[[1.7.10] ASM transforming causes ArrayIndexOutOfBoundsException]

What I'm trying to do is adding a hooks for changing sky color without creating a new biome.

(I'm new to ASM, I used this tutorial : http://www.minecraftforum.net/forums/mapping-and-modding/mapping-and-modding-tutorials/1571568-tutorial-1-6-2-changing-vanilla-without-editing)

 

The crash:

 

java.lang.NoClassDefFoundError: net/minecraftforge/client/ForgeHooksClient

at net.minecraft.client.Minecraft.startGame(Minecraft.java:474)

at net.minecraft.client.Minecraft.run(Minecraft.java:931)

at net.minecraft.client.main.Main.main(Main.java:164)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

at java.lang.reflect.Method.invoke(Unknown Source)

at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)

at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:78)

at GradleStart.main(GradleStart.java:45)

Caused by: java.lang.ClassNotFoundException: net.minecraftforge.client.ForgeHooksClient

at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)

at java.lang.ClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

... 11 more

Caused by: java.lang.ArrayIndexOutOfBoundsException: -1

at org.objectweb.asm.Frame.merge(Frame.java:1311)

at org.objectweb.asm.MethodWriter.visitMaxs(MethodWriter.java:1475)

at org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:834)

at org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:726)

at org.objectweb.asm.tree.ClassNode.accept(ClassNode.java:412)

at com.starsheep.colorevents.ColorTransformer.transformClientHooks(ColorTransformer.java:114)

at com.starsheep.colorevents.ColorTransformer.transform(ColorTransformer.java:43)

at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279)

at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176)

... 13 more

 

 

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

 

-- Head --

Stacktrace:

at net.minecraft.client.Minecraft.startGame(Minecraft.java:474)

 

-- Initialization --

Details:

Stacktrace:

at net.minecraft.client.Minecraft.run(Minecraft.java:931)

at net.minecraft.client.main.Main.main(Main.java:164)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

at java.lang.reflect.Method.invoke(Unknown Source)

at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)

at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:78)

at GradleStart.main(GradleStart.java:45)

 

 

The code:

 

package com.starsheep.colorevents;

 

import static org.objectweb.asm.Opcodes.*;

 

import net.minecraft.launchwrapper.IClassTransformer;

 

import org.objectweb.asm.ClassReader;

import org.objectweb.asm.ClassWriter;

import org.objectweb.asm.Type;

import org.objectweb.asm.commons.LocalVariablesSorter;

import org.objectweb.asm.tree.AbstractInsnNode;

import org.objectweb.asm.tree.ClassNode;

import org.objectweb.asm.tree.FieldInsnNode;

import org.objectweb.asm.tree.InsnList;

import org.objectweb.asm.tree.InsnNode;

import org.objectweb.asm.tree.IntInsnNode;

import org.objectweb.asm.tree.MethodInsnNode;

import org.objectweb.asm.tree.MethodNode;

import org.objectweb.asm.tree.VarInsnNode;

 

public class ColorTransformer implements IClassTransformer {

 

@Override

public byte[] transform(String name, String transformedName, byte[] bytes)

{

if(name.equals("net.minecraftforge.client.ForgeHooksClient"))

{

System.out.println("Going To Transform: " + name);

return transformClientHooks(bytes);

}

return bytes;

}

 

private byte[] transformClientHooks(byte[] bytes)

{

ClassNode classNode = new ClassNode();

ClassReader classReader = new ClassReader(bytes);

classReader.accept(classNode, 0);

 

MethodNode method = ASMHelper.findMethod(classNode.methods, new String[] {"getSkyBlendColour"}, "(Lnet/minecraft/world/World;III)I");

LocalVariablesSorter sorter = new LocalVariablesSorter(method.access, method.desc, method);

 

InsnList toFind = new InsnList();

