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 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package sun.reflect;

import java.io.OptionalDataException;
import java.lang.invoke.MethodHandle;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.security.AccessController;
import java.security.Permission;
import java.security.PrivilegedAction;

/**
 * ReflectionFactory supports custom serialization.
 * Its methods support the creation of uninitialized objects, invoking serialization
 * private methods for readObject, writeObject, readResolve, and writeReplace.
 * <p>
 * ReflectionFactory access is restricted, if a security manager is active,
 * unless the permission {@code RuntimePermission("reflectionFactoryAccess")}
 * is granted.
 */
public class ReflectionFactory {

    private static final ReflectionFactory soleInstance = new ReflectionFactory();
    private static final jdk.internal.reflect.ReflectionFactory delegate = AccessController.doPrivileged(
            new PrivilegedAction<jdk.internal.reflect.ReflectionFactory>() {
                public jdk.internal.reflect.ReflectionFactory run() {
                    return jdk.internal.reflect.ReflectionFactory.getReflectionFactory();
                }
            });

    private ReflectionFactory() {}

    private static final Permission REFLECTION_FACTORY_ACCESS_PERM
            = new RuntimePermission("reflectionFactoryAccess");

    /**
     * Provides the caller with the capability to instantiate reflective
     * objects.
     *
     * <p> First, if there is a security manager, its {@code checkPermission}
     * method is called with a {@link java.lang.RuntimePermission} with target
     * {@code "reflectionFactoryAccess"}.  This may result in a security
     * exception.
     *
     * <p> The returned {@code ReflectionFactory} object should be carefully
     * guarded by the caller, since it can be used to read and write private
     * data and invoke private methods, as well as to load unverified bytecodes.
     * It must never be passed to untrusted code.
     *
     * @return the ReflectionFactory
     * @throws SecurityException if a security manager exists and its
     *         {@code checkPermission} method doesn't allow access to
     *         the RuntimePermission "reflectionFactoryAccess".
     */
    public static ReflectionFactory getReflectionFactory() {
        SecurityManager security = System.getSecurityManager();
        if (security != null) {
            security.checkPermission(REFLECTION_FACTORY_ACCESS_PERM);
        }
        return soleInstance;
    }

    /**
     * Returns an accessible constructor capable of creating instances
     * of the given class, initialized by the given constructor.
     *
     * @param cl the class to instantiate
     * @param constructorToCall the constructor to call
     * @return an accessible constructor
     */
    public Constructor<?> newConstructorForSerialization(Class<?> cl,
                                                         Constructor<?> constructorToCall)
    {
        return delegate.newConstructorForSerialization(cl,
                                                       constructorToCall);
    }

    /**
     * Returns an accessible no-arg constructor for a class.
     * The no-arg constructor is found searching the class and its supertypes.
     *
     * @param cl the class to instantiate
     * @return a no-arg constructor for the class or {@code null} if
     *     the class or supertypes do not have a suitable no-arg constructor
     */
    public final Constructor<?> newConstructorForSerialization(Class<?> cl)
    {
        return delegate.newConstructorForSerialization(cl);
    }

    /**
     * Returns an accessible no-arg constructor for an externalizable class to be
     * initialized using a public no-argument constructor.
     *
     * @param cl the class to instantiate
     * @return A no-arg constructor for the class; returns {@code null} if
     *     the class does not implement {@link java.io.Externalizable}
     */
    public final Constructor<?> newConstructorForExternalization(Class<?> cl) {
        return delegate.newConstructorForExternalization(cl);
    }

    /**
     * Returns a direct MethodHandle for the {@code readObject} method on
     * a Serializable class.
     * The first argument of {@link MethodHandle#invoke} is the serializable
     * object and the second argument is the {@code ObjectInputStream} passed to
     * {@code readObject}.
     *
     * @param cl a Serializable class
     * @return  a direct MethodHandle for the {@code readObject} method of the class or
     *          {@code null} if the class does not have a {@code readObject} method
     */
    public final MethodHandle readObjectForSerialization(Class<?> cl) {
        return delegate.readObjectForSerialization(cl);
    }

    /**
     * Returns a direct MethodHandle for the {@code readObjectNoData} method on
     * a Serializable class.
     * The first argument of {@link MethodHandle#invoke} is the serializable
     * object and the second argument is the {@code ObjectInputStream} passed to
     * {@code readObjectNoData}.
     *
     * @param cl a Serializable class
     * @return  a direct MethodHandle for the {@code readObjectNoData} method
     *          of the class or {@code null} if the class does not have a
     *          {@code readObjectNoData} method
     */
    public final MethodHandle readObjectNoDataForSerialization(Class<?> cl) {
        return delegate.readObjectNoDataForSerialization(cl);
    }

    /**
     * Returns a direct MethodHandle for the {@code writeObject} method on
     * a Serializable class.
     * The first argument of {@link MethodHandle#invoke} is the serializable
     * object and the second argument is the {@code ObjectOutputStream} passed to
     * {@code writeObject}.
     *
     * @param cl a Serializable class
     * @return  a direct MethodHandle for the {@code writeObject} method of the class or
     *          {@code null} if the class does not have a {@code writeObject} method
     */
    public final MethodHandle writeObjectForSerialization(Class<?> cl) {
        return delegate.writeObjectForSerialization(cl);
    }

    /**
     * Returns a direct MethodHandle for the {@code readResolve} method on
     * a serializable class.
     * The single argument of {@link MethodHandle#invoke} is the serializable
     * object.
     *
     * @param cl the Serializable class
     * @return  a direct MethodHandle for the {@code readResolve} method of the class or
     *          {@code null} if the class does not have a {@code readResolve} method
     */
    public final MethodHandle readResolveForSerialization(Class<?> cl) {
        return delegate.readResolveForSerialization(cl);
    }

    /**
     * Returns a direct MethodHandle for the {@code writeReplace} method on
     * a serializable class.
     * The single argument of {@link MethodHandle#invoke} is the serializable
     * object.
     *
     * @param cl the Serializable class
     * @return  a direct MethodHandle for the {@code writeReplace} method of the class or
     *          {@code null} if the class does not have a {@code writeReplace} method
     */
    public final MethodHandle writeReplaceForSerialization(Class<?> cl) {
        return delegate.writeReplaceForSerialization(cl);
    }

    /**
     * Returns true if the class has a static initializer.
     * The presence of a static initializer is used to compute the serialVersionUID.
     * @param cl a serializable class
     * @return {@code true} if the class has a static initializer,
     *          otherwise {@code false}
     */
    public final boolean hasStaticInitializerForSerialization(Class<?> cl) {
        return delegate.hasStaticInitializerForSerialization(cl);
    }

    /**
     * Returns a new OptionalDataException with {@code eof} set to {@code true}
     * or {@code false}.
     * @param bool the value of {@code eof} in the created OptionalDataException
     * @return  a new OptionalDataException
     */
    public final OptionalDataException newOptionalDataExceptionForSerialization(boolean bool) {
        Constructor<OptionalDataException> cons = delegate.newOptionalDataExceptionForSerialization();
        try {
            return cons.newInstance(bool);
        } catch (InstantiationException|IllegalAccessException|InvocationTargetException ex) {
            throw new InternalError("unable to create OptionalDataException", ex);
        }
    }
}
