reactos/drivers/base/null/null.c

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/*
* PROJECT: ReactOS Kernel
* LICENSE: GPL - See COPYING in the top level directory
* FILE: drivers/base/null/null.c
* PURPOSE: Null Device Driver
* PROGRAMMERS: Alex Ionescu (alex.ionescu@reactos.org)
* David Welch (welch@mcmail.com)
*/
/* INCLUDES ******************************************************************/
#include <wdm.h>
/* FUNCTIONS *****************************************************************/
NTSTATUS
NTAPI
NullQueryFileInformation(OUT PVOID Buffer,
IN PULONG Length,
IN FILE_INFORMATION_CLASS InformationClass)
{
PFILE_STANDARD_INFORMATION StandardInfo = Buffer;
PAGED_CODE();
/* We only support one class */
if (InformationClass != FileStandardInformation)
{
/* Fail */
return STATUS_INVALID_INFO_CLASS;
}
/* Fill out the information */
RtlZeroMemory(StandardInfo, sizeof(FILE_STANDARD_INFORMATION));
StandardInfo->NumberOfLinks = 1;
/* Return the length and success */
*Length = sizeof(FILE_STANDARD_INFORMATION);
return STATUS_SUCCESS;
}
BOOLEAN
NTAPI
NullRead(IN PFILE_OBJECT FileObject,
IN PLARGE_INTEGER FileOffset,
IN ULONG Length,
IN BOOLEAN Wait,
IN ULONG LockKey,
OUT PVOID Buffer,
OUT PIO_STATUS_BLOCK IoStatus,
IN PDEVICE_OBJECT DeviceObject)
{
PAGED_CODE();
/* Complete successfully */
IoStatus->Status = STATUS_END_OF_FILE;
IoStatus->Information = 0;
return TRUE;
}
BOOLEAN
NTAPI
NullWrite(IN PFILE_OBJECT FileObject,
IN PLARGE_INTEGER FileOffset,
IN ULONG Length,
IN BOOLEAN Wait,
IN ULONG LockKey,
IN PVOID Buffer,
OUT PIO_STATUS_BLOCK IoStatus,
IN PDEVICE_OBJECT DeviceObject)
{
PAGED_CODE();
/* Complete successfully */
IoStatus->Status = STATUS_SUCCESS;
IoStatus->Information = Length;
return TRUE;
}
NTSTATUS
NTAPI
NullDispatch(IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp)
{
PIO_STACK_LOCATION IoStack = IoGetCurrentIrpStackLocation(Irp);
NTSTATUS Status;
PFILE_OBJECT FileObject;
ULONG Length;
PAGED_CODE();
/* Get the file object and check what kind of request this is */
FileObject = IoStack->FileObject;
switch (IoStack->MajorFunction)
{
case IRP_MJ_CREATE:
case IRP_MJ_CLOSE:
/* Check if this is synch I/O */
if (FileObject->Flags & FO_SYNCHRONOUS_IO)
{
/* Set distinguished value for Cc */
FileObject->PrivateCacheMap = (PVOID)1;
}
/* Complete successfully */
Irp->IoStatus.Status = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
break;
case IRP_MJ_READ:
/* Return as if we read the entire file */
Irp->IoStatus.Status = STATUS_END_OF_FILE;
Irp->IoStatus.Information = 0;
break;
case IRP_MJ_WRITE:
/* Return as if we wrote the entire request */
Irp->IoStatus.Status = STATUS_SUCCESS;
Irp->IoStatus.Information = IoStack->Parameters.Write.Length;
break;
case IRP_MJ_LOCK_CONTROL:
/* Dummy */
Irp->IoStatus.Status = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
break;
case IRP_MJ_QUERY_INFORMATION:
/* Get the length inputted and do the request */
Length = IoStack->Parameters.QueryFile.Length;
Irp->IoStatus.Status = NullQueryFileInformation(Irp->AssociatedIrp.
SystemBuffer,
&Length,
IoStack->
Parameters.
QueryFile.
FileInformationClass);
/* Return the actual length */
Irp->IoStatus.Information = Length;
break;
}
/* Complete the request */
Status = Irp->IoStatus.Status;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return Status;
}
NTSTATUS
NTAPI
DriverEntry(IN PDRIVER_OBJECT DriverObject,
IN PUNICODE_STRING RegistryPath)
{
PDEVICE_OBJECT DeviceObject;
UNICODE_STRING DeviceName = RTL_CONSTANT_STRING(L"\\Device\\Null");
NTSTATUS Status;
PFAST_IO_DISPATCH FastIoDispatch;
PAGED_CODE();
/* Page the driver */
MmPageEntireDriver(DriverEntry);
/* Create null device */
Status = IoCreateDevice(DriverObject,
0,
&DeviceName,
FILE_DEVICE_NULL,
0,
FALSE,
&DeviceObject);
if (!NT_SUCCESS(Status)) return Status;
/* Register driver routines */
DriverObject->MajorFunction[IRP_MJ_CLOSE] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_CREATE] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_WRITE] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_READ] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_LOCK_CONTROL] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_QUERY_INFORMATION] = NullDispatch;
/* Allocate the fast I/O dispatch table */
FastIoDispatch = ExAllocatePoolWithTag(NonPagedPool,
sizeof(FAST_IO_DISPATCH),
'llun');
if (!FastIoDispatch)
{
/* Failed, cleanup */
IoDeleteDevice(DeviceObject);
return STATUS_INSUFFICIENT_RESOURCES;
}
/* Initialize it */
RtlZeroMemory(FastIoDispatch, sizeof(FAST_IO_DISPATCH));
FastIoDispatch->SizeOfFastIoDispatch = sizeof(FAST_IO_DISPATCH);
/* Setup our pointers */
FastIoDispatch->FastIoRead = NullRead;
FastIoDispatch->FastIoWrite = NullWrite;
DriverObject->FastIoDispatch = FastIoDispatch;
/* Return success */
return STATUS_SUCCESS;
}
/* EOF */