core: define a full sort order for nm_settings_connection_cmp_timestamp()

We want to have some guaranteed order when comparing different connections.
So, in case of equal timestamps, proceed with comparing more properties.

It makes sense to consider the autoconnect-priority next.
This is what get_existing_connection() needs, thus we no longer
need to pre-sort the list.

src/nm-manager.c

@@ -1749,7 +1749,7 @@ get_existing_connection (NMManager *self, NMDevice *device, gboolean *out_genera
 
 		/* XXX: this code will go away soon. Copy the array over to a GSList
 		 * and don't bother for now. */
-		cons = nm_manager_get_activatable_connections (self, &len, TRUE);
+		cons = nm_manager_get_activatable_connections (self, &len, FALSE);
 		for (i = len; i > 0; )
 			connections = g_slist_prepend (connections, cons[--i]);
 		connections = g_slist_sort (connections, (GCompareFunc) nm_settings_connection_cmp_timestamp);

src/settings/nm-settings-connection.c

@@ -2162,29 +2162,64 @@ nm_settings_connection_set_flags_all (NMSettingsConnection *self, NMSettingsConn
 
 /*****************************************************************************/
 
+static int
+_cmp_timestamp (NMSettingsConnection *a, NMSettingsConnection *b)
+{
+	gboolean a_has_ts, b_has_ts;
+	guint64 ats = 0, bts = 0;
+
+	nm_assert (NM_IS_SETTINGS_CONNECTION (a));
+	nm_assert (NM_IS_SETTINGS_CONNECTION (b));
+
+	a_has_ts = !!nm_settings_connection_get_timestamp (a, &ats);
+	b_has_ts = !!nm_settings_connection_get_timestamp (b, &bts);
+	if (a_has_ts != b_has_ts)
+		return a_has_ts ? -1 : 1;
+	if (a_has_ts && ats != bts)
+		return (ats > bts) ? -1 : 1;
+	return 0;
+}
+
+static int
+_cmp_last_resort (NMSettingsConnection *a, NMSettingsConnection *b)
+{
+	int c;
+
+	nm_assert (NM_IS_SETTINGS_CONNECTION (a));
+	nm_assert (NM_IS_SETTINGS_CONNECTION (b));
+
+	c = g_strcmp0 (nm_connection_get_uuid (NM_CONNECTION (a)),
+	               nm_connection_get_uuid (NM_CONNECTION (b)));
+	if (c)
+		return c;
+
+	/* hm, same UUID. Use their pointer value to give them a stable
+	 * order. */
+	return (a > b) ? -1 : 1;
+}
+
 /* sorting for "best" connections.
  * The function sorts connections in descending timestamp order.
  * That means an older connection (lower timestamp) goes after
  * a newer one.
  */
 int
-nm_settings_connection_cmp_timestamp (NMSettingsConnection *ac, NMSettingsConnection *bc)
+nm_settings_connection_cmp_timestamp (NMSettingsConnection *a, NMSettingsConnection *b)
 {
-	guint64 ats = 0, bts = 0;
+	int c;
 
-	if (ac == bc)
+	if (a == b)
 		return 0;
-	if (!ac)
+	if (!a)
 		return 1;
-	if (!bc)
+	if (!b)
 		return -1;
 
-	nm_settings_connection_get_timestamp (ac, &ats);
+	if ((c = _cmp_timestamp (a, b)))
-	nm_settings_connection_get_timestamp (bc, &bts);
+		return c;
-	if (ats != bts)
+	if ((c = nm_utils_cmp_connection_by_autoconnect_priority (NM_CONNECTION (a), NM_CONNECTION (b))))
-		return (ats > bts) ? -1 : 1;
+		return c;
-
+	return _cmp_last_resort (a, b);
-	return 0;
 }
 
 int
@@ -2197,32 +2232,15 @@ nm_settings_connection_cmp_timestamp_p_with_data (gconstpointer pa, gconstpointe
 int
 nm_settings_connection_cmp_autoconnect_priority (NMSettingsConnection *a, NMSettingsConnection *b)
 {
-	guint64 ats = 0, bts = 0;
 	int c;
 
 	if (a == b)
 		return 0;
-
+	if ((c = nm_utils_cmp_connection_by_autoconnect_priority (NM_CONNECTION (a), NM_CONNECTION (b))))
-	/* first we compare them by their autoconnect priority. */
-	c = nm_utils_cmp_connection_by_autoconnect_priority (NM_CONNECTION (a), NM_CONNECTION (b));
-	if (c)
 		return c;
-
+	if ((c = _cmp_timestamp (a, b)))
-	/* then by their last activation timestamp (with the more recently connected one first) */
-	nm_settings_connection_get_timestamp (a, &ats);
-	nm_settings_connection_get_timestamp (b, &bts);
-	if (ats != bts)
-		return (ats > bts) ? -1 : 1;
-
-	/* if they are still equal, sort them by their UUID to give them an arbitrary, but stable
-	 * order. */
-	c = g_strcmp0 (nm_connection_get_uuid (NM_CONNECTION (a)),
-	               nm_connection_get_uuid (NM_CONNECTION (b)));
-	if (c)
 		return c;
-
+	return _cmp_last_resort (a, b);
-	/* hm, still the same. Use their pointer value. */
-	return (a > b) ? -1 : 1;
 }
 
 int