From 4c6f6b07cf3d94f7369c182bcd084c7dcd3aaf4d Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Fri, 3 Jul 2020 20:16:37 +0100
Subject: [PATCH] Store mapped local variable names in the OriginalPcTable

We could use LocalVariableTable in theory, but it's more complicated as
we'd need to do live variable analysis and type inference. It's much
easier to leave that for the decompiler.

Signed-off-by: Graham <gpe@openrs2.dev>
---
 .../java/dev/openrs2/deob/OriginalPcTable.kt  | 13 ++++-
 .../transform/OriginalPcRestoreTransformer.kt | 47 ++++++++++++++++++-
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/deob/src/main/java/dev/openrs2/deob/OriginalPcTable.kt b/deob/src/main/java/dev/openrs2/deob/OriginalPcTable.kt
index 91c094d993..fe8abfed6a 100644
--- a/deob/src/main/java/dev/openrs2/deob/OriginalPcTable.kt
+++ b/deob/src/main/java/dev/openrs2/deob/OriginalPcTable.kt
@@ -6,7 +6,10 @@ import org.objectweb.asm.ClassWriter
 import org.objectweb.asm.Label
 import org.objectweb.asm.tree.LabelNode
 
-class OriginalPcTable(private val pcs: Map<LabelNode, Int>) : Attribute("OriginalPcTable") {
+class OriginalPcTable(
+    private val pcs: Map<LabelNode, Int>,
+    private val names: Map<Int, String>
+) : Attribute("OriginalPcTable") {
     override fun isCodeAttribute(): Boolean {
         return true
     }
@@ -27,11 +30,19 @@ class OriginalPcTable(private val pcs: Map<LabelNode, Int>) : Attribute("Origina
         maxLocals: Int
     ): ByteVector {
         val buf = ByteVector()
+
         buf.putShort(pcs.size)
         for ((label, pc) in pcs) {
             buf.putShort(label.label.offset)
             buf.putShort(pc)
         }
+
+        buf.putShort(names.size)
+        for ((pc, name) in names) {
+            buf.putShort(pc)
+            buf.putShort(classWriter.newUTF8(name))
+        }
+
         return buf
     }
 }
diff --git a/deob/src/main/java/dev/openrs2/deob/transform/OriginalPcRestoreTransformer.kt b/deob/src/main/java/dev/openrs2/deob/transform/OriginalPcRestoreTransformer.kt
index 5984566ade..aee515159d 100644
--- a/deob/src/main/java/dev/openrs2/deob/transform/OriginalPcRestoreTransformer.kt
+++ b/deob/src/main/java/dev/openrs2/deob/transform/OriginalPcRestoreTransformer.kt
@@ -1,18 +1,23 @@
 package dev.openrs2.deob.transform
 
 import com.github.michaelbull.logging.InlineLogger
+import dev.openrs2.asm.MemberRef
 import dev.openrs2.asm.classpath.ClassPath
 import dev.openrs2.asm.classpath.Library
 import dev.openrs2.asm.removeDeadCode
 import dev.openrs2.asm.transform.Transformer
 import dev.openrs2.deob.OriginalPcTable
+import dev.openrs2.deob.annotation.OriginalMember
+import dev.openrs2.deob.util.map.NameMap
+import org.objectweb.asm.Type
 import org.objectweb.asm.tree.ClassNode
 import org.objectweb.asm.tree.LabelNode
 import org.objectweb.asm.tree.MethodNode
+import javax.inject.Inject
 import javax.inject.Singleton
 
 @Singleton
-class OriginalPcRestoreTransformer : Transformer() {
+class OriginalPcRestoreTransformer @Inject constructor(private val nameMap: NameMap) : Transformer() {
     private var originalPcsRestored = 0
 
     override fun preTransform(classPath: ClassPath) {
@@ -39,10 +44,17 @@ class OriginalPcRestoreTransformer : Transformer() {
             originalPcsRestored++
         }
 
+        val originalMember = method.getOriginalMember()
+        val names: Map<Int, String> = if (originalMember != null) {
+            nameMap.methods[originalMember]?.locals ?: emptyMap()
+        } else {
+            emptyMap()
+        }
+
         if (method.attrs == null) {
             method.attrs = mutableListOf()
         }
-        method.attrs.add(OriginalPcTable(pcs))
+        method.attrs.add(OriginalPcTable(pcs, names))
 
         return false
     }
@@ -51,6 +63,37 @@ class OriginalPcRestoreTransformer : Transformer() {
         logger.info { "Restored $originalPcsRestored original instruction indexes" }
     }
 
+    private fun MethodNode.getOriginalMember(): MemberRef? {
+        if (invisibleAnnotations == null) {
+            return null
+        }
+
+        for (annotation in invisibleAnnotations) {
+            if (annotation.desc != Type.getDescriptor(OriginalMember::class.java)) {
+                continue
+            }
+
+            var owner: String? = null
+            var name: String? = null
+            var desc: String? = null
+            for ((key, value) in annotation.values.windowed(2, 2)) {
+                when (key) {
+                    "owner" -> owner = value as String
+                    "name" -> name = value as String
+                    "descriptor" -> desc = value as String
+                }
+            }
+
+            check(owner != null) { "Failed to extract owner from OriginalMember" }
+            check(name != null) { "Failed to extract name from OriginalMember" }
+            check(desc != null) { "Failed to extract descriptor from OriginalMember" }
+
+            return MemberRef(owner, name, desc)
+        }
+
+        return null
+    }
+
     private companion object {
         private val logger = InlineLogger()
     }