 

toFind.add(new VarInsnNode(ILOAD, 7));

toFind.add(new VarInsnNode(ILOAD, 10));

toFind.add(new InsnNode(IDIV));

toFind.add(new IntInsnNode(SIPUSH, 255));

toFind.add(new InsnNode(IAND));

toFind.add(new IntInsnNode(BIPUSH, 16));

toFind.add(new InsnNode(ISHL));

toFind.add(new VarInsnNode(ILOAD, );

toFind.add(new VarInsnNode(ILOAD, 10));

toFind.add(new InsnNode(IDIV));

toFind.add(new IntInsnNode(SIPUSH, 255));

toFind.add(new InsnNode(IAND));

toFind.add(new IntInsnNode(BIPUSH, );

toFind.add(new InsnNode(ISHL));

toFind.add(new InsnNode(IOR));

toFind.add(new VarInsnNode(ILOAD, 9));

toFind.add(new VarInsnNode(ILOAD, 10));

toFind.add(new InsnNode(IDIV));

toFind.add(new IntInsnNode(SIPUSH, 255));

toFind.add(new InsnNode(IAND));

toFind.add(new InsnNode(IOR));

toFind.add(new VarInsnNode(ISTORE, 11)); //int multiplier = (r / divider & 255) << 16 | (g / divider & 255) << 8 | b / divider & 255;

 

AbstractInsnNode node = ASMHelper.findFirst(toFind, method.instructions);

 

InsnList toInject = new InsnList();

 

int fieldEvent = sorter.newLocal(Type.getType(EventSkyColor.class));

toInject.add(new InsnNode(DUP));

toInject.add(new VarInsnNode(ILOAD, 7));

toInject.add(new VarInsnNode(ILOAD, );

toInject.add(new VarInsnNode(ILOAD, 9));

toInject.add(new MethodInsnNode(INVOKESPECIAL, "com/starsheep/colorevents/EventSkyColor", "<init>", "(III)V", false));

toInject.add(new VarInsnNode(ASTORE, fieldEvent)); //EventSkyColor event = new EventSkyColor(red, green, blue);

 

toInject.add(new FieldInsnNode(GETSTATIC, "net/minecraftforge/common/MinecraftForge", "EVENT_BUS", "Lcpw/mods/fml/common/eventhandler/EventBus;"));

toInject.add(new VarInsnNode(ALOAD, fieldEvent));

toInject.add(new FieldInsnNode(INVOKEVIRTUAL, "cpw/mods/fml/common/eventhandler/EventBus", "post", "(Lcpw/mods/fml/common/eventhandler/Event;)Z"));

toInject.add(new InsnNode(POP)); //MinecraftForge.EVENT_BUS.post(event);

 

toInject.add(new VarInsnNode(ALOAD, fieldEvent));

toInject.add(new FieldInsnNode(GETFIELD, "com/starsheep/colorevents/EventSkyColor", "red", "I"));

toInject.add(new VarInsnNode(ASTORE, 7)); // red = event.red;

 

toInject.add(new VarInsnNode(ALOAD, fieldEvent));

toInject.add(new FieldInsnNode(GETFIELD, "com/starsheep/colorevents/EventSkyColor", "green", "I"));

toInject.add(new VarInsnNode(ASTORE, ); // green = event.green;

 

toInject.add(new VarInsnNode(ALOAD, fieldEvent));

toInject.add(new FieldInsnNode(GETFIELD, "com/starsheep/colorevents/EventSkyColor", "blue", "I"));

toInject.add(new VarInsnNode(ASTORE, 9)); //blue = event.blue;

 

method.instructions.insertBefore(node, toInject);

 

ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

classNode.accept(writer);

return writer.toByteArray();

}

}

 

 

 

ASMHelper (some parts are stolen from https://github.com/SanAndreasP/SAPManagerPack/blob/master/java/de/sanandrew/core/manpack/transformer/ASMHelper.java)

 

package com.starsheep.colorevents;

 

import java.util.Iterator;

import java.util.List;

 

import org.objectweb.asm.tree.*;

 

import static org.objectweb.asm.tree.AbstractInsnNode.*;

 

public class ASMHelper {

 

 

public static MethodNode findMethod(List<MethodNode> methods, String[] names, String desc)

{

Iterator<MethodNode> iterator = methods.iterator();

MethodNode method = null;

while(iterator.hasNext())

