From 0d21d49d2de7bba32e12f98e822312a3598ce778 Mon Sep 17 00:00:00 2001
From: Adam <Adam@anope.org>
Date: Tue, 5 May 2015 13:36:54 -0400
Subject: [PATCH] Can detect unused parameters

---
 src/main/java/info/sigterm/deob/Deob.java     | 45 +++++++++++++++++++
 src/main/java/info/sigterm/deob/Method.java   | 37 +++++++++++++++
 .../deob/attributes/code/Instructions.java    |  5 +++
 .../info/sigterm/deob/pool/NameAndType.java   |  8 ++++
 4 files changed, 95 insertions(+)

diff --git a/src/main/java/info/sigterm/deob/Deob.java b/src/main/java/info/sigterm/deob/Deob.java
index 771dad7f38..440a8be1d9 100644
--- a/src/main/java/info/sigterm/deob/Deob.java
+++ b/src/main/java/info/sigterm/deob/Deob.java
@@ -1,6 +1,9 @@
 package info.sigterm.deob;
 
 import info.sigterm.deob.execution.Execution;
+import info.sigterm.deob.pool.NameAndType;
+import info.sigterm.deob.attributes.code.Instruction;
+import info.sigterm.deob.attributes.code.instruction.types.LVTInstruction;
 
 import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
@@ -10,6 +13,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Enumeration;
+import java.util.List;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.jar.JarOutputStream;
@@ -39,6 +43,7 @@ public class Deob
 		group.buildCallGraph();
 		
 		checkCallGraph(group);
+		checkParameters(group);
 		
 		//execute(group);
 		
@@ -89,4 +94,44 @@ public class Deob
 		}
 		System.out.println("Removed " + i + " methods");
 	}
+	
+	private static boolean parameterUsed(int num, List lv)
+	{
+		if (lv.isEmpty())
+			return false;
+		
+		// these instructions aren't in order so we can't do this
+		//LVTInstruction ins = (LVTInstruction) lv.get(0);
+		//return !ins.store();
+		return true;
+	}
+	
+	private static void checkParameters(ClassGroup group)
+	{
+		int count = 0;
+		for (ClassFile cf : group.getClasses())
+		{
+			for (Method m : new ArrayList<>(cf.getMethods().getMethods()))
+			{
+				int start = m.isStatic() ? 0 : 1;
+				NameAndType nat = m.getNameAndType();
+				int numParams = start + nat.getNumberOfArgs();
+				
+				for (int i = start; i < numParams; ++i)
+				{
+					List lv = m.findLVTInstructionsForVariable(i);
+					
+					if (lv == null)
+						continue;
+					
+					if (!parameterUsed(i, lv))
+					{
+						System.out.println("Not used param " + i + " of " + cf.getName() + " " + m.getName() + " static: " + m.isStatic());
+						++count;
+					}
+				}
+			}
+		}
+		System.out.println("Detected " + count + " unused parameters");
+	}
 }
diff --git a/src/main/java/info/sigterm/deob/Method.java b/src/main/java/info/sigterm/deob/Method.java
index 707d5d9d4b..b4180b4a44 100644
--- a/src/main/java/info/sigterm/deob/Method.java
+++ b/src/main/java/info/sigterm/deob/Method.java
@@ -4,7 +4,9 @@ import info.sigterm.deob.attributes.AttributeType;
 import info.sigterm.deob.attributes.Attributes;
 import info.sigterm.deob.attributes.Code;
 import info.sigterm.deob.attributes.code.Instruction;
+import info.sigterm.deob.attributes.code.instruction.types.LVTInstruction;
 import info.sigterm.deob.callgraph.Node;
+import info.sigterm.deob.pool.NameAndType;
 import info.sigterm.deob.pool.UTF8;
 
 import java.io.DataInputStream;
@@ -15,6 +17,8 @@ import java.util.List;
 
 public class Method
 {
+	public static final int ACC_STATIC = 0x8;
+	
 	private Methods methods;
 
 	private short accessFlags;
@@ -65,6 +69,17 @@ public class Method
 		UTF8 u = (UTF8) methods.getClassFile().getPool().getEntry(descriptorIndex);
 		return u.getValue();
 	}
+	
+	public NameAndType getNameAndType()
+	{
+		// this isn't really from the pool ..
+		return new NameAndType(methods.getClassFile().getPool(), nameIndex, descriptorIndex);
+	}
+	
+	public boolean isStatic()
+	{
+		return (accessFlags & ACC_STATIC) != 0;
+	}
 
 	public Code getCode()
 	{
@@ -129,4 +144,26 @@ public class Method
 		callsTo.add(node);
 		method.callsFrom.add(node);
 	}
+	
+	@SuppressWarnings("unchecked")
+	public <T extends Instruction & LVTInstruction> List<T> findLVTInstructionsForVariable(int index)
+	{
+		List<T> list = new ArrayList<>();
+		
+		if (getCode() == null)
+			return null;
+		
+		for (Instruction ins : getCode().getInstructions().getInstructions())
+			if (ins instanceof LVTInstruction)
+			{
+				LVTInstruction lv = (LVTInstruction) ins;
+				
+				if (lv.getVariableIndex() != index)
+					continue;
+				
+				list.add((T) ins);
+			}
+		
+		return list;
+	} 
 }
diff --git a/src/main/java/info/sigterm/deob/attributes/code/Instructions.java b/src/main/java/info/sigterm/deob/attributes/code/Instructions.java
index 1d19ffa23a..aa6ed37024 100644
--- a/src/main/java/info/sigterm/deob/attributes/code/Instructions.java
+++ b/src/main/java/info/sigterm/deob/attributes/code/Instructions.java
@@ -50,6 +50,11 @@ public class Instructions
 		buildJumpGraph();
 	}
 	
+	public List<Instruction> getInstructions()
+	{
+		return instructions;
+	}
+	
 	public void write(DataOutputStream out) throws IOException
 	{
 		ByteArrayOutputStream b = new ByteArrayOutputStream();
diff --git a/src/main/java/info/sigterm/deob/pool/NameAndType.java b/src/main/java/info/sigterm/deob/pool/NameAndType.java
index 034514e6c7..2f69d4b116 100644
--- a/src/main/java/info/sigterm/deob/pool/NameAndType.java
+++ b/src/main/java/info/sigterm/deob/pool/NameAndType.java
@@ -22,6 +22,14 @@ public class NameAndType extends PoolEntry
 		nameIndex = is.readUnsignedShort();
 		descriptorIndex = is.readUnsignedShort();
 	}
+	
+	public NameAndType(ConstantPool pool, int name, int type)
+	{
+		super(pool, ConstantType.NAME_AND_TYPE);
+		
+		this.nameIndex = name;
+		this.descriptorIndex = type;
+	}
 
 	public java.lang.String getName()
 	{