Merge pull request #400 from sfPlayer1/master

Fix various registry issues

fml/patches/minecraft/net/minecraft/block/Block.java.patch

@@ -12,7 +12,7 @@
  public class Block
  {
 -    public static final RegistryNamespaced field_149771_c = new RegistryNamespacedDefaultedByKey("air");
-+    public static final RegistryNamespaced field_149771_c = GameData.blockRegistry;
++    public static final RegistryNamespaced field_149771_c = GameData.getBlockRegistry();
      private CreativeTabs field_149772_a;
      protected String field_149768_d;
      public static final Block.SoundType field_149769_e = new Block.SoundType("stone", 1.0F, 1.0F);

fml/patches/minecraft/net/minecraft/client/LoadingScreenRenderer.java.patch

@@ -0,0 +1,26 @@
+--- ../src-base/minecraft/net/minecraft/client/LoadingScreenRenderer.java
++++ ../src-work/minecraft/net/minecraft/client/LoadingScreenRenderer.java
+@@ -1,5 +1,6 @@
+ package net.minecraft.client;
+ 
++import cpw.mods.fml.client.FMLClientHandler;
+ import cpw.mods.fml.relauncher.Side;
+ import cpw.mods.fml.relauncher.SideOnly;
+ import net.minecraft.client.gui.Gui;
+@@ -147,6 +148,8 @@
+                     GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);
+                 }
+ 
++                if (!FMLClientHandler.instance().handleLoadingScreen(scaledresolution))
++                {
+                 Tessellator tessellator = Tessellator.field_78398_a;
+                 this.field_73725_b.func_110434_K().func_110577_a(Gui.field_110325_k);
+                 float f = 32.0F;
+@@ -184,6 +187,7 @@
+                 OpenGlHelper.func_148821_a(770, 771, 1, 0);
+                 this.field_73725_b.field_71466_p.func_78261_a(this.field_73726_c, (l - this.field_73725_b.field_71466_p.func_78256_a(this.field_73726_c)) / 2, i1 / 2 - 4 - 16, 16777215);
+                 this.field_73725_b.field_71466_p.func_78261_a(this.field_73727_a, (l - this.field_73725_b.field_71466_p.func_78256_a(this.field_73727_a)) / 2, i1 / 2 - 4 + 8, 16777215);
++                }
+                 this.field_146588_g.func_147609_e();
+ 
+                 if (OpenGlHelper.func_148822_b())

fml/patches/minecraft/net/minecraft/client/Minecraft.java.patch

@@ -1,16 +1,17 @@
 --- ../src-base/minecraft/net/minecraft/client/Minecraft.java
 +++ ../src-work/minecraft/net/minecraft/client/Minecraft.java
-@@ -1,6 +1,9 @@
+@@ -1,6 +1,10 @@
  package net.minecraft.client;
  
  import com.google.common.collect.Lists;
 +
 +import cpw.mods.fml.client.FMLClientHandler;
 +import cpw.mods.fml.common.FMLCommonHandler;
++import cpw.mods.fml.common.StartupQuery;
  import cpw.mods.fml.relauncher.Side;
  import cpw.mods.fml.relauncher.SideOnly;
  import io.netty.util.concurrent.GenericFutureListener;
-@@ -146,6 +149,8 @@
+@@ -146,6 +150,8 @@
  import org.lwjgl.opengl.PixelFormat;
  import org.lwjgl.util.glu.GLU;
  
@@ -19,21 +20,7 @@
  @SideOnly(Side.CLIENT)
  public class Minecraft implements IPlayerUsage
  {
-@@ -323,8 +328,11 @@
+@@ -448,7 +454,7 @@
- 
-     public void func_71404_a(CrashReport p_71404_1_)
-     {
--        this.field_71434_R = true;
--        this.field_71433_S = p_71404_1_;
-+        if (!FMLClientHandler.instance().handlingCrash(p_71404_1_))
-+        {
-+            this.field_71434_R = true;
-+            this.field_71433_S = p_71404_1_;
-+        }
-     }
- 
-     public void func_71377_b(CrashReport p_71377_1_)
-@@ -448,7 +456,7 @@
          this.field_110451_am = new SimpleReloadableResourceManager(this.field_110452_an);
          this.field_135017_as = new LanguageManager(this.field_110452_an, this.field_71474_y.field_74363_ab);
          this.field_110451_am.func_110542_a(this.field_135017_as);
@@ -42,7 +29,7 @@
          this.field_71446_o = new TextureManager(this.field_110451_am);
          this.field_110451_am.func_110542_a(this.field_71446_o);
          this.field_147127_av = new SoundHandler(this.field_110451_am, this.field_71474_y);
-@@ -508,12 +516,13 @@
+@@ -508,12 +514,13 @@
          this.field_71446_o.func_130088_a(TextureMap.field_110576_c, new TextureMap(1, "textures/items"));
          GL11.glViewport(0, 0, this.field_71443_c, this.field_71440_d);
          this.field_71452_i = new EffectRenderer(this.field_71441_e, this.field_71446_o);
@@ -57,7 +44,7 @@
          }
          else
          {
-@@ -527,6 +536,7 @@
+@@ -527,6 +534,7 @@
              this.func_71352_k();
          }
  
@@ -65,7 +52,7 @@
          Display.setVSyncEnabled(this.field_71474_y.field_74352_v);
      }
  
-@@ -916,9 +926,11 @@
+@@ -916,9 +924,11 @@
  
          if (!this.field_71454_w)
          {
@@ -77,7 +64,7 @@
          }
  
          GL11.glFlush();
-@@ -1496,6 +1508,8 @@
+@@ -1496,6 +1506,8 @@
              --this.field_71467_ac;
          }
  
@@ -86,7 +73,7 @@
          this.field_71424_I.func_76320_a("gui");
  
          if (!this.field_71445_n)
-@@ -1646,6 +1660,7 @@
+@@ -1646,6 +1658,7 @@
                          this.field_71462_r.func_146274_d();
                      }
                  }
@@ -94,7 +81,7 @@
              }
  
              if (this.field_71429_W > 0)
-@@ -1787,6 +1802,7 @@
+@@ -1787,6 +1800,7 @@
                              }
                          }
                      }
@@ -102,7 +89,7 @@
                  }
              }
  
-@@ -1978,12 +1994,15 @@
+@@ -1978,12 +1992,15 @@
              this.field_71453_ak.func_74428_b();
          }
  
@@ -118,7 +105,20 @@
          this.func_71403_a((WorldClient)null);
          System.gc();
          ISaveHandler isavehandler = this.field_71469_aa.func_75804_a(p_71371_1_, false);
-@@ -2094,6 +2113,7 @@
+@@ -2019,6 +2036,12 @@
+ 
+         while (!this.field_71437_Z.func_71200_ad())
+         {
++            if (!StartupQuery.check())
++            {
++                func_71403_a(null);
++                func_147108_a(null);
++                return;
++            }
+             String s2 = this.field_71437_Z.func_71195_b_();
+ 
+             if (s2 != null)
+@@ -2094,6 +2117,7 @@
              this.field_110448_aq.func_148529_f();
              this.func_71351_a((ServerData)null);
              this.field_71455_al = false;

fml/patches/minecraft/net/minecraft/item/Item.java.patch

@@ -14,7 +14,7 @@
  public class Item
  {
 -    public static final RegistryNamespaced field_150901_e = new RegistryNamespaced();
-+    public static final RegistryNamespaced field_150901_e = GameData.itemRegistry;
++    public static final RegistryNamespaced field_150901_e = GameData.getItemRegistry();
      protected static final UUID field_111210_e = UUID.fromString("CB3F55D3-645C-4F38-A497-9C13A33DB5CF");
      private CreativeTabs field_77701_a;
      protected static Random field_77697_d = new Random();

fml/patches/minecraft/net/minecraft/server/MinecraftServer.java.patch

@@ -1,6 +1,6 @@
 --- ../src-base/minecraft/net/minecraft/server/MinecraftServer.java
 +++ ../src-work/minecraft/net/minecraft/server/MinecraftServer.java
-@@ -4,6 +4,10 @@
+@@ -4,6 +4,11 @@
  import com.mojang.authlib.GameProfile;
  import com.mojang.authlib.minecraft.MinecraftSessionService;
  import com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService;
@@ -8,10 +8,20 @@
 +import cpw.mods.fml.common.FMLCommonHandler;
 +import cpw.mods.fml.common.Loader;
 +import cpw.mods.fml.common.LoaderState;
++import cpw.mods.fml.common.StartupQuery;
  import cpw.mods.fml.relauncher.Side;
  import cpw.mods.fml.relauncher.SideOnly;
  import io.netty.buffer.ByteBuf;
-@@ -381,6 +385,7 @@
+@@ -333,7 +338,7 @@
+ 
+     public void func_71260_j()
+     {
+-        if (!this.field_71290_O)
++        if (!this.field_71290_O && Loader.instance().hasReachedState(LoaderState.SERVER_STARTED))
+         {
+             field_147145_h.info("Stopping server");
+ 
+@@ -381,6 +386,7 @@
          {
              if (this.func_71197_b())
              {
@@ -19,7 +29,7 @@
                  long i = func_130071_aq();
                  long l = 0L;
                  this.field_147147_p.func_151315_a(new ChatComponentText(this.field_71286_C));
-@@ -425,6 +430,7 @@
+@@ -425,12 +431,17 @@
                      Thread.sleep(1L);
                      this.field_71296_Q = true;
                  }
@@ -27,18 +37,17 @@
              }
              else
              {
-@@ -462,7 +468,10 @@
+                 this.func_71228_a((CrashReport)null);
-         {
-             try
-             {
-+                if (Loader.instance().hasReachedState(LoaderState.SERVER_STARTED))
-+                {
-                 this.func_71260_j();
-+                }
-                 this.field_71316_v = true;
              }
-             catch (Throwable throwable)
+         }
-@@ -471,6 +480,8 @@
++        catch (StartupQuery.AbortedException e)
++        {
++            // ignore silently
++        }
+         catch (Throwable throwable1)
+         {
+             field_147145_h.error("Encountered an unexpected exception", throwable1);
+@@ -471,6 +482,8 @@
              }
              finally
              {
@@ -47,7 +56,7 @@
                  this.func_71240_o();
              }
          }
-@@ -513,6 +524,7 @@
+@@ -513,6 +526,7 @@
      {
          long i = System.nanoTime();
          AxisAlignedBB.func_72332_a().func_72298_a();
@@ -55,7 +64,7 @@
          ++this.field_71315_w;
  
          if (this.field_71295_T)
-@@ -566,6 +578,7 @@
+@@ -566,6 +580,7 @@
  
          this.field_71304_b.func_76319_b();
          this.field_71304_b.func_76319_b();
@@ -63,7 +72,7 @@
      }
  
      public void func_71190_q()
-@@ -593,6 +606,7 @@
+@@ -593,6 +608,7 @@
                  }
  
                  this.field_71304_b.func_76320_a("tick");
@@ -71,7 +80,7 @@
                  CrashReport crashreport;
  
                  try
-@@ -617,6 +631,7 @@
+@@ -617,6 +633,7 @@
                      throw new ReportedException(crashreport);
                  }
  
