Chris Cant - Writing Windows WDM Device Drivers

}

///////////////////////////////////////////////////////////////////////

//Wdm1Close:

//

//Description:

//Handle IRP_MJ_CLOSE requests

//

//Arguments:

//Pointer to our FDO

//Pointer to the IRP

//

//Return Value:

//This function returns STATUS_XXX

NTSTATUS Wdm1Close(IN PDEVICE_OBJECT fdo, IN PIRP Irp) {

DebugPrintMsg("Close");

// Complete successfully

return CompleteIrp(Irp,STATUS_SUCCESS,0);

}

///////////////////////////////////////////////////////////////////////

//Wdm1Read:

//

//Description:

//Handle IRP_MJ_READ requests

//

//Arguments:

//Pointer to our FDO

//Pointer to the IRP

//IrpStack->Parameters.Read.xxx has read parameters

//User buffer at:AssociatedIrp.SystemBuffer(buffered I/O)

//MdlAddress(direct I/O)

//

//Return Value:

//This function returns STATUS_XXX

NTSTATUS Wdm1Read(IN PDEVICE_OBJECT fdo, IN PIRP Irp) {

PIO_STACK_LOCATION IrpStack = IoGetCurrentIrpStackLocation(Irp);

NTSTATUS status = STATUS_SUCCESS;

LONG BytesTxd = 0;

// Get call parameters

LONGLONG FilePointer = IrpStack->Parameters.Read.ByteOffset.QuadPart;

ULONG ReadLen = IrpStack->Parameters.Read.Length;

DebugPrint("Read %d bytes from file pointer %d",(int)ReadLen,(int)FilePointer);

// Get access to the shared buffer

KIRQL irql;

KeAcquireSpinLock(&BufferLock,&irql);

// Check file pointer

if (FilePointer<0) status = STATUS_INVALID_PARAMETER;

if (FilePointer>=(LONGLONG)BufferSize) status = STATUS_END_OF_FILE;

if (status==STATUS_SUCCESS) {

// Get transfer count

if ( ((ULONG)FilePointer)+ReadLen>BufferSize) {

BytesTxd = BufferSize – (ULONG)FilePointer;

if (BytesTxd<0) BytesTxd = 0;

} else BytesTxd = ReadLen;

// Read from shared buffer

if (BytesTxd>0 && Buffer!=NULL) RtlCopyMemory(Irp->AssociatedIrp.SystemBuffer, Buffer+FilePointer, BytesTxd);

}

// Release shared buffer

KeReleaseSpinlock(&BufferLock,irql);

DebugPrint("Read: %d bytes returned",(int)BytesTxd);

// Complete IRP

return Completelrp(Irp.status.BytesTxd);

}

///////////////////////////////////////////////////////////////////////

//Wdm1Write: //

//Description:

//Handle IRP_MJ_WRITE requests

//

//Arguments:

//Pointer to our FDO

//Pointer to the IRP

//IrpStack->Parameters.Write.xxx has write parameters

//User buffer at:AssociatedIrp.SystemBuffer(buffered I/O)

//MdlAddress(direct I/O)

//

//Return Value:

//This function returns STATUS_XXX

NTSTATUS Wdm1Write(IN PDEVICE_OBJECT fdo, IN PIRP Irp) {

PIO_STACK_LOCATION IrpStack = IoGetCurrentIrpStackLocation(Irp);

NTSTATUS status = STATUS_SUCCESS;

LONG BytesTxd = 0;

// Get call parameters

LONGLONG FilePointer = IrpStack->Parameters.Write.ByteOffset.QuadPart;

ULONG WriteLen = IrpStack->Parameters.Write.Length;

DebugPrint("Write %d bytes from file pointer %d",(int)WriteLen,(int)FilePointer);

if (FilePointer<0) status = STATUS_INVALID_PARAMETER;

else {

// Get access to the shared buffer

KIRQL irql;

KeAcquireSpinLock(&BufferLock,&irql);

BytesTxd = WriteLen;

// (Re)allocate buffer if necessary

if ( ((ULONG)FilePointer)+WriteLen>BufferSize) {

ULONG NewBufferSize = ((ULONG)FilePointer)+WriteLen;

PVOID NewBuffer = ExAllocatePool(NonPagedPool.NewBufferSize);

if (NewBuffer==NULL) {

BytesTxd = BufferSize – (ULONG)FilePointer;

if (BytesTxd<0) BytesTxd = 0;

} else {

RtlZeroMemory(NewBuffer,NewBufferSize);

if (Buffer==NULL) {

RtlCopyMemory(NewBuffer,Buffer,BufferSize);

ExFreePool(Buffer);

}

Buffer = (PUCHAR)NewBuffer;

BufferSize = NewBufferSize;

}

}

// Write to shared memory

if (BytesTxd>0 && Buffer!=NULL) RtlCopyMemory(Buffer+FilePointer, Irp->AssociatedIrp.SystemBuffer, BytesTxd);

// Release shared buffer

KeReleaseSpinLock(&BufferLock,irq1);

}

DebugPrint("Write: %d bytes written", (int)BytesTxd);

// Complete IRP

return CompleteIrp(Irp,status,BytesTxd);

}

///////////////////////////////////////////////////////////////////////

//WdmlDeviceControl:

//

//Description:

//Handle IRP_MJ_DEVICE_CONTROL requests

//

//Arguments:

//Pointer to our FDO

//Pointer to the IRP

//Buffered:AssociatedIrp.SystemBuffer (and IrpStack-Parameters.DeviceIoControl.Type3InputBuffer)

//Direct:MdlAddress

//

//IrpStack->Parameters.DeviceIoControl.InputBufferLength

//IrpStack->Parameters.DeviceIoControl.OutputBufferLength

//

//Return Value:

//This function returns STATUS_XXX

NTSTATUS Wdm1DeviceControl(IN PDEVICE_OBJECT fdo, IN PIRP Irp) {

PIO_STACK_LOCATION IrpStack = IoGetCurrentIrpStackLocation(Irp);

NTSTATUS status – STATUS_SUCCESS;

ULONG BytesTxd = 0;

ULONG ControlCode = IrpStack->Parameters.DeviceIoControl.IoControlCode;

ULONG InputLength = IrpStack->Parameters.DeviceIoControl.InputBufferLength;

ULONG OutputLength = IrpStack->Parameters.DeviceIoControl.OutputBufferLength;

DebugPrint("DeviceIoControl: Control code %x InputLength %d OutputLength %d", ControlCode, InputLength, OutputLength);

// Get access to the shared buffer KIRQL irql ;

KeAcquireSpinLock(&BufferLock,&irql);

switch (ControlCode) {

///////Zero Buffer

case IOCTL_WDM1_ZERO_BUFFER:

// Zero the buffer

if (Buffer!=NULL && BufferSize>0) RtlZeroMemory(Buffer,BufferSize);

break;

///////Remove Buffer

case IOCTL_WDM1_REMOVE_BUFFER:

if (Buffer!=NULL) {

ExFreePool(Buffer);