派遣函数学习3）其他方式读写设备

来源：互联网发布：js json 数组编辑：程序博客网时间：2024/05/29 14:36

首先既不设置 DO_DIRECT_IO / DO_BUFFER_IO

派遣函数直接读写应用程序提供的缓冲区地址。直接操应用程序的缓冲区地址是很危险的

只有驱动程序与应用程序运行再相同线程上下文的时候，才能用这种方式

探测可读可写用： ProbeForWrite + try 块

NTSTATUS HelloDDKRead(IN PDEVICE_OBJECT pDevObj, IN PIRP pIrp) {KdPrint(("Enter HelloDDKRead\n"));PDEVICE_EXTENSION pDevExt = (PDEVICE_EXTENSION)pDevObj->DeviceExtension;NTSTATUS status = STATUS_SUCCESS;//得到当前堆栈PIO_STACK_LOCATION stack = IoGetCurrentIrpStackLocation(pIrp);//得到读的长度ULONG ulReadLength = stack->Parameters.Read.Length;//得到读的偏移量ULONG ulReadOffset = (ULONG)stack->Parameters.Read.ByteOffset.QuadPart;//得到用户模式地址PVOID user_address = pIrp->UserBuffer;KdPrint(("user_address:0X%0X\n",user_address));__try{KdPrint(("Enter __try block\n"));//判断空指针是否可写，显然会导致异常ProbeForWrite(user_address,ulReadLength,4);memset(user_address,0xAA,ulReadLength);//由于在上面引发异常，所以以后语句不会被执行!KdPrint(("Leave __try block\n"));}__except(EXCEPTION_EXECUTE_HANDLER){KdPrint(("Catch the exception\n"));KdPrint(("The program will keep going\n"));status = STATUS_UNSUCCESSFUL;}pIrp->IoStatus.Status = status;pIrp->IoStatus.Information = ulReadLength;// bytes xferedIoCompleteRequest( pIrp, IO_NO_INCREMENT );KdPrint(("Leave HelloDDKRead\n"));return status;}