@@ -79,7 +88,15 @@
                  this.field_71304_b.func_76319_b();
                  this.field_71304_b.func_76320_a("tracker");
                  worldserver.func_73039_n().func_72788_a();
-@@ -695,7 +710,7 @@
+@@ -648,6 +665,7 @@
+ 
+     public void func_71256_s()
+     {
++        StartupQuery.reset();
+         (new Thread("Server thread")
+         {
+             private static final String __OBFID = "CL_00001418";
+@@ -695,7 +713,7 @@
  
      public String getServerModName()
      {

fml/patches/minecraft/net/minecraft/world/storage/SaveHandler.java.patch

@@ -6,11 +6,11 @@
  import java.io.IOException;
 +
 +import cpw.mods.fml.common.FMLCommonHandler;
-+import cpw.mods.fml.common.registry.GameRegistryException;
++import cpw.mods.fml.common.StartupQuery;
  import net.minecraft.entity.player.EntityPlayer;
  import net.minecraft.nbt.CompressedStreamTools;
  import net.minecraft.nbt.NBTTagCompound;
-@@ -107,14 +110,22 @@
+@@ -107,20 +110,29 @@
          NBTTagCompound nbttagcompound;
          NBTTagCompound nbttagcompound1;
  
@@ -27,14 +27,21 @@
 +                FMLCommonHandler.instance().handleWorldDataLoad(this, worldInfo, nbttagcompound);
 +                return worldInfo;
              }
-+            catch (GameRegistryException gre)
++            catch (StartupQuery.AbortedException e)
 +            {
-+                throw gre;
++                throw e;
 +            }
              catch (Exception exception1)
              {
                  exception1.printStackTrace();
-@@ -129,8 +140,14 @@
+             }
+         }
+ 
++        FMLCommonHandler.instance().confirmBackupLevelDatUse(this);
+         file1 = new File(this.field_75770_b, "level.dat_old");
+ 
+         if (file1.exists())
+@@ -129,8 +141,14 @@
              {
                  nbttagcompound = CompressedStreamTools.func_74796_a(new FileInputStream(file1));
                  nbttagcompound1 = nbttagcompound.func_74775_l("Data");
@@ -43,14 +50,14 @@
 +                FMLCommonHandler.instance().handleWorldDataLoad(this, worldInfo, nbttagcompound);
 +                return worldInfo;
              }
-+            catch (GameRegistryException gre)
++            catch (StartupQuery.AbortedException e)
 +            {
-+                throw gre;
++                throw e;
 +            }
              catch (Exception exception)
              {
                  exception.printStackTrace();
-@@ -146,6 +163,8 @@
+@@ -146,6 +164,8 @@
          NBTTagCompound nbttagcompound2 = new NBTTagCompound();
          nbttagcompound2.func_74782_a("Data", nbttagcompound1);
  
@@ -59,7 +66,7 @@
          try
          {
              File file1 = new File(this.field_75770_b, "level.dat_new");
-@@ -184,6 +203,8 @@
+@@ -184,6 +204,8 @@
          NBTTagCompound nbttagcompound1 = new NBTTagCompound();
          nbttagcompound1.func_74782_a("Data", nbttagcompound);
  

fml/src/main/java/cpw/mods/fml/client/FMLClientHandler.java

@@ -21,10 +21,9 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
+
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.entity.EntityClientPlayerMP;
 import net.minecraft.client.gui.Gui;
@@ -32,6 +31,7 @@ import net.minecraft.client.gui.GuiIngameMenu;
 import net.minecraft.client.gui.GuiMainMenu;
 import net.minecraft.client.gui.GuiScreen;
 import net.minecraft.client.gui.GuiSelectWorld;
+import net.minecraft.client.gui.ScaledResolution;
 import net.minecraft.client.gui.ServerListEntryNormal;
 import net.minecraft.client.multiplayer.GuiConnecting;
 import net.minecraft.client.multiplayer.ServerData;
@@ -55,7 +55,11 @@ import net.minecraft.network.ServerStatusResponse;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.world.WorldSettings;
+import net.minecraft.world.storage.SaveFormatOld;
+
 import org.apache.logging.log4j.Level;
+import org.lwjgl.input.Mouse;
+
 import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 import com.google.common.collect.BiMap;
@@ -67,11 +71,11 @@ import com.google.common.collect.Maps;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+
 import cpw.mods.fml.client.registry.RenderingRegistry;
 import cpw.mods.fml.common.DummyModContainer;
 import cpw.mods.fml.common.DuplicateModsFoundException;
 import cpw.mods.fml.common.FMLCommonHandler;
-import cpw.mods.fml.common.FMLContainer;
 import cpw.mods.fml.common.FMLLog;
 import cpw.mods.fml.common.IFMLSidedHandler;
 import cpw.mods.fml.common.Loader;
@@ -81,14 +85,11 @@ import cpw.mods.fml.common.MissingModsException;
 import cpw.mods.fml.common.ModContainer;
 import cpw.mods.fml.common.ModMetadata;
 import cpw.mods.fml.common.ObfuscationReflectionHelper;
-import cpw.mods.fml.common.WorldAccessContainer;
+import cpw.mods.fml.common.StartupQuery;
 import cpw.mods.fml.common.WrongMinecraftVersionException;
-import cpw.mods.fml.common.event.FMLMissingMappingsEvent;
-import cpw.mods.fml.common.event.FMLMissingMappingsEvent.Action;
 import cpw.mods.fml.common.eventhandler.EventBus;
 import cpw.mods.fml.common.network.FMLNetworkEvent;
 import cpw.mods.fml.common.registry.GameData;
-import cpw.mods.fml.common.registry.GameRegistryException;
 import cpw.mods.fml.common.registry.LanguageRegistry;
 import cpw.mods.fml.common.toposort.ModSortingException;
 import cpw.mods.fml.relauncher.Side;
@@ -424,6 +425,53 @@ public class FMLClientHandler implements IFMLSidedHandler
         client.displayGuiScreen(gui);
     }
 
+    @Override
+    public void queryUser(StartupQuery query) throws InterruptedException
+    {
+        if (query.getResult() == null)
+        {
+            client.displayGuiScreen(new GuiNotification(query));
+        }
+        else
+        {
+            client.displayGuiScreen(new GuiConfirmation(query));
+        }
+
+        if (query.isSynchronous())
+        {
+            while (client.currentScreen instanceof GuiNotification)
+            {
+                if (Thread.interrupted()) throw new InterruptedException();
+
+                client.loadingScreen.resetProgresAndWorkingMessage("");
+
+                Thread.sleep(50);
+            }
+
+            client.loadingScreen.resetProgresAndWorkingMessage(""); // make sure the blank screen is being drawn at the end
+        }
+    }
+
+    public boolean handleLoadingScreen(ScaledResolution scaledResolution)
+    {
+        if (client.currentScreen instanceof GuiNotification)
+        {
+            int width = scaledResolution.getScaledWidth();
+            int height = scaledResolution.getScaledHeight();
+            int mouseX = Mouse.getX() * width / client.displayWidth;
+            int mouseZ = height - Mouse.getY() * height / client.displayHeight - 1;
+
+            client.currentScreen.drawScreen(mouseX, mouseZ, 0);
+            client.currentScreen.handleInput();
+
+            return true;
+        }
+        else
+        {
+            return false;
+        }
+    }
+
     public WorldClient getWorldClient()
     {
         return client.theWorld;
@@ -447,6 +495,12 @@ public class FMLClientHandler implements IFMLSidedHandler
         // NOOP
     }
 
+    @Override
+    public File getSavesDirectory()
+    {
+        return ((SaveFormatOld) client.getSaveLoader()).savesDirectory;
+    }
+
     @Override
     public MinecraftServer getServer()
     {
@@ -595,41 +649,16 @@ public class FMLClientHandler implements IFMLSidedHandler
             showGuiScreen(new GuiOldSaveLoadConfirm(dirName, saveName, selectWorldGUI));
         }
         else
-        {
-
-            launchIntegratedServerCallback(dirName, saveName);
-        }
-    }
-
-    private CountDownLatch gameReleaseLatch;
-    private Thread clientWaiter;
-    private GameRegistryException gre;
-
-    public void launchIntegratedServerCallback(String dirName, String saveName)
         {
             try
             {
-            try
-            {
-                Thread.interrupted();
-                gameReleaseLatch = new CountDownLatch(1);
-                clientWaiter = Thread.currentThread();
                 client.launchIntegratedServer(dirName, saveName, (WorldSettings)null);
-                System.out.printf("POKEE %b\n", Thread.currentThread().isInterrupted());
-                gameReleaseLatch.await();
             }
-            catch (InterruptedException ie)
+            catch (StartupQuery.AbortedException e)
             {
-                Thread.interrupted();
+                // ignore
-                throw gre;
             }
         }
-        catch (GameRegistryException gre)
-        {
-            client.loadWorld(null);
-            showGuiScreen(new GuiModItemsMissing(gre.getItems(), gre.getMessage()));
-        }
-        Thread.interrupted();
     }
 
     public void showInGameModOptions(GuiIngameMenu guiIngameMenu)
@@ -813,70 +842,6 @@ public class FMLClientHandler implements IFMLSidedHandler
         }
     }
 
