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.

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.

For more information, see I/O Status Blocks.

Requirements

Headers: Defined in Wdm.h. Include Wdm.h, Ntddk.h, or Ntifs.h.

See Also

IO_STACK_LOCATION, IoCompleteRequest, IoSetCompletionRoutine, IRP