From 9f4d779d17e407aed688c4bee48e6d3474da16f5 Mon Sep 17 00:00:00 2001
From: Iain Lane <iainl@gnome.org>
Date: Mon, 14 May 2018 15:26:14 +0100
Subject: [PATCH] act-user-manager: Find the user's graphical session instead
 of assuming we are in it

If we were started by systemd --user, we won't be in a login session.
Find the user's graphical session by asking logind for it.

https://bugs.freedesktop.org/show_bug.cgi?id=107062
---
 src/libaccountsservice/act-user-manager.c | 96 ++++++++++++++++++++---
 1 file changed, 84 insertions(+), 12 deletions(-)

diff --git a/src/libaccountsservice/act-user-manager.c b/src/libaccountsservice/act-user-manager.c
index 325421b..862e530 100644
--- a/src/libaccountsservice/act-user-manager.c
+++ b/src/libaccountsservice/act-user-manager.c
@@ -487,8 +487,8 @@ _can_activate_systemd_sessions (ActUserManager *manager)
 
         res = sd_seat_can_multi_session (manager->priv->seat.id);
         if (res < 0) {
-                g_warning ("unable to determine if seat can activate sessions: %s",
-                           strerror (-res));
+                g_warning ("unable to determine if seat %s can activate sessions: %s",
+                           manager->priv->seat.id, strerror (-res));
                 return FALSE;
         }
 
@@ -698,13 +698,92 @@ on_get_seat_id_finished (GObject        *object,
 }
 
 #ifdef WITH_SYSTEMD
+static gboolean
+act_systemd_find_session (char **session_id)
+{
+        const gchar * const graphical_session_types[] = { "wayland", "x11", "mir", NULL };
+        g_autofree gchar *class = NULL;
+        g_autofree gchar *local_session_id = NULL;
+        g_autofree gchar *type = NULL;
+        g_auto(GStrv) sessions = NULL;
+        int n_sessions;
+        int saved_errno;
+
+        g_return_val_if_fail (session_id != NULL, FALSE);
+
+        if ((saved_errno = sd_uid_get_display (getuid (), &local_session_id)) < 0) {
+                /* no session, maybe there's a greeter session */
+                if (saved_errno == -ENODATA) {
+                        if ((n_sessions = sd_uid_get_sessions (getuid (), 1, &sessions)) < 0) {
+                                g_critical ("Failed to get all sessions for user %d", getuid ());
+                                return FALSE;
+                        }
+
+                        if (n_sessions == 0) {
+                                g_critical ("User %d has no sessions", getuid ());
+                                return FALSE;
+                        }
+
+                        for (int i = 0; i < n_sessions; ++i) {
+                                if ((saved_errno = sd_session_get_class (sessions[i], &class)) < 0) {
+                                        g_warning ("Couldn't get class for session '%d': %s",
+                                                   i,
+                                                   g_strerror (-saved_errno));
+                                        continue;
+                                }
+
+                                if (g_strcmp0 (class, "greeter") == 0) {
+                                        local_session_id = g_strdup (sessions[i]);
+                                        break;
+                                }
+                        }
+
+                        if (!local_session_id) {
+                                g_critical ("Couldn't find a session or a greeter session for user %d", getuid ());
+                                return FALSE;
+                        }
+                } else {
+                        g_critical ("Couldn't get display: %s (%s)", g_strerror (-saved_errno), local_session_id);
+                        return FALSE;
+                }
+        }
+
+        /* sd_uid_get_display will return any session if there is no graphical
+         * one, so let's check it really is graphical. */
+        if ((saved_errno = sd_session_get_type (local_session_id, &type)) < 0) {
+                g_critical ("Couldn't get type for session '%s': %s",
+                            local_session_id,
+                            g_strerror (-saved_errno));
+                return FALSE;
+        }
+
+        if (!g_strv_contains (graphical_session_types, type)) {
+                g_critical ("Session '%s' is not a graphical session (type: '%s')",
+                            local_session_id,
+                            type);
+                return FALSE;
+        }
+
+        *session_id = g_steal_pointer (&local_session_id);
+
+        return TRUE;
+}
+
 static void
 _get_systemd_seat_id (ActUserManager *manager)
 {
-        int   res;
+        int               res;
         g_autofree gchar *seat_id = NULL;
 
-        res = sd_session_get_seat (NULL, &seat_id);
+        if (manager->priv->seat.session_id == NULL) {
+                if (!act_systemd_find_session (&manager->priv->seat.session_id)) {
+                        g_warning ("Could not get session");
+                        return;
+                }
+        }
+
+        res = sd_session_get_seat (manager->priv->seat.session_id, &seat_id);
+
         if (res == -ENOENT) {
                 seat_id = NULL;
         } else if (res < 0) {
@@ -1134,15 +1213,8 @@ static void
 _get_current_systemd_session_id (ActUserManager *manager)
 {
         g_autofree gchar *session_id = NULL;
-        int   res;
 
-        res = sd_pid_get_session (0, &session_id);
-
-        if (res == -ENOENT) {
-                session_id = NULL;
-        } else if (res < 0) {
-                g_debug ("Failed to identify the current session: %s",
-                         strerror (-res));
+        if (!act_systemd_find_session (&session_id)) {
                 unload_seat (manager);
                 return;
         }
-- 
2.17.1