Win32Api USB SetupDiGetDeviceInterfaceDetail fail
Solution 1
I believe I found the problem.
After poking around pinvoke.net, I found the following
// 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
Changing this in my code allows me to obtain the DevicePath properly.
Reference for those interested.
http://pinvoke.net/default.aspx/setupapi.SetupDiGetDeviceInterfaceDetail
Solution 2
Congratulations, it is working. You'll get a Unicode string, it's twice as long. And a FALSE return is correct. You just need to call Marshal.GetLastWin32Error() and verify that you got ERROR_INSUFFICIENT_BUFFER. Your C code is broken, probably because you forgot to initialize theBytesReturned to zero.
galford13x
Updated on June 04, 2022Comments
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galford13x almost 2 years
I am attempting to connect to a USB GPS device. I can successfully connect to the device if I manually create a file via CreateFile WinApi (using the path specified in Device Manager).
However, when I try to select the device through enumeration I fail @ the SetupDiGetDeviceInterfaceDetail call.
I have C code that works correctly, but my C# translation does not appear to work correctly. I have tried many variations with essentially the same results.
C Code that works
// 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
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user1703401 about 12 yearsNo, that corrupts the stack. Use Marshal.AllocHGlobal() to allocate the buffer with the required size. The size you got from the first call.
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galford13x about 12 yearsThe C code works properly. It was the C# code that did not work properly. theBytesReturned is initialized to 0, it's just not shown in the above code as I didn't put the entire function to save space. I guess the C code returned 83 bytes due to being ASCII, but if the C# code was expecting a UNICODE string, why is it 162 and not 83x2 = 166?
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user1703401 about 12 yearsI don't know, post the strings and I'll tell you why. There really is a problem with the C code, the function must return FALSE and GetLastError() must return ERROR_INSUFFICIENT_BUFFER. You then know the required buffer size, allocate it and call the function again.
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galford13x about 12 yearsOh yes I agree, the first call does return false, there is a second call that I apparently didn't put that is the actually deviceDetailData read. I'll edit my post to be correct. Here is the string @"\\?\usb#vid_091e&pid_0003#5&4a03a84&0&5#{2c9c45c2-8e7d-4c08-a12d-816bbae722c0}"
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galford13x about 12 yearswhy/how is the stack corrupted? Wont the proper memory be marshaled when I make the Win32api call?
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Ohad Schneider almost 10 years@HansPassant any chance you could explain why the test for
IntPtr.Size
is necessary and we can't rely on the marshaler to getSizeOf(SP_DEVICE_INTERFACE_DETAIL_DATA)
right? I'm guessing it has to do with padding somehow? -
user1703401 almost 10 years@Ohad - an old quirk in SetupAPI, it used 1 byte packing in the 32-bit version of Windows. Corrected to 8 byte packing in 64-bit. It can be done by the marshaller but you'd have to declare two different structs with different Pack property values.
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Ohad Schneider almost 10 years@HansPassant Thanks for the quick turnaround! As long as I have to declare two different structs I don't see it as being much better, so I guess I'll stick with this code.