From 6e34774a46c8ab9140bf4a197f3131e79543a782 Mon Sep 17 00:00:00 2001
From: Agaricus <agaricusb@yahoo.com>
Date: Tue, 5 Feb 2013 21:09:08 -0800
Subject: [PATCH] Initial implementation of field reflection remapper

Remaps the string constant in class.getDeclaredField("fieldname")
---
 .../specialsource/ReflectionRemapper.java     | 91 +++++++++++++++++++
 .../net/md_5/specialsource/SpecialSource.java |  2 +
 2 files changed, 93 insertions(+)
 create mode 100644 src/main/java/net/md_5/specialsource/ReflectionRemapper.java

diff --git a/src/main/java/net/md_5/specialsource/ReflectionRemapper.java b/src/main/java/net/md_5/specialsource/ReflectionRemapper.java
new file mode 100644
index 0000000..3ca6976
--- /dev/null
+++ b/src/main/java/net/md_5/specialsource/ReflectionRemapper.java
@@ -0,0 +1,91 @@
+package net.md_5.specialsource;
+
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.*;
+import org.objectweb.asm.Type;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+
+public class ReflectionRemapper {
+
+    private JarMapping jarMapping;
+    private IInheritanceProvider inheritanceProvider;
+
+    public ReflectionRemapper(JarMapping jarMapping, IInheritanceProvider inheritanceProvider) {
+        this.jarMapping = jarMapping;
+        this.inheritanceProvider = inheritanceProvider;
+    }
+
+    @SuppressWarnings("unchecked")
+    public byte[] remapClassFile(InputStream is) throws IOException {
+        ClassReader cr = new ClassReader(is);
+        ClassNode classNode = new ClassNode();
+        ClassWriter cw = new ClassWriter(0);
+
+        cr.accept(classNode, ClassReader.SKIP_DEBUG);
+
+        for (MethodNode methodNode : (List<MethodNode>) classNode.methods) {
+            AbstractInsnNode insn = methodNode.instructions.getFirst();
+            while (insn != null) {
+                if (insn.getOpcode() == Opcodes.INVOKEVIRTUAL) {
+                    remapGetDeclaredField(insn);
+                }
+
+                insn = insn.getNext();
+            }
+        }
+
+        classNode.accept(cw);
+
+        return cw.toByteArray();
+    }
+
+    private void remapGetDeclaredField(AbstractInsnNode insn) {
+        MethodInsnNode mi = (MethodInsnNode) insn;
+
+        System.out.println("methodnode "+mi.owner+" "+mi.name+" "+mi.desc);
+        if (!mi.owner.equals("java/lang/Class") || !mi.name.equals("getDeclaredField") || !mi.desc.equals("(Ljava/lang/String;)Ljava/lang/reflect/Field;")) {
+            return;
+        }
+
+        System.out.println("found getDeclaredField!");
+
+        if (insn.getPrevious() == null || insn.getPrevious().getOpcode() != Opcodes.LDC) {
+            System.out.println("- not constant field; skipping");
+            return;
+        }
+        LdcInsnNode ldcField = (LdcInsnNode) insn.getPrevious();
+        System.out.println("field constant = "+ldcField.cst);
+        if (!(ldcField.cst instanceof String)) {
+            System.out.println("- not field string; skipping");
+            return;
+        }
+        String fieldName = (String) ldcField.cst;
+
+        if (ldcField.getPrevious() == null || ldcField.getPrevious().getOpcode() != Opcodes.LDC) {
+            System.out.println("- not constant class; skipping");
+            return;
+        }
+        LdcInsnNode ldcClass = (LdcInsnNode) ldcField.getPrevious();
+        if (!(ldcClass.cst instanceof Type)) {
+            System.out.println("- not class type; skipping");
+            return;
+        }
+        System.out.println("class = "+ldcClass.cst);
+        String className = ((Type) ldcClass.cst).getInternalName();
+
+        System.out.println("Remapping "+className+"/"+fieldName);
+
+        String newName = jarMapping.fields.get(className + "/" + fieldName); // TODO: tryClimb etc
+        if (newName != null) {
+            // Change the string literal to the correct name
+            ldcField.cst = newName;
+            //ldcClass.cst = className; // not remapped here - taken care of by JarRemapper
+            System.out.println(" -> to "+newName);
+        }
+    }
+}
diff --git a/src/main/java/net/md_5/specialsource/SpecialSource.java b/src/main/java/net/md_5/specialsource/SpecialSource.java
index 556f69f..856ebfb 100644
--- a/src/main/java/net/md_5/specialsource/SpecialSource.java
+++ b/src/main/java/net/md_5/specialsource/SpecialSource.java
@@ -92,6 +92,8 @@ public class SpecialSource {
                         .withRequiredArg()
                         .ofType(File.class);
 
+                //acceptsAll(asList("G", "remap-reflect-field"), "Remap reflection calls to getDeclaredField()"); // TODO
+
                 acceptsAll(asList("q", "quiet"), "Quiet mode");
             }
         };