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[NULL] Additions for the Null driver.

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- Allow the driver to be unloaded, as on Windows.
- Use a static fast IO dispatch table, instead of allocating one and
  risking any potential memory allocation failure.
- Update the file header.
This commit is contained in:
Hermès Bélusca-Maïto 2018-04-22 22:13:52 +02:00
parent 63b6df6bc5
commit da5dcdcbf2
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GPG key ID: 3B2539C65E7B93D0
1 changed files with 36 additions and 28 deletions
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64
drivers/base/null/null.c
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@ -1,16 +1,19 @@
/*
* 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)
* PROJECT: ReactOS Kernel
* LICENSE: GPL-2.0+ (https://spdx.org/licenses/GPL-2.0+)
* PURPOSE: Null Device Driver
* COPYRIGHT: Copyright 1998-2018 David Welch (welch@mcmail.com)
* Copyright 2007-2018 Alex Ionescu (alex.ionescu@reactos.org)
*/
/* INCLUDES ******************************************************************/
#include <wdm.h>
/* GLOBALS *******************************************************************/
FAST_IO_DISPATCH FastIoDispatch;
/* FUNCTIONS *****************************************************************/
NTSTATUS
@ -20,6 +23,7 @@ NullQueryFileInformation(OUT PVOID Buffer,
IN FILE_INFORMATION_CLASS InformationClass)
{
PFILE_STANDARD_INFORMATION StandardInfo = Buffer;
PAGED_CODE();
/* We only support one class */
@ -81,10 +85,11 @@ NTAPI
NullDispatch(IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp)
{
PIO_STACK_LOCATION IoStack = IoGetCurrentIrpStackLocation(Irp);
NTSTATUS Status;
PIO_STACK_LOCATION IoStack = IoGetCurrentIrpStackLocation(Irp);
PFILE_OBJECT FileObject;
ULONG Length;
PAGED_CODE();
/* Get the file object and check what kind of request this is */
@ -150,21 +155,33 @@ NullDispatch(IN PDEVICE_OBJECT DeviceObject,
return Status;
}
VOID
NTAPI
NullUnload(IN PDRIVER_OBJECT DriverObject)
{
PDEVICE_OBJECT DeviceObject = DriverObject->DeviceObject;
/* Delete the Null device */
IoDeleteDevice(DeviceObject);
}
NTSTATUS
NTAPI
DriverEntry(IN PDRIVER_OBJECT DriverObject,
IN PUNICODE_STRING RegistryPath)
{
NTSTATUS Status;
PDEVICE_OBJECT DeviceObject;
UNICODE_STRING DeviceName = RTL_CONSTANT_STRING(L"\\Device\\Null");
NTSTATUS Status;
PFAST_IO_DISPATCH FastIoDispatch;
PAGED_CODE();
UNREFERENCED_PARAMETER(RegistryPath);
/* Page the driver */
MmPageEntireDriver(DriverEntry);
/* Create null device */
/* Create the Null device */
Status = IoCreateDevice(DriverObject,
0,
&DeviceName,
@ -172,7 +189,8 @@ DriverEntry(IN PDRIVER_OBJECT DriverObject,
0,
FALSE,
&DeviceObject);
if (!NT_SUCCESS(Status)) return Status;
if (!NT_SUCCESS(Status))
return Status;
/* Register driver routines */
DriverObject->MajorFunction[IRP_MJ_CLOSE] = NullDispatch;
@ -181,26 +199,16 @@ DriverEntry(IN PDRIVER_OBJECT DriverObject,
DriverObject->MajorFunction[IRP_MJ_READ] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_LOCK_CONTROL] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_QUERY_INFORMATION] = NullDispatch;
DriverObject->DriverUnload = NullUnload;
/* 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);
/* Initialize the fast I/O dispatch table */
RtlZeroMemory(&FastIoDispatch, sizeof(FastIoDispatch));
FastIoDispatch.SizeOfFastIoDispatch = sizeof(FastIoDispatch);
/* Setup our pointers */
FastIoDispatch->FastIoRead = NullRead;
FastIoDispatch->FastIoWrite = NullWrite;
DriverObject->FastIoDispatch = FastIoDispatch;
FastIoDispatch.FastIoRead = NullRead;
FastIoDispatch.FastIoWrite = NullWrite;
DriverObject->FastIoDispatch = &FastIoDispatch;
/* Return success */
return STATUS_SUCCESS;