PIRP MupBuildIoControlRequest( IN OUT PIRP Irp OPTIONAL, IN PFILE_OBJECT FileObject OPTIONAL, IN PVOID Context, IN UCHAR MajorFunction, IN ULONG IoControlCode, IN PVOID MainBuffer, IN ULONG InputBufferLength, IN PVOID AuxiliaryBuffer OPTIONAL, IN ULONG OutputBufferLength, IN PIO_COMPLETION_ROUTINE CompletionRoutine ); Routine Description: This function builds an I/O request packet for a device or file system I/O control request. Arguments: Irp - Supplies a pointer to an IRP. If NULL, this routine allocates an IRP and returns its address. Otherwise, it supplies the address of an IRP allocated by the caller. FileObject - Supplies a pointer the file object to which this request is directed. This pointer is copied into the IRP, so that the called driver can find its file-based context. NOTE THAT THIS IS NOT A REFERENCED POINTER. The caller must ensure that the file object is not deleted while the I/O operation is in progress. The server accomplishes this by incrementing a reference count in a local block to account for the I/O; the local block in turn references the file object. Context - Supplies a PVOID value that is passed to the completion routine. MajorFunction - The major function that we are calling. Currently this most be one of IRP_MJ_FILE_SYSTEM_CONTROL or IRP_MJ_DEVICE_IO_CONTROL. IoControlCode - Supplies the control code for the operation. MainBuffer - Supplies the address of the main buffer. This must be a system virtual address, and the buffer must be locked in memory. If ControlCode specifies a method 0 request, the actual length of the buffer must be the greater of InputBufferLength and OutputBufferLength. InputBufferLength - Supplies the length of the input buffer. AuxiliaryBuffer - Supplies the address of the auxiliary buffer. If the control code method is 0, this is a buffered I/O buffer, but the data returned by the called driver in the system buffer is not automatically copied into the auxiliary buffer. Instead, the auxiliary data ends up in MainBuffer. If the caller wishes the data to be in AuxiliaryBuffer, it must copy the data at some point after the completion routine runs. If the control code method is 1 or 2, this parameter is ignored; instead, the Mdl parameter is used to obtain the starting virtual address of the buffer. CompletionRoutine - The IO completion routine. Return Value: PIRP - Returns a pointer to the constructed IRP. If the Irp parameter was not NULL on input, the function return value will be the same value (so it is safe to discard the return value in this case). It is the responsibility of the calling program to deallocate the IRP after the I/O request is complete.