Lillero

Lillero is a lightweight and simple ASM patching framework, empowering you to easily modify block game (byte)code, dunking on all the naysayers who said you absolutely had to use Mixin.

How

This library provides the core interface, IInjector, as well as a small set of utils to make your life easier. All patches should implement IInjector and be declared as services.

Some methods must be implemented, specifying which class and method will be patched:

• targetClass(): returns the fully qualified name of the class to patch (example: net.minecraft.client.Minecraft).
• methodName(): returns the "Searge name" of the method to patch.
• methodDesc(): returns descriptor (arguments and return type) of method to patch.
• inject(ClassNode clazz, MethodNode method): will be invoked providing you the ClassNode and MethodNode you requested. This is where the actual patching will happen.

There's some more optional methods you don't have to implement, but really should because they will make your life considerably easier when it's time to debug:

• name() : returns patch name
• reason() : returns patch description

Finally, you should mark your classes as service providers, by creating a text file called ftbsc.lll.IInjector in src/main/resources/META-INF/services on your project. Inside, put the fully qualified names of your patches (example: ftbsc.bscv.asm.patches.TestPatch$TickPatch).

If you use Gradle (you do) don't forget to add this library as a dependency in your build.gradle:

repositories {
	maven { url = 'https://maven.fantabos.co' }
}
dependencies {
    implementation 'ftbsc:lll:0.2.2'
}

You are going to need a loader to use patches created with this library. You can use our loader or write your own: as long as it uses IInjector as patch interface, it won't break compatibility.

Example

The following is an example patch, located at src/main/java/example/patches/SamplePatch.java:

  package example.patches;
  import ftbsc.lll.IInjector;
  public class SamplePatch implements IInjector {
    public String name()        { return "SamplePatch"; }
    public String targetClass() { return "net.minecraft.client.Minecraft"; }
    public String methodName()  { return "func_71407_l"; } // tick()
    public String methodDesc()  { return "()V"; }
    public void inject(ClassNode clazz, MethodNode main) {
      InsnList insnList = new InsnList();
      insnList.add(new InsnNode(POP));
      main.instructions.insert(insnList);
    }
  }

The patch will crash the game with a NegativeArraySizeException as soon as it's done loading - so you know it's working.

The following is the service registration file, located at src/main/resources/META-INF/services/ftbsc.lll.IInjector:

  example.patches.SamplePatch

Happy patching! And remember...

"Don't do coremods!"