直接方式读写

NTSTATUS DRIVER_DispatchRead(PDEVICE_OBJECT pDeviceObject,PIRP pIrp)
{
	NTSTATUS ntStatus=STATUS_UNSUCCESSFUL;
	__try
	{
		PIO_STACK_LOCATION pStack=IoGetCurrentIrpStackLocation(pIrp);
		PDEVICE_EXTENSION pdx=(PDEVICE_EXTENSION)pDeviceObject->DeviceExtension;

		ULONG ulReadLen=pStack->Parameters.Read.Length;	// 要读取的长度
		LONGLONG ulReadOffset=pStack->Parameters.Read.ByteOffset.QuadPart;
		PVOID pMdlAdd=MmGetMdlVirtualAddress(pIrp->MdlAddress);	// 锁定缓冲区虚拟地址
		ULONG ulMdlOffset=MmGetMdlByteOffset(pIrp->MdlAddress);	// 锁定缓冲区虚拟偏移
		ULONG ulMdlLen=MmGetMdlByteCount(pIrp->MdlAddress);	// 锁定缓冲区长度
		if (ulReadLen==ulMdlLen)
		{
			PVOID pKernelAdd=MmGetSystemAddressForMdlSafe(pIrp->MdlAddress,NormalPagePriority);	//锁定缓冲区内核映射
			RtlCopyMemory(pKernelAdd,pdx->pBuf+ulReadOffset,ulReadLen);
			pIrp->IoStatus.Information=ulReadLen;
			pIrp->IoStatus.Status=STATUS_SUCCESS;
			ntStatus=STATUS_SUCCESS;
			IoCompleteRequest(pIrp,IO_NO_INCREMENT);
			KdPrint(("Read Successfulrn"));
		}
		else
		{
			pIrp->IoStatus.Information=0;
			pIrp->IoStatus.Status=STATUS_UNSUCCESSFUL;
			ntStatus=STATUS_UNSUCCESSFUL;
			KdPrint(("Read exceptrn"));
		}
	}
	__except(EXCEPTION_EXECUTE_HANDLER)
	{
		KdPrint(("Read Failern"));
		pIrp->IoStatus.Information=0;
		pIrp->IoStatus.Status=STATUS_UNSUCCESSFUL;
		ntStatus=STATUS_UNSUCCESSFUL;
	}
	return ntStatus;
}

NTSTATUS DRIVER_DispatchWrite(PDEVICE_OBJECT pDeviceObject,PIRP pIrp)
{
	NTSTATUS ntStatus=STATUS_UNSUCCESSFUL;
	__try
	{
		PIO_STACK_LOCATION pStack=IoGetCurrentIrpStackLocation(pIrp);
		PDEVICE_EXTENSION pdx=(PDEVICE_EXTENSION)pDeviceObject->DeviceExtension;

		PVOID pMdlAdd=MmGetMdlVirtualAddress(pIrp->MdlAddress);	// 锁定缓冲区虚拟地址
		ULONG ulMdlOffset=MmGetMdlByteOffset(pIrp->MdlAddress);	// 锁定缓冲区虚拟偏移
		ULONG ulMdlLen=MmGetMdlByteCount(pIrp->MdlAddress);	// 锁定缓冲区长度

		ULONG ulWriteLen=pStack->Parameters.Write.Length;
		LONGLONG ulWriteOffset=pStack->Parameters.Write.ByteOffset.QuadPart;
		PVOID pKernelAdd=MmGetSystemAddressForMdlSafe(pIrp->MdlAddress,NormalPagePriority);
		RtlCopyMemory(pdx->pBuf+ulWriteOffset,pKernelAdd,ulWriteLen);	// 将用户数据存储至设备扩展
		pdx->ulFileLen+=ulWriteLen;
		pIrp->IoStatus.Information=ulWriteLen;
		pIrp->IoStatus.Status=STATUS_SUCCESS;
		ntStatus=STATUS_SUCCESS;
		KdPrint(("Write successfulrn"));
	}
	__except(EXCEPTION_EXECUTE_HANDLER)
	{
		pIrp->IoStatus.Information=0;
		pIrp->IoStatus.Status=STATUS_UNSUCCESSFUL;
		ntStatus=STATUS_UNSUCCESSFUL;
		KdPrint(("Write exceptrn"));
	}
	IoCompleteRequest(pIrp,IO_NO_INCREMENT);
	return ntStatus;
}

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