Fix: "Error loading pidgin.dll" in Pidgin Portable (Testers Needed - even if you don't have the problem)

When renaming pidgin.exe to pidgin-portable.exe, Pidgin is running in portable mode. Then Pidgin is always assuming GTK folder is "\\path\to\Pidgin\..\GTK" (see source code below). It will work only with a GTK in folder "\PortableApps\PidginPortable\App\GTK" because pidgin-portable.exe is located in folder "\PortableApps\PidginPortable\App\Pidgin". Then your trick couldn't work with a GTK in folder "\CommonFiles\GTK".

As I can see in the source code, pidgin.exe shoudn't be renamed at all (no more use of portable mode). Instead a registry key must be created in order to setup the path to GTK folder ("\PortableApps\PidginPortable\App\GTK" or "\CommonFiles\GTK"): "HKCU\SOFTWARE\\GTK\\2.0" or "HKLM\SOFTWARE\\GTK\\2.0". Then Pidgin could find where the GTK folder is located. In Pidgin PE launcher I didn't see any setup of this registry key. That may cause the pidgin.dll loading error.

winpidgin.c

static void dll_prep() {
	char path[MAX_PATH + 1];
	HMODULE hmod;
	HKEY hkey;
#ifdef PORTABLE
	/* We assume that GTK+ is installed under \\path\to\Pidgin\..\GTK
	 * First we find \\path\to
	 */
	if (GetModuleFileName(NULL, path, MAX_PATH) != 0) {
		char *tmp = path;
		char *prev = NULL;
		char *prev2 = NULL;

		while ((tmp = strchr(tmp, '\\'))) {
			prev2 = prev;
			prev = tmp;
			tmp++;
		}

		if (prev2) {
			prev2[0] = '\0';
		}
	} else {
		printf("Unable to determine current executable path. \n"
			"This will prevent the settings dir from being set.\n"
			"Assuming GTK+ is in the PATH.\n");
	}

	if (path) {
		/* Set up the settings dir base to be \\path\to
		 * The actual settings dir will be \\path\to\.purple */
		char settingsdir[strlen(path) + strlen("PURPLEHOME=") + 1];
		char aspelldir[strlen(path) + strlen("PIDGIN_ASPELL_DIR=\\Aspell\\bin") + 1];

		snprintf(settingsdir, sizeof(settingsdir), "PURPLEHOME=%s", path);
		printf("Setting settings dir: %s\n", settingsdir);
		putenv(settingsdir);

		snprintf(aspelldir, sizeof(aspelldir), "PIDGIN_ASPELL_DIR=%s\\Aspell\\bin", path);
		printf("%s", aspelldir);
		putenv(aspelldir);

		/* set the GTK+ path to be \\path\to\GTK\bin */
		strcat(path, "\\GTK\\bin");
	} else
		return;
#else /* PORTABLE */
	char gtkpath[MAX_PATH + 1];
	DWORD plen;

	plen = sizeof(gtkpath);
	hkey = HKEY_CURRENT_USER;
	if (!read_reg_string(hkey, "SOFTWARE\\GTK\\2.0", "Path",
			(LPBYTE) &gtkpath, &plen)) {
		hkey = HKEY_LOCAL_MACHINE;
		if (!read_reg_string(hkey, "SOFTWARE\\GTK\\2.0", "Path",
				(LPBYTE) &gtkpath, &plen)) {
			printf("GTK+ Path Registry Key not found. "
				"Assuming GTK+ is in the PATH.\n");
			return;
		}
	}

	/* this value is replaced during a successful RegQueryValueEx() */
	plen = sizeof(path);
	/* Determine GTK+ dll path .. */
	if (!read_reg_string(hkey, "SOFTWARE\\GTK\\2.0", "DllPath",
				(LPBYTE) &path, &plen)) {
		strcpy(path, gtkpath);
		strcat(path, "\\bin");
	}
#endif
	printf("GTK+ path found: %s\n", path);

	if ((hmod = GetModuleHandle("kernel32.dll"))) {
		MySetDllDirectory = (LPFNSETDLLDIRECTORY) GetProcAddress(
			hmod, "SetDllDirectoryA");
		if (!MySetDllDirectory)
			printf("SetDllDirectory not supported\n");
	} else
		printf("Error getting kernel32.dll module handle\n");

	/* For Windows XP SP1+ / Server 2003 we use SetDllDirectory to avoid dll hell */
	if (MySetDllDirectory) {
		printf("Using SetDllDirectory\n");
		MySetDllDirectory(path);
	}

	/* For the rest, we set the current directory and make sure
	 * SafeDllSearch is set to 0 where needed. */
	else {
		OSVERSIONINFO osinfo;

		printf("Setting current directory to GTK+ dll directory\n");
		SetCurrentDirectory(path);
		/* For Windows 2000 (SP3+) / WinXP (No SP):
		 * If SafeDllSearchMode is set to 1, Windows system directories are
		 * searched for dlls before the current directory. Therefore we set it
		 * to 0.
		 */
		osinfo.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
		GetVersionEx(&osinfo);
		if ((osinfo.dwMajorVersion == 5 &&
			osinfo.dwMinorVersion == 0 &&
			strcmp(osinfo.szCSDVersion, "Service Pack 3") >= 0) ||
			(osinfo.dwMajorVersion == 5 &&
			osinfo.dwMinorVersion == 1 &&
			strcmp(osinfo.szCSDVersion, "") >= 0)
		) {
			DWORD regval = 1;
			DWORD reglen = sizeof(DWORD);

			printf("Using Win2k (SP3+) / WinXP (No SP)... Checking SafeDllSearch\n");
			read_reg_string(HKEY_LOCAL_MACHINE,
				"System\\CurrentControlSet\\Control\\Session Manager",
				"SafeDllSearchMode",
				(LPBYTE) &regval,
				&reglen);

			if (regval != 0) {
				printf("Trying to set SafeDllSearchMode to 0\n");
				regval = 0;
				if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
					"System\\CurrentControlSet\\Control\\Session Manager",
					0,  KEY_SET_VALUE, &hkey
				) == ERROR_SUCCESS) {
					if (RegSetValueEx(hkey,
						"SafeDllSearchMode", 0,
						REG_DWORD, (LPBYTE) &regval,
						sizeof(DWORD)
					) != ERROR_SUCCESS)
						printf("Error writing SafeDllSearchMode. Error: %u\n",
						(UINT) GetLastError());
					RegCloseKey(hkey);
				} else
					printf("Error opening Session Manager key for writing. Error: %u\n",
						(UINT) GetLastError());
			} else
				printf("SafeDllSearchMode is set to 0\n");
		}/*end else*/
	}
}