Question

我正在尝试连接USB GPS设备。如果我通过CreateFile WinApi手动创建文件（使用设备管理器中指定的路径），我可以成功连接到设备。

但是，当我尝试通过枚举选择设备时，我失败了@ SetupDiGetDeviceInterfaceDetail调用。

我的C代码工作正常，但我的C＃转换似乎无法正常工作。我尝试了很多变化，结果基本相同。

可行的C代码

// Get enumerator handle for the specified ClassGuid
HDEVINFO theDevInfo = SetupDiGetClassDevs((GUID*)&GUID_DEVINTERFACE_GRMNUSB, NULL, NULL,
    DIGCF_PRESENT | DIGCF_INTERFACEDEVICE);

SP_DEVICE_INTERFACE_DATA theInterfaceData;
theInterfaceData.cbSize = sizeof(theInterfaceData);

// populate theInterfaceData which contains device class information
if (!SetupDiEnumDeviceInterfaces(theDevInfo, NULL, (GUID*)&GUID_DEVINTERFACE_GRMNUSB, 0, &theInterfaceData) &&
    GetLastError() == ERROR_NO_MORE_ITEMS)
{
  gHandle = 0;
  return;
}
// This is normally used to obtain the device path information using theInterfaceData obtained above
bool initialized = SetupDiGetDeviceInterfaceDetail(theDevInfo, &theInterfaceData, NULL, 0, &theBytesReturned, NULL);
// theBytesReturned = 83
theDevDetailData =
(PSP_INTERFACE_DEVICE_DETAIL_DATA)malloc(theBytesReturned);
theDevDetailData->cbSize = sizeof(SP_INTERFACE_DEVICE_DETAIL_DATA);

bool initialized = SetupDiGetDeviceInterfaceDetail(theDevInfo, &theInterfaceData, theDevDetailData, theBytesReturned, NULL, &theDevInfoData);

C＃

[DllImport(@"setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern Boolean SetupDiGetDeviceInterfaceDetail(
    IntPtr hDevInfo,
    ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData,
    IntPtr deviceInterfaceDetailData,
    UInt32 deviceInterfaceDetailDataSize,
    out UInt32 requiredSize,
    IntPtr deviceInfoData
    );

[StructLayout(LayoutKind.Sequential)]
public struct SP_DEVICE_INTERFACE_DATA
{
    public Int32 cbSize;
    public Guid interfaceClassGuid;
    public Int32 flags;
    private UIntPtr reserved;
}


// Get enumerator handle for the specified ClassGuid
IntPtr theDevInfo = SetupDiGetClassDevs(ref ClassGuid, (DiGetClassFlags.DIGCF_PRESENT | DiGetClassFlags.DIGCF_DEVICEINTERFACE));

SP_DEVICE_INTERFACE_DATA DevInterfaceData = new SP_DEVICE_INTERFACE_DATA();
DevInterfaceData.cbSize = Marshal.SizeOf(DevInterfaceData);

initialized = SetupDiEnumDeviceInterfaces(theDevInfo, IntPtr.Zero, ref ClassGuid, 0,
        ref DevInterfaceData); 
// I assume The DevInterfaceData is populated correctly as it matches the C Code
// And I've compared the values in memory and they match

uint bytesReturned = 0;
initialized = SetupDiGetDeviceInterfaceDetail(theDevInfo, ref DevInterfaceData, IntPtr.Zero, 0, out bytesReturned, IntPtr.Zero);
// I expect bytesReturned = 83 and initialized = true which is the value that is returned in the C Code
// Instead the value 162 is returned

Answer 1

恭喜，它正在运作。你会得到一个Unicode字符串，它的长度是你的两倍。并且FALSE返回是正确的。您只需要调用Marshal.GetLastWin32Error（）并验证您是否获得了ERROR_INSUFFICIENT_BUFFER。你的C代码坏了，可能是因为你忘了将theBytesReturned初始化为零。

Answer 2

我相信我发现了问题。

在pinvoke.net上戳了之后，我发现了以下内容

// build a Device Interface Detail Data structure
 SP_DEVICE_INTERFACE_DETAIL_DATA didd = new SP_DEVICE_INTERFACE_DETAIL_DATA();
 if (IntPtr.Size == 8) // for 64 bit operating systems
     didd.cbSize = 8; 
 else  didd.cbSize = 4 + Marshal.SystemDefaultCharSize; // for 32 bit systems

在我的代码中更改此设置可让我正确获取DevicePath。

感兴趣的人的参考。

http://pinvoke.net/default.aspx/setupapi.SetupDiGetDeviceInterfaceDetail

Win32Api USB SetupDiGetDeviceInterfaceDetail失败

2 个答案: