Fixed incompatibility with JDK 8 build b121, fixes #3

There were multiple breaking changes at play: - The ClassFileTransformer.transform method now gets className=null as parameter for lambda classes. The class name must be parsed from bytecode. - The naming pattern of lambda implementation methods was changed from lambda$1 to lambda$invokingMethod$1 - The lambda class now calls private instance methods (i.e. lambda accesses the invoker's instance variables) using the invokespecial instruction, to avoid a subclass accidentally overriding the generated lambda implementation method. But using invokespecial to call methods of other classes is not allowed in bytecode (see the spec http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-6.html#jvms-6.5.invokespecial) and lambdas can get away with it only because JDK 8 relaxes the verification of lambda classes. Our workaround is to change the opcode to invokevirtual at the risk of calling a malicious subclass method.
luontola · Jan 7, 2014 · fe772bd · fe772bd
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diff --git a/README.md b/README.md
@@ -114,10 +114,19 @@ May break if a future JDK 8 build stops generating a new class for each
 that `java.lang.invoke.LambdaMetafactory` generates dynamically, so
 optimizations to that mechanism may break Retrolambda.
 
+Does not implement JDK 8's safety measure of using `invokespecial` to call
+lambda implementation methods that are private instance methods (i.e. when
+the lambda accesses an instance variable).
+
 
 Version History
 ---------------
 
+### Upcoming
+
+- Updated to work with JDK 8 Early Access Build b121 (2013-12-19)
+  ([Issue #3](https://github.com/orfjackal/retrolambda/issues/3))
+
 ### Retrolambda 1.1.1 (2013-11-27)
 
 - Show help if the `-javaagent` parameter is missing

diff --git a/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaClassBackporter.java b/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaClassBackporter.java
@@ -1,4 +1,4 @@
-// Copyright © 2013 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2014 Esko Luontola <www.orfjackal.net>
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -11,8 +11,6 @@
 public class LambdaClassBackporter {
 
     private static final String SINGLETON_FIELD_NAME = "instance";
-
-    private static final String MAGIC_LAMBDA_IMPL = "java/lang/invoke/MagicLambdaImpl";
     private static final String JAVA_LANG_OBJECT = "java/lang/Object";
 
     public static byte[] transform(byte[] bytecode, int targetVersion) {
@@ -41,7 +39,7 @@ public void visit(int version, int access, String name, String signature, String
             if (version > targetVersion) {
                 version = targetVersion;
             }
-            if (superName.equals(MAGIC_LAMBDA_IMPL)) {
+            if (superName.equals(LambdaNaming.MAGIC_LAMBDA_IMPL)) {
                 superName = JAVA_LANG_OBJECT;
             }
             super.visit(version, access, name, signature, superName, interfaces);
@@ -53,7 +51,9 @@ public MethodVisitor visitMethod(int access, String name, String desc, String si
                 constructor = Type.getMethodType(desc);
             }
             MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
-            return new MagicLambdaRemovingMethodVisitor(mv);
+            mv = new MagicLambdaRemovingMethodVisitor(mv);
+            mv = new PrivateMethodInvocationFixingMethodVisitor(mv, factoryMethod.getInvoker());
+            return mv;
         }
 