-    public void setDefaultMissingAction(FMLMissingMappingsEvent.Action action)
-    {
-        this.defaultMissingAction = action;
-    }
-
-    private Action defaultMissingAction = FMLMissingMappingsEvent.Action.FAIL;
-
-    @Override
-    public Action getDefaultMissingAction()
-    {
-        return defaultMissingAction;
-    }
-
-    @Override
-    public void serverLoadedSuccessfully()
-    {
-        if (gameReleaseLatch!=null)
-        {
-            gameReleaseLatch.countDown();
-        }
-    }
-
-    @Override
-    public void failedServerLoading(RuntimeException ex, WorldAccessContainer wac)
-    {
-        if (wac instanceof FMLContainer && ex instanceof GameRegistryException)
-        {
-            try
-            {
-                gre = (GameRegistryException) ex;
-                Executors.newSingleThreadExecutor().submit(new Callable<Void>()
-                {
-                    // This needs to happen in a separate thread so that the server can "crash"
-                    // The three pokes are for the client - it's in a sleep loop, and needs to get
-                    // out of it
-                    @Override
-                    public Void call() throws Exception
-                    {
-                        System.err.println("POKE");
-                        clientWaiter.interrupt();
-                        Thread.sleep(50);
-                        System.err.println("POKE");
-                        clientWaiter.interrupt();
-                        Thread.sleep(50);
-                        System.err.println("POKE");
-                        clientWaiter.interrupt();
-                        return null;
-                    }
-
-                });
-
-            }
-            catch (Throwable t)
-            {
-                FMLLog.log(Level.ERROR, t, "stuff");
-            }
-        }
-    }
-
-    public boolean handlingCrash(CrashReport report)
-    {
-        return report.getCrashCause() instanceof GameRegistryException;
-    }
-
     @Override
     public boolean shouldAllowPlayerLogins()
     {

fml/src/main/java/cpw/mods/fml/client/GuiConfirmation.java

@@ -0,0 +1,33 @@
+package cpw.mods.fml.client;
+
+import net.minecraft.client.gui.GuiButton;
+import net.minecraft.client.gui.GuiOptionButton;
+import net.minecraft.client.resources.I18n;
+import cpw.mods.fml.common.StartupQuery;
+
+public class GuiConfirmation extends GuiNotification
+{
+    public GuiConfirmation(StartupQuery query)
+    {
+        super(query);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void initGui()
+    {
+        this.buttonList.add(new GuiOptionButton(0, this.width / 2 - 155, this.height - 38, I18n.format("gui.yes")));
+        this.buttonList.add(new GuiOptionButton(1, this.width / 2 - 155 + 160, this.height - 38, I18n.format("gui.no")));
+    }
+
+    @Override
+    protected void actionPerformed(GuiButton button)
+    {
+        if (button.enabled && (button.id == 0 || button.id == 1))
+        {
+            FMLClientHandler.instance().showGuiScreen(null);
+            query.setResult(button.id == 0);
+            query.finish();
+        }
+    }
+}

fml/src/main/java/cpw/mods/fml/client/GuiModItemsMissing.java

@@ -1,58 +0,0 @@
-/*
- * Forge Mod Loader
- * Copyright (c) 2012-2013 cpw.
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the GNU Lesser Public License v2.1
- * which accompanies this distribution, and is available at
- * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
- *
- * Contributors:
- *     cpw - implementation
- */
-
-package cpw.mods.fml.client;
-
-import java.util.List;
-import net.minecraft.client.gui.GuiButton;
-import net.minecraft.client.gui.GuiScreen;
-import net.minecraft.client.resources.I18n;
-
-public class GuiModItemsMissing extends GuiScreen
-{
-    private List<String> missingItems;
-    private String message;
-
-    public GuiModItemsMissing(List<String> items, String message)
-    {
-        this.missingItems = items;
-        this.message = message;
-    }
-
-    @SuppressWarnings("unchecked")
-    @Override
-    public void initGui()
-    {
-        this.buttonList.add(new GuiButton(1, this.width / 2 - 75, this.height - 38, I18n.format("gui.done")));
-    }
-
-    @Override
-    protected void actionPerformed(GuiButton p_73875_1_)
-    {
-        if (p_73875_1_.enabled && p_73875_1_.id == 1)
-        {
-            FMLClientHandler.instance().showGuiScreen(null);
-        }
-    }
-    @Override
-    public void drawScreen(int p_73863_1_, int p_73863_2_, float p_73863_3_)
-    {
-        this.drawDefaultBackground();
-        int offset = 85;
-        this.drawCenteredString(this.fontRendererObj, "Forge Mod Loader could load this save", this.width / 2, offset, 0xFFFFFF);
-        offset += 10;
-        this.drawCenteredString(this.fontRendererObj, String.format("There are %d unassigned blocks and items in this save", missingItems.size()), this.width / 2, offset, 0xFFFFFF);
-        offset += 10;
-        this.drawCenteredString(this.fontRendererObj, "You will not be able to load until they are present again", this.width / 2, offset, 0xFFFFFF);
-        super.drawScreen(p_73863_1_, p_73863_2_, p_73863_3_);
-    }
-}

fml/src/main/java/cpw/mods/fml/client/GuiNotification.java

@@ -0,0 +1,62 @@
+package cpw.mods.fml.client;
+
+import net.minecraft.client.gui.GuiButton;
+import net.minecraft.client.gui.GuiScreen;
+import net.minecraft.client.resources.I18n;
+import cpw.mods.fml.common.StartupQuery;
+
+public class GuiNotification extends GuiScreen
+{
+    public GuiNotification(StartupQuery query)
+    {
+        this.query = query;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void initGui()
+    {
+        this.buttonList.add(new GuiButton(0, this.width / 2 - 100, this.height - 38, I18n.format("gui.done")));
+    }
+
+    @Override
+    protected void actionPerformed(GuiButton button)
+    {
+        if (button.enabled && button.id == 0)
+        {
+            FMLClientHandler.instance().showGuiScreen(null);
+            query.finish();
+        }
+    }
+
+    @Override
+    public void drawScreen(int p_73863_1_, int p_73863_2_, float p_73863_3_)
+    {
+        this.drawDefaultBackground();
+
+        String[] lines = query.getText().split("\n");
+
+        int spaceAvailable = this.height - 38 - 20;
+        int spaceRequired = Math.min(spaceAvailable, 10 + 10 * lines.length);
+
+        int offset = 10 + (spaceAvailable - spaceRequired) / 2; // vertically centered
+
+        for (String line : lines)
+        {
+            if (offset >= spaceAvailable)
+            {
+                this.drawCenteredString(this.fontRendererObj, "...", this.width / 2, offset, 0xFFFFFF);
+                break;
+            }
+            else
+            {
+                if (!line.isEmpty()) this.drawCenteredString(this.fontRendererObj, line, this.width / 2, offset, 0xFFFFFF);
+                offset += 10;
+            }
+        }
+
+        super.drawScreen(p_73863_1_, p_73863_2_, p_73863_3_);
+    }
+
+    protected final StartupQuery query;
+}

fml/src/main/java/cpw/mods/fml/client/GuiOldSaveLoadConfirm.java

@@ -2,14 +2,19 @@ package cpw.mods.fml.client;
 
 import java.io.File;
 import java.io.IOException;
+
 import net.minecraft.client.gui.GuiButton;
 import net.minecraft.client.gui.GuiLabel;
 import net.minecraft.client.gui.GuiScreen;
 import net.minecraft.client.gui.GuiSelectWorld;
 import net.minecraft.client.gui.GuiYesNo;
+import net.minecraft.world.WorldSettings;
+
 import org.apache.logging.log4j.Level;
+
 import cpw.mods.fml.common.FMLLog;
 import cpw.mods.fml.common.ObfuscationReflectionHelper;
+import cpw.mods.fml.common.StartupQuery;
 import cpw.mods.fml.common.ZipperUtil;
 
 public class GuiOldSaveLoadConfirm extends GuiYesNo {
@@ -65,9 +70,15 @@ public class GuiOldSaveLoadConfirm extends GuiYesNo {
                 return;
             }
             FMLClientHandler.instance().showGuiScreen(null);
-            FMLClientHandler.instance().launchIntegratedServerCallback(dirName, saveName);
-        }
 
+            try
+            {
+                mc.launchIntegratedServer(dirName, saveName, (WorldSettings)null);
+            }
+            catch (StartupQuery.AbortedException e)
+            {
+                // ignore
+            }
+        }
     }
-
 }

fml/src/main/java/cpw/mods/fml/common/FMLCommonHandler.java

@@ -12,9 +12,12 @@
 
 package cpw.mods.fml.common;
 
+import java.io.File;
+import java.lang.ref.WeakReference;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+
 import net.minecraft.crash.CrashReport;
 import net.minecraft.crash.CrashReportCategory;
 import net.minecraft.entity.item.EntityItem;
@@ -29,8 +32,10 @@ import net.minecraft.server.MinecraftServer;
 import net.minecraft.world.World;
 import net.minecraft.world.storage.SaveHandler;
 import net.minecraft.world.storage.WorldInfo;
+
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.Logger;
+
 import com.google.common.base.Joiner;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
@@ -39,7 +44,7 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.MapMaker;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
-import cpw.mods.fml.common.event.FMLMissingMappingsEvent;
+
 import cpw.mods.fml.common.eventhandler.EventBus;
 import cpw.mods.fml.common.gameevent.InputEvent;
 import cpw.mods.fml.common.gameevent.PlayerEvent;
@@ -79,6 +84,7 @@ public class FMLCommonHandler
     private List<String> brandingsNoMC;
     private List<ICrashCallable> crashCallables = Lists.newArrayList(Loader.instance().getCallableCrashInformation());
     private Set<SaveHandler> handlerSet = Sets.newSetFromMap(new MapMaker().weakKeys().<SaveHandler,Boolean>makeMap());
+    private WeakReference<SaveHandler> handlerToCheck;
     private EventBus eventBus = new EventBus();
     /**
      * The FML event bus. Subscribe here for FML related events
@@ -266,7 +272,6 @@ public class FMLCommonHandler
 
     public boolean handleServerStarting(MinecraftServer server)
     {
-        sidedDelegate.serverLoadedSuccessfully();
         return Loader.instance().serverStarting(server);
     }
 
@@ -280,6 +285,10 @@ public class FMLCommonHandler
         Loader.instance().serverStopping();
     }
 
+    public File getSavesDirectory() {
+        return sidedDelegate.getSavesDirectory();
+    }
+
     public MinecraftServer getMinecraftServerInstance()
     {
         return sidedDelegate.getServer();
@@ -290,6 +299,11 @@ public class FMLCommonHandler
         sidedDelegate.showGuiScreen(clientGuiElement);
     }
 
+    public void queryUser(StartupQuery query) throws InterruptedException
+    {
+        sidedDelegate.queryUser(query);
+    }
+
     public void onServerStart(MinecraftServer dedicatedServer)
     {
         FMLServerHandler.instance();
@@ -372,6 +386,7 @@ public class FMLCommonHandler
             return;
         }
         handlerSet.add(handler);
+        handlerToCheck = new WeakReference<SaveHandler>(handler); // for confirmBackupLevelDatUse
         Map<String,NBTBase> additionalProperties = Maps.newHashMap();
         worldInfo.setAdditionalProperties(additionalProperties);
         for (ModContainer mc : Loader.instance().getModList())
@@ -380,19 +395,28 @@ public class FMLCommonHandler
             {
                 WorldAccessContainer wac = ((InjectedModContainer)mc).getWrappedWorldAccessContainer();
                 if (wac != null)
-                {
-                    try
                 {
                     wac.readData(handler, worldInfo, additionalProperties, tagCompound.getCompoundTag(mc.getModId()));
                 }
-                    catch (RuntimeException ex)
+            }
+        }
+    }
+
+    public void confirmBackupLevelDatUse(SaveHandler handler)
     {
-                        sidedDelegate.failedServerLoading(ex, wac);
+        if (handlerToCheck == null || handlerToCheck.get() != handler) {
-                        throw ex;
+            // only run if the save has been initially loaded
-                    }
+            handlerToCheck = null;
-                }
+            return;
-            }
         }
+
+        String text = "Forge Mod Loader detected that the backup level.dat is being used.\n\n" +
+                "This may happen due to a bug or corruption, continuing can damage\n" +
+                "your world beyond repair or lose data / progress.\n\n" +
+                "It's recommended to create a world backup before continuing.";
+
+        boolean confirmed = StartupQuery.confirm(text);
+        if (!confirmed) StartupQuery.abort();
     }
 
     public boolean shouldServerBeKilledQuietly()
@@ -514,11 +538,6 @@ public class FMLCommonHandler
         sidedDelegate.fireNetRegistrationEvent(bus(), manager, channelSet, channel, side);
     }
 
-    public FMLMissingMappingsEvent.Action getDefaultMissingAction()
-    {
-        return sidedDelegate.getDefaultMissingAction();
-    }
-
     public boolean shouldAllowPlayerLogins()
     {
         return sidedDelegate.shouldAllowPlayerLogins();

fml/src/main/java/cpw/mods/fml/common/FMLContainer.java

@@ -15,19 +15,26 @@ package cpw.mods.fml.common;
 import java.io.File;
 import java.security.cert.Certificate;
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
+
 import net.minecraft.item.Item;
 import net.minecraft.nbt.NBTBase;
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.nbt.NBTTagList;
 import net.minecraft.world.storage.SaveHandler;
 import net.minecraft.world.storage.WorldInfo;
+
 import org.apache.logging.log4j.Level;
+
 import com.google.common.collect.Maps;
 import com.google.common.eventbus.EventBus;
 import com.google.common.eventbus.Subscribe;
+
 import cpw.mods.fml.client.FMLFileResourcePack;
 import cpw.mods.fml.client.FMLFolderResourcePack;
 import cpw.mods.fml.common.asm.FMLSanityChecker;
@@ -36,7 +43,6 @@ import cpw.mods.fml.common.network.NetworkCheckHandler;
 import cpw.mods.fml.common.network.NetworkRegistry;
 import cpw.mods.fml.common.network.internal.FMLNetworkHandler;
 import cpw.mods.fml.common.registry.GameData;
-import cpw.mods.fml.common.registry.GameRegistryException;
 import cpw.mods.fml.relauncher.Side;
 
 /**
@@ -95,6 +101,7 @@ public class FMLContainer extends DummyModContainer implements WorldAccessContai
             list.appendTag(mod);
         }
         fmlData.setTag("ModList", list);
+        // name <-> id mappings
         NBTTagList dataList = new NBTTagList();
         FMLLog.fine("Gathering id map for writing to world save %s", info.getWorldName());
         Map<String,Integer> itemList = GameData.buildItemDataList();
@@ -106,6 +113,29 @@ public class FMLContainer extends DummyModContainer implements WorldAccessContai
             dataList.appendTag(tag);
         }
         fmlData.setTag("ItemData", dataList);
+        // blocked ids
+        fmlData.setIntArray("BlockedItemIds", GameData.getBlockedIds());
+        // block aliases
+        NBTTagList blockAliasList = new NBTTagList();
+        for (Entry<String, String> entry : GameData.getBlockRegistry().getAliases().entrySet())
+        {
+            NBTTagCompound tag = new NBTTagCompound();
+            tag.setString("K", entry.getKey());
+            tag.setString("V", entry.getValue());
+            blockAliasList.appendTag(tag);
+        }
+        fmlData.setTag("BlockAliases", blockAliasList);
+        // item aliases
+        NBTTagList itemAliasList = new NBTTagList();
+        for (Entry<String, String> entry : GameData.getItemRegistry().getAliases().entrySet())
+        {
+            NBTTagCompound tag = new NBTTagCompound();
+            tag.setString("K", entry.getKey());
+            tag.setString("V", entry.getValue());
+            itemAliasList.appendTag(tag);
+        }
+        fmlData.setTag("ItemAliases", itemAliasList);
+
         return fmlData;
     }
 
@@ -132,6 +162,9 @@ public class FMLContainer extends DummyModContainer implements WorldAccessContai
                 }
             }
         }
+
+        List<String> failedElements = null;
+
         if (tag.hasKey("ModItemData"))
         {
             FMLLog.info("Attempting to convert old world data to new system. This may be trouble!");
@@ -172,26 +205,65 @@ public class FMLContainer extends DummyModContainer implements WorldAccessContai
                     dataList.put(itemLabel, itemId);
                 }
             }
-            List<String> failedElements = GameData.injectWorldIDMap(dataList, true, true);
+            failedElements = GameData.injectWorldIDMap(dataList, true, true);
-            if (!failedElements.isEmpty())
+
-            {
-                throw new GameRegistryException("Failed to load the world - there are fatal block and item id issues", failedElements);
-            }
         }
         else if (tag.hasKey("ItemData"))
         {
-            NBTTagList list = tag.getTagList("ItemData", (byte)10);
+            // name <-> id mappings
+            NBTTagList list = tag.getTagList("ItemData", 10);
             Map<String,Integer> dataList = Maps.newLinkedHashMap();
             for (int i = 0; i < list.tagCount(); i++)
             {
                 NBTTagCompound dataTag = list.getCompoundTagAt(i);
                 dataList.put(dataTag.getString("K"), dataTag.getInteger("V"));
             }
-            List<String> failedElements = GameData.injectWorldIDMap(dataList, true, true);
+
-            if (!failedElements.isEmpty())
+            Set<Integer> blockedIds = new HashSet<Integer>();
+
+            if (!tag.hasKey("BlockedItemIds")) // no blocked id info -> old 1.7 save
             {
-                throw new GameRegistryException("Failed to load the world - there are fatal block and item id issues", failedElements);
+                // old early 1.7 save potentially affected by the registry mapping bug
+                // fix the ids the best we can...
+                GameData.fixBrokenIds(dataList, blockedIds);
             }
+
+            // blocked ids
+            for (int id : tag.getIntArray("BlockedItemIds"))
+            {
+                blockedIds.add(id);
+            }
+            // block aliases
+            Map<String, String> blockAliases = new HashMap<String, String>();
+            list = tag.getTagList("BlockAliases", 10);
+            for (int i = 0; i < list.tagCount(); i++)
+            {
+                NBTTagCompound dataTag = list.getCompoundTagAt(i);
+                blockAliases.put(dataTag.getString("K"), dataTag.getString("V"));
+            }
+            // item aliases
+            Map<String, String> itemAliases = new HashMap<String, String>();
+            list = tag.getTagList("ItemAliases", 10);
+            for (int i = 0; i < list.tagCount(); i++)
+            {
+                NBTTagCompound dataTag = list.getCompoundTagAt(i);
+                itemAliases.put(dataTag.getString("K"), dataTag.getString("V"));
+            }
+
+            failedElements = GameData.injectWorldIDMap(dataList, blockedIds, blockAliases, itemAliases, true, true);
+        }
+
+        if (failedElements != null && !failedElements.isEmpty())
+        {
+            String text = "Forge Mod Loader could not load this save.\n\n" +
+            "There are "+failedElements.size()+" unassigned blocks and items in this save.\n" +
+                    "You will not be able to load until they are present again.\n\n" +
+                    "Missing Blocks/Items:\n";
+
+            for (String s : failedElements) text += s + "\n";
+
+            StartupQuery.notify(text);
+            StartupQuery.abort();
         }
     }
 

fml/src/main/java/cpw/mods/fml/common/FMLLog.java

@@ -45,6 +45,13 @@ public class FMLLog
         log(Level.ERROR, format, data);
     }
 
+    public static void bigWarning(String format, Object... data)
+    {
+        log(Level.WARN, "****************************************");
+        log(Level.WARN, "* "+format, data);
+        log(Level.WARN, "****************************************");
+    }
+
     public static void warning(String format, Object... data)
     {
         log(Level.WARN, format, data);

fml/src/main/java/cpw/mods/fml/common/IFMLSidedHandler.java

@@ -12,13 +12,13 @@
 
 package cpw.mods.fml.common;
 
+import java.io.File;
 import java.util.List;
 import java.util.Set;
 
 import net.minecraft.network.INetHandler;
 import net.minecraft.network.NetworkManager;
 import net.minecraft.server.MinecraftServer;
-import cpw.mods.fml.common.event.FMLMissingMappingsEvent;
 import cpw.mods.fml.common.eventhandler.EventBus;
 import cpw.mods.fml.relauncher.Side;
 
@@ -32,10 +32,14 @@ public interface IFMLSidedHandler
 
     void showGuiScreen(Object clientGuiElement);
 
+    void queryUser(StartupQuery query) throws InterruptedException;
+
     void beginServerLoading(MinecraftServer server);
 
     void finishServerLoading();
 
+    File getSavesDirectory();
+
     MinecraftServer getServer();
 
     boolean shouldServerShouldBeKilledQuietly();
@@ -56,11 +60,5 @@ public interface IFMLSidedHandler
 
     void fireNetRegistrationEvent(EventBus bus, NetworkManager manager, Set<String> channelSet, String channel, Side side);
 
-    FMLMissingMappingsEvent.Action getDefaultMissingAction();
-
-    void serverLoadedSuccessfully();
-
-    void failedServerLoading(RuntimeException ex, WorldAccessContainer wac);
-
     boolean shouldAllowPlayerLogins();
 }

fml/src/main/java/cpw/mods/fml/common/LoadController.java

@@ -130,7 +130,7 @@ public class LoadController
             FMLLog.severe("Fatal errors were detected during the transition from %s to %s. Loading cannot continue", oldState, desiredState);
             StringBuilder sb = new StringBuilder();
             printModStates(sb);
-            FMLLog.severe(sb.toString());
+            FMLLog.severe("%s", sb.toString());
             if (errors.size()>0)
             {
                 FMLLog.severe("The following problems were captured during this phase");

fml/src/main/java/cpw/mods/fml/common/Loader.java

@@ -17,13 +17,17 @@ import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.net.MalformedURLException;
+import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.Iterator;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
+
 import org.apache.logging.log4j.Level;
+
 import com.google.common.base.CharMatcher;
 import com.google.common.base.Function;
 import com.google.common.base.Joiner;
@@ -45,6 +49,7 @@ import com.google.common.collect.Ordering;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 import com.google.common.collect.TreeMultimap;
+
 import cpw.mods.fml.common.LoaderState.ModState;
 import cpw.mods.fml.common.ModContainer.Disableable;
 import cpw.mods.fml.common.discovery.ModDiscoverer;
@@ -56,6 +61,7 @@ import cpw.mods.fml.common.event.FMLModIdMappingEvent;
 import cpw.mods.fml.common.functions.ArtifactVersionNameFunction;
 import cpw.mods.fml.common.functions.ModIdFunction;
 import cpw.mods.fml.common.registry.GameData;
+import cpw.mods.fml.common.registry.GameRegistry.Type;
 import cpw.mods.fml.common.toposort.ModSorter;
 import cpw.mods.fml.common.toposort.ModSortingException;
 import cpw.mods.fml.common.toposort.ModSortingException.SortingExceptionData;
@@ -453,7 +459,6 @@ public class Loader
     {
         initializeLoader();
         mods = Lists.newArrayList();
-        GameData.fixupRegistries();
         namedMods = Maps.newHashMap();
         modController = new LoadController(this);
         modController.transition(LoaderState.LOADING, false);
@@ -493,7 +498,6 @@ public class Loader
         }
         modController.transition(LoaderState.PREINITIALIZATION, false);
         modController.distributeStateMessage(LoaderState.PREINITIALIZATION, disc.getASMTable(), canonicalConfigDir);
-        GameData.freezeData();
         modController.transition(LoaderState.INITIALIZATION, false);
     }
 
