logind: only allow one shutdown/sleep action to be queued at the same time

This should make sure that closing the lid while shutting down won't
suspend the machine but will simply cause the shutdown to complete.

src/login/logind-action.c

@@ -56,10 +56,15 @@ int manager_handle_action(
         DBusError error;
         int r;
         InhibitWhat inhibit_operation;
-        bool supported = true;
+        bool supported;
 
         assert(m);
 
+        if (m->action_job || m->delayed_unit) {
+                log_debug("Action already in progress, ignoring.");
+                return -EALREADY;
+        }
+
         /* If the key handling is turned off, don't do anything */
         if (handle == HANDLE_IGNORE) {
                 log_debug("Refusing operation, as it is turned off.");
@@ -74,6 +79,8 @@ int manager_handle_action(
                 supported = can_sleep("disk") > 0 && can_sleep_disk("suspend") > 0;
         else if (handle == HANDLE_KEXEC)
                 supported = access("/sbin/kexec", X_OK) >= 0;
+        else
+                supported = true;
 
         if (!supported) {
                 log_warning("Requested operation not supported, ignoring.");

src/login/logind-dbus.c

@@ -990,22 +990,44 @@ static int have_multiple_sessions(
         return false;
 }
 
-static int send_start_unit(DBusConnection *connection, const char *unit_name, DBusError *error) {
-        const char *mode = "replace";
+static int send_start_unit(Manager *m, const char *unit_name, DBusError *error) {
+        _cleanup_dbus_message_unref_ DBusMessage *reply = NULL;
+        const char *mode = "replace", *p;
+        int r;
+        char *c;
 
+        assert(m);
         assert(unit_name);
 
-        return bus_method_call_with_reply (
-                        connection,
+        r = bus_method_call_with_reply(
+                        m->bus,
                         "org.freedesktop.systemd1",
                         "/org/freedesktop/systemd1",
                         "org.freedesktop.systemd1.Manager",
                         "StartUnit",
-                        NULL,
-                        NULL,
+                        &reply,
+                        error,
                         DBUS_TYPE_STRING, &unit_name,
                         DBUS_TYPE_STRING, &mode,
                         DBUS_TYPE_INVALID);
+        if (r < 0)
+                return r;
+
+        if (!dbus_message_get_args(
+                            reply,
+                            error,
+                            DBUS_TYPE_OBJECT_PATH, &p,
+                            DBUS_TYPE_INVALID))
+                return -EINVAL;
+
+        c = strdup(p);
+        if (!c)
+                return -ENOMEM;
+
+        free(m->action_job);
+        m->action_job = c;
+
+        return 0;
 }
 
 static int send_prepare_for(Manager *m, InhibitWhat w, bool _active) {
@@ -1226,6 +1248,7 @@ int bus_manager_shutdown_or_sleep_now_or_later(
         assert(unit_name);
         assert(w >= 0);
         assert(w <= _INHIBIT_WHAT_MAX);
+        assert(!m->action_job);
 
         delayed =
                 m->inhibit_delay_max > 0 &&
@@ -1240,7 +1263,7 @@ int bus_manager_shutdown_or_sleep_now_or_later(
 
                 /* Shutdown is not delayed, execute it
                  * immediately */
-                r = send_start_unit(m->bus, unit_name, error);
+                r = send_start_unit(m, unit_name, error);
         }
 
         return r;
@@ -1278,6 +1301,9 @@ static int bus_manager_do_shutdown_or_sleep(
         assert(error);
         assert(_reply);
 
+        if (m->action_job || m->delayed_unit)
+                return -EALREADY;
+
         if (!dbus_message_get_args(
                             message,
                             error,
@@ -2327,6 +2353,23 @@ DBusHandlerResult bus_message_filter(
                         log_error("Failed to parse Released message: %s", bus_error_message(&error));
                 else
                         manager_cgroup_notify_empty(m, cgroup);
+
+        } else if (dbus_message_is_signal(message, "org.freedesktop.systemd1.Manager", "JobRemoved")) {
+                uint32_t id;
+                const char *path, *result, *unit;
+
+                if (!dbus_message_get_args(message, &error,
+                                           DBUS_TYPE_UINT32, &id,
+                                           DBUS_TYPE_OBJECT_PATH, &path,
+                                           DBUS_TYPE_STRING, &unit,
+                                           DBUS_TYPE_STRING, &result,
+                                           DBUS_TYPE_INVALID))
+                        log_error("Failed to parse JobRemoved message: %s", bus_error_message(&error));
+                else if (m->action_job && streq(m->action_job, path)) {
+                        log_info("Action is complete, result is '%s'.", result);
+                        free(m->action_job);
+                        m->action_job = NULL;
+                }
         }
 
         dbus_error_free(&error);
@@ -2376,21 +2419,21 @@ int manager_dispatch_delayed(Manager *manager) {
 
         bus_manager_log_shutdown(manager, manager->delayed_what, manager->delayed_unit);
 
+        /* Tell people about it */
+        send_prepare_for(manager, manager->delayed_what, false);
+
         /* Reset delay data */
         unit_name = manager->delayed_unit;
         manager->delayed_unit = NULL;
 
         /* Actually do the shutdown */
         dbus_error_init(&error);
-        r = send_start_unit(manager->bus, unit_name, &error);
+        r = send_start_unit(manager, unit_name, &error);
         if (r < 0) {
                 log_warning("Failed to send delayed message: %s", bus_error_message_or_strerror(&error, -r));
                 dbus_error_free(&error);
                 return r;
         }
 
-        /* Tell people about it */
-        send_prepare_for(manager, manager->delayed_what, false);
-
         return 1;
 }

src/login/logind.c

@@ -187,6 +187,8 @@ void manager_free(Manager *m) {
         strv_free(m->kill_only_users);
         strv_free(m->kill_exclude_users);
 
+        free(m->action_job);
+
         free(m->cgroup_path);
         free(m);
 }

src/login/logind.h

@@ -100,7 +100,9 @@ struct Manager {
 
         usec_t inhibit_delay_max;
 
-        int idle_action_fd;
+        char* action_job;
+
+        int idle_action_fd; /* the timer_fd */
         usec_t idle_action_usec;
         usec_t idle_action_not_before_usec;
         HandleAction idle_action;