COMMON: Add initial config file option.

This allows an initial/default configuration file to be specified via the command line.  This allows a default settings file to be bundled and loaded even if it's installed to a read-only location, such as Program Files on Windows, and allows the written config file to be deleted without losing the custom defaults.

base/commandLine.cpp

@@ -94,7 +94,8 @@ static const char HELP_STRING1[] =
 	"  --console                Enable the console window (default:enabled)\n"
 #endif
 	"\n"
-	"  -c, --config=CONFIG      Use alternate configuration file\n"
+	"  -c, --config=CONFIG      Use alternate configuration file path\n"
+	"  -i, --initial-cfg=CONFIG Load an initial configuration file if no configuration file has been saved yet\n"
 #if defined(SDL_BACKEND)
 	"  -l, --logfile=PATH       Use alternate path for log file\n"
 	"  --screenshotpath=PATH    Specify path where screenshot files are created\n"
@@ -633,6 +634,9 @@ Common::String parseCommandLine(Common::StringMap &settings, int argc, const cha
 			DO_OPTION('c', "config")
 			END_OPTION
 
+			DO_OPTION('i', "initial-cfg")
+			END_OPTION
+
 #if defined(SDL_BACKEND)
 			DO_OPTION('l', "logfile")
 			END_OPTION
@@ -1884,6 +1888,7 @@ bool processSettings(Common::String &command, Common::StringMap &settings, Commo
 	// Finally, store the command line settings into the config manager.
 	static const char * const sessionSettings[] = {
 		"config",
+		"initial-cfg",
 		"fullscreen",
 		"gfx-mode",
 		"stretch-mode",

base/main.cpp

@@ -493,10 +493,14 @@ extern "C" int scummvm_main(int argc, const char * const argv[]) {
 		command = autoCommand;
 
 	// Load the config file (possibly overridden via command line):
+	Common::String initConfigFilename;
+	if (settings.contains("initial-cfg"))
+		initConfigFilename = settings["initial-cfg"];
+
 	if (settings.contains("config")) {
-		ConfMan.loadConfigFile(settings["config"]);
+		ConfMan.loadConfigFile(settings["config"], initConfigFilename);
 	} else {
-		ConfMan.loadDefaultConfigFile();
+		ConfMan.loadDefaultConfigFile(initConfigFilename);
 	}
 
 	// Update the config file

common/config-manager.cpp

@@ -78,7 +78,7 @@ void ConfigManager::copyFrom(ConfigManager &source) {
 }
 
 
-void ConfigManager::loadDefaultConfigFile() {
+void ConfigManager::loadDefaultConfigFile(const String &fallbackFilename) {
 	// Open the default config file
 	assert(g_system);
 	SeekableReadStream *stream = g_system->createConfigReadStream();
@@ -92,26 +92,41 @@ void ConfigManager::loadDefaultConfigFile() {
 		delete stream;
 
 	} else {
-		// No config file -> create new one!
-		debug("Default configuration file missing, creating a new one");
+		// No config file -> try to load fallback, flush initial config to disk
+		if (!loadFallbackConfigFile(fallbackFilename))
+			debug("Default configuration file missing, creating a new one");
 
 		flushToDisk();
 	}
 }
 
-void ConfigManager::loadConfigFile(const String &filename) {
+void ConfigManager::loadConfigFile(const String &filename, const String &fallbackFilename) {
 	_filename = filename;
 
 	FSNode node(filename);
 	File cfg_file;
 	if (!cfg_file.open(node)) {
-		debug("Creating configuration file: %s", filename.c_str());
+		if (!loadFallbackConfigFile(fallbackFilename))
+			debug("Creating configuration file: %s", filename.c_str());
 	} else {
 		debug("Using configuration file: %s", _filename.c_str());
 		loadFromStream(cfg_file);
 	}
 }
 
+bool ConfigManager::loadFallbackConfigFile(const String &filename) {
+	if (filename.empty())
+		return false;
+
+	File fallbackFile;
+	if (!fallbackFile.open(FSNode(filename)))
+		return false;
+
+	debug("Using initial configuration file: %s", filename.c_str());
+	loadFromStream(fallbackFile);
+	return true;
+}
+
 /**
  * Add a ready-made domain based on its name and contents
  * The domain name should not already exist in the ConfigManager.

common/config-manager.h

@@ -125,8 +125,8 @@ public:
 	static char const *const kCloudDomain;
 #endif
 
-	void                     loadDefaultConfigFile(); /*!< Load the default configuration file. */
-	void                     loadConfigFile(const String &filename); /*!< Load a specific configuration file. */
+	void                     loadDefaultConfigFile(const String &fallbackFilename); /*!< Load the default configuration file. */
+	void                     loadConfigFile(const String &filename, const String &fallbackFilename); /*!< Load a specific configuration file. */
 
 	/**
 	 * Retrieve the config domain with the given name.
@@ -222,6 +222,7 @@ private:
 	friend class Singleton<SingletonBaseType>;
 	ConfigManager();
 
+	bool            loadFallbackConfigFile(const String &filename);
 	void			loadFromStream(SeekableReadStream &stream);
 	void			addDomain(const String &domainName, const Domain &domain);
 	void			writeDomain(WriteStream &stream, const String &name, const Domain &domain);