up-backend: add inhibitor lock interface

Phones are suspended most of the time so they are not awake for > 20s
to allow UPower to take action when battery is critical.
Add an interface to take and release inhibitor locks which
prevent the device from suspending to allow UPower to execute
the critical power action.

src/bsd/up-backend-common.c

@@ -126,4 +126,19 @@ up_backend_take_action (UpBackend *backend)
 			   NULL);
 }
 
-
+/**
+ * up_backend_inhibitor_lock_take:
+ * @backend: The %UpBackend class instance
+ * @reason: Why the inhibitor lock is taken
+ * @mode: The mode of the lock ('delay' or 'block')
+ *
+ * BSD does not support inhibitor locks so they are simply ignored.
+ */
+int
+up_backend_inhibitor_lock_take (UpBackend  *backend,
+                                const char *reason,
+                                const char *mode)
+{
+    g_debug ("Taking inhibitor locks are not supported in BSD");
+    return -1;
+}

src/dummy/up-backend.c

@@ -170,6 +170,23 @@ up_backend_take_action (UpBackend *backend)
 	g_debug ("Not taking any action, dummy backend is used");
 }
 
+/**
+ * up_backend_inhibitor_lock_take:
+ * @backend: The %UpBackend class instance
+ * @reason: Why the inhibitor lock is taken
+ * @mode: The mode of the lock ('delay' or 'block')
+ *
+ * Dummy does not support inhibitor locks so they are simply ignored.
+ */
+int
+up_backend_inhibitor_lock_take (UpBackend  *backend,
+                                const char *reason,
+                                const char *mode)
+{
+    g_debug ("Not taking inhibitor, dummy backend is used");
+    return -ENOTSUP;
+}
+
 /**
  * up_backend_class_init:
  * @klass: The UpBackendClass

src/linux/up-backend.c

@@ -62,7 +62,7 @@ struct UpBackendPrivate
 	UpConfig		*config;
 	GDBusProxy		*logind_proxy;
 	guint                    logind_sleep_id;
-	int                      logind_inhibitor_fd;
+	int                      logind_delay_inhibitor_fd;
 
 	/* BlueZ */
 	guint			 bluez_watch_id;
@@ -648,28 +648,32 @@ up_backend_take_action (UpBackend *backend)
 /**
  * up_backend_inhibitor_lock_take:
  * @backend: The %UpBackend class instance
+ * @reason: Why the inhibitor lock is taken
+ * @mode: The mode of the lock ('delay' or 'block')
  *
- * Acquire a sleep 'delay lock' via systemd's logind that will
- * inhibit going to sleep until the lock is released again via
- * up_backend_inhibitor_lock_release().
- * Does nothing if the lock was already acquired.
+ * Acquire a sleep inhibitor lock via systemd's logind that will
+ * inhibit going to sleep until the lock is released again by
+ * closing the file descriptor.
  */
-static void
-up_backend_inhibitor_lock_take (UpBackend *backend)
+int
+up_backend_inhibitor_lock_take (UpBackend  *backend,
+                                const char *reason,
+                                const char *mode)
 {
 	GVariant *out, *input;
 	GUnixFDList *fds = NULL;
+	int fd;
 	GError *error = NULL;
 
-	if (backend->priv->logind_inhibitor_fd > -1) {
-		return;
-	}
+	g_return_val_if_fail (reason != NULL, -1);
+	g_return_val_if_fail (mode != NULL, -1);
+	g_return_val_if_fail (g_str_equal (mode, "delay") || g_str_equal (mode, "block"), -1);
 
 	input = g_variant_new ("(ssss)",
-			       "sleep",                /* what */
-			       "UPower",               /* who */
-			       "Pause device polling", /* why */
-			       "delay");               /* mode */
+			       "sleep",  /* what */
+			       "UPower", /* who */
+			       reason,   /* why */
+			       mode);    /* mode */
 
 	out = g_dbus_proxy_call_with_unix_fd_list_sync (backend->priv->logind_proxy,
 							"Inhibit",
@@ -684,41 +688,24 @@ up_backend_inhibitor_lock_take (UpBackend *backend)
 		g_warning ("Could not acquire inhibitor lock: %s",
 			   error ? error->message : "Unknown reason");
 		g_clear_error (&error);
-		return;
+		return -1;
 	}
 
 	if (g_unix_fd_list_get_length (fds) != 1) {
 		g_warning ("Unexpected values returned by logind's 'Inhibit'");
 		g_variant_unref (out);
 		g_object_unref (fds);
-		return;
+		return -1;
 	}
 
