IO_STATUS_BLOCK

A driver sets an IRP's I/O status block to indicate the final status of an I/O request, before calling IoCompleteRequest for the IRP.

typedef struct _IO_STATUS_BLOCK {
    union {
        NTSTATUS Status;
        PVOID Pointer;
    };
    ULONG_PTR Information;
} IO_STATUS_BLOCK, *PIO_STATUS_BLOCK;

Members

Status

This is the completion status, either STATUS_SUCCESS if the requested operation was completed successfully or an informational, warning, or error STATUS_XXX value. For more information, see Using NTSTATUS values.

Pointer

Reserved. For internal use only.

Information

This is set to a request-dependent value. For example, on successful completion of a transfer request, this is set to the number of bytes transferred. If a transfer request is completed with another STATUS_XXX, this member is set to zero.

Headers

Defined in wdm.h and ntddk.h. Include wdm.h or ntddk.h.

Comments

Unless a driver's dispatch routine completes an IRP with an error status value, the lowest-level driver in the chain frequently sets the IRP's I/O status block to the values that will be returned to the original requester of the I/O operation.

The IoCompletion routines of higher-level drivers usually check the I/O status block in IRPs completed by lower drivers. By design, the I/O status block in an IRP is the only information passed back from the underlying device driver to all higher-level drivers’ IoCompletion routines.

See Also

IO_STACK_LOCATION, IoCompleteRequest, IoSetCompletionRoutine, IRP