WDF内部IOCTL未返回输出

Question

我目前正在编写一个公开虚拟COM端口的驱动程序。在驱动程序中，我从端口FDO沿堆栈向下发送一个内部IOCTL，它是从PDO IO队列处理的。由于某些原因，输出数据未写入所提供的输出存储器。

我已经通过windbg确认了IoCtl_Vcp_GetPortInfo (如下所示)正在被调用，并且工作正常。该请求已使用STATUS_SUCCESS完成。在我调用WdfRequestComplete时，输出缓冲区具有有效数据。但是，当控制返回到GetPortInfo (见下文)时，提供的缓冲区没有被覆盖。我在访问接收缓冲区时使用硬件断点确认了这一点。在WdfIoTargetSendInteralIoctlSynchronously调用期间，它不会被读取或写入。

负责发送IOCTL的代码如下：

NTSTATUS GetPortInfo(WDFDEVICE device, _Out_ PVCH_PORT_INFO port_info)
{
       NTSTATUS status;
       WDFIOTARGET io_target;
       WDF_MEMORY_DESCRIPTOR output_descriptor;
       PVOID buffer = ExAllocatePoolWithTag(NonPagedPool, sizeof(VCH_PORT_INFO), VCH_POOL_TAG);

       //WDF_MEMORY_DESCRIPTOR_INIT_BUFFER(&output_descriptor, port_info, sizeof(VCH_PORT_INFO));
       WDF_MEMORY_DESCRIPTOR_INIT_BUFFER(&output_descriptor, buffer, sizeof(VCH_PORT_INFO));

       io_target = WdfDeviceGetIoTarget(device);
       status = WdfIoTargetSendInternalIoctlSynchronously(io_target, NULL, IOCTL_VCP_INTERNAL_GET_PORT_INFO, NULL, &output_descriptor, NULL, NULL);
       DbgBreakPoint();
       if (!NT_SUCCESS(status))
              return status;

       memcpy(port_info, buffer, sizeof(VCH_PORT_INFO));
       ExFreePoolWithTag(buffer, VCH_POOL_TAG);

       return STATUS_SUCCESS;
}

处理IOCTL的代码：

NTSTATUS IoCtl_Vcp_GetPortInfo(WDFDEVICE device, WDFREQUEST request)
{
       NTSTATUS status;
       PVCH_PORT_INFO buffer;
       PPORT_PDO_DESCRIPTOR descriptor = PortPdoGetContext(device);

       status = WdfRequestRetrieveOutputBuffer(request, sizeof(VCH_PORT_INFO), (PVOID*)&buffer, NULL);
       if (!NT_SUCCESS(status))
              return status;

       buffer->Address = descriptor->Address;
       buffer->ForceComIndex = FALSE; // TODO: Implement
       buffer->Writeable = descriptor->Writeable;
       DbgBreakPoint();
       return STATUS_SUCCESS;
}

IOCTL代码定义：

#define DEVICE_TYPE_VIRTUAL_COM_PORT 0xC51
#define IOCTL_VCP_INTERNAL_GET_PORT_INFO CTL_CODE(DEVICE_TYPE_VIRTUAL_COM_PORT, 0x30, METHOD_BUFFERED, FILE_READ_DATA)

Answer 1

将请求完成信息设置为输出字节数可以解决此问题。