         @Override
@@ -124,12 +124,32 @@ public MagicLambdaRemovingMethodVisitor(MethodVisitor mv) {
         @Override
         public void visitMethodInsn(int opcode, String owner, String name, String desc) {
             if (opcode == INVOKESPECIAL
-                    && owner.equals(MAGIC_LAMBDA_IMPL)
+                    && owner.equals(LambdaNaming.MAGIC_LAMBDA_IMPL)
                     && name.equals("<init>")
                     && desc.equals("()V")) {
                 owner = JAVA_LANG_OBJECT;
             }
             super.visitMethodInsn(opcode, owner, name, desc);
         }
     }
+
+    private static class PrivateMethodInvocationFixingMethodVisitor extends MethodVisitor {
+
+        private final String invoker;
+
+        public PrivateMethodInvocationFixingMethodVisitor(MethodVisitor mv, Class<?> invoker) {
+            super(ASM4, mv);
+            this.invoker = Type.getInternalName(invoker);
+        }
+
+        @Override
+        public void visitMethodInsn(int opcode, String owner, String name, String desc) {
+            if (opcode == INVOKESPECIAL
+                    && owner.equals(invoker)
+                    && LambdaNaming.LAMBDA_IMPL_METHOD.matcher(name).matches()) {
+                opcode = INVOKEVIRTUAL;
+            }
+            super.visitMethodInsn(opcode, owner, name, desc);
+        }
+    }
 }
diff --git a/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaFactoryMethod.java b/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaFactoryMethod.java
@@ -1,4 +1,4 @@
-// Copyright © 2013 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2014 Esko Luontola <www.orfjackal.net>
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -10,10 +10,12 @@ public class LambdaFactoryMethod {
 
     private final String owner;
     private final String desc;
+    private final Class<?> invoker;
 
-    public LambdaFactoryMethod(String lambdaClass, Type invokedType) {
+    public LambdaFactoryMethod(String lambdaClass, Type invokedType, Class<?> invoker) {
         owner = lambdaClass;
         desc = invokedType.getDescriptor();
+        this.invoker = invoker;
     }
 
     public String getOwner() {
@@ -27,4 +29,8 @@ public String getName() {
     public String getDesc() {
         return desc;
     }
+
+    public Class<?> getInvoker() {
+        return invoker;
+    }
 }
diff --git a/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaNaming.java b/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaNaming.java
@@ -0,0 +1,15 @@
+// Copyright © 2013-2014 Esko Luontola <www.orfjackal.net>
+// This software is released under the Apache License 2.0.
+// The license text is at http://www.apache.org/licenses/LICENSE-2.0
+
+package net.orfjackal.retrolambda;
+
+import java.util.regex.Pattern;
+
+public class LambdaNaming {
+
+    public static final String LAMBDA_METAFACTORY = "java/lang/invoke/LambdaMetafactory";
+    public static final String MAGIC_LAMBDA_IMPL = "java/lang/invoke/MagicLambdaImpl";
+    public static final Pattern LAMBDA_CLASS = Pattern.compile("^.+\\$\\$Lambda\\$\\d+$");
+    public static final Pattern LAMBDA_IMPL_METHOD = Pattern.compile("^lambda\\$.*\\$\\d+$");
+}
diff --git a/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaReifier.java b/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaReifier.java
@@ -1,4 +1,4 @@
-// Copyright © 2013 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2014 Esko Luontola <www.orfjackal.net>
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -19,11 +19,13 @@ public class LambdaReifier {
     // is spying on the LambdaMetafactory's dynamically generated bytecode.
     // We expect only one class being processed at a time, so it should
     // be an error if these collections contain more than one element.
+    private static final BlockingDeque<Class<?>> currentInvoker = new LinkedBlockingDeque<>(1);
     private static final BlockingDeque<Type> currentInvokedType = new LinkedBlockingDeque<>(1);
     private static final BlockingDeque<String> currentLambdaClass = new LinkedBlockingDeque<>(1);
 
     public static LambdaFactoryMethod reifyLambdaClass(Class<?> invoker, String invokedName, Type invokedType, Handle bsm, Object[] bsmArgs) {
         try {
+            setInvoker(invoker);
             setInvokedType(invokedType);
             callBootstrapMethod(invoker, invokedName, invokedType, bsm, bsmArgs);
             return getLambdaFactoryMethod();
@@ -35,6 +37,10 @@ public static LambdaFactoryMethod reifyLambdaClass(Class<?> invoker, String invo
         }
     }
 
