Improve usage error reporting

Print usage information when there is an error in the command line
arguments. Also, wait for keypress before exiting on Windows so that the
user can read the error message.

src/system4.c

@@ -120,12 +120,12 @@ static void read_mixer_channels(struct ini_entry *entry)
 	}
 }
 
-static void read_config(const char *path)
+static bool read_config(const char *path)
 {
 	int ini_size;
 	struct ini_entry *ini = ini_parse(path, &ini_size);
 	if (!ini)
-		ERROR("Failed to read %s", path);
+		return false;
 
 	for (int i = 0; i < ini_size; i++) {
 		if (!strcmp(ini[i].name->text, "GameName")) {
@@ -148,6 +148,7 @@ static void read_config(const char *path)
 		ini_free_entry(&ini[i]);
 	}
 	free(ini);
+	return true;
 }
 
 static void read_user_config_file(const char *path)
@@ -258,25 +259,29 @@ static void config_init(void)
 	mkdir_p(new_save_dir);
 }
 
-static void config_init_with_ini(const char *ini_path)
+static bool config_init_with_ini(const char *ini_path)
 {
-	read_config(ini_path);
+	if (!read_config(ini_path))
+		return false;
 	if (!config.ain_filename)
 		ERROR("No AIN filename specified in %s", ini_path);
 	char *tmp = strdup(ini_path);
 	config.game_dir = strdup(dirname(tmp));
 	free(tmp);
 	config_init();
+	return true;
 }
 
-static void config_init_with_dir(const char *dir)
+static bool config_init_with_dir(const char *dir)
 {
 	char path[PATH_MAX];
 	snprintf(path, PATH_MAX, "%s/System40.ini", dir);
 	if (!file_exists(path)) {
 		snprintf(path, PATH_MAX, "%s/AliceStart.ini", dir);
+		if (!file_exists(path))
+			return false;
 	}
-	config_init_with_ini(path);
+	return config_init_with_ini(path);
 }
 
 static void config_init_with_ain(const char *ain_path)
@@ -335,7 +340,7 @@ static void ain_audit(FILE *f, struct ain *ain)
 
 static void usage(void)
 {
-	puts("Usage: xsystem4 <options> <inifile>");
+	puts("Usage: xsystem4 [options] [inifile-or-directory]");
 	puts("    -h, --help          Display this message and exit");
 	puts("    -v, --version       Display the version and exit");
 	puts("    -a, --audit         Audit AIN file for xsystem4 compatibility");
@@ -352,6 +357,17 @@ static void usage(void)
 #endif
 }
 
+static _Noreturn void _usage_error(const char *fmt, ...)
+{
+	usage();
+	puts("");
+
+	va_list ap;
+	va_start(ap, fmt);
+	sys_verror(fmt, ap);
+}
+#define usage_error(fmt, ...) _usage_error("Error: " fmt "\n", ##__VA_ARGS__)
+
 enum {
 	LOPT_HELP = 256,
 	LOPT_VERSION,
@@ -369,8 +385,19 @@ enum {
 #endif
 };
 
+static void windows_error_handler(const char *msg)
+{
+	sys_warning("%s", msg);
+	sys_warning("Press any key to exit...\n");
+	getchar();
+	sys_exit(1);
+}
+
 int main(int argc, char *argv[])
 {
+#ifdef _WIN32
+	sys_error_handler = windows_error_handler;
+#endif
 	initialize_instructions();
 	char *ainfile;
 	int err = AIN_SUCCESS;
@@ -464,19 +491,22 @@ int main(int argc, char *argv[])
 	argv += optind;
 
 	if (argc < 1) {
-		config_init_with_dir(".");
+		if (!config_init_with_dir(".")) {
+			if (!config_init_with_dir("../"))
+				usage_error("Failed to find game in current or parent directory");
+		}
 	} else if (argc > 1) {
-		usage();
-		ERROR("Too many arguments");
+		usage_error("Too many arguments");
 	} else if (is_directory(argv[0])) {
-		config_init_with_dir(argv[0]);
+		if (!config_init_with_dir(argv[0]))
+			usage_error("Failed to find game in '%s'", argv[0]);
 	} else if (!strcasecmp(file_extension(argv[0]), "ini")) {
-		config_init_with_ini(argv[0]);
+		if (!config_init_with_ini(argv[0]))
+			usage_error("Failed to read .ini file '%s'", argv[0]);
 	} else if (!strcasecmp(file_extension(argv[0]), "ain")) {
 		config_init_with_ain(argv[0]);
 	} else {
-		usage();
-		ERROR("Can't initialize game with argument '%s'", argv[0]);
+		usage_error("Can't initialize game with argument '%s'", argv[0]);
 	}
 	ainfile = gamedir_path(config.ain_filename);