private static string GetHKEY(HKEY key)
{
string keyPath = null;
char[] buff = new char[1];
if (key != null)
{
DWORD size = 0;
DWORD result;
/*
* SUPPLYING THE FUNCTION "KEY_NAME_INFORMATION" (enumerated as integer 3) structure of the
* registry key. However, since the buffer size is smaller, required size of the buffer will
* be assigned to "size" variable, while returning STATUS_BUFFER_TOO_SMALL.
*/
result = SetupAPI.NtQueryKey(key, 3, ref buff[0], 0, ref size);
if (result == ((DWORD)0xC0000023L))
{
// Additional 2-byte for extra space when trimming first two insignificant bytes.
size += 2;
buff = new char[size];
result = SetupAPI.NtQueryKey(key, 3, ref buff[0], size, ref size);
if (result == ((DWORD)0x00000000L))
{
keyPath = new string(buff);
keyPath = keyPath.Substring(2);
keyPath = keyPath.TrimEnd('\0');
}
}
}
return(keyPath);
}
static void Main(string[] args)
{
//==============================================================
// EXTRACTING MONITOR EDID
//==============================================================
const string msgCaption = "EDID.Framework.cs";
/*
* IF THE FUNCTION "SetupDiClassGuidsFromNameW()" is passed buffer of GUID smaller
* than the very last argument "ref dwSize", the function returns FALSE while assigning
* dwSize a required buffer size to store GUIDs of the specified classes.
*
* However, C# can only pass variable as ref, and cannot convert null to Guid.
* Therefore, in C# takes different approach by allowing ptrGUID to have elligible size,
* but setting `GuidClassListSize` parameter as 0. The function will think buffer doesn't
* have any size at all, resulting FAILED operation.
*
* REFERENCE: https://docs.microsoft.com/en-us/windows/win32/api/setupapi/nf-setupapi-setupdiclassguidsfromnamew
*/
DWORD dwSize = 1;
Guid[] ptrGUID = new Guid[1];
bool bResult = SetupAPI.SetupDiClassGuidsFromNameW("Monitor", ref ptrGUID[0], 0, ref dwSize);
if (bResult == false)
{
if (Marshal.GetLastWin32Error() == (int)ERROR.INSUFFICIENT_BUFFER)
{
/*
* IN SECOND ATTEMPT, now that the required buffer size is known,
* array of GUID data type is created with the length of dwSize.
* The GUID array "ptrGUID" will be assigned with GUID of the
* "Monitor" class which is {4d36e96e-e325-11ce-bfc1-08002be10318}.
*
* REFERENCE: https://docs.microsoft.com/en-us/windows-hardware/drivers/install/system-defined-device-setup-classes-available-to-vendors
*/
ptrGUID = new Guid[dwSize];
bResult = SetupAPI.SetupDiClassGuidsFromNameW("Monitor", ref ptrGUID[0], dwSize, ref dwSize);
if (!bResult)
{
MessageBox.Show("Unable to retrieve GUID of the specified class.", msgCaption, MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
}
else
{
/*
* HOWEVER, in case the "SetupDiClassGuidsFromNameW()" failed to return
* required buffer size due to a certain matter, alert a message box.
*/
MessageBox.Show("Unable to retrieve GUID of the specified class.", msgCaption, MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
}
/*
* GET ALL THE device information of the "Monitor" GUID that are currently presented
* within the system in HDEVINFO data type. This data type is merely a void pointer
* of the collection of device information set, thus is categorized as "Handle".
*
* FLAG: DIGCF_PRESENT - Return only devices that are currently present in a system.
*/
HDEVINFO devINFO = INVALID_HANDLE_VALUE;
devINFO = SetupAPI.SetupDiGetClassDevsW(ref ptrGUID[0], null, IntPtr.Zero, (DWORD)DIGCF.PRESENT);
if (devINFO == INVALID_HANDLE_VALUE)
{
MessageBox.Show("Failed to retrieve device information of the GUID class.", msgCaption, MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
/*
* SP_DEVINFO_DATA is a structure for a single device instance of the HDEVINFO device information set.
