Clsid

[bilm_ks]

A dll, ocx,... may have more than one COM object and so more than one CLSID. If you want to find which CLSIDs a library registers you must search the registry. The following code searches for CLSIDs registered by comctl32.ocx.

#include <windows.h>
#include <string.h>

void SearchRegistry()
{
	LONG lr = ERROR_SUCCESS;
	HKEY hKey = NULL;
	HKEY hEnumKey = NULL;
	HKEY hIpsKey = NULL;
	DWORD dwIndex = 0;
	char szClsidName[0xff];
	char szDLLName[0xff];
	char szProgID[0xff];
	char * szSearchStr = "C:\\WINDOWS\\SYSTEM32\\COMCTL32.OCX";
	DWORD dwCount = 0xff;
	LONG lcnt = 0;

	lr = RegOpenKeyExA(HKEY_CLASSES_ROOT, "CLSID", 0, KEY_READ, &hKey);
	
	while (lr = RegEnumKeyA(hKey, dwIndex++, szClsidName, dwCount) == ERROR_SUCCESS)
	{
		lr = RegOpenKeyExA(hKey, szClsidName, 0, KEY_READ, &hEnumKey);
		lr = RegOpenKeyExA(hEnumKey, "InprocServer32", 0, KEY_READ, &hIpsKey);
		lr = RegQueryValueA(hIpsKey, NULL, szDLLName, &lcnt);
		if (lr == ERROR_SUCCESS)
		{
			_strupr(szDLLName);
			if (strcmp(szSearchStr, szDLLName) == 0)
			{
				printf("CLSID: %s\n", szClsidName);
				RegCloseKey(hIpsKey);
				lr = RegOpenKeyExA(hEnumKey, "ProgID", 0, KEY_READ, &hIpsKey);
				lr = RegQueryValueA(hIpsKey, NULL, szProgID, &lcnt);
				if (lr == ERROR_SUCCESS)
					printf("ProgID: %s\n\n", szProgID);
				else
					printf("ProgID: not found\n\n");
			}
		}
		RegCloseKey(hIpsKey);
		RegCloseKey(hEnumKey);
	}
	RegCloseKey(hKey);
}

int main()
{
	SearchRegistry();
	return 0;
}

Note that with the above we may not find all the entries for comctl32.ocx since it may be defined with the alternatives "%SystemRoot%\Windows\System32\comctl32.ocx" or "comctl32.ocx" so it would be more appropriate to check the last 12 chars of the string.