@@ -676,6 +680,7 @@ public class Loader
         modController.distributeStateMessage(LoaderState.POSTINITIALIZATION);
         modController.transition(LoaderState.AVAILABLE, false);
         modController.distributeStateMessage(LoaderState.AVAILABLE);
+        GameData.freezeData();
         // Dump the custom registry data map, if necessary
         GameData.dumpRegistry(minecraftDir);
         FMLLog.info("Forge Mod Loader has successfully loaded %d mod%s", mods.size(), mods.size() == 1 ? "" : "s");
@@ -842,41 +847,74 @@ public class Loader
         return true;
     }
 
-    public List<String> fireMissingMappingEvent(ArrayListMultimap<String,String> missing, boolean isLocalWorld)
+    /**
+     * Fire a FMLMissingMappingsEvent to let mods determine how blocks/items defined in the world
+     * save, but missing from the runtime, are to be handled.
+     *
+     * @param missing Map containing missing names with their associated id, blocks need to come before items for remapping.
+     * @param isLocalWorld Whether this is executing for a world load (local/server) or a client.
+     * @param gameData GameData instance where the new map's config is to be loaded into.
+     * @return List with the mapping results.
+     */
+    public List<String> fireMissingMappingEvent(LinkedHashMap<String, Integer> missing, boolean isLocalWorld, GameData gameData, Map<String, Integer[]> remaps)
     {
-        if (!missing.isEmpty())
+        if (missing.isEmpty()) // nothing to do
         {
-            FMLLog.fine("There are %d mappings missing - attempting a mod remap", missing.size());
-            ArrayListMultimap<String,MissingMapping> missingMappings = ArrayListMultimap.create();
-            List<MissingMapping> remaps = Lists.newArrayList();
-            for (Map.Entry<String, String> mapping : missing.entries())
-            {
-                MissingMapping m = new MissingMapping(mapping.getValue(), remaps);
-                missingMappings.put(mapping.getKey(), m);
-            }
-            FMLMissingMappingsEvent missingEvent = new FMLMissingMappingsEvent(missingMappings);
-            modController.propogateStateMessage(missingEvent);
-            if (!missingMappings.isEmpty() && isLocalWorld)
-            {
-                FMLLog.severe("There are unidentified mappings in this world - we are going to attempt to process anyway");
-                for (java.util.Map.Entry<String, MissingMapping> missed : missingMappings.entries())
-                {
-                    remaps.add(missed.getValue());
-                }
-            }
-            else if (!missingMappings.isEmpty() && !isLocalWorld)
-            {
-                List<String> missedMapping = Lists.newArrayList();
-                for (java.util.Map.Entry<String, MissingMapping> missed : missingMappings.entries())
-                {
-                    missedMapping.add(missed.getKey()+ ":" + missed.getValue().name);
-                }
-                return ImmutableList.copyOf(missedMapping);
-            }
-            return GameData.processIdRematches(remaps, isLocalWorld);
-        }
             return ImmutableList.of();
         }
+
+        FMLLog.fine("There are %d mappings missing - attempting a mod remap", missing.size());
+        ArrayListMultimap<String, MissingMapping> missingMappings = ArrayListMultimap.create();
+
+        for (Map.Entry<String, Integer> mapping : missing.entrySet())
+        {
+            int id = mapping.getValue();
+            MissingMapping m = new MissingMapping(mapping.getKey(), id);
+            missingMappings.put(m.name.substring(0, m.name.indexOf(':')), m);
+        }
+
+        FMLMissingMappingsEvent missingEvent = new FMLMissingMappingsEvent(missingMappings);
+        modController.propogateStateMessage(missingEvent);
+
+        if (isLocalWorld) // local world, warn about entries still being set to the default action
+        {
+            boolean didWarn = false;
+
+            for (MissingMapping mapping : missingMappings.values())
+            {
+                if (mapping.getAction() == FMLMissingMappingsEvent.Action.DEFAULT)
+                {
+                    if (!didWarn)
+                    {
+                        FMLLog.severe("There are unidentified mappings in this world - we are going to attempt to process anyway");
+                        didWarn = true;
+                    }
+
+                    FMLLog.severe("Unidentified %s: %s, id %d", mapping.type == Type.BLOCK ? "block" : "item", mapping.name, mapping.id);
+                }
+            }
+        }
+        else // remote world, fail on entries with the default action
+        {
+            List<String> missedMapping = new ArrayList<String>();
+
+            for (MissingMapping mapping : missingMappings.values())
+            {
+                if (mapping.getAction() == FMLMissingMappingsEvent.Action.DEFAULT)
+                {
+                    missedMapping.add(mapping.name);
+                }
+            }
+
+            if (!missedMapping.isEmpty())
+            {
+                return ImmutableList.copyOf(missedMapping);
+            }
+        }
+
+        return GameData.processIdRematches(missingMappings.values(), isLocalWorld, gameData, remaps);
+    }
+
     public void fireRemapEvent(Map<String, Integer[]> remaps)
     {
         if (remaps.isEmpty())

fml/src/main/java/cpw/mods/fml/common/StartupQuery.java

@@ -0,0 +1,160 @@
+package cpw.mods.fml.common;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import net.minecraft.server.MinecraftServer;
+
+public class StartupQuery {
+    // internal class/functionality, do not use
+
+    public static boolean confirm(String text)
+    {
+        StartupQuery query = new StartupQuery(text, new AtomicBoolean());
+        query.execute();
+        return query.getResult();
+    }
+
+    public static void notify(String text)
+    {
+        StartupQuery query = new StartupQuery(text, null);
+        query.execute();
+    }
+
+    public static void abort()
+    {
+        MinecraftServer server = FMLCommonHandler.instance().getMinecraftServerInstance();
+        if (server != null) server.initiateShutdown();
+
+        aborted = true; // to abort loading and go back to the main menu
+        throw new AbortedException(); // to halt the server
+    }
+
+
+    public static void reset()
+    {
+        pending = null;
+        aborted = false;
+    }
+
+    public static boolean check()
+    {
+        if (pending != null)
+        {
+            try
+            {
+                FMLCommonHandler.instance().queryUser(pending);
+            }
+            catch (InterruptedException e)
+            {
+                FMLLog.warning("query interrupted");
+                abort();
+            }
+
+            pending = null;
+        }
+
+        return !aborted;
+    }
+
+    private static volatile StartupQuery pending;
+    private static volatile boolean aborted = false;
+
+
+    private StartupQuery(String text, AtomicBoolean result)
+    {
+        this.text = text;
+        this.result = result;
+    }
+
+    public Boolean getResult()
+    {
+        return result == null ? null : result.get();
+    }
+
+    public void setResult(boolean result)
+    {
+        this.result.set(result);
+    }
+
+    public String getText()
+    {
+        return text;
+    }
+
+    public boolean isSynchronous()
+    {
+        return synchronous;
+    }
+
+    public void finish()
+    {
+        signal.countDown();
+    }
+
+    private void execute()
+    {
+        String prop = System.getProperty("fml.queryResult");
+
+        if (result != null && prop != null)
+        {
+            FMLLog.info("Using fml.queryResult %s to answer the following query:\n%s", prop, text);
+
+            if (prop.equalsIgnoreCase("confirm"))
+            {
+                setResult(true);
+                return;
+            }
+            else if (prop.equalsIgnoreCase("cancel"))
+            {
+                setResult(false);
+                return;
+            }
+
+            FMLLog.warning("Invalid value for fml.queryResult: %s, expected confirm or cancel", prop);
+        }
+
+        synchronous = false;
+        pending = this; // let the other thread start the query
+
+        // from the integrated server thread: the client will eventually check pending and execute the query
+        // from the client thread: synchronous execution
+        // dedicated server: command handling in mc is synchronous, execute the server-side query directly
+        if (FMLCommonHandler.instance().getSide().isServer() ||
+                FMLCommonHandler.instance().getEffectiveSide().isClient())
+        {
+            synchronous = true;
+            check();
+        }
+
+        try
+        {
+            signal.await();
+            reset();
+        }
+        catch (InterruptedException e)
+        {
+            FMLLog.warning("query interrupted");
+            abort();
+        }
+    }
+
+    private String text;
+    private AtomicBoolean result;
+    private CountDownLatch signal = new CountDownLatch(1);
+    private volatile boolean synchronous;
+
+
+    /**
+     * Exception not being caught by the crash report generation logic.
+     */
+    public static class AbortedException extends RuntimeException
+    {
+        private static final long serialVersionUID = -5933665223696833921L;
+
+        private AbortedException()
+        {
+            super();
+        }
+    }
+}

fml/src/main/java/cpw/mods/fml/common/ZipperUtil.java

@@ -10,8 +10,13 @@ import java.util.Deque;
 import java.util.LinkedList;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;
+
+import org.apache.logging.log4j.Level;
+
 import com.google.common.io.Files;
 
+import cpw.mods.fml.client.FMLClientHandler;
+
 /**
  * Copied from http://stackoverflow.com/questions/1399126/java-util-zip-recreating-directory-structure
  * because the code looked very tidy and neat. Thanks, McDowell!
@@ -55,4 +60,39 @@ public class ZipperUtil {
             res.close();
         }
     }
+
+    public static void backupWorld() throws IOException
+    {
+        String dirName = FMLCommonHandler.instance().getMinecraftServerInstance().getFolderName();
+        String saveName;
+
+        if (FMLCommonHandler.instance().getSide().isClient())
+        {
+            saveName = FMLCommonHandler.instance().getMinecraftServerInstance().getWorldName();
+        }
+        else
+        {
+            saveName = dirName;
+        }
+
+        backupWorld(dirName, saveName);
+    }
+
+    public static void backupWorld(String dirName, String saveName) throws IOException
+    {
+        File dstFolder = FMLCommonHandler.instance().getSavesDirectory();
+        File zip = new File(dstFolder, String.format("%s-%2$tY%2$tm%2$td-%2$tH%2$tM%2$tS.zip", saveName, System.currentTimeMillis()));
+
+        try
+        {
+            ZipperUtil.zip(new File(dstFolder, dirName), zip);
+        }
+        catch (IOException e)
+        {
+            FMLLog.log(Level.WARN, e, "World backup failed.");
+            throw e;
+        }
+
+        FMLLog.info("World backup created at %s.", zip.getCanonicalPath());
+    }
 }

fml/src/main/java/cpw/mods/fml/common/event/FMLMissingMappingsEvent.java

@@ -2,19 +2,23 @@ package cpw.mods.fml.common.event;
 
 import java.util.List;
 
