No error
scsiBusInvalid	-7869	The bus ID is invalid
scsiRequestInvalid	-7870	The parameter block request is invalid
scsiPBLengthError	-7872	The parameter block is too small for this SIM
scsiQLinkInvalid	-7881	The qLink field was not 0
scsiUnableToAbort	-7933	Unable to abort parameter block request

SEE ALSO

See the description of the SCSITerminateIO function on page 4-48 for information about another method of canceling a request.