[gnome-software] Enforce that the GsAppState gets set to sane values

[Richard Hughes <rhughes src gnome org>]

commit 3acad578a6b48e936801b10d914449b0d6e368ff
Author: Richard Hughes <richard hughsie com>
Date:   Tue Sep 10 09:49:21 2013 +0100

    Enforce that the GsAppState gets set to sane values

 src/gs-app.c |   69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 65 insertions(+), 4 deletions(-)
---
diff --git a/src/gs-app.c b/src/gs-app.c
index 9b6f7ff..c52f84b 100644
--- a/src/gs-app.c
+++ b/src/gs-app.c
@@ -231,15 +231,76 @@ gs_app_get_state (GsApp *app)
 
 /**
  * gs_app_set_state:
+ *
+ * This sets the state of the application. The following state diagram explains
+ * the typical states. All applications start in state %GS_APP_STATE_UNKNOWN.
+ *
+ * UPDATABLE --> INSTALLING --> INSTALLED
+ * UPDATABLE --> REMOVING   --> AVAILABLE
+ * INSTALLED --> REMOVING   --> AVAILABLE
+ * AVAILABLE --> INSTALLING --> INSTALLED
  */
 void
 gs_app_set_state (GsApp *app, GsAppState state)
 {
+       gboolean state_change_ok = FALSE;
+       GsAppPrivate *priv = app->priv;
+
        g_return_if_fail (GS_IS_APP (app));
-        if (app->priv->state == state)
-                return;
-       app->priv->state = state;
-        g_object_notify (G_OBJECT (app), "state");
+       if (priv->state == state)
+               return;
+
+       /* check the state change is allowed */
+       switch (priv->state) {
+       case GS_APP_STATE_UNKNOWN:
+               /* unknown has to go into one of the stable states */
+               if (state == GS_APP_STATE_INSTALLED ||
+                   state == GS_APP_STATE_AVAILABLE ||
+                   state == GS_APP_STATE_UPDATABLE)
+                       state_change_ok = TRUE;
+               break;
+       case GS_APP_STATE_INSTALLED:
+               /* installed has to go into an action state */
+               if (state == GS_APP_STATE_REMOVING)
+                       state_change_ok = TRUE;
+               break;
+       case GS_APP_STATE_AVAILABLE:
+               /* available has to go into an action state */
+               if (state == GS_APP_STATE_INSTALLING)
+                       state_change_ok = TRUE;
+               break;
+       case GS_APP_STATE_INSTALLING:
+               /* installing has to go into an stable state */
+               if (state == GS_APP_STATE_INSTALLED)
+                       state_change_ok = TRUE;
+               break;
+       case GS_APP_STATE_REMOVING:
+               /* removing has to go into an stable state */
+               if (state == GS_APP_STATE_AVAILABLE)
+                       state_change_ok = TRUE;
+               break;
+       case GS_APP_STATE_UPDATABLE:
+               /* updatable has to go into an action state */
+               if (state == GS_APP_STATE_REMOVING)
+                       state_change_ok = TRUE;
+               break;
+       default:
+               g_warning ("state %s unhandled",
+                          gs_app_state_to_string (priv->state));
+               g_assert_not_reached ();
+       }
+
+       /* this state change was unexpected */
+       if (!state_change_ok) {
+               g_warning ("State change on %s from %s to %s is not OK",
+                          priv->id,
+                          gs_app_state_to_string (priv->state),
+                          gs_app_state_to_string (state));
+               return;
+       }
+
+       priv->state = state;
+       g_object_notify (G_OBJECT (app), "state");
        g_signal_emit (app, signals[SIGNAL_STATE_CHANGED], 0);
 }