COM in plain C, Part 5

// Unregisters the IExample.DLL COM component.

#include <windows.h>
#include <tchar.h>
#include <initguid.h>
#include "../IExample/IExample.h"



static const TCHAR	OurDllName[] = _T("IExample.dll");
static const TCHAR	ObjectDescription[] = _T("IExample COM component");
static const TCHAR	FileDlgTitle[] = _T("Locate IExample.dll to de-register it");
static const TCHAR	FileDlgExt[] = _T("DLL files\000*.dll\000\000");
static const TCHAR	ClassKeyName[] = _T("Software\\Classes");
static const TCHAR	CLSID_Str[] = _T("CLSID");
static const TCHAR	InprocServer32Name[] = _T("InprocServer32");
static const TCHAR	GUID_Format[] = _T("{%08lX-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X}");





/************************ stringFromCLSID() ***********************
 * Converts an object's GUID (array) to an ascii string (in a special
 * format where there are groups of ascii digits separated by a dash).
 * NOTE: Using wsprintf() avoids needing to load ole32.dll just to
 * call StringFromCLSID(). We're just doing the same thing it would do.
 */

static void stringFromCLSID(LPTSTR buffer, REFCLSID ri)
{
	wsprintf(buffer, &GUID_Format[0],
		((REFCLSID)ri)->Data1, ((REFCLSID)ri)->Data2, ((REFCLSID)ri)->Data3, ((REFCLSID)ri)->Data4[0],
		((REFCLSID)ri)->Data4[1], ((REFCLSID)ri)->Data4[2], ((REFCLSID)ri)->Data4[3],
		((REFCLSID)ri)->Data4[4], ((REFCLSID)ri)->Data4[5], ((REFCLSID)ri)->Data4[6],
		((REFCLSID)ri)->Data4[7]);
}





/************************** WinMain() ************************
 * Program Entry point
 */

int WINAPI WinMain(HINSTANCE hinstExe, HINSTANCE hinstPrev, LPSTR lpszCmdLine, int nCmdShow)
{
	int				result;
	TCHAR			filename[MAX_PATH];

	{
	OPENFILENAME	ofn;

	// Pick out where our DLL is located. We need to know its location in
	// order to register it as a COM component
	lstrcpy(&filename[0], &OurDllName[0]);
	ZeroMemory(&ofn, sizeof(OPENFILENAME));
	ofn.lStructSize = sizeof(OPENFILENAME);
	ofn.lpstrFilter = &FileDlgExt[0];
	ofn.lpstrFile = &filename[0];
	ofn.nMaxFile = MAX_PATH;
	ofn.lpstrTitle = &FileDlgTitle[0];
	ofn.Flags = OFN_FILEMUSTEXIST|OFN_EXPLORER|OFN_PATHMUSTEXIST;
	result = GetOpenFileName(&ofn);
	}

	if (result > 0)
	{
		HKEY		rootKey;
		HKEY		hKey;
		HKEY		hKey2;
		TCHAR		buffer[39];

		stringFromCLSID(&buffer[0], (REFCLSID)(&CLSID_IExample));

		// Open "HKEY_LOCAL_MACHINE\Software\Classes"
		if (!RegOpenKeyEx(HKEY_LOCAL_MACHINE, &ClassKeyName[0], 0, KEY_WRITE, &rootKey))
		{
			// Delete our CLSID key and everything under it
			if (!RegOpenKeyEx(rootKey, &CLSID_Str[0], 0, KEY_ALL_ACCESS, &hKey))
			{
				if (!RegOpenKeyEx(hKey, &buffer[0], 0, KEY_ALL_ACCESS, &hKey2))
				{
					RegDeleteKey(hKey2, &InprocServer32Name[0]);

					RegCloseKey(hKey2);
					RegDeleteKey(hKey, &buffer[0]);
				}

				RegCloseKey(hKey);
			}

			RegCloseKey(rootKey);
		}

		MessageBox(0, "De-registered IExample.DLL as a COM component.", &ObjectDescription[0], MB_OK|MB_ICONEXCLAMATION);
	}

	return(0);
}