1 files changed, 263 insertions, 0 deletions

diff --git a/src/cuchaz/enigma/bytecode/ConstPoolEditor.java b/src/cuchaz/enigma/bytecode/ConstPoolEditor.java
new file mode 100644
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--- /dev/null
+++ b/src/cuchaz/enigma/bytecode/ConstPoolEditor.java
@@ -0,0 +1,263 @@
+/*******************************************************************************
+ * Copyright (c) 2015 Jeff Martin.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Lesser General Public
+ * License v3.0 which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/lgpl.html
+ * 
+ * Contributors:
+ *     Jeff Martin - initial API and implementation
+ ******************************************************************************/
+package cuchaz.enigma.bytecode;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+
+import javassist.bytecode.ConstPool;
+import javassist.bytecode.Descriptor;
+import cuchaz.enigma.bytecode.accessors.ClassInfoAccessor;
+import cuchaz.enigma.bytecode.accessors.ConstInfoAccessor;
+import cuchaz.enigma.bytecode.accessors.MemberRefInfoAccessor;
+
+public class ConstPoolEditor {
+        
+        private static Method m_getItem;
+        private static Method m_addItem;
+        private static Method m_addItem0;
+        private static Field m_items;
+        private static Field m_cache;
+        private static Field m_numItems;
+        private static Field m_objects;
+        private static Field m_elements;
+        private static Method m_methodWritePool;
+        private static Constructor<ConstPool> m_constructorPool;
+        
+        static {
+                try {
+                        m_getItem = ConstPool.class.getDeclaredMethod("getItem", int.class);
+                        m_getItem.setAccessible(true);
+                        
+                        m_addItem = ConstPool.class.getDeclaredMethod("addItem", Class.forName("javassist.bytecode.ConstInfo"));
+                        m_addItem.setAccessible(true);
+                        
+                        m_addItem0 = ConstPool.class.getDeclaredMethod("addItem0", Class.forName("javassist.bytecode.ConstInfo"));
+                        m_addItem0.setAccessible(true);
+                        
+                        m_items = ConstPool.class.getDeclaredField("items");
+                        m_items.setAccessible(true);
+                        
+                        m_cache = ConstPool.class.getDeclaredField("itemsCache");
+                        m_cache.setAccessible(true);
+                        
+                        m_numItems = ConstPool.class.getDeclaredField("numOfItems");
+                        m_numItems.setAccessible(true);
+                        
+                        m_objects = Class.forName("javassist.bytecode.LongVector").getDeclaredField("objects");
+                        m_objects.setAccessible(true);
+                        
+                        m_elements = Class.forName("javassist.bytecode.LongVector").getDeclaredField("elements");
+                        m_elements.setAccessible(true);
+                        
+                        m_methodWritePool = ConstPool.class.getDeclaredMethod("write", DataOutputStream.class);
+                        m_methodWritePool.setAccessible(true);
+                        
+                        m_constructorPool = ConstPool.class.getDeclaredConstructor(DataInputStream.class);
+                        m_constructorPool.setAccessible(true);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        private ConstPool m_pool;
+        
+        public ConstPoolEditor(ConstPool pool) {
+                m_pool = pool;
+        }
+        
+        public void writePool(DataOutputStream out) {
+                try {
+                        m_methodWritePool.invoke(m_pool, out);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        public static ConstPool readPool(DataInputStream in) {
+                try {
+                        return m_constructorPool.newInstance(in);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        public String getMemberrefClassname(int memberrefIndex) {
+                return Descriptor.toJvmName(m_pool.getClassInfo(m_pool.getMemberClass(memberrefIndex)));
+        }
+        
+        public String getMemberrefName(int memberrefIndex) {
+                return m_pool.getUtf8Info(m_pool.getNameAndTypeName(m_pool.getMemberNameAndType(memberrefIndex)));
+        }
+        
+        public String getMemberrefType(int memberrefIndex) {
+                return m_pool.getUtf8Info(m_pool.getNameAndTypeDescriptor(m_pool.getMemberNameAndType(memberrefIndex)));
+        }
+        
+        public ConstInfoAccessor getItem(int index) {
+                try {
+                        Object entry = m_getItem.invoke(m_pool, index);
+                        if (entry == null) {
+                                return null;
+                        }
+                        return new ConstInfoAccessor(entry);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        public int addItem(Object item) {
+                try {
+                        return (Integer)m_addItem.invoke(m_pool, item);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        public int addItemForceNew(Object item) {
+                try {
+                        return (Integer)m_addItem0.invoke(m_pool, item);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        @SuppressWarnings("rawtypes")