+import net.minecraft.block.Block;
+import net.minecraft.item.Item;
+
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ListMultimap;
 
-import cpw.mods.fml.common.FMLCommonHandler;
 import cpw.mods.fml.common.ModContainer;
+import cpw.mods.fml.common.registry.GameData;
 import cpw.mods.fml.common.registry.GameRegistry;
 
 /**
  * This event is fired if a world is loaded that has block and item mappings referring the mod that are not
  * in existence.
  * These can be remapped to other existing objects, or simply discarded.
+ * Use get() and getAll() to process this event.
  *
- * @author cpw
+ * @author cpw, Player
  *
  */
 public class FMLMissingMappingsEvent extends FMLEvent {
@@ -28,56 +32,143 @@ public class FMLMissingMappingsEvent extends FMLEvent {
      * @author cpw
      *
      */
-    public static enum Action { IGNORE, WARN, FAIL }
+    public static enum Action { DEFAULT, IGNORE, WARN, FAIL, REMAP }
     public static class MissingMapping {
         public final GameRegistry.Type type;
         public final String name;
-        private Action action;
+        public final int id;
-        private List<MissingMapping> remaps;
+        private Action action = Action.DEFAULT;
-        public MissingMapping(String name, List<MissingMapping> remaps)
+        private Object target;
+
+        public MissingMapping(String name, int id)
         {
             this.type = name.charAt(0) == '\u0001' ? GameRegistry.Type.BLOCK : GameRegistry.Type.ITEM;
-            this.name = name;
+            this.name = name.substring(1);
-            this.remaps = remaps;
+            this.id = id;
-            this.action = FMLCommonHandler.instance().getDefaultMissingAction();
         }
+        /**
+         * @deprecated use ignore(), warn(), fail() or remap() instead
+         */
+        @Deprecated
         public void setAction(Action target)
         {
+            if (target == Action.DEFAULT || target == Action.REMAP) throw new IllegalArgumentException();
+
             this.action = target;
-            remaps.add(this);
         }
 
+        /**
+         * Ignore the missing item.
+         */
+        public void ignore()
+        {
+            action = Action.IGNORE;
+        }
+
+        /**
+         * Warn the user about the missing item.
+         */
+        public void warn()
+        {
+            action = Action.WARN;
+        }
+
+        /**
+         * Prevent the world from loading due to the missing item.
+         */
+        public void fail()
+        {
+            action = Action.FAIL;
+        }
+
+        /**
+         * Remap the missing item to the specified Block.
+         *
+         * Use this if you have renamed a Block, don't forget to handle the ItemBlock.
+         * Existing references using the old name will point to the new one.
+         *
+         * @param target Block to remap to.
+         */
+        public void remap(Block target)
+        {
+            if (type != GameRegistry.Type.BLOCK) throw new IllegalArgumentException("Can't remap an item to a block.");
+            if (target == null) throw new NullPointerException("remap target is null");
+            if (GameData.getBlockRegistry().getId(target) < 0) throw new IllegalArgumentException(String.format("The specified block %s hasn't been registered at startup.", target));
+
+            action = Action.REMAP;
+            this.target = target;
+        }
+
+        /**
+         * Remap the missing item to the specified Item.
+         *
+         * Use this if you have renamed an Item.
+         * Existing references using the old name will point to the new one.
+         *
+         * @param target Item to remap to.
+         */
+        public void remap(Item target)
+        {
+            if (type != GameRegistry.Type.ITEM) throw new IllegalArgumentException("Can't remap a block to an item.");
+            if (target == null) throw new NullPointerException("remap target is null");
+            if (GameData.getItemRegistry().getId(target) < 0) throw new IllegalArgumentException(String.format("The specified item %s hasn't been registered at startup.", target));
+
+            action = Action.REMAP;
+            this.target = target;
+        }
+
+        // internal
+
         public Action getAction()
         {
             return this.action;
         }
+
+        public Object getTarget()
+        {
+            return target;
+        }
     }
     private ListMultimap<String,MissingMapping> missing;
     private ModContainer activeContainer;
-    private List<MissingMapping> currentList;
 
     public FMLMissingMappingsEvent(ListMultimap<String,MissingMapping> missingMappings)
     {
         this.missing = missingMappings;
     }
+
     @Override
     public void applyModContainer(ModContainer activeContainer)
     {
         super.applyModContainer(activeContainer);
         this.activeContainer = activeContainer;
-        this.currentList = null;
     }
 
     /**
      * Get the list of missing mappings for the active mod.
-     * @return
+     *
+     * Process the list entries by calling ignore(), warn(), fail() or remap() on each entry.
+     *
+     * @return list of missing mappings
      */
     public List<MissingMapping> get()
     {
-        if (currentList == null)
+        return ImmutableList.copyOf(missing.get(activeContainer.getModId()));
-        {
-            currentList = ImmutableList.copyOf(missing.removeAll(activeContainer.getModId()));
     }
-        return currentList;
+
+    /**
+     * Get the list of missing mappings for all mods.
+     *
+     * Only use this if you need to handle mod id changes, e.g. if you renamed your mod or
+     * split/merge into/from multiple mods.
+     *
+     * Process the list entries by calling ignore(), warn(), fail() or remap() on each entry you
+     * want to handle.
+     *
+     * @return list of missing mappings
+     */
+    public List<MissingMapping> getAll()
+    {
+        return ImmutableList.copyOf(missing.values());
     }
 }

fml/src/main/java/cpw/mods/fml/common/network/internal/EntitySpawnHandler.java

@@ -57,7 +57,6 @@ public class EntitySpawnHandler extends SimpleChannelInboundHandler<FMLMessage.E
 
     private void spawnEntity(FMLMessage.EntitySpawnMessage spawnMsg)
     {
-        System.out.println("Spawning entity on client");
         ModContainer mc = Loader.instance().getIndexedModList().get(spawnMsg.modId);
         EntityRegistration er = EntityRegistry.instance().lookupModSpawn(mc, spawnMsg.modEntityTypeId);
         WorldClient wc = FMLClientHandler.instance().getWorldClient();
@@ -116,7 +115,6 @@ public class EntitySpawnHandler extends SimpleChannelInboundHandler<FMLMessage.E
                 ((IEntityAdditionalSpawnData) entity).readSpawnData(spawnMsg.dataStream);
             }
             wc.addEntityToWorld(spawnMsg.entityId, entity);
-            System.out.println("Entity spawned on client");
         } catch (Exception e)
         {
             FMLLog.log(Level.ERROR, e, "A severe problem occurred during the spawning of an entity");

fml/src/main/java/cpw/mods/fml/common/registry/FMLControlledNamespacedRegistry.java

@@ -1,159 +1,284 @@
 package cpw.mods.fml.common.registry;
 
-import gnu.trove.map.hash.TIntIntHashMap;
 import java.util.ArrayList;
 import java.util.BitSet;
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
+
 import net.minecraft.util.ObjectIntIdentityMap;
 import net.minecraft.util.RegistryNamespaced;
-import com.google.common.collect.BiMap;
+
-import com.google.common.collect.HashBiMap;
+import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableBiMap;
+
-import com.google.common.collect.Maps;
-import com.google.common.primitives.Ints;
 import cpw.mods.fml.common.FMLLog;
 import cpw.mods.fml.common.Loader;
 import cpw.mods.fml.common.ModContainer;
 
 public class FMLControlledNamespacedRegistry<I> extends RegistryNamespaced {
-    static class FMLObjectIntIdentityMap extends ObjectIntIdentityMap {
-        private TIntIntHashMap frozenMap;
-        private TIntIntHashMap oldMap;
-        private TIntIntHashMap newMap;
-        private ArrayList<Integer> frozenIndex;
-        private ArrayList<Integer> oldIndex;
-        private ArrayList<Integer> newIndex;
-
-        public FMLObjectIntIdentityMap()
-        {
-        }
-
-        boolean containsID(int id)
-        {
-            return func_148744_b(id);
-        }
-
-        Object get(int id)
-        {
-            return func_148745_a(id);
-        }
-
-        int get(Object obj)
-        {
-            return func_148747_b(obj);
-        }
-
-        @SuppressWarnings("unchecked")
-        void beginSwap()
-        {
-            oldMap = field_148749_a;
-            newMap  = new TIntIntHashMap(256, 0.5F, -1, -1);
-            oldIndex = (ArrayList<Integer>) field_148748_b;
-            newIndex = new ArrayList<Integer>(oldIndex.size());
-        }
-
-        @SuppressWarnings("unchecked")
-        void freezeMap()
-        {
-            frozenMap = new TIntIntHashMap(field_148749_a);
-            frozenIndex = new ArrayList<Integer>(field_148748_b);
-        }
-
-        void revertToFrozen()
-        {
-            field_148749_a = frozenMap;
-            field_148748_b = frozenIndex;
-        }
-        void completeSwap()
-        {
-            field_148749_a = newMap;
-            field_148748_b = newIndex;
-            oldIndex = newIndex = null;
-            oldMap = newMap = null;
-        }
-
-        void revertSwap()
-        {
-            field_148749_a = oldMap;
-            field_148748_b = oldIndex;
-            oldIndex = newIndex = null;
-            oldMap = newMap = null;
-        }
-
-        void putNew(int id, Object item)
-        {
-            field_148749_a = newMap;
-            field_148748_b = newIndex;
-            super.func_148746_a(item, id);
-            field_148749_a = oldMap;
-            field_148748_b = oldIndex;
-        }
-
-        List<Integer> usedIds()
-        {
-            return Ints.asList(field_148749_a.keys());
-        }
-
-    }
-
     private final Class<I> superType;
     private String optionalDefaultName;
     private I optionalDefaultObject;
-
+    private int maxId;
-    private BiMap<String,Integer> namedIds = HashBiMap.create();
-    private BiMap<String,Integer> frozenIds;
-    private Map<String,Integer> transactionalNamedIds;
-    private BitSet transactionalAvailabilityMap;
-    private BitSet availabilityMap;
-    int maxId;
     private int minId;
     private char discriminator;
+    // aliases redirecting legacy names to the actual name, may need recursive application to find the final name.
+    // these need to be registry specific, it's possible to only have a loosely linked item for a block which may get renamed by itself.
+    private final Map<String, String> aliases = new HashMap<String, String>();
 