+    public static void setInvoker(Class<?> invoker) {
+        currentInvoker.push(invoker);
+    }
+
     private static void setInvokedType(Type invokedType) {
         currentInvokedType.push(invokedType);
     }
@@ -46,10 +52,12 @@ public static void setLambdaClass(String lambdaClass) {
     public static LambdaFactoryMethod getLambdaFactoryMethod() {
         String lambdaClass = currentLambdaClass.getFirst();
         Type invokedType = currentInvokedType.getFirst();
-        return new LambdaFactoryMethod(lambdaClass, invokedType);
+        Class<?> invoker = currentInvoker.getFirst();
+        return new LambdaFactoryMethod(lambdaClass, invokedType, invoker);
     }
 
     private static void resetGlobals() {
+        currentInvoker.clear();
         currentInvokedType.clear();
         currentLambdaClass.clear();
     }

diff --git a/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaSavingClassFileTransformer.java b/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaSavingClassFileTransformer.java
@@ -1,20 +1,19 @@
-// Copyright © 2013 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2014 Esko Luontola <www.orfjackal.net>
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
 package net.orfjackal.retrolambda;
 
+import org.objectweb.asm.ClassReader;
+
 import java.io.IOException;
 import java.lang.instrument.*;
 import java.nio.file.*;
 import java.security.ProtectionDomain;
 import java.util.*;
-import java.util.regex.Pattern;
 
 public class LambdaSavingClassFileTransformer implements ClassFileTransformer {
 
-    private static final Pattern LAMBDA_CLASS = Pattern.compile("^.+\\$\\$Lambda\\$\\d+$");
-
     private final Path outputDir;
     private final int targetVersion;
     private final List<ClassLoader> ignoredClassLoaders = new ArrayList<>();
@@ -35,6 +34,11 @@ public byte[] transform(ClassLoader loader, String className, Class<?> classBein
             // The transformed application classes have their own class loader.
             return null;
         }
+        if (className == null) {
+            // Since JDK 8 build b121 or so, lambda classes have a null class name,
+            // but we can read it from the bytecode where the name still exists.
+            className = new ClassReader(classfileBuffer).getClassName();
+        }
         if (!isLambdaClass(className)) {
             return null;
         }
@@ -52,6 +56,6 @@ public byte[] transform(ClassLoader loader, String className, Class<?> classBein
     }
 
     private static boolean isLambdaClass(String className) {
-        return LAMBDA_CLASS.matcher(className).matches();
+        return LambdaNaming.LAMBDA_CLASS.matcher(className).matches();
     }
 }
diff --git a/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaUsageBackporter.java b/retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaUsageBackporter.java
@@ -8,15 +8,11 @@
 
 import java.lang.reflect.Field;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.regex.Pattern;
 
 import static org.objectweb.asm.Opcodes.*;
 
 public class LambdaUsageBackporter {
 
-    private static final String LAMBDA_METAFACTORY = "java/lang/invoke/LambdaMetafactory";
-    private static final Pattern LAMBDA_IMPL_METHOD = Pattern.compile("^lambda\\$\\d+$");
-
     public static byte[] transform(byte[] bytecode, int targetVersion) {
         resetLambdaClassSequenceNumber();
         ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
@@ -58,7 +54,7 @@ public void visit(int version, int access, String name, String signature, String
 
         @Override
         public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
-            if (LAMBDA_IMPL_METHOD.matcher(name).matches()) {
+            if (LambdaNaming.LAMBDA_IMPL_METHOD.matcher(name).matches()) {
                 access = Flags.makeNonPrivate(access);
             }
             MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
@@ -76,7 +72,7 @@ public InvokeDynamicInsnConvertingMethodVisitor(int api, MethodVisitor mv, Strin
 
         @Override
         public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs) {
-            if (bsm.getOwner().equals(LAMBDA_METAFACTORY)) {
+            if (bsm.getOwner().equals(LambdaNaming.LAMBDA_METAFACTORY)) {
                 backportLambda(name, Type.getType(desc), bsm, bsmArgs);
             } else {
                 super.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);