FLT_PARAMETERS for IRP_MJ_DEVICE_CONTROL and IRP_MJ_INTERNAL_DEVICE_CONTROL union
Union component used when the MajorFunction field of the FLT_IO_PARAMETER_BLOCK structure for the operation is IRP_MJ_DEVICE_CONTROL or IRP_MJ_INTERNAL_DEVICE_CONTROL.
Syntax
typedef union _FLT_PARAMETERS {
... ;
union {
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT IoControlCode;
} Common;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT IoControlCode;
PVOID InputBuffer;
PVOID OutputBuffer;
PMDL OutputMdlAddress;
} Neither;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT IoControlCode;
PVOID SystemBuffer;
} Buffered;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT IoControlCode;
PVOID InputSystemBuffer;
PVOID OutputBuffer;
PMDL OutputMdlAddress;
} Direct;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT IoControlCode;
PVOID InputBuffer;
PVOID OutputBuffer;
} FastIo;
} DeviceIoControl;
... ;
} FLT_PARAMETERS, *PFLT_PARAMETERS;
Members
Common: Union component used for all buffering methods (Neither, Buffered, and FastIo).
OutputBufferLength: Length, in bytes, of the buffer that the Neither.OutputBuffer, Direct.OutputBuffer, or FastIo.OutputBuffer member points to.
InputBufferLength: Length, in bytes, of the buffer that the Neither.InputBuffer, Buffered.SystemBuffer, Direct.InputSystemBuffer, or FastIo.InputBuffer member points to.
IoControlCode: IOCTL function code to be passed to the device driver for the target device. For detailed information about IOCTL requests, see Using I/O Control Codes and "Device Input and Output Control Codes" in the Microsoft Windows SDK documentation. (This resource may not be available in some languages and countries.)
Neither: Union component used when the buffering method is METHOD_NEITHER. For more information about buffering methods, see Defining I/O Control Codes in the Kernel Mode Architecture Guide.
Neither.InputBuffer: User-mode virtual address of the input buffer that the original requester of the operation supplied. The I/O Manager and Filter Manager do not validate these addresses. To ensure that user-space addresses are valid, the minifilter must use routines such as ProbeForRead, ProbeForWrite, and FltLockUserBuffer, enclosing all buffer references in try/except blocks. For more information, see Using Neither Buffered Nor Direct I/O and Errors in Referencing User-Space Addresses.
Neither.OutputBuffer: User-mode virtual address of the output buffer that the original requester of the operation supplied. The I/O Manager and Filter Manager do not validate these addresses. To ensure that user-space addresses are valid, the minifilter must use routines such as ProbeForRead, ProbeForWrite, and FltLockUserBuffer, enclosing all buffer references in try/except blocks. For more information, see Using Neither Buffered Nor Direct I/O and Errors in Referencing User-Space Addresses in the Kernel Mode Architecture Guide.
Neither.OutputMdlAddress: Address of a memory descriptor list (MDL) that describes the buffer that the Neither.OutputBuffer member points to. This member is optional and can be NULL.
Buffered: Union component used when the buffering method is METHOD_BUFFERED. For more information about buffering methods, see Defining I/O Control Codes.
Buffered.SystemBuffer: Address of the system-allocated buffer for the operation. In METHOD_BUFFERED I/O, this buffer is used for both input and output. For more information, see Methods for Accessing Data Buffers.
Direct: Union component used when the buffering method is METHOD_IN_DIRECT or METHOD_OUT_DIRECT. For more information about buffering methods, see Defining I/O Control Codes.
Direct.InputSystemBuffer: Address of the input buffer for the operation. This buffer is locked down by the operating system so that it is safe to access from kernel mode. For more information, see Methods for Accessing Data Buffers.
Direct.OutputBuffer: User-mode virtual address of the output buffer that the original requester of the operation supplied. In direct I/O, unlike METHOD_NEITHER I/O, the operating system locks down this buffer so that it is safe to access from kernel mode, as long as the minifilter is in the same process context as the original requester of the I/O operation. (Otherwise it must call MmGetSystemAddressForMdlSafe to get the system address from the memory descriptor list (MDL) that the OutputMdlAddress member points to.) For more information, see Using Direct I/O and Errors in Direct I/O.
Direct.OutputMdlAddress: Address of an MDL that describes the buffer that the Direct.OutputBuffer member points to. This member is required and cannot be NULL.
FastIo: Union component used when the FLT_CALLBACK_DATA structure represents a fast I/O IRP_MJ_DEVICE_CONTROL operation.
FastIo.InputBuffer: User-mode virtual address of the input buffer that the original requester of the operation supplied. The I/O Manager and Filter Manager do not validate these addresses. To ensure that user-space addresses are valid, the minifilter must use routines such as ProbeForRead, ProbeForWrite, and FltLockUserBuffer, enclosing all buffer references in try/except blocks. For more information, see Errors in Referencing User-Space Addresses.
FastIo.OutputBuffer: User-mode virtual address of the output buffer that the original requester of the operation supplied. The I/O Manager and Filter Manager do not validate these addresses. To ensure that user-space addresses are valid, the minifilter must use routines such as ProbeForRead, ProbeForWrite, and FltLockUserBuffer, enclosing all buffer references in try/except blocks. For more information, see Errors in Referencing User-Space Addresses.
Remarks
The FLT_PARAMETERS structure for IRP_MJ_DEVICE_CONTROL and IRP_MJ_INTERNAL_DEVICE_CONTROL operations contains the parameters for an IRP-based device-I/O-control information operation represented by a callback data (FLT_CALLBACK_DATA) structure. It is contained in an FLT_IO_PARAMETER_BLOCK structure.
IRP_MJ_DEVICE_CONTROL can be an IRP-based operation or a fast I/O operation.
IRP_MJ_INTERNAL_DEVICE_CONTROL is an IRP-based I/O operation.
Requirements
| Requirement type | Requirement |
|---|---|
| Header | Fltkernel.h (include Fltkernel.h) |