Implement class file version upgrading

src/main/java/moe/yushi/authlibinjector/transform/AuthlibLogInterceptor.java

@@ -212,7 +212,7 @@ public class AuthlibLogInterceptor implements TransformUnit {
 	}
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		if (className.startsWith("com.mojang.authlib.")) {
 			synchronized (interceptedClassloaders) {
 				if (interceptedClassloaders.contains(classLoader)) {
@@ -228,11 +228,11 @@ public class AuthlibLogInterceptor implements TransformUnit {
 							@Override
 							public void visitCode() {
 								super.visitCode();
-								CallbackInvocation callback = CallbackInvocation.push(mv, AuthlibLogInterceptor.class, "onClassLoading");
+								CallbackInvocation callback = CallbackInvocation.push(ctx, mv, AuthlibLogInterceptor.class, "onClassLoading");
 								super.visitLdcInsn(Type.getType("L" + className.replace('.', '/') + ";"));
 								super.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "getClassLoader", "()Ljava/lang/ClassLoader;", false);
 								callback.invoke();
-								modifiedCallback.run();
+								ctx.markModified();
 							}
 						};
 					} else {

src/main/java/moe/yushi/authlibinjector/transform/CallbackInvocation.java

@@ -16,7 +16,6 @@
  */
 package moe.yushi.authlibinjector.transform;
 
-import static org.objectweb.asm.Opcodes.ACONST_NULL;
 import static org.objectweb.asm.Opcodes.INVOKESTATIC;
 import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
 
@@ -26,6 +25,8 @@ import java.lang.reflect.Modifier;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Type;
 
+import moe.yushi.authlibinjector.transform.TransformUnit.TransformContext;
+
 public class CallbackInvocation {
 
 	private static Method findCallbackMethod(Class<?> owner, String methodName) {
@@ -40,7 +41,10 @@ public class CallbackInvocation {
 		throw new IllegalArgumentException("No such method: " + methodName);
 	}
 
-	public static CallbackInvocation push(MethodVisitor mv, Class<?> owner, String methodName) {
+	public static CallbackInvocation push(TransformContext ctx, MethodVisitor mv, Class<?> owner, String methodName) {
+		ctx.requireMinimumClassVersion(50);
+		ctx.upgradeClassVersion(51);
+
 		String descriptor = Type.getMethodDescriptor(findCallbackMethod(owner, methodName));
 
 		mv.visitMethodInsn(INVOKESTATIC, "java/lang/invoke/MethodHandles", "publicLookup", "()Ljava/lang/invoke/MethodHandles$Lookup;", false);
@@ -48,10 +52,7 @@ public class CallbackInvocation {
 		mv.visitLdcInsn(owner.getName());
 		mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/ClassLoader", "loadClass", "(Ljava/lang/String;)Ljava/lang/Class;", false);
 		mv.visitLdcInsn(methodName);
-		// we cannot use CONSTANT_MethodType_info here because the class file version may be lower than 51
+		mv.visitLdcInsn(Type.getMethodType(descriptor));
-		mv.visitLdcInsn(descriptor);
-		mv.visitInsn(ACONST_NULL);
-		mv.visitMethodInsn(INVOKESTATIC, "java/lang/invoke/MethodType", "fromMethodDescriptorString", "(Ljava/lang/String;Ljava/lang/ClassLoader;)Ljava/lang/invoke/MethodType;", false);
 		mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/invoke/MethodHandles$Lookup", "findStatic", "(Ljava/lang/Class;Ljava/lang/String;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/MethodHandle;", false);
 
 		return new CallbackInvocation(mv, descriptor);

src/main/java/moe/yushi/authlibinjector/transform/ClassTransformer.java

@@ -17,6 +17,7 @@
 package moe.yushi.authlibinjector.transform;
 
 import static java.util.Collections.emptyList;
+import static org.objectweb.asm.Opcodes.ASM7;
 
 import java.lang.instrument.ClassFileTransformer;
 import java.lang.instrument.IllegalClassFormatException;
@@ -34,6 +35,7 @@ import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.ClassWriter;
 
 import moe.yushi.authlibinjector.AuthlibInjector;
+import moe.yushi.authlibinjector.transform.TransformUnit.TransformContext;
 import moe.yushi.authlibinjector.util.Logging;
 
 public class ClassTransformer implements ClassFileTransformer {
@@ -46,12 +48,71 @@ public class ClassTransformer implements ClassFileTransformer {
 
