c# - Win32Api USB SetupDiGetDeviceInterfaceDetail 失败

Question

我正在尝试连接到 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，SetupDiGetDeviceInterfaceDetail 调用失败。

我的 C 代码可以正常工作，但我的 C# 翻译似乎无法正常工作。我尝试了许多变体，但结果基本相同。

有效的 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);

<小时/>

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，它正在工作。您将得到一个 Unicode 字符串，它的长度是原来的两倍。 FALSE 返回是正确的。您只需调用 Marshal.GetLastWin32Error() 并验证您是否收到 ERROR_INSUFFICIENT_BUFFER。您的 C 代码已损坏，可能是因为您忘记初始化 theBytesReturned 为零。