-    public FMLControlledNamespacedRegistry(String optionalDefault, int maxIdValue, int minIdValue, Class<I> type, char discriminator)
+    FMLControlledNamespacedRegistry(String optionalDefault, int maxIdValue, int minIdValue, Class<I> type, char discriminator)
     {
         this.superType = type;
         this.discriminator = discriminator;
         this.optionalDefaultName = optionalDefault;
-        this.availabilityMap = new BitSet(maxIdValue);
         this.maxId = maxIdValue;
         this.minId = minIdValue;
-        this.underlyingIntegerMap = new FMLObjectIntIdentityMap();
     }
 
+    @SuppressWarnings("unchecked")
+    void set(FMLControlledNamespacedRegistry<I> registry)
+    {
+        if (this.superType != registry.superType) throw new IllegalArgumentException("incompatible registry");
+
+        this.discriminator = registry.discriminator;
+        this.optionalDefaultName = registry.optionalDefaultName;
+        this.maxId = registry.maxId;
+        this.minId = registry.minId;
+        this.aliases.clear();
+        this.aliases.putAll(registry.aliases);
+        underlyingIntegerMap = new ObjectIntIdentityMap();
+        registryObjects.clear();
+
+        for (I thing : (Iterable<I>) registry)
+        {
+            addObjectRaw(registry.getId(thing), registry.getNameForObject(thing), thing);
+        }
+    }
+
+    // public api
+
+    /**
+     * Add an object to the registry, trying to use the specified id.
+     *
+     * @deprecated register through {@link GameRegistry} instead.
+     */
     @Override
+    @Deprecated
     public void addObject(int id, String name, Object thing)
     {
-        FMLLog.finer("Add : %s %d %s", name, id, thing);
+        GameData.getMain().register(thing, name, id);
-        add(id, name, superType.cast(thing));
     }
 
-    int swap(int id, String name, I thing)
+    /**
+     * DANGEROUS! EVIL! DO NOT USE!
+     *
+     * @deprecated register through {@link GameRegistry} instead.
+     */
+    @Override
+    @Deprecated
+    public void putObject(Object objName, Object obj)
     {
-        FMLLog.fine("Swap : %s %d %s", name, id, thing);
+        String name = (String) objName;
-        BitSet temporary = availabilityMap;
+        I thing = (I) obj;
-        availabilityMap = transactionalAvailabilityMap;
 
-        int idToUse = id;
+        if (name == null) throw new NullPointerException("Can't use a null-name for the registry.");
-        if (id == 0 || availabilityMap.get(id))
+        if (name.isEmpty()) throw new IllegalArgumentException("Can't use an empty name for the registry.");
+        if (thing == null) throw new NullPointerException("Can't add null-object to the registry.");
+
+        String existingName = getNameForObject(thing);
+
+        if (existingName == null)
         {
-            idToUse = availabilityMap.nextClearBit(minId);
+            FMLLog.bigWarning("Ignoring putObject(%s, %s), not resolvable", name, thing);
         }
-        if (idToUse >= maxId)
+        else if (existingName.equals(name))
         {
-            throw new RuntimeException(String.format("Invalid id %s - not accepted",id));
+            FMLLog.bigWarning("Ignoring putObject(%s, %s), already added", name, thing);
+        }
+        else
+        {
+            FMLLog.bigWarning("Ignoring putObject(%s, %s), adding alias to %s instead", name, thing, existingName);
+            addAlias(name, existingName);
+        }
     }
 
-        namedIds.forcePut(ensureNamespaced(name),idToUse);
+    /**
-        reassignMapping(name, idToUse);
+     * Fetch the object identified by the specified name or the default object.
-        useSlot(idToUse);
+     *
-        availabilityMap = temporary;
+     * For blocks the default object is the air block, for items it's null.
-        FMLLog.fine("Swap : %s %d %s", name, idToUse, thing);
+     *
-        return idToUse;
+     * @param name Unique name identifying the object.
-    }
+     * @return Registered object of the default object if it wasn't found-
-    public int add(int id, String name, I thing)
+     */
+    @Override
+    public I getObject(String name)
     {
+        I object = getRaw(name);
+        return object == null ? this.optionalDefaultObject : object;
+    }
+
+    /**
+     * Fetch the object identified by the specified id or the default object.
+     *
+     * For blocks the default object is the air block, for items it's null.
+     *
+     * @param id ID identifying the object.
+     * @return Registered object of the default object if it wasn't found-
+     */
+    @Override
+    public I getObjectById(int id)
+    {
+        I object = getRaw(id);
+        return object == null ? this.optionalDefaultObject : object;
+    }
+
+    /**
+     * @deprecated use getObjectById instead
+     */
+    @Deprecated
+    public I get(int id)
+    {
+        return getObjectById(id);
+    }
+
+    /**
+     * @deprecated use getObject instead
+     */
+    @Deprecated
+    public I get(String name)
+    {
+        return getObject(name);
+    }
+
+    /**
+     * Get the id for the specified object.
+     *
+     * Don't hold onto the id across the world, it's being dynamically re-mapped as needed.
+     *
+     * Usually the name should be used instead of the id, if using the Block/Item object itself is
+     * not suitable for the task.
+     *
+     * @param thing Block/Item object.
+     * @return Block/Item id or -1 if it wasn't found.
+     */
+    public int getId(I thing)
+    {
+        return getIDForObject(thing);
+    }
+
+    /**
+     * Get the object identified by the specified id.
+     *
+     * @param id Block/Item id.
+     * @return Block/Item object or null if it wasn't found.
+     */
+    public I getRaw(int id)
+    {
+        return superType.cast(super.getObjectById(id));
+    }
+
+    /**
+     * Get the object identified by the specified name.
+     *
+     * @param name Block/Item name.
+     * @return Block/Item object or null if it wasn't found.
+     */
+    public I getRaw(String name)
+    {
+        I ret = superType.cast(super.getObject(name));
+
+        if (ret == null) // no match, try aliases recursively
+        {
+            name = aliases.get(name);
+
+            if (name != null) return getRaw(name);
+        }
+
+        return ret;
+    }
+
+    /**
+     * Determine if the registry has an entry for the specified name.
+     *
+     * Aliased names will be resolved as well.
+     *
+     * @param name Object name to check.
+     * @return true if a matching entry was found.
+     */
+    @Override
+    public boolean containsKey(String name)
+    {
+        boolean ret = super.containsKey(name);
+
+        if (!ret) // no match, try aliases recursively
+        {
+            name = aliases.get(name);
+
+            if (name != null) return containsKey(name);
+        }
+
+        return ret;
+    }
+
+    /**
+     * Get the id for the specified object.
+     *
+     * Don't hold onto the id across the world, it's being dynamically re-mapped as needed.
+     *
+     * Usually the name should be used instead of the id, if using the Block/Item object itself is
+     * not suitable for the task.
+     *
+     * @param itemName Block/Item registry name.
+     * @return Block/Item id or -1 if it wasn't found.
+     */
+    public int getId(String itemName)
+    {
+        I obj = getRaw(itemName);
+        if (obj == null) return -1;
+
+        return getId(obj);
+    }
+
+    /**
+     * @deprecated use containsKey instead
+     */
+    @Deprecated
+    public boolean contains(String itemName)
+    {
+        return containsKey(itemName);
+    }
+
+    // internal
+
+    @SuppressWarnings("unchecked")
+    public void serializeInto(Map<String, Integer> idMapping) // for saving
+    {
+        for (I thing : (Iterable<I>) this)
+        {
+            idMapping.put(discriminator+getNameForObject(thing), getId(thing));
+        }
+    }
+
+    public Map<String, String> getAliases() // for saving
+    {
+        return ImmutableMap.copyOf(aliases);
+    }
+
+    /**
+     * Add the specified object to the registry.
+     *
+     * @param id ID to use if available, auto-assigned otherwise.
+     * @param name Name to use, prefixed by the mod id.
+     * @param thing Object to add.
+     * @param availabilityMap Map marking available IDs for auto assignment.
+     * @return ID eventually allocated.
+     */
+    int add(int id, String name, I thing, BitSet availabilityMap)
+    {
+        if (name == null) throw new NullPointerException("Can't use a null-name for the registry.");
+        if (name.isEmpty()) throw new IllegalArgumentException("Can't use an empty name for the registry.");
+        if (thing == null) throw new NullPointerException("Can't add null-object to the registry.");
         if (name.equals(optionalDefaultName))
         {
             this.optionalDefaultObject = thing;
@@ -164,9 +289,9 @@ public class FMLControlledNamespacedRegistry<I> extends RegistryNamespaced {
         {
             idToUse = availabilityMap.nextClearBit(minId);
         }
-        if (idToUse >= maxId)
+        if (idToUse > maxId)
         {
-            throw new RuntimeException(String.format("Invalid id %s - not accepted",id));
+            throw new RuntimeException(String.format("Invalid id %d - maximum id range exceeded.", id));
         }
 
         ModContainer mc = Loader.instance().activeModContainer();
@@ -175,150 +300,79 @@ public class FMLControlledNamespacedRegistry<I> extends RegistryNamespaced {
             String prefix = mc.getModId();
             name = prefix + ":"+ name;
         }
-        namedIds.forcePut(ensureNamespaced(name),idToUse);
+
-        super.addObject(idToUse, name, thing);
+        if (getRaw(name) == thing) // already registered, return prev registration's id
-        useSlot(idToUse);
+        {
-        FMLLog.finer("Add : %s %d %s", name, idToUse, thing);
+            FMLLog.bigWarning("The object %s has been registered twice for the same name %s.", thing, name);
+            return getId(thing);
+        }
+        if (getRaw(name) != null) // duplicate name, will crash later due to the BiMap
+        {
+            FMLLog.bigWarning("The name %s has been registered twice, for %s and %s.", name, getRaw(name), thing);
+        }
+        if (getId(thing) >= 0) // duplicate object, will crash later due to the BiMap
+        {
+            FMLLog.bigWarning("The object %s has been registered twice, using the names %s and %s.", thing, getNameForObject(thing), name);
+        }
+        if (GameData.isFrozen(this))
+        {
+            FMLLog.bigWarning("The object %s (name %s) is being added too late.", thing, name);
+        }
+
+        addObjectRaw(idToUse, name, thing);
+
+        FMLLog.finer("Registry add: %s %d %s", name, idToUse, thing);
         return idToUse;
     }
 
-    @Override
+    void addAlias(String from, String to)
-    public I getObject(String name)
     {
-        I object = superType.cast(super.getObject(name));
+        aliases.put(from, to);
-        return object == null ? this.optionalDefaultObject : object;
+        FMLLog.finer("Registry alias: %s -> %s", from, to);
-    }
-
-    @Override
-    public I getObjectById(int id)
-    {
-        I object = superType.cast(super.getObjectById(id));
-        return object == null ? this.optionalDefaultObject : object;
-    }
-
-
-    private FMLObjectIntIdentityMap idMap()
-    {
-        return (FMLObjectIntIdentityMap) underlyingIntegerMap;
     }
 
