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https://github.com/florianreuth/asmfabricloader

A series of cursed Fabric hacks and utilities which break everything.
https://github.com/florianreuth/asmfabricloader

asm cursed fabric grossfabrichacks injection mixin

Last synced: 2 months ago
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A series of cursed Fabric hacks and utilities which break everything.

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README 

          
# AsmFabricLoader



A series of cursed Fabric hacks and utilities which break everything.



* [AsmFabricLoader](#asmfabricloader)

  * [Why?](#why)

  * [Contact](#contact)

  * [How to add this to your project](#how-to-add-this-to-your-project)

    * [Gradle/Maven](#gradlemaven)

    * [Jar File](#jar-file)

  * [How to use](#how-to-use)

    * [PreLaunch Entry Points](#prelaunch-entry-points)

    * [Get a Java instrumentation (Requires Java 9+)](#get-a-java-instrumentation-requires-java-9)

    * [Unmixer](#unmixer)

    * [Jar Booter](#jar-booter)

    * [Early riser](#early-riser)

    * [Class Transform (Requires Java 9+)](#class-transform-requires-java-9)

      * [Setting up mappings](#setting-up-mappings)

      * [Transformer config](#transformer-config)

      * [Example transformer](#example-transformer)

      * [Registering transformers](#registering-transformers)

    * [Environments](#environments)

    * [Debug options](#debug-options)

    * [Testing](#testing)



## Why?



There are many use cases for direct ASM injections and the power to re-transform every loaded class.



This is basically a cleanup rewrite of [GrossFabricHacks](https://github.com/Devan-Kerman/GrossFabricHacks/tree/master)

using the [ClassTransform](https://www.github.com/Lenni0451/ClassTransform)

and [Reflect](https://www.github.com/Lenni0451/Reflect) libraries.



It also provides the same functionality as [MixinSquared](https://github.com/Bawnorton/MixinSquared).



## Contact



If you encounter any issues, please report them on

the [issue tracker](https://github.com/florianreuth/AsmFabricLoader/issues).  

If you just want to talk or need help with AsmFabricLoader feel free to join

my [Discord](https://florianreuth.de/discord).



## How to add this to your project



### Gradle/Maven



To use AsmFabricLoader with Gradle/Maven you can

use [the Maven Central repository](https://mvnrepository.com/artifact/de.florianreuth/asmfabricloader)

or [my own repository](https://maven.florianreuth.de/#/releases/de/florianreuth/asmfabricloader).  

You can also find instructions how to implement it into your build script there.



### Jar File



If you just want the latest jar file you can download it

from [my build server](https://build.florianreuth.de/job/AsmFabricLoader), [GitHub Actions](https://github.com/florianreuth/AsmFabricLoader/actions)

or use the [releases tab](https://github.com/florianreuth/AsmFabricLoader/releases).



## How to use



AsmFabricLoader allows you to access a series of utilities and hacks to make your life easier.



### PreLaunch Entry Points



AsmFabricLoader adds an even more early entry point than FabricMC's `PreLaunchEntrypoint`.



You can use the `PrePreLaunchEntrypoint`, which will be called when Fabric bootstraps the mixin service. The name

of the entry point is `afl:prePreLaunch`.



The `PrePrePreLaunchEntrypoint` is the earliest entry point possible. It is getting bootstrapped before the loader

even starts. The name of the entry point is `afl:prePrePreLaunch`.



You can use both just like the `PreLaunchEntrypoint` from FabricMC.



### Get a Java instrumentation (Requires Java 9+)



AsmFabricLoader allows you to get a Java instrumentation instance which you can use to transform classes directly.



You can use the `InstrumentationEntrypoint` to get the instrumentation instance. The name of the entry point is

`afl:instrumentation`.



### Unmixer



AsmFabricLoader adds a new API which allows you to unload Mixin classes meaning they aren't injected anymore. This is

useful if another mod is breaking your Mixins or if you want to unload Mixins after they have been applied.



```java

final Unmixer unmixer = AsmFabricLoader.getLoader().getUnmixer();



// This method accepts the mixin classes of all loaded mods including the Fabric internals

unmixer.unloadMixinClass("net/fabricmc/api/mixin/v1/MixinEnvironment");

```



You can also use the Unmixer via the `fabric.mod.json` file:



```json

{

  "custom": {

    "afl:unmixer": [

      "net.fabricmc.api.mixin.v1.MixinEnvironment"

    ]

  }

}

```



You can also group the packages together:



```json

{

  "custom": {

    "afl:unmixer": {

      "net.fabricmc.api.mixin.v1": [

        "MixinEnvironment"

      ]

    }

  }

}

```



### Jar Booter



AsmFabricLoader allows you to define a list of folders where it will load all jar files from to the front of the

classpath.