 	private static class TransformHandle {
 
+		private static class TransformContextImpl implements TransformContext {
+			public boolean modifiedMark;
+			public int minVersionMark = -1;
+			public int upgradedVersionMark = -1;
+
+			@Override
+			public void markModified() {
+				modifiedMark = true;
+			}
+
+			@Override
+			public void requireMinimumClassVersion(int version) {
+				if (this.minVersionMark < version) {
+					this.minVersionMark = version;
+				}
+			}
+
+			@Override
+			public void upgradeClassVersion(int version) {
+				if (this.upgradedVersionMark < version) {
+					this.upgradedVersionMark = version;
+				}
+			}
+		}
+
+		private static class ClassVersionException extends RuntimeException {
+			public ClassVersionException(String message) {
+				super(message);
+			}
+		}
+
+		private class ClassVersionTransformUnit implements TransformUnit {
+			@Override
+			public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext context) {
+				return Optional.of(new ClassVisitor(ASM7, writer) {
+					@Override
+					public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
+						int major = version & 0xffff;
+
+						if (minVersion != -1 && major < minVersion) {
+							throw new ClassVersionException("class version (" + major + ") is lower than required(" + minVersion + ")");
+						}
+
+						if (upgradedVersion != -1 && major < upgradedVersion) {
+							Logging.TRANSFORM.fine("Upgrading class version from " + major + " to " + upgradedVersion);
+							version = upgradedVersion;
+							context.markModified();
+						}
+						super.visit(version, access, name, signature, superName, interfaces);
+					}
+				});
+			}
+
+			@Override
+			public String toString() {
+				return "Class File Version Transformer";
+			}
+		}
+
 		private List<TransformUnit> appliedTransformers;
-		private boolean currentModified;
 		private String className;
 		private byte[] classBuffer;
-		private ClassWriter pooledClassWriter;
 		private ClassLoader classLoader;
+		private int minVersion = -1;
+		private int upgradedVersion = -1;
 
 		public TransformHandle(ClassLoader classLoader, String className, byte[] classBuffer) {
 			this.className = className;
@@ -60,37 +121,45 @@ public class ClassTransformer implements ClassFileTransformer {
 		}
 
 		public void accept(TransformUnit unit) {
-			ClassWriter writer;
+			ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
-			if (pooledClassWriter == null) {
+			TransformContextImpl ctx = new TransformContextImpl();
-				writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
-			} else {
-				writer = pooledClassWriter;
-				pooledClassWriter = null;
-			}
 
-			Optional<ClassVisitor> optionalVisitor = unit.transform(classLoader, className, writer, () -> currentModified = true);
+			Optional<ClassVisitor> optionalVisitor = unit.transform(classLoader, className, writer, ctx);
 			if (optionalVisitor.isPresent()) {
-				currentModified = false;
 				ClassReader reader = new ClassReader(classBuffer);
 				reader.accept(optionalVisitor.get(), 0);
-				if (currentModified) {
+				if (ctx.modifiedMark) {
 					Logging.TRANSFORM.info("Transformed [" + className + "] with [" + unit + "]");
 					if (appliedTransformers == null) {
 						appliedTransformers = new ArrayList<>();
 					}
 					appliedTransformers.add(unit);
 					classBuffer = writer.toByteArray();
+					if (ctx.minVersionMark > this.minVersion) {
+						this.minVersion = ctx.minVersionMark;
+					}
+					if (ctx.upgradedVersionMark > this.upgradedVersion) {
+						this.upgradedVersion = ctx.upgradedVersionMark;
+					}
 				}
-			} else {
-				pooledClassWriter = writer;
 			}
 		}
 
-		public Optional<byte[]> getTransformResult() {
+		public Optional<byte[]> finish() {
 			if (appliedTransformers == null || appliedTransformers.isEmpty()) {
 				return Optional.empty();
 			} else {
-				return Optional.of(classBuffer);
+				if (minVersion == -1 && upgradedVersion == -1) {
+					return Optional.of(classBuffer);
+				} else {
+					try {
+						accept(new ClassVersionTransformUnit());
+						return Optional.of(classBuffer);
+					} catch (ClassVersionException e) {
+						Logging.TRANSFORM.warning("Skipping [" + className + "], " + e.getMessage());
+						return Optional.empty();
+					}
+				}
 			}
 		}
 
@@ -119,7 +188,7 @@ public class ClassTransformer implements ClassFileTransformer {
 				units.forEach(handle::accept);
 				listeners.forEach(it -> it.onClassLoading(loader, className, handle.getFinalResult(), handle.getAppliedTransformers()));
 
