使用C++ WRL打开UsbDevice - ERROR_INVALID_HANDLE

Question

我正在尝试获取一个Windows::Devices::Usb::UsbDevice引用我所拥有的特定USB设备的对象,以便将其传递给第三方插件.由于项目限制,我无法使用C++/CX扩展名.

在查看了无数的线程,答案和引用之后,我想出了一个初始实现,它可以在我需要的WinRT类上调用静态方法.唯一的问题是,即使没有调用导致失败HRESULT,最后一次调用FromIdAsync也不起作用,给我me ERROR_INVALID_HANDLE(6)作为结果GetLastError().

简单地读取错误名称会让我误认为是获取设备的ID,因为这是我传递该调用的唯一句柄,但我尝试传递一个常量字符串(我知道这是正确的)并且它产生了相同的结果.

这就是我调用FromIdAsync*的方式:

// Retrieves static methods for UsbDevice class
ComPtr<IUsbDeviceStatics> usbDevSt;
hr = GetActivationFactory(
    HStringReference(RuntimeClass_Windows_Devices_Usb_UsbDevice).Get(),
    &usbDevSt
);

// Creates an event to work as a 'semaphore', for waiting for the 'FromIdAsync'
// call to be completed
Event openEvent(CreateEventEx(
    nullptr,
    nullptr,
    CREATE_EVENT_MANUAL_RESET,
    WRITE_OWNER | EVENT_ALL_ACCESS
));
if (!openEvent.IsValid()) return nullptr;

// Setups a callback for when the device enumeration is done
auto asyncOpenCb = Callback<IAsyncOperationCompletedHandler<UsbDevice*>>(
    [&openEvent](IAsyncOperation<UsbDevice*> *opHandler, AsyncStatus status) -> HRESULT {
        if (!opHandler || status != AsyncStatus::Completed) {
            DWORD x = GetLastError(); // ERROR_INVALID_HANDLE (6)
        }

        SetEvent(openEvent.Get());
        return S_OK;
    }
);

// Invokes the 'asyncOpenOp' method, equivalent to UsbDevice::FromIdAsync(String)
ComPtr<IAsyncOperation<UsbDevice*>> asyncOpenOp;
hr = usbDevSt->FromIdAsync(
    devId.Get(),
    asyncOpenOp.GetAddressOf()
);

// Registers completed callback
hr = asyncOpenOp->put_Completed(asyncOpenCb.Get());

// Waits for open operation to complete before continuing
WaitForSingleObjectEx(openEvent.Get(), INFINITE, false);

// Retrieves the result from the asynchronous call
ComPtr<IUsbDevice> dev;
hr = asyncOpenOp->GetResults(dev.GetAddressOf());

这就是我得到的方式devId*:

// Retrieve static methods for DeviceInformation class
ComPtr<IDeviceInformationStatics> devInfoSt;
HRESULT hr = GetActivationFactory(
    HStringReference(RuntimeClass_Windows_Devices_Enumeration_DeviceInformation).Get(),
    &devInfoSt
);

// Create an event to work as a 'semaphore', for waiting for the 'FindAllAsyncAqsFilter' call to be completed
Event findEvent(CreateEventEx(
    nullptr,
    nullptr,
    CREATE_EVENT_MANUAL_RESET,
    WRITE_OWNER | EVENT_ALL_ACCESS
));
if (!findEvent.IsValid()) return nullptr;

// Setup a callback for when the device enumeration is done
auto asyncFindCb = Callback<IAsyncOperationCompletedHandler<DeviceInformationCollection*>>(
    [&findEvent](IAsyncOperation<DeviceInformationCollection*> *opHandler, AsyncStatus status) -> HRESULT {
        SetEvent(findEvent.Get());
        return S_OK;
    }
);

// Invoke the 'FindAllAsyncAqsFilter' method, equivalent to DeviceInformation::FindAllAsync(String)
ComPtr<IAsyncOperation<DeviceInformationCollection*>> asyncFindOp;
hr = devInfoSt->FindAllAsyncAqsFilter(
    HStringReference(DEVICE_FILTER).Get(),
    asyncFindOp.GetAddressOf()
);

// Registers completed callback
hr = asyncFindOp->put_Completed(asyncFindCb.Get());

// Waits for enumeration to complete before continuing
WaitForSingleObjectEx(findEvent.Get(), INFINITE, FALSE);

// Retrieves the result from the asynchronous call
ComPtr<IVectorView<DeviceInformation*>> devColl;
hr = asyncFindOp->GetResults(devColl.GetAddressOf());

// Checks for collection size
unsigned int collSize;
hr = devColl->get_Size(&collSize);

if (collSize == 0) {
    return nullptr;
}

// Retrieves the first DeviceInformation object from the collection
ComPtr<IDeviceInformation> devInfo;
hr = devColl->GetAt(0, devInfo.GetAddressOf());

// Retrieves the device's id
HString devId;
hr = devInfo->get_Id(devId.GetAddressOf());

另外,我这样做初始化WinRT:

RoInitializeWrapper initialize(RO_INIT_MULTITHREADED);
if (FAILED(initialize)) return nullptr;

---

*if (FAILED(hr)) return nullptr;为简洁起见,删除了多个.

Answer 1

GetLastError function

检索调用线程的最后一个错误代码值。
最后的错误代码是基于每个线程维护的。
多个线程不会覆盖彼此的最后一个错误代码。

但我尝试传递一个常量字符串（我知道这是正确的），它产生了相同的结果。

ERROR_INVALID_HANDLE
调用者在 InterfaceHandle 参数中传递了 NULL。

如上所述，您必须从以下位置获得结果HRESULT

[&openEvent](IAsyncOperation<UsbDevice*> *opHandler, AsyncStatus status) -> HRESULT 

我会尝试遍历集合以找出如何从中获取错误

https://msdn.microsoft.com/en-us/library/windows/apps/windows.devices.enumeration.deviceinformationcollection.indexof