(svn r1579) Fix: [ 1105963 ] Buoys can now only be removed if no ship has it in their schedule.

This makes buoys more useable in multiplayer games again, as buoys can't be deleted by other players if they are used.

lang/english.txt

@@ -1140,6 +1140,8 @@ STR_CANT_BUILD_LOCKS						:{WHITE}Can't build locks here...
 STR_BUILD_LOCKS_TIP						:{BLACK}Build locks
 STR_LANDINFO_LOCK						:Lock
 
+STR_BUOY_IS_IN_USE					:{WHITE}... buoy is in use!
+
 STR_LANDINFO_COORDS						:{BLACK}Coordinates: {LTBLUE}{NUMU16}x{NUMU16} ({STRING})
 
 STR_CANT_REMOVE_PART_OF_STATION					:{WHITE}Can't remove part of station...

station_cmd.c

@@ -1751,6 +1751,23 @@ int32 CmdBuildBuoy(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 	return _price.build_dock;
 }
 
+/* Checks if any ship is servicing the buoy specified. Returns yes or no */
+static bool CheckShipsOnBuoy(Station *st)
+{
+	const Vehicle *v;
+	FOR_ALL_VEHICLES(v) {
+		if (v->type == VEH_Ship) {
+			const Order *order;
+			FOR_VEHICLE_ORDERS(v, order) {
+				if (order->type == OT_GOTO_STATION && order->station == st->index) {
+					return true;
+				}
+			}
+		}
+	}
+	return false;
+}
+
 static int32 RemoveBuoy(Station *st, uint32 flags)
 {
 	uint tile;
@@ -1762,6 +1779,9 @@ static int32 RemoveBuoy(Station *st, uint32 flags)
 
 	tile = st->dock_tile;
 
+	if (CheckShipsOnBuoy(st))
+		return_cmd_error(STR_BUOY_IS_IN_USE);
+
 	if (!EnsureNoVehicle(tile))
 		return CMD_ERROR;