-				Optional<byte[]> transformResult = handle.getTransformResult();
+				Optional<byte[]> transformResult = handle.finish();
 				if (PRINT_UNTRANSFORMED_CLASSES && !transformResult.isPresent()) {
 					Logging.TRANSFORM.fine("No transformation is applied to [" + className + "]");
 				}

src/main/java/moe/yushi/authlibinjector/transform/LdcTransformUnit.java

@@ -24,7 +24,7 @@ import org.objectweb.asm.MethodVisitor;
 public abstract class LdcTransformUnit implements TransformUnit {
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		return Optional.of(new ClassVisitor(ASM7, writer) {
 
 			@Override
@@ -36,7 +36,7 @@ public abstract class LdcTransformUnit implements TransformUnit {
 						if (cst instanceof String) {
 							Optional<String> transformed = transformLdc((String) cst);
 							if (transformed.isPresent() && !transformed.get().equals(cst)) {
-								modifiedCallback.run();
+								ctx.markModified();
 								super.visitLdcInsn(transformed.get());
 							} else {
 								super.visitLdcInsn(cst);

src/main/java/moe/yushi/authlibinjector/transform/MainArgumentsTransformer.java

@@ -36,7 +36,7 @@ import moe.yushi.authlibinjector.util.Logging;
 public class MainArgumentsTransformer implements TransformUnit {
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		if ("net.minecraft.client.main.Main".equals(className)) {
 			return Optional.of(new ClassVisitor(ASM7, writer) {
 				@Override
@@ -46,9 +46,9 @@ public class MainArgumentsTransformer implements TransformUnit {
 							@Override
 							public void visitCode() {
 								super.visitCode();
-								modifiedCallback.run();
+								ctx.markModified();
 
-								CallbackInvocation callback = CallbackInvocation.push(mv, MainArgumentsTransformer.class, "processMainArguments");
+								CallbackInvocation callback = CallbackInvocation.push(ctx, mv, MainArgumentsTransformer.class, "processMainArguments");
 								super.visitVarInsn(ALOAD, 0);
 								callback.invoke();
 								super.visitVarInsn(ASTORE, 0);

src/main/java/moe/yushi/authlibinjector/transform/SkinWhitelistTransformUnit.java

@@ -37,7 +37,7 @@ public class SkinWhitelistTransformUnit implements TransformUnit {
 	}
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		if ("com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService".equals(className)) {
 			return Optional.of(new ClassVisitor(ASM7, writer) {
 
@@ -59,7 +59,7 @@ public class SkinWhitelistTransformUnit implements TransformUnit {
 								} else if ((status == 5 || status == 9) && opcode == AASTORE) {
 									status++;
 									if (status == 10) {
-										modifiedCallback.run();
+										ctx.markModified();
 										super.visitIntInsn(SIPUSH, skinWhitelist.length + 2);
 										super.visitTypeInsn(ANEWARRAY, "java/lang/String");
 										super.visitInsn(DUP);

src/main/java/moe/yushi/authlibinjector/transform/TransformUnit.java

@@ -21,6 +21,16 @@ import org.objectweb.asm.ClassVisitor;
 
 public interface TransformUnit {
 
-	Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback);
+	public interface TransformContext {
+
+		void markModified();
+
+		void requireMinimumClassVersion(int version);
+
+		void upgradeClassVersion(int version);
+
+	}
+
+	Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext context);
 
 }

src/main/java/moe/yushi/authlibinjector/transform/YggdrasilKeyTransformUnit.java

@@ -54,7 +54,7 @@ public class YggdrasilKeyTransformUnit implements TransformUnit {
 	}
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		if ("com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService".equals(className)) {
 			return Optional.of(new ClassVisitor(ASM7, writer) {
 
@@ -76,7 +76,7 @@ public class YggdrasilKeyTransformUnit implements TransformUnit {
 					mv.visitInsn(IRETURN);
 					mv.visitLabel(l0);
 					mv.visitFrame(F_SAME, 0, null, 0, null);
-					CallbackInvocation.push(mv, YggdrasilKeyTransformUnit.class, "getPublicKeys").invoke();
+					CallbackInvocation.push(ctx, mv, YggdrasilKeyTransformUnit.class, "getPublicKeys").invoke();
 					mv.visitMethodInsn(INVOKEINTERFACE, "java/util/List", "iterator", "()Ljava/util/Iterator;", true);
 					mv.visitVarInsn(ASTORE, 2);
 					Label l1 = new Label();
@@ -117,7 +117,7 @@ public class YggdrasilKeyTransformUnit implements TransformUnit {
 									&& "com/mojang/authlib/properties/Property".equals(owner)
 									&& "isSignatureValid".equals(name)
 									&& "(Ljava/security/PublicKey;)Z".equals(descriptor)) {
-								modifiedCallback.run();
+								ctx.markModified();
 								super.visitMethodInsn(INVOKESTATIC,
 										"com/mojang/authlib/yggdrasil/YggdrasilMinecraftSessionService",
 										"authlib_injector_isSignatureValid",

src/main/java/moe/yushi/authlibinjector/transform/support/CitizensTransformer.java

