Merge pull request #4359 from jensj12/infinite-loop

Fix #2081: Prevent infinite loop

distribution/changelog.txt

@@ -6,6 +6,7 @@
 - Feature: Implementation of the user-defined currency
 - Feature: Add ability to rotate map elements with the tile inspector.
 - Feature: Add ride console command for diagnostics and changing vehicle type.
+- Feature: Allow selecting corners when using the mountain tool.
 - Feature: Allow setting ownership of map edges.
 - Feature: Allow up to 255 cars per train.
 - Feature: Importing SV4 and SC4 files with rides.
@@ -28,6 +29,7 @@
 - Removed: BMP screenshots.
 - Removed: Intamin and Phoenix easter eggs.
 - Fix: [#1038] Guest List is out of order.
+- Fix: [#2081] Game hangs when track has infinite loop.
 - Fix: [#2754] Dragging scrollview fails when scaled.
 - Fix: [#3210] Scenery window scrolls too far.
 - Fix: [#3282] Launched Freefall ride ratings are fixed for Downward Launch (original bug).

src/ride/ride.c

@@ -743,7 +743,7 @@ int ride_find_track_gap(rct_xy_element *input, rct_xy_element *output)
 {
 	rct_window *w;
 	rct_ride *ride;
-	track_circuit_iterator it;
+	track_circuit_iterator it, slowIt;
 	int rideIndex;
 
 	rideIndex = input->element->properties.track.ride_index;
@@ -756,12 +756,27 @@ int ride_find_track_gap(rct_xy_element *input, rct_xy_element *output)
 	if (w != NULL && _rideConstructionState != RIDE_CONSTRUCTION_STATE_0 && _currentRideIndex == rideIndex)
 		sub_6C9627();
 
+	bool counter = true;
 	track_circuit_iterator_begin(&it, *input);
+	slowIt = it;
 	while (track_circuit_iterator_next(&it)) {
 		if (!track_is_connected_by_shape(it.last.element, it.current.element)) {
 			*output = it.current;
 			return 1;
 		}
+		//#2081: prevent an infinite loop
+		counter = !counter;
+		if (counter) {
+			track_circuit_iterator_next(&slowIt);
+			if (slowIt.currentZ == it.currentZ &&
+				slowIt.currentDirection == it.currentDirection &&
+				slowIt.current.x == it.current.x &&
+				slowIt.current.y == it.current.y) {
+				*output = it.current;
+				return 1;
+			}
+		}
+
 	}
 	if (!it.looped) {
 		*output = it.last;

src/ride/vehicle.c

@@ -5753,7 +5753,11 @@ static void vehicle_update_block_breaks_open_previous_section(rct_vehicle *vehic
 	int x = vehicle->track_x;
 	int y = vehicle->track_y;
 	int z = vehicle->track_z;
-	track_begin_end trackBeginEnd;
+	track_begin_end trackBeginEnd, slowTrackBeginEnd;
+	rct_map_element slowMapElement = *mapElement;
+	bool counter = true;
+	int slowX = x;
+	int slowY = y;
 	do {
 		if (!track_block_get_previous(x, y, mapElement, &trackBeginEnd)) {
 			return;
@@ -5768,6 +5772,21 @@ static void vehicle_update_block_breaks_open_previous_section(rct_vehicle *vehic
 		y = trackBeginEnd.end_y;
 		z = trackBeginEnd.begin_z;
 		mapElement = trackBeginEnd.begin_element;
+
+		//#2081: prevent infinite loop
+		counter = !counter;
+		if (counter) {
+			track_block_get_previous(slowX, slowY, &slowMapElement, &slowTrackBeginEnd);
+			slowX = slowTrackBeginEnd.end_x;
+			slowY = slowTrackBeginEnd.end_y;
+			slowMapElement = *(slowTrackBeginEnd.begin_element);
+			if (slowX == x &&
+				slowY == y &&
+				slowMapElement.base_height == mapElement->base_height &&
+				slowMapElement.type == mapElement->type ) {
+				return;
+			}
+		}
 	} while (!track_element_is_block_start(trackBeginEnd.begin_element));
 
 	// Get the start of the track block instead of the end