COM in plain C, Part 5

// Registers our IExample2.DLL as a COM component.

#include <windows.h>
#include <tchar.h>
#include "../IExample2/IExample2.h"



static const TCHAR	OurDllName[] = _T("IExample2.dll");
static const TCHAR	OurProgID[] = _T("IExample2.object");
static const TCHAR	TypeLibName[] = _T("IExample2.tlb");
static const TCHAR	ObjectDescription[] = _T("IExample2 COM component");
static const TCHAR	FileDlgTitle[] = _T("Locate IExample2.dll to 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	ThreadingModel[] = _T("ThreadingModel");
static const TCHAR	ProgIDName[] = "ProgID";
static const TCHAR	BothStr[] = _T("both");
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]);
}





/************************ cleanup() ***********************
 * Removes all of the registry entries we create in WinMain.
 * This is called to do cleanup if there's an error
 * installing our DLL as a COM component.
 */

static void cleanup(void)
{
	HKEY		rootKey;
	HKEY		hKey;
	HKEY		hKey2;
	TCHAR		buffer[39];

	stringFromCLSID(&buffer[0], (REFCLSID)(&CLSID_IExample2));

	// Open "HKEY_LOCAL_MACHINE\Software\Classes"
	if (!RegOpenKeyEx(HKEY_LOCAL_MACHINE, &ClassKeyName[0], 0, KEY_WRITE, &rootKey))
	{
		// Delete ProgID subkey and everything under it
		if (!RegOpenKeyEx(rootKey, &OurProgID[0], 0, KEY_ALL_ACCESS, &hKey))
		{
			RegDeleteKey(hKey, &CLSID_Str[0]);
			RegCloseKey(hKey);
			RegDeleteKey(rootKey, &OurProgID[0]);

			// 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]);

					RegDeleteKey(hKey2, &ProgIDName[0]);

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

				RegCloseKey(hKey);
			}
		}

		RegCloseKey(rootKey);

		// Unregister type library
		UnRegisterTypeLib(&CLSID_TypeLib, 1, 0, LOCALE_NEUTRAL, SYS_WIN32);
	}
}





/************************** 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;
		HKEY		hkExtra;
		TCHAR		buffer[39];
		DWORD		disposition;

		// Assume an error
		result = 1;

		// Open "HKEY_LOCAL_MACHINE\Software\Classes"
		if (!RegOpenKeyEx(HKEY_LOCAL_MACHINE, &ClassKeyName[0], 0, KEY_WRITE, &rootKey))
		{
			// For a script engine to call the OLE function CLSIDFromProgID() (passing
			// our registered ProgID in order to get our IExample2 object's GUID), then 
			// we need to create a subkey named with our IExample2 ProgID string. We've
			// decided to use the ProgID "IExample2.object"
			if (!RegCreateKeyEx(rootKey, &OurProgID[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hKey, &disposition))
			{
				// Set its default value to some "friendly" string that helps
				// a user identify what this COM DLL is for. Setting this value
				// is optional. You don't need to do it
				RegSetValueEx(hKey, 0, 0, REG_SZ, (const BYTE *)&ObjectDescription[0], sizeof(ObjectDescription));

				// Create a "CLSID" subkey whose default value is our IExample2 object's GUID (in ascii string format)
				if (!(disposition = RegCreateKeyEx(hKey, &CLSID_Str[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hKey2, &disposition)))
				{
					stringFromCLSID(&buffer[0], (REFCLSID)(&CLSID_IExample2));
					disposition = RegSetValueEx(hKey2, 0, 0, REG_SZ, (const BYTE *)&buffer[0], lstrlen(&buffer[0]) + 1);
					RegCloseKey(hKey2);
				}
				RegCloseKey(hKey);

				if (!disposition)
				{
					// Open "HKEY_LOCAL_MACHINE\Software\Classes\CLSID"
					if (!RegOpenKeyEx(rootKey, &CLSID_Str[0], 0, KEY_ALL_ACCESS, &hKey))
					{
						// Create a subkey whose name is the ascii string that represents
						// our IExample2 object's GUID
						if (!RegCreateKeyEx(hKey, &buffer[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hKey2, &disposition))
						{
							// Set its default value to some "friendly" string that helps
							// a user identify what this COM DLL is for. Setting this value
							// is optional. You don't need to do it
							RegSetValueEx(hKey2, 0, 0, REG_SZ, (const BYTE *)&ObjectDescription[0], sizeof(ObjectDescription));

							// Create an "InprocServer32" key whose default value is the path of this DLL
							if (!RegCreateKeyEx(hKey2, &InprocServer32Name[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hkExtra, &disposition))
							{
								disposition = 1;
								if (!RegSetValueEx(hkExtra, 0, 0, REG_SZ, (const BYTE *)&filename[0], lstrlen(&filename[0]) + 1))
								{
									// Create a "ThreadingModel" value set to the string "both" (ie, we don't need to restrict an
									// application to calling this DLL's functions only from a single thread. We don't use global
									// data in our IExample2 functions, so we're thread-safe)
									disposition = RegSetValueEx(hkExtra, &ThreadingModel[0], 0, REG_SZ, (const BYTE *)&BothStr[0], sizeof(BothStr));
								}

								RegCloseKey(hkExtra);

								// Create a "ProgID" subkey whose default value is our ProgID. This allows the app to call ProgIDFromCLSID()
								if (!disposition && !(disposition = RegCreateKeyEx(hKey2, &ProgIDName[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hkExtra, &disposition)))
								{
									disposition = RegSetValueEx(hkExtra, 0, 0, REG_SZ, (const BYTE *)&OurProgID[0], sizeof(OurProgID));
									RegCloseKey(hkExtra);
									if (!disposition) result = 0;
								}
							}

							RegCloseKey(hKey2);
						}

						RegCloseKey(hKey);
					}

					// Register the type lib (which is assumed to be a .TLB file in the same dir as this DLL)
					if (!result)
					{
						ITypeLib	*pTypeLib;
						LPTSTR		str;

						str = &filename[0] + lstrlen(&filename[0]);
						while (str > &filename[0] && *(str - 1) != '\\') --str;
						lstrcpy(str, &TypeLibName[0]);

					#ifdef UNICODE
						if (!(result = LoadTypeLib(&filename[0], &pTypeLib)))
						{
							result = RegisterTypeLib(pTypeLib, &filename[0], 0);
							pTypeLib->lpVtbl->Release(pTypeLib);
						}
					#else
						{
						wchar_t		wbuffer[MAX_PATH];

						MultiByteToWideChar(CP_ACP, 0, &filename[0], -1, &wbuffer[0], MAX_PATH);
						if (!(result = LoadTypeLib(&wbuffer[0], &pTypeLib)))
						{
							result = RegisterTypeLib(pTypeLib, &wbuffer[0], 0);
							pTypeLib->lpVtbl->Release(pTypeLib);
						}
						}
					#endif
					}

					if (!result)
						MessageBox(0, "Successfully registered IExample2.DLL as a COM component.", &ObjectDescription[0], MB_OK);
				}
			}

			RegCloseKey(rootKey);
		}

		// If an error, make sure we clean everything up
		if (result)
		{
			cleanup();
			MessageBox(0, "Failed to register IExample2.DLL as a COM component.", &ObjectDescription[0], MB_OK|MB_ICONEXCLAMATION);
		}
	}

	return(0);
}