@@ -42,7 +42,7 @@ import moe.yushi.authlibinjector.transform.TransformUnit;
 public class CitizensTransformer implements TransformUnit {
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		if ("net.citizensnpcs.Settings$Setting".equals(className)) {
 			return Optional.of(new ClassVisitor(ASM7, writer) {
 				@Override
@@ -62,7 +62,7 @@ public class CitizensTransformer implements TransformUnit {
 								super.visitInsn(RETURN);
 								super.visitLabel(lbl);
 								super.visitFrame(F_SAME, 0, null, 0, null);
-								modifiedCallback.run();
+								ctx.markModified();
 							}
 						};
 					}

src/main/java/moe/yushi/authlibinjector/transform/support/MC52974Workaround.java

@@ -60,7 +60,7 @@ public class MC52974Workaround implements TransformUnit {
 	}
 
 	@Override
-	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 		if ("com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService".equals(className)) {
 			return Optional.of(new ClassVisitor(ASM7, writer) {
 				@Override
@@ -70,7 +70,7 @@ public class MC52974Workaround implements TransformUnit {
 							@Override
 							public void visitCode() {
 								super.visitCode();
-								modifiedCallback.run();
+								ctx.markModified();
 								super.visitLdcInsn(1);
 								super.visitVarInsn(ISTORE, 2);
 							}

src/main/java/moe/yushi/authlibinjector/transform/support/MC52974_1710Workaround.java

@@ -109,7 +109,7 @@ public class MC52974_1710Workaround {
 
 	private static class SessionTransformer implements TransformUnit {
 		@Override
-		public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+		public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 			return detectNotchName(className, "bbs", "net.minecraft.util.Session", isNotchName -> new ClassVisitor(ASM7, writer) {
 				@Override
 				public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
@@ -121,9 +121,9 @@ public class MC52974_1710Workaround {
 							@Override
 							public void visitInsn(int opcode) {
 								if (opcode == ARETURN) {
-									modifiedCallback.run();
+									ctx.markModified();
 									super.visitInsn(DUP);
-									CallbackInvocation callback = CallbackInvocation.push(mv, MC52974_1710Workaround.class, "markGameProfile");
+									CallbackInvocation callback = CallbackInvocation.push(ctx, mv, MC52974_1710Workaround.class, "markGameProfile");
 									super.visitInsn(SWAP);
 									callback.invoke();
 									super.visitTypeInsn(CHECKCAST, "com/mojang/authlib/GameProfile");
@@ -146,7 +146,7 @@ public class MC52974_1710Workaround {
 
 	private static class S0CPacketSpawnPlayerTransformer implements TransformUnit {
 		@Override
-		public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, Runnable modifiedCallback) {
+		public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
 			return detectNotchName(className, "gb", "net.minecraft.network.play.server.S0CPacketSpawnPlayer", isNotchName -> new ClassVisitor(ASM7, writer) {
 				@Override
 				public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
@@ -160,8 +160,8 @@ public class MC52974_1710Workaround {
 								if (opcode == GETFIELD && (isNotchName
 										? "gb".equals(owner) && "b".equals(name) && "Lcom/mojang/authlib/GameProfile;".equals(descriptor)
 										: "net/minecraft/network/play/server/S0CPacketSpawnPlayer".equals(owner) && "field_148955_b".equals(name) && "Lcom/mojang/authlib/GameProfile;".equals(descriptor))) {
-									modifiedCallback.run();
+									ctx.markModified();
-									CallbackInvocation callback = CallbackInvocation.push(mv, MC52974_1710Workaround.class, "accessGameProfile");
+									CallbackInvocation callback = CallbackInvocation.push(ctx, mv, MC52974_1710Workaround.class, "accessGameProfile");
 									super.visitInsn(SWAP);
 									super.visitFieldInsn(opcode, owner, name, descriptor);
 									if (isNotchName) {