{

MethodNode m = iterator.next();

boolean flag = true;

for(String name : names)

{

if(m.name.equals(name)) flag = false;

}

if(flag) continue;

if(m.desc.equals("(Lnet/minecraft/world/World;III)I"))

{

System.out.println("Found Method: " + m.name);

method = m;

break;

}

}

return method;

}

 

public static AbstractInsnNode findFirst(InsnList key, InsnList fings)

{

Iterator<AbstractInsnNode> iterator = fings.iterator();

while(iterator.hasNext())

{

AbstractInsnNode n = iterator.next();

if(isInsnEqual(key, n))

{

return n;

}

}

return null;

}

 

public static AbstractInsnNode findLast(InsnList key, InsnList fings)

{

Iterator<AbstractInsnNode> iterator = fings.iterator();

int number = 0;

while(iterator.hasNext())

{

AbstractInsnNode n = iterator.next();

if(isInsnEqual(key, n))

{

return fings.get(number + key.size() - 1);

}

number++;

}

return null;

}

 

public static boolean isInsnEqual(InsnList key, AbstractInsnNode node)

{

Iterator<AbstractInsnNode> iterator = key.iterator();

while(iterator.hasNext())

{

AbstractInsnNode n = iterator.next();

if(!nodeEqual(node, n))

{

return false;

}

node = node.getNext();

}

return true;

}

 

public static boolean nodeEqual(AbstractInsnNode node1, AbstractInsnNode node2)

{

        if( node1.getType() != node2.getType() ) {

            return false;

        } else if( node1.getOpcode() != node2.getOpcode() ) {

            return false;

        }

 

        switch( node2.getType() )

        {

            case VAR_INSN :

                return varInsnEqual((VarInsnNode) node1, (VarInsnNode) node2);

            case TYPE_INSN :

                return typeInsnEqual((TypeInsnNode) node1, (TypeInsnNode) node2);

            case FIELD_INSN :

                return fieldInsnEqual((FieldInsnNode) node1, (FieldInsnNode) node2);

            case METHOD_INSN :

                return methodInsnEqual((MethodInsnNode) node1, (MethodInsnNode) node2);

            case LDC_INSN :

                return ldcInsnEqual((LdcInsnNode) node1, (LdcInsnNode) node2);

            case IINC_INSN :

                return iincInsnEqual((IincInsnNode) node1, (IincInsnNode) node2);

            case INT_INSN :

                return intInsnEqual((IntInsnNode) node1, (IntInsnNode) node2);

            default :

                return true;

        }

    }

 

public static boolean varInsnEqual(VarInsnNode insn1, VarInsnNode insn2)

{

        return insn1.var == -1 || insn2.var == -1 || insn1.var == insn2.var;

}

 

public static boolean typeInsnEqual(TypeInsnNode insn1, TypeInsnNode insn2)

{

        return insn1.desc.equals("~") || insn2.desc.equals("~") || insn1.desc.equals(insn2.desc);

}

 

public static boolean fieldInsnEqual(FieldInsnNode insn1, FieldInsnNode insn2)

{

      return insn1.owner.equals(insn2.owner) && insn1.name.equals(insn2.name) && insn1.desc.equals(insn2.desc);

}

 

public static boolean methodInsnEqual(MethodInsnNode insn1, MethodInsnNode insn2)

{

      return insn1.owner.equals(insn2.owner) && insn1.name.equals(insn2.name) && insn1.desc.equals(insn2.desc);

}

 

public static boolean ldcInsnEqual(LdcInsnNode insn1, LdcInsnNode insn2)

{

      return insn1.cst.equals("~") || insn2.cst.equals("~") || insn1.cst.equals(insn2.cst);

}

 

public static boolean iincInsnEqual(IincInsnNode node1, IincInsnNode node2)

{

    return node1.var == node2.var && node1.incr == node2.incr;

}

 

public static boolean intInsnEqual(IntInsnNode node1, IntInsnNode node2)

{

return node1.operand == -1 || node2.operand == -1 || node1.operand == node2.operand;

}

 

}