Rework session handling

Sessions can now be retrieved from a backend in a more general manner.
Multi-backend gets back its `session` field that contains the session
if one was created, removing the interfacing from multi backend with the
drm backend directly. This adds the possibility to use sessions even
without the drm backend.

It additionally fixes the bug that 2 session objects got created when
WLR_BACKENDS were set to "libinput,drm".

To allow vt switching without drm backend (and drm fd) on logind, start
listening to PropertiesChanged signals from dbus and parse the session
"Active" property when no master fd was created (this does not change
current drm backend behaviour in any way).

1 files changed, 7 insertions, 12 deletions

diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index 3707fe34..2f4b929f 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -1,7 +1,6 @@
 #include <assert.h>
 #include <stdbool.h>
 #include <stdlib.h>
-#include <wlr/backend/drm.h>
 #include <wlr/backend/interface.h>
 #include <wlr/backend/session.h>
 #include <wlr/util/log.h>
@@ -72,10 +71,17 @@ static struct wlr_renderer *multi_backend_get_renderer(
 	return NULL;
 }
 
+static struct wlr_session *multi_backend_get_session(
+		struct wlr_backend *_backend) {
+	struct wlr_multi_backend *backend = multi_backend_from_backend(_backend);
+	return backend->session;
+}
+
 struct wlr_backend_impl backend_impl = {
 	.start = multi_backend_start,
 	.destroy = multi_backend_destroy,
 	.get_renderer = multi_backend_get_renderer,
+	.get_session = multi_backend_get_session,
 };
 
 static void handle_display_destroy(struct wl_listener *listener, void *data) {
@@ -191,17 +197,6 @@ void wlr_multi_backend_remove(struct wlr_backend *_multi,
 	}
 }
 
-struct wlr_session *wlr_multi_get_session(struct wlr_backend *_backend) {
-	struct wlr_multi_backend *backend = multi_backend_from_backend(_backend);
-	struct subbackend_state *sub;
-	wl_list_for_each(sub, &backend->backends, link) {
-		if (wlr_backend_is_drm(sub->backend)) {
-			return wlr_drm_backend_get_session(sub->backend);
-		}
-	}
-	return NULL;
-}
-
 bool wlr_multi_is_empty(struct wlr_backend *_backend) {
 	assert(wlr_backend_is_multi(_backend));
 	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)_backend;