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 *

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 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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/*

 * @test

 * @bug 8076110

 * @summary Redefine running methods that have cached resolution errors

 * @library /testlibrary

 * @build RedefineClassHelper

 * @run main RedefineClassHelper

 * @run main/othervm -javaagent:redefineagent.jar -XX:TraceRedefineClasses=0x600 RedefineRunningMethodsWithResolutionErrors

 */

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.Label;

import jdk.internal.org.objectweb.asm.MethodVisitor;

import jdk.internal.org.objectweb.asm.Opcodes;

import java.lang.reflect.InvocationTargetException;

public class RedefineRunningMethodsWithResolutionErrors extends ClassLoader implements Opcodes {

    @Override

    protected Class<?> findClass(String name) throws ClassNotFoundException {

        if (name.equals("C")) {

            byte[] b = loadC(false);

            return defineClass(name, b, 0, b.length);

        } else {

            return super.findClass(name);

        }

    }

    private static byte[] loadC(boolean redefine) {

        ClassWriter cw = new ClassWriter(0);

        cw.visit(52, ACC_SUPER | ACC_PUBLIC, "C", null, "java/lang/Object", null);

        {

            MethodVisitor mv;

            mv = cw.visitMethod(ACC_PUBLIC | ACC_STATIC, "m", "()V", null, null);

            mv.visitCode();

            // First time we run we will:

            // 1) Cache resolution errors

            // 2) Redefine the class / method

            // 3) Try to read the resolution errors that were cached

            //

            // The redefined method will never run, throw error to be sure

            if (redefine) {

                createThrowRuntimeExceptionCode(mv, "The redefined method was called");

            } else {

                createMethodBody(mv);

            }

            mv.visitMaxs(3, 0);

            mv.visitEnd();

        }

        cw.visitEnd();

        return cw.toByteArray();

    }

    private static void createMethodBody(MethodVisitor mv) {

        Label classExists = new Label();

        // Cache resolution errors

        createLoadNonExistentClassCode(mv, classExists);

        // Redefine our own class and method

        mv.visitMethodInsn(INVOKESTATIC, "RedefineRunningMethodsWithResolutionErrors", "redefine", "()V");

        // Provoke the same error again to make sure the resolution error cache works

        createLoadNonExistentClassCode(mv, classExists);

        // Test passed

        mv.visitInsn(RETURN);

        mv.visitFrame(F_SAME, 0, new Object[0], 0, new Object[0]);

        mv.visitLabel(classExists);

        createThrowRuntimeExceptionCode(mv, "Loaded class that shouldn't exist (\"NonExistentClass\")");

    }

    private static void createLoadNonExistentClassCode(MethodVisitor mv, Label classExists) {

        Label tryLoadBegin = new Label();

        Label tryLoadEnd = new Label();

        Label catchLoadBlock = new Label();

        mv.visitTryCatchBlock(tryLoadBegin, tryLoadEnd, catchLoadBlock, "java/lang/NoClassDefFoundError");

        // Try to load a class that does not exist to provoke resolution errors

        mv.visitLabel(tryLoadBegin);

        mv.visitMethodInsn(INVOKESTATIC, "NonExistentClass", "nonExistentMethod", "()V");

        mv.visitLabel(tryLoadEnd);

        // No NoClassDefFoundError means NonExistentClass existed, which shouldn't happen

        mv.visitJumpInsn(GOTO, classExists);

        mv.visitFrame(F_SAME1, 0, new Object[0], 1, new Object[] { "java/lang/NoClassDefFoundError" });

        mv.visitLabel(catchLoadBlock);

        // Ignore the expected NoClassDefFoundError

        mv.visitInsn(POP);

    }

    private static void createThrowRuntimeExceptionCode(MethodVisitor mv, String msg) {

        mv.visitTypeInsn(NEW, "java/lang/RuntimeException");

        mv.visitInsn(DUP);

        mv.visitLdcInsn(msg);

        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/RuntimeException", "<init>", "(Ljava/lang/String;)V");

        mv.visitInsn(ATHROW);

    }

    private static Class<?> c;

    public static void redefine() throws Exception {

        RedefineClassHelper.redefineClass(c, loadC(true));

    }

    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {

        c = Class.forName("C", true, new RedefineRunningMethodsWithResolutionErrors());

        c.getMethod("m").invoke(null);

    }

}