xdg: implement a better way

Brief about changes:
- add get_irssi_cache_dir()
- add get_irssi_runtime_dir()
- remove is_xdg_supported()

About the proposed implementation:
- use XDG only when the user has the XDG_CONFIG_HOME/irssi directory
- irssi_dir would equal XDG_DATA_HOME/irssi or ~/.irssi, depending on
whether XDG is enabled or not, respectively.
- if xdg is enabled, variables irssi_cache, irssi_runtime, would equal
their respective XDG paths.
- if xdg is *not* enabled, variables irssi_cache, irssi_runtime, would
equal irssi_dir

Notes for future code:
- functions that use the irssi config file would use get_irssi_config()
- functions that use the irssi data directory would use get_irssi_dir()
- functions that use the irssi cache directory would use
get_irssi_cache_dir()
- functions that use the irssi runtime directory would use
get_irssi_runtime_dir()

Stuff that are still missing for complete implementation:
- add checks to ensure the new referenced directories are present
- docs

src/core/core.c

@@ -65,18 +65,25 @@ void log_away_deinit(void);
 void wcwidth_wrapper_init(void);
 void wcwidth_wrapper_deinit(void);
 
-int xdg_support;
 int irssi_gui;
 int irssi_init_finished;
 int sighup_received;
 time_t client_start_time;
 
-static char *irssi_dir, *irssi_config_file;
+static char *irssi_dir, /* XDG_DATA_HOME or ~/.irssi */
+    *irssi_config_file, /* XDG_CONFIG_HOME/irssi/config or ~/.irssi/config */
+    *irssi_cache_dir,   /* XDG_CACHE_HOME/irssi or ~/.irssi */
+    *irssi_runtime_dir; /* XDG_RUNTIME_HOME/irssi or ~/.irssi */
 static GSList *dialog_type_queue, *dialog_text_queue;
 
-int is_xdg_supported()
+const char *get_irssi_runtime_dir(void)
 {
-	return xdg_support;
+	return irssi_runtime_dir;
+}
+
+const char *get_irssi_cache_dir(void)
+{
+	return irssi_cache_dir;
 }
 
 const char *get_irssi_dir(void)
@@ -84,7 +91,7 @@ const char *get_irssi_dir(void)
 	return irssi_dir;
 }
 
-/* return full path for ~/.irssi/config */
+/* return full path for irssi config */
 const char *get_irssi_config(void)
 {
         return irssi_config_file;
@@ -199,22 +206,27 @@ void core_preinit(const char *path)
 	const char *home;
 	char *str;
 	int len;
+	int use_xdg = 0;
 
-	xdg_support = 0;
 	if (irssi_dir == NULL) {
-		/* check if %XDG_CONFIG_HOME/irssi exists and default to it */
+		/* check if %XDG_CONFIG_HOME/irssi exists and use to it */
 		char *dirp = g_build_filename(g_get_user_config_dir(), "irssi", NULL);
 		if (stat(dirp, &statbuf) == 0) {
-			xdg_support = 1;
-			irssi_dir = dirp;
+			use_xdg = 1;
+			irssi_dir = g_build_filename(g_get_user_data_dir(), "irssi", NULL);
+			irssi_cache_dir = g_build_filename(g_get_user_cache_dir(), "irssi", NULL);
+			irssi_runtime_dir =
+			    g_build_filename(g_get_user_runtime_dir(), "irssi", NULL);
 		} else { /* fallback to non-xdg location */
 			g_free(dirp);
 			home = g_get_home_dir();
 			if (home == NULL)
 				home = ".";
-
 			irssi_dir = g_strdup_printf(IRSSI_DIR_FULL, home);
-			xdg_support = 0;
+			/* all special XDG paths are equal to irssi_dir if XDG is not
+			 * supported */
+			irssi_cache_dir = irssi_dir;
+			irssi_runtime_dir = irssi_dir;
 		}
 	} else {
 	   str = irssi_dir;
@@ -225,10 +237,9 @@ void core_preinit(const char *path)
 	      irssi_dir[len-1] = '\0';
 	}
 	if (irssi_config_file == NULL)
-		if (is_xdg_supported())
-			irssi_config_file = g_build_filename(irssi_dir, IRSSI_HOME_CONFIG, NULL);
-		else
-			irssi_config_file = g_strdup_printf("%s/" IRSSI_HOME_CONFIG, irssi_dir);
+		irssi_config_file = use_xdg ? g_build_filename(g_get_user_config_dir(), "irssi",
+		                                               IRSSI_HOME_CONFIG, NULL) :
+                                              g_strdup_printf("%s/" IRSSI_HOME_CONFIG, irssi_dir);
 	else {
 		str = irssi_config_file;
 		irssi_config_file = fix_path(str);

src/core/log-away.c

@@ -111,10 +111,7 @@ void log_away_init(void)
 	away_filepos = 0;
 	away_msgs = 0;
 
-	if (is_xdg_supported())
-		awaylog_file = g_build_filename(g_get_user_cache_dir(), "irssi", "away.log", NULL);
-	else
-		awaylog_file = g_strconcat(get_irssi_dir(), "/away.log", NULL);
+	awaylog_file = g_strconcat(get_irssi_cache_dir(), "/away.log", NULL);
 	settings_add_str("log", "awaylog_file", awaylog_file);
 	g_free(awaylog_file);
 	settings_add_level("log", "awaylog_level", "msgs hilight");

src/core/modules-load.c

@@ -115,10 +115,7 @@ static GModule *module_open(const char *name, int *found)
 		path = g_strdup(name);
 	else {
 		/* first try from home dir */
-		if (is_xdg_supported())
-			str = g_build_filename(g_get_user_data_dir(), "irssi", "modules", NULL);
-		else
-			str = g_strdup_printf("%s/modules", get_irssi_dir());
+		str = g_strdup_printf("%s/modules", get_irssi_dir());
 		path = g_module_build_path(str, name);
 		g_free(str);