* Here, variable "devDATA" is used to temporary store a single device information from "devINFO" data.
*
* SP_DEVINFO_DATA.cbSize field must be specified as function that accpets SP_DEVINFO_DATA
* always check whether the byte size of the SP_DEVINFO_DATA structure is the same as the cbSize field.
*
* REFERENCE: https://docs.microsoft.com/en-us/windows/win32/api/setupapi/ns-setupapi-sp_devinfo_data
*
* SP_DEVINFO_DATA in C# is custom-created structure, thus does not have predefined size.
* Unsafe context is needed to acquire the size of the SP_DEVINFO_DATA, which require "Allow unsafe code" enabled in C# Build configureation.
* SP_DEVINFO_DATA has been initialized for call by reference with "ref" keyword, instead of "out" keyword.
*
* REFERENCE: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/unsafe
*/
SP_DEVINFO_DATA devDATA;
unsafe {
devDATA = new SP_DEVINFO_DATA {
cbSize = (DWORD)sizeof(SP_DEVINFO_DATA), ClassGuid = Guid.Empty, DevInst = 0, Reserved = IntPtr.Zero
};
}
bool devFOUND = true;
for (DWORD index = 0; devFOUND; index++)
{
/*
* THE FUNCTION "SetupDiEnumDeviceInfo()" passes single "index"th device instance to devDATA
* from device information set devINFO. When no device instance is found on "index"th element,
* the function return FALSE.
*
* REFERENCE: https://docs.microsoft.com/en-us/windows/win32/api/setupapi/nf-setupapi-setupdienumdeviceinfo
*/
devFOUND = SetupAPI.SetupDiEnumDeviceInfo(devINFO, index, ref devDATA);
if (devFOUND)
{
if (index != 0)
{
Console.WriteLine();
}
/*
* THE FUNCTION "SetupDiOpenDevRegKey()" returns handle for the registry key (HKEY) of the
* devDATA included in the device information set devINFO. Device has two registry key:
* hardware (DIREG_DEV) and software (DIREG_DRV) key. EDID can be found in hardware key.
*
* DEV: \REGISTRY\MACHINE\SYSTEM\ControlSet001\Enum\DISPLAY\??????\*&********&*&UID****\Device Parameters
* \REGISTRY\MACHINE\SYSTEM\ControlSet001\Enum\DISPLAY\??????\*&********&*&UID****\Device Parameters
*
* DRV: \REGISTRY\MACHINE\SYSTEM\ControlSet001\Control\Class\{????????-****-????-****-????????????}\0001
* \REGISTRY\MACHINE\SYSTEM\ControlSet001\Control\Class\{????????-****-????-****-????????????}\0000
*/
HKEY devKEY = SetupAPI.SetupDiOpenDevRegKey(devINFO, ref devDATA, (DWORD)DICS_FLAG.GLOBAL, 0, (DWORD)DIREG.DEV, (DWORD)KEY.READ);
Console.WriteLine("Registry Key: \"{0}\"", GetHKEY(devKEY));
/*
* OPENING and querying registry key has already been dealt in other repository.
* Refer to GKO95/MFC.CommonRegistry repository for more information.
*
* REFERENCE: https://github.com/GKO95/MFC.CommonRegistry
*/
byte[] byteBuffer = new byte[128];
DWORD regSize = 128;
DWORD regType = (DWORD)REG.BINARY;
LRESULT lResult = SetupAPI.RegQueryValueExW(devKEY, "EDID", 0, ref regType, ref byteBuffer[0], ref regSize);
if (lResult != (int)ERROR.SUCCESS)
{
Console.WriteLine("ERROR!");
}
else
{
string hexBuffer = BitConverter.ToString(byteBuffer).Replace("-", " ").ToLower();
Console.Write(hexBuffer + "\n");
}
}
}
}