+        public void removeLastItem() {
+                try {
+                        // remove the item from the cache
+                        HashMap cache = getCache();
+                        if (cache != null) {
+                                Object item = getItem(m_pool.getSize() - 1);
+                                cache.remove(item);
+                        }
+                        
+                        // remove the actual item
+                        // based off of LongVector.addElement()
+                        Object items = m_items.get(m_pool);
+                        Object[][] objects = (Object[][])m_objects.get(items);
+                        int numElements = (Integer)m_elements.get(items) - 1;
+                        int nth = numElements >> 7;
+                        int offset = numElements & (128 - 1);
+                        objects[nth][offset] = null;
+                        
+                        // decrement the number of items
+                        m_elements.set(items, numElements);
+                        m_numItems.set(m_pool, (Integer)m_numItems.get(m_pool) - 1);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        @SuppressWarnings("rawtypes")
+        public HashMap getCache() {
+                try {
+                        return (HashMap)m_cache.get(m_pool);
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        @SuppressWarnings({ "rawtypes", "unchecked" })
+        public void changeMemberrefNameAndType(int memberrefIndex, String newName, String newType) {
+                // NOTE: when changing values, we always need to copy-on-write
+                try {
+                        // get the memberref item
+                        Object item = getItem(memberrefIndex).getItem();
+                        
+                        // update the cache
+                        HashMap cache = getCache();
+                        if (cache != null) {
+                                cache.remove(item);
+                        }
+                        
+                        new MemberRefInfoAccessor(item).setNameAndTypeIndex(m_pool.addNameAndTypeInfo(newName, newType));
+                        
+                        // update the cache
+                        if (cache != null) {
+                                cache.put(item, item);
+                        }
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+                
+                // make sure the change worked
+                assert (newName.equals(getMemberrefName(memberrefIndex)));
+                assert (newType.equals(getMemberrefType(memberrefIndex)));
+        }
+        
+        @SuppressWarnings({ "rawtypes", "unchecked" })
+        public void changeClassName(int classNameIndex, String newName) {
+                // NOTE: when changing values, we always need to copy-on-write
+                try {
+                        // get the class item
+                        Object item = getItem(classNameIndex).getItem();
+                        
+                        // update the cache
+                        HashMap cache = getCache();
+                        if (cache != null) {
+                                cache.remove(item);
+                        }
+                        
+                        // add the new name and repoint the name-and-type to it
+                        new ClassInfoAccessor(item).setNameIndex(m_pool.addUtf8Info(newName));
+                        
+                        // update the cache
+                        if (cache != null) {
+                                cache.put(item, item);
+                        }
+                } catch (Exception ex) {
+                        throw new Error(ex);
+                }
+        }
+        
+        public static ConstPool newConstPool() {
+                // const pool expects the name of a class to initialize itself
+                // but we want an empty pool
+                // so give it a bogus name, and then clear the entries afterwards
+                ConstPool pool = new ConstPool("a");
+                
+                ConstPoolEditor editor = new ConstPoolEditor(pool);
+                int size = pool.getSize();
+                for (int i = 0; i < size - 1; i++) {
+                        editor.removeLastItem();
+                }
+                
+                // make sure the pool is actually empty
+                // although, in this case "empty" means one thing in it
+                // the JVM spec says index 0 should be reserved
+                assert (pool.getSize() == 1);
+                assert (editor.getItem(0) == null);
+                assert (editor.getItem(1) == null);
+                assert (editor.getItem(2) == null);
+                assert (editor.getItem(3) == null);
+                
+                // also, clear the cache
+                editor.getCache().clear();
+                
+                return pool;
+        }
+        
+        public String dump() {
+                StringBuilder buf = new StringBuilder();
+                for (int i = 1; i < m_pool.getSize(); i++) {
+                        buf.append(String.format("%4d", i));
+                        buf.append("   ");
+                        buf.append(getItem(i).toString());
+                        buf.append("\n");
+                }
+                return buf.toString();
+        }
+}