-	backend->priv->logind_inhibitor_fd = g_unix_fd_list_get (fds, 0, NULL);
+	fd = g_unix_fd_list_get (fds, 0, NULL);
+
 	g_variant_unref (out);
 	g_object_unref (fds);
 
-	g_debug ("Acquired inhibitor lock (%i)", backend->priv->logind_inhibitor_fd);
-}
+	g_debug ("Acquired inhibitor lock (%i, %s)", fd, mode);
 
-/**
- * up_backend_inhibitor_lock_release:
- * @backend: The %UpBackend class instance
- *
- * Releases a previously acquired inhibitor lock or does nothing
- * if no lock is held;
- */
-static void
-up_backend_inhibitor_lock_release (UpBackend *backend)
-{
-	if (backend->priv->logind_inhibitor_fd == -1) {
-		return;
-	}
-
-	close (backend->priv->logind_inhibitor_fd);
-	backend->priv->logind_inhibitor_fd = -1;
-
-	g_debug ("Released inhibitor lock");
+	return fd;
 }
 
 /**
@@ -754,11 +741,15 @@ up_backend_prepare_for_sleep (GDBusConnection *connection,
 
 	if (will_sleep) {
 		up_daemon_pause_poll (backend->priv->daemon);
-		up_backend_inhibitor_lock_release (backend);
+		if (backend->priv->logind_delay_inhibitor_fd > 0) {
+			close (backend->priv->logind_delay_inhibitor_fd);
+			backend->priv->logind_delay_inhibitor_fd = 0;
+		}
 		return;
 	}
 
-	up_backend_inhibitor_lock_take (backend);
+	if (backend->priv->logind_delay_inhibitor_fd < 0)
+		backend->priv->logind_delay_inhibitor_fd = up_backend_inhibitor_lock_take (backend, "Pause device polling", "delay");
 
 	/* we are waking up, lets refresh all battery devices */
 	g_debug ("Woke up from sleep; about to refresh devices");
@@ -825,9 +816,9 @@ up_backend_init (UpBackend *backend)
 						       backend,
 						       NULL);
 	backend->priv->logind_sleep_id = sleep_id;
-	backend->priv->logind_inhibitor_fd = -1;
+	backend->priv->logind_delay_inhibitor_fd = -1;
 
-	up_backend_inhibitor_lock_take (backend);
+	backend->priv->logind_delay_inhibitor_fd = up_backend_inhibitor_lock_take (backend, "Pause device polling", "delay");
 }
 
 static void
@@ -855,7 +846,8 @@ up_backend_finalize (GObject *object)
 	g_dbus_connection_signal_unsubscribe (bus,
 					      backend->priv->logind_sleep_id);
 
-	up_backend_inhibitor_lock_release (backend);
+	if (backend->priv->logind_delay_inhibitor_fd >= 0)
+		close (backend->priv->logind_delay_inhibitor_fd);
 
 	g_clear_object (&backend->priv->logind_proxy);
 

src/up-backend.h

@@ -71,6 +71,9 @@ gboolean	 up_backend_coldplug			(UpBackend	*backend,
 void		 up_backend_unplug			(UpBackend	*backend);
 void		 up_backend_take_action			(UpBackend	*backend);
 const char	*up_backend_get_critical_action		(UpBackend	*backend);
+int		 up_backend_inhibitor_lock_take		(UpBackend	*backend,
+							 const char	*reason,
+							 const char	*mode);
 
 G_END_DECLS