This can be useful if you want to allow the user to replace a library jar file you are using with a different version.



```json

{

  "custom": {

    "afl:jarbooter": [

      "libs"

    ]

  }

}

```



This will load all jar files from the run directory/libs folder to the front of the classpath.



### Early riser



Utility to create and invoke mod entrypoints before Fabric has finished loading entrypoints. See the `EarlyRiser` class



### Class Transform (Requires Java 9+)



AsmFabricLoader bootstraps the [ClassTransform](https://www.github.com/Lenni0451/ClassTransform) library which allows

you to transform classes directly without using Mixins.



#### Setting up mappings



AsmFabricLoader uses tiny mappings internally to remap Minecraft classes for transformers.



AsmFabricLoader itself **does not** ship these mappings. Your mod has to provide the Tiny mappings file so that AFL can

load it at runtime.



AsmFabricLoader looks for a resource named:



- `/afl_mappings.tiny`



You can override this path per mod via `fabric.mod.json` using `afl:mappings_path`. The value must be a string

and is resolved as a resource path inside the mod jar (a leading / is added automatically if missing), for example:



```json

{

  "custom": {

    "afl:mappings_path": "custom/afl_mappings.tiny"

  }

}

```



Example for **Gradle Kotlin DSL** (`build.gradle.kts`) in your mod project:



```kotlin

tasks {

    jar {

        dependsOn(configurations["mappings"])

        val mappingsJar = configurations["mappings"].resolvedConfiguration.resolvedArtifacts.firstOrNull {

            it.name.contains("mappings") || it.name.contains("yarn")

        }?.file



        if (mappingsJar != null && mappingsJar.exists()) {

            val mappingsFile = zipTree(mappingsJar).matching {

                include("mappings/mappings.tiny")

            }.singleFile



            from(mappingsFile) {

                rename { "afl_mappings.tiny" }

            }

        }

    }

}

```



Example for **Gradle Groovy DSL** (`build.gradle`) in your mod project:



```groovy

tasks {

    jar {

        dependsOn(configurations.mappings)

        def mappingsJar = configurations.mappings

            .resolvedConfiguration

            .resolvedArtifacts

            .find { it.name.contains("mappings") || it.name.contains("yarn") }

            ?.file



        if (mappingsJar != null && mappingsJar.exists()) {

            def mappingsFile = zipTree(mappingsJar).matching {

                include "mappings/mappings.tiny"

            }.singleFile



            from(mappingsFile) {

                rename { "afl_mappings.tiny" }

            }

        }

    }

}

```



#### Transformer config



You just have to create a json file called `.classtransform.json` in your resources folder and add the following



```json

{

  "package": "net.example.injection.transformer",

  "java": [

  ],

  "mixins": [

  ]

}

```



The `package` field is the package where your transformers are located.



Now AsmFabricLoader provides two ways to add transformers to the ClassTransform library:



The `java` field will apply all the transformers using a runtime injected java agent after Mixins and the loader

has been initialized. Meaning you can transform all classes in your runtime, even Java standard library classes.



The `mixins` field will apply all the transformers before Mixins are getting applied, therefore you can only add

transformers targeting other mods mixin classes. These transformers will be applied before those Mixins are getting

applied to the game code, this is basically a replacement for [MixinSquared](https://github.com/Bawnorton/MixinSquared).



#### Example transformer



```java

@CTransformer(String.class)

public class Test {



    @CInline

    @CInject(method = "equals", target = @CTarget("HEAD"))

    public void printInput(Object anObject, InjectionCallback callback) {

        System.out.println("Input: " + anObject);

    }



}

```



#### Registering transformers



To register your json file, you have to add the following to your `fabric.mod.json` file:



```json

{

  "custom": {

    "afl:classtransform": ".classtransform.json"

  }

}

```



### Environments



AsmFabricLoader allows you to limit the execution of all the features to specific environments. This can be useful if

you want to use the same mod jar file for multiple environments.



This snippet will only apply the unmixer if the mod is loaded on the client:



```json

{

  "custom": {

    "afl:client:unmixer": [

    ]

  }

}

```



### Debug options



There are a few system properties you can enable to debug AsmFabricLoader:



```-DAsmFabricLoader.debug=true``` will print a lot of useful debug information including loading states



```-Dclasstransform.dumpClasses=``` will dump all classes transformed by ClassTransform

to `run directory` / `classtransform`



### Testing



The `TestMod` submodule contains a Fabric mod to test various features of AsmFabricLoader. You can run the tests by

building both root project and the test mod project and then running them in a production environment.



A test running successfully will be indicated by the following message in the console:



```

[TestMod]  passed!

```



All tests have been passed if you see the following message in the console:



```

[TestMod] All tests passed!

```