manager: merge /etc/xdg/systemd/session and /etc/systemd/session

Makefile.am

@@ -250,3 +250,8 @@ CLEANFILES = \
 	systemadm.c \
 	systemd-initctl.service \
 	systemd-logger.service
+
+install-data-hook:
+	$(MKDIR_P) $(DESTDIR)$(pkgsysconfdir)/system $(DESTDIR)$(pkgsysconfdir)/session $(DESTDIR)$(sysconfdir)/xdg/systemd
+	rm -f $(DESTDIR)$(sysconfdir)/xdg/systemd/session
+	ln -sf $(DESTDIR)$(pkgsysconfdir)/session $(DESTDIR)$(sysconfdir)/xdg/systemd/session

manager.c

@@ -149,12 +149,12 @@ static char** session_dirs(void) {
         }
 
         if ((e = getenv("XDG_CONFIG_DIRS")))
-                config_dirs = strv_split(e, ":");
-        else
-                config_dirs = strv_new("/etc/xdg", NULL);
+                if (!(config_dirs = strv_split(e, ":")))
+                        goto fail;
 
-        if (!config_dirs)
-                goto fail;
+        /* We don't treat /etc/xdg/systemd here as the spec
+         * suggests because we assume that that is a link to
+         * /etc/systemd/ anyway. */
 
         if ((e = getenv("XDG_DATA_HOME"))) {
                 if (asprintf(&data_home, "%s/systemd/session", e) < 0)