Leet hax for kernel mode debug redirection

#define DbgPrint WriteLog //IN ALL HEADERS AFTER INCLUDING DDK HEADERS

void WriteLog(char *fmt, ...)
{
	va_list arglist;
	va_start(arglist, fmt);
	char *buffer = (char*)ExAllocatePool(NonPagedPool, 4096);
	memset(buffer, 0 , 4096);
	RtlStringCbVPrintfA(buffer, 4096, fmt, arglist);
	ULONG buflen = 0;
	RtlStringCbLengthA(buffer, 4096, (size_t*)&buflen);

	DbgPrintEx(DPFLTR_IHVDRIVER_ID, 0, buffer);

	if (buflen > 0)
	{
		/*setup log file*/
		UNICODE_STRING logName;
		OBJECT_ATTRIBUTES objAttribs;
		NTSTATUS status;
		HANDLE hFile;
		IO_STATUS_BLOCK ioStatus;
		RtlInitUnicodeString(&logName, L"\\DosDevices\\C:\\roothop.log");
		InitializeObjectAttributes(&objAttribs, &logName,
			OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
			NULL, NULL);
		if(KeGetCurrentIrql() != PASSIVE_LEVEL) goto _exitlogwrite;
		status = ZwCreateFile(&hFile, FILE_APPEND_DATA,
			&objAttribs, &ioStatus, NULL, FILE_ATTRIBUTE_NORMAL, 0,
			FILE_OPEN_IF, FILE_NON_DIRECTORY_FILE | FILE_RANDOM_ACCESS |
			FILE_NO_INTERMEDIATE_BUFFERING | FILE_SYNCHRONOUS_IO_NONALERT,
			NULL, 0);
		if (!NT_SUCCESS(status)) {
			DbgPrint("Failed to create log file\n");
			goto _exitlogwrite;
		}
		/*write log file*/
		ZwWriteFile(hFile, 0, 0, 0,
			&ioStatus, buffer, buflen, 0, 0);
		/*close log file*/
		ZwClose(hFile);
	}

	_exitlogwrite:;
	ExFreePool(buffer);
	va_end(arglist);
}