     @SuppressWarnings("unchecked")
-    private BiMap<String,I> nameMap()
+    Map<String,Integer> getEntriesNotIn(FMLControlledNamespacedRegistry<I> registry)
     {
-        return (BiMap<String,I>) registryObjects;
+        Map<String,Integer> ret = new HashMap<String, Integer>();
+
+        for (I thing : (Iterable<I>) this)
+        {
+            if (!registry.field_148758_b.containsKey(thing)) ret.put(getNameForObject(thing), getId(thing));
         }
 
-    void beginIdSwap()
+        return ret;
-    {
-        idMap().beginSwap();
-        transactionalNamedIds = Maps.newHashMap();
-        transactionalAvailabilityMap = new BitSet();
-    }
-
-    void reassignMapping(String name, int newId)
-    {
-        Object item = nameMap().get(name);
-        idMap().putNew(newId, item);
-        transactionalNamedIds.put(name,newId);
-        transactionalAvailabilityMap.set(newId);
-    }
-
-    void freezeMap()
-    {
-        if (frozenIds == null)
-        {
-            frozenIds = ImmutableBiMap.copyOf(namedIds);
-            idMap().freezeMap();
-        }
-    }
-
-    void revertToFrozen()
-    {
-        namedIds = HashBiMap.create(frozenIds);
-        idMap().revertToFrozen();
-    }
-
-    Map<String,Integer> getMissingMappings()
-    {
-        return Maps.difference(frozenIds, transactionalNamedIds).entriesOnlyOnLeft();
-    }
-    void completeIdSwap()
-    {
-        idMap().completeSwap();
-        namedIds.clear();
-        namedIds.putAll(transactionalNamedIds);
-        transactionalNamedIds = null;
-    }
-
-    void revertSwap()
-    {
-        idMap().revertSwap();
-        transactionalNamedIds = null;
-    }
-
-    public I get(int id)
-    {
-        return getObjectById(id);
-    }
-
-    public I get(String name)
-    {
-        return getObject(name);
-    }
-
-    public int getId(I thing)
-    {
-        return getIDForObject(thing);
-    }
-
-    public void serializeInto(Map<String, Integer> idMapping)
-    {
-        for (Entry<String, Integer> id: namedIds.entrySet())
-        {
-            idMapping.put(discriminator+id.getKey(), id.getValue());
-        }
-    }
-
-    public void useSlot(int id)
-    {
-        if (id >= maxId) return;
-        availabilityMap.set(id);
-    }
-
-    List<Integer> usedIds()
-    {
-        return ((FMLObjectIntIdentityMap)underlyingIntegerMap).usedIds();
-    }
-
-    public int getId(String itemName)
-    {
-        if (namedIds.containsKey(itemName))
-        {
-            return namedIds.get(itemName);
-        }
-        else
-        {
-            return -1;
-        }
-    }
-
-    public boolean contains(String itemName)
-    {
-        return namedIds.containsKey(itemName);
     }
 
+    @SuppressWarnings("unchecked")
     void dump()
     {
-        for (Entry<String, Integer> entry : namedIds.entrySet())
+        List<Integer> ids = new ArrayList<Integer>();
+
+        for (I thing : (Iterable<I>) this)
         {
-            String name = entry.getKey();
+            ids.add(getId(thing));
-            Object thing = idMap().get(entry.getValue().intValue());
+        }
-            FMLLog.finer("Registry : %s %d %s", name, entry.getValue(), thing);
+
+        // sort by id
+        Collections.sort(ids);
+
+        for (int id : ids)
+        {
+            I thing = getRaw(id);
+            FMLLog.finer("Registry: %s %d %s", getNameForObject(thing), id, thing);
         }
     }
 
-    BitSet slots()
+    /**
+     * Version of addObject not using the API restricting overrides.
+     */
+    private void addObjectRaw(int id, String name, I thing)
     {
-    	return (BitSet) availabilityMap.clone();
+        if (name == null) throw new NullPointerException();
+        if (thing == null) throw new NullPointerException();
+
+        underlyingIntegerMap.func_148746_a(thing, id); // obj <-> id
+        super.putObject(ensureNamespaced(name), thing); // name <-> obj
     }
 }

fml/src/main/java/cpw/mods/fml/common/registry/GameRegistry.java

@@ -136,7 +136,7 @@ public class GameRegistry
      */
     public static Item registerItem(Item item, String name, String modId)
     {
-        GameData.registerItem(item, name, modId);
+        GameData.getMain().registerItem(item, name, modId);
         return item;
     }
 
@@ -192,13 +192,11 @@ public class GameRegistry
                 Constructor<? extends ItemBlock> itemCtor = itemclass.getConstructor(ctorArgClasses);
                 i = itemCtor.newInstance(ObjectArrays.concat(block, itemCtorArgs));
             }
+            // block registration has to happen first
+            GameData.getMain().registerBlock(block, name, modId);
             if (i != null)
             {
-                GameData.registerBlockAndItem(i, block, name, modId);
+                GameData.getMain().registerItem(i, name, modId);
-            }
-            else
-            {
-                GameData.registerBlock(block, name, modId);
             }
             return block;
         }

fml/src/main/java/cpw/mods/fml/common/registry/GameRegistryException.java

@@ -1,19 +0,0 @@
-package cpw.mods.fml.common.registry;
-
-import java.util.List;
-
-public class GameRegistryException extends RuntimeException {
-    private static final long serialVersionUID = 1L;
-    private List<String> items;
-
-    public GameRegistryException(String message, List<String> items)
-    {
-        super(message);
-        this.items = items;
-    }
-
-    public List<String> getItems()
-    {
-        return this.items;
-    }
-}

fml/src/main/java/cpw/mods/fml/server/FMLServerHandler.java

@@ -12,20 +12,27 @@
  */
 package cpw.mods.fml.server;
 
+import java.io.File;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
+
+import net.minecraft.command.ServerCommand;
 import net.minecraft.network.INetHandler;
 import net.minecraft.network.NetHandlerPlayServer;
 import net.minecraft.network.NetworkManager;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.dedicated.DedicatedServer;
+import net.minecraft.world.storage.SaveFormatOld;
+
 import com.google.common.collect.ImmutableList;
+
 import cpw.mods.fml.common.FMLCommonHandler;
+import cpw.mods.fml.common.FMLLog;
 import cpw.mods.fml.common.IFMLSidedHandler;
 import cpw.mods.fml.common.Loader;
 import cpw.mods.fml.common.ModContainer;
-import cpw.mods.fml.common.WorldAccessContainer;
+import cpw.mods.fml.common.StartupQuery;
-import cpw.mods.fml.common.event.FMLMissingMappingsEvent;
 import cpw.mods.fml.common.eventhandler.EventBus;
 import cpw.mods.fml.common.network.FMLNetworkEvent;
 import cpw.mods.fml.common.registry.LanguageRegistry;
@@ -94,6 +101,12 @@ public class FMLServerHandler implements IFMLSidedHandler
         throw new RuntimeException(message, exception);
     }
 
+    @Override
+    public File getSavesDirectory()
+    {
+        return ((SaveFormatOld) server.getActiveAnvilConverter()).savesDirectory;
+    }
+
     /**
      * Get the server instance
      */
@@ -134,6 +147,67 @@ public class FMLServerHandler implements IFMLSidedHandler
     {
 
     }
+
+    @Override
+    public void queryUser(StartupQuery query) throws InterruptedException
+    {
+        if (query.getResult() == null)
+        {
+            FMLLog.warning("%s", query.getText());
+            query.finish();
+        }
+        else
+        {
+            String text = query.getText() +
+                    "\n\nRun the command /fml confirm or or /fml cancel to proceed." +
+                    "\nAlternatively start the server with -Dfml.queryResult=confirm or -Dfml.queryResult=cancel to preselect the answer.";
+            FMLLog.warning("%s", text);
+
+            if (!query.isSynchronous()) return; // no-op until mc does commands in another thread (if ever)
+
+            boolean done = false;
+
+            while (!done && server.isServerRunning())
+            {
+                if (Thread.interrupted()) throw new InterruptedException();
+
+                DedicatedServer dedServer = (DedicatedServer) server;
+
+                // rudimentary command processing, check for fml confirm/cancel and stop commands
+                synchronized (dedServer.pendingCommandList)
+                {
+                    for (Iterator<ServerCommand> it = dedServer.pendingCommandList.iterator(); it.hasNext(); )
+                    {
+                        String cmd = it.next().command.trim().toLowerCase();
+
+                        if (cmd.equals("/fml confirm"))
+                        {
+                            FMLLog.info("confirmed");
+                            query.setResult(true);
+                            done = true;
+                            it.remove();
+                        }
+                        else if (cmd.equals("/fml cancel"))
+                        {
+                            FMLLog.info("cancelled");
+                            query.setResult(false);
+                            done = true;
+                            it.remove();
+                        }
+                        else if (cmd.equals("/stop"))
+                        {
+                            StartupQuery.abort();
+                        }
+                    }
+                }
+
+                Thread.sleep(10L);
+            }
+
+            query.finish();
+        }
+    }
+
     @Override
     public boolean shouldServerShouldBeKilledQuietly()
     {
@@ -182,21 +256,7 @@ public class FMLServerHandler implements IFMLSidedHandler
     {
         bus.post(new FMLNetworkEvent.CustomPacketRegistrationEvent<NetHandlerPlayServer>(manager, channelSet, channel, side, NetHandlerPlayServer.class));
     }
-    @Override
-    public FMLMissingMappingsEvent.Action getDefaultMissingAction()
-    {
-        return FMLMissingMappingsEvent.Action.valueOf(System.getProperty("fml.missingBlockAction", "FAIL"));
-    }
-    @Override
-    public void serverLoadedSuccessfully()
-    {
 
-    }
-    @Override
-    public void failedServerLoading(RuntimeException ex, WorldAccessContainer wac)
-    {
-
-    }
     @Override
     public boolean shouldAllowPlayerLogins()
     {

fml/src/main/resources/fml_at.cfg

@@ -74,6 +74,12 @@ public net.minecraft.client.gui.GuiScreen field_146297_k # minecraft instance -
 # Minecraft
 #public atv.D #FD:Minecraft/field_71425_J #running
 public net.minecraft.client.Minecraft field_71446_o # textureManager
+## ItemBlock
+public net.minecraft.item.ItemBlock field_150939_a
+## DedicatedServer
+public net.minecraft.server.dedicated.DedicatedServer field_71341_l # pendingCommandList
+## SaveFormatOld
+public net.minecraft.world.storage.SaveFormatOld field_75808_a # savesDirectory
 
 protected net.minecraft.util.ObjectIntIdentityMap field_148749_a # internal map
 protected net.minecraft.util.ObjectIntIdentityMap field_148748_b # internal index list