ChangerGetElementStatus function (mcd.h)

Article
10/21/2021

ChangerGetElementStatus handles the device-specific aspects of a device-control IRP with the IOCTL code IOCTL_CHANGER_GET_ELEMENT_STATUS.

Syntax

NTSTATUS ChangerGetElementStatus(
  [in] PDEVICE_OBJECT DeviceObject,
  [in] PIRP           Irp
);

Parameters

[in] DeviceObject

Pointer to the device object that represents the changer.

[in] Irp

Pointer to the IRP.

Return value

ChangerGetElementStatus returns the status returned by the system port driver or one of the following values:

STATUS_SUCCESS

STATUS_INFO_LENGTH_MISMATCH

STATUS_INSUFFICIENT_RESOURCES

STATUS_INVALID_DEVICE_REQUEST

STATUS_INVALID_ELEMENT_ADDRESS

If VolumeTagInfo is set for a changer that does not support volume tag information, ChangerGetElementStatus returns STATUS_INVALID_PARAMETER.

Remarks

This routine is required.

ChangerGetElementStatus returns the status and, optionally, volume tag information for all elements in a changer, or the status of a specific number of elements of a particular type.

The changer class driver checks the input and output buffer lengths in the I/O stack location before calling ChangerGetElementStatus.

Irp->SystemBuffer points to a CHANGER_READ_ELEMENT_STATUS structure as an input parameter that indicates the elements for which to report status and whether to report volume tag information.

ChangerGetElementStatus first builds an SRB with a CDB to read element status command and sends it to the system port driver to retrieve the status of the changer's elements. For most element types, ChangerGetElementStatus then fills in a CHANGER_ELEMENT_STATUS structure at Irp->AssociatedIrp.SystemBuffer for each element for which it reports status. However, some elements of type ChangerDrive return product information data. If the device provides product information, the miniclass driver must report the element status data in a structure of type CHANGER_ELEMENT_STATUS_EX instead of using CHANGER_ELEMENT_STATUS. ChangerGetElementStatus must indicate that product information is present by setting ELEMENT_STATUS_PRODUCT_DATA in the Flags member of the structure.

ChangerGetElementStatus sets the Information field in the I/O status block to the number of bytes returned before returning to the changer class driver.

Requirements

Requirement	Value
Target Platform	Desktop
Header	mcd.h (include Mcd.h, Ntddchgr.h)
IRQL	PASSIVE_LEVEL