WDF内部IOCTL不返回输出

问题描述：

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向下发送从PDO IO队列处理的内部IOCTL。出于某种原因，输出数据不会写入所提供的输出存储器。WDF内部IOCTL不返回输出

我已经通过windbg确认IoCtl_Vcp_GetPortInfo（见下文）被调用，并按预期工作。该请求通过STATUS_SUCCESS完成。在我调用WdfRequestComplete的时候，输出缓冲区有有效的数据。但是，当控制权返回到GetPortInfo（见下文）时，所提供的缓冲区未被覆盖。我用接收缓冲区的访问硬件断点证实了这一点。它不会在WdfIoTargetSendInteralIoctlSynchronously调用期间读取或写入。

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; 
}

处理该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; 
}

的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)

答

设置请求带有输出字节数的完成信息修复了问题。

WDF内部IOCTL不返回输出

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