44 lines
2.4 KiB
Markdown
44 lines
2.4 KiB
Markdown
# libjf-unsafe-v0
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libjf-unsafe-v0 provides an entrypoint which is called extremely early and ASM modification.
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It also ensures dependency libraries are on the classpath during both.
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Due to the fact that it accesses several internal components of fabric loader,
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it is probably incompatible with versions of fabric loader it was not explicitly developed for.
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### UltraEarlyInit
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Implement `UltraEarlyInit` on your entrypoint and add it as a `libjf:early` entrypoint
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Please be aware that using any non-jdk classes during the ultra early init stage prevents them from being modified by Mixin/ASM.
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### ASM
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Implement `AsmConfig` on a class and add it to your fabric.mod.json as a `libjf:asm` entrypoint.
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Use skipClasses to prevent a class from being modified by any ASM patches.
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getPatches should return a Set of patches that should be applied to classes (more on that later).
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skipClasses and getPatches will only be called once during the initialization process.
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Please be aware that using un-excluded classes during ASM modification can cause infinite loops.
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Please also note that during runtime, class names may be in intermediary, yarn or other mappings.
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You can use AsmTransformer.MAPPING_RESOLVER to resolve intermediary names to their runtime counterparts
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### Creating an ASM patch
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The current ClassNode will be passed to the apply method of every registered Patch instance.
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You may modify it as you like, but some default things are provided to make this easier:
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- InterfaceImplTargetPatch will apply a Patch only on classes implementing or extending the interface or class specified as the first parameter
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- MethodModificationPatch allows applying MethodPatches only to specific methods on specific classes
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- MethodReplacementPatch is a MethodPatch which replaces the content of its target method with a predefined InsnList
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Of course, you can (and should) implement your own patches in addition to these,
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Examples can be found in libjf-data-manipulation-v0 and GWWHIT
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### Debugging ASM
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Debugging ASM is difficult, but you can use the asm.log/asm.export flags to get additional output.
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You can do so either by adding `-Plibjf.asm.log -Plibjf.asm.export` to your JVM args or the following to your fabric.mod.json:
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```json
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{
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"custom": {
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"libjf": {
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"asm.log": true,
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"asm.export": true
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}
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}
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}
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```
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I also recommend using IDEAs bytecode viewer on resulting classes to understand the bytecode
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