Re: JDK 8 incorectly processes nameless parameters in MethodParameters Attribute

[dalibor topic]

Hi Mihail,

could you file an issue at bugs.java.com and let us know which incident 
id you receive, please?

cheers,
dalibor topic

On 14.11.2016 10:58, Михаил Богданов wrote:
JDK 8 incorrectly processes nameless (name=null) parameters in MethodParameters 
attribute. Actually problem in inconsistency between Hotspot and reflection:
Hotspot  VM constructs nameless parameter with empty string name that cause 
Executable.verifyParameters to throw MalformedParametersException.
//Code to reproduce:import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;

import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

public class Bug {

    public static void main(String[] args) throws ClassNotFoundException, 
NoSuchMethodException {
        ClassWriter writer = new ClassWriter(Opcodes.ASM5);
        writer.visit(Opcodes.V1_8, Opcodes.ACC_PUBLIC | Opcodes.ACC_INTERFACE | 
Opcodes.ACC_ABSTRACT, "Test", null, "java/lang/Object", null);
        MethodVisitor test = writer.visitMethod(Opcodes.ACC_PUBLIC | Opcodes.ACC_ABSTRACT, 
"test", "(I)V", null, null);
        test.visitParameter(null, 0);
        test.visitEnd();

        writer.visitEnd();
        final byte[] bytes = writer.toByteArray();

        URLClassLoader urlClassLoader = new URLClassLoader(new URL[0], 
ClassLoader.getSystemClassLoader()) {
            @Override
            protected Class<?> findClass(String name) throws 
ClassNotFoundException {
                if (name.equals("Test")) {
                    return defineClass("Test", bytes, 0, bytes.length);
                }
                return super.findClass(name);
            }
        };


        Class<?> clazz = urlClassLoader.loadClass("Test");
        Method method = clazz.getDeclaredMethod("test", Integer.TYPE);
//        Exception in thread "main" java.lang.reflect.MalformedParametersException: 
Invalid parameter name ""
//        at java.lang.reflect.Executable.verifyParameters(Executable.java:386)
//        at 
java.lang.reflect.Executable.privateGetParameters(Executable.java:416)
//        at java.lang.reflect.Executable.getParameters(Executable.java:357)
//        at Bug.main(Bug.java:37)
        method.getParameters();
    }
}
Best regards,   Max


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