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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

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

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.internal.reflect;

import java.lang.reflect.*;

import java.util.HashMap;

import java.util.Map;

import java.util.Objects;

import jdk.internal.HotSpotIntrinsicCandidate;

import jdk.internal.loader.ClassLoaders;

import jdk.internal.misc.VM;

/** Common utility routines used by both java.lang and

    java.lang.reflect */

public class Reflection {

    /** Used to filter out fields and methods from certain classes from public

        view, where they are sensitive or they may contain VM-internal objects.

        These Maps are updated very rarely. Rather than synchronize on

        each access, we use copy-on-write */

    private static volatile Map<Class<?>,String[]> fieldFilterMap;

    private static volatile Map<Class<?>,String[]> methodFilterMap;

    static {

        Map<Class<?>,String[]> map = new HashMap<Class<?>,String[]>();

        map.put(Reflection.class,

            new String[] {"fieldFilterMap", "methodFilterMap"});

        map.put(System.class, new String[] {"security"});

        map.put(Class.class, new String[] {"classLoader"});

        fieldFilterMap = map;

        methodFilterMap = new HashMap<>();

    }

    /** Returns the class of the caller of the method calling this method,

        ignoring frames associated with java.lang.reflect.Method.invoke()

        and its implementation. */

    @CallerSensitive

    @HotSpotIntrinsicCandidate

    public static native Class<?> getCallerClass();

    /** Retrieves the access flags written to the class file. For

        inner classes these flags may differ from those returned by

        Class.getModifiers(), which searches the InnerClasses

        attribute to find the source-level access flags. This is used

        instead of Class.getModifiers() for run-time access checks due

        to compatibility reasons; see 4471811. Only the values of the

        low 13 bits (i.e., a mask of 0x1FFF) are guaranteed to be

        valid. */

    @HotSpotIntrinsicCandidate

    public static native int getClassAccessFlags(Class<?> c);

    /**

     * Ensures that access to a member is granted and throws

     * IllegalAccessException if not.

     *

     * @param currentClass the class performing the access

     * @param memberClass the declaring class of the member being accessed

     * @param targetClass the class of target object if accessing instance

     *                    field or method;

     *                    or the declaring class if accessing constructor;

     *                    or null if accessing static field or method

     * @param modifiers the member's access modifiers

     * @throws IllegalAccessException if access to member is denied

     */

    public static void ensureMemberAccess(Class<?> currentClass,

                                          Class<?> memberClass,

                                          Class<?> targetClass,

                                          int modifiers)

        throws IllegalAccessException

    {

        if (!verifyMemberAccess(currentClass, memberClass, targetClass, modifiers)) {

            throw newIllegalAccessException(currentClass, memberClass, targetClass, modifiers);

        }

    }

    /**

     * Verify access to a member and return {@code true} if it is granted.

     *

     * @param currentClass the class performing the access

     * @param memberClass the declaring class of the member being accessed

     * @param targetClass the class of target object if accessing instance

     *                    field or method;

     *                    or the declaring class if accessing constructor;

     *                    or null if accessing static field or method

     * @param modifiers the member's access modifiers

     * @return {@code true} if access to member is granted

     */

    public static boolean verifyMemberAccess(Class<?> currentClass,

                                             Class<?> memberClass,

                                             Class<?> targetClass,

                                             int modifiers)

    {

        if (currentClass == memberClass) {

            // Always succeeds

            return true;

        }

        if (!verifyModuleAccess(currentClass.getModule(), memberClass)) {

            return false;

        }

        boolean gotIsSameClassPackage = false;

        boolean isSameClassPackage = false;

        if (!Modifier.isPublic(getClassAccessFlags(memberClass))) {

            isSameClassPackage = isSameClassPackage(currentClass, memberClass);

            gotIsSameClassPackage = true;

            if (!isSameClassPackage) {

                return false;

            }

        }

        // At this point we know that currentClass can access memberClass.

        if (Modifier.isPublic(modifiers)) {

            return true;

        }

        boolean successSoFar = false;

        if (Modifier.isProtected(modifiers)) {

            // See if currentClass is a subclass of memberClass

            if (isSubclassOf(currentClass, memberClass)) {

                successSoFar = true;

            }

        }

        if (!successSoFar && !Modifier.isPrivate(modifiers)) {

            if (!gotIsSameClassPackage) {

                isSameClassPackage = isSameClassPackage(currentClass,

                                                        memberClass);

                gotIsSameClassPackage = true;

            }

            if (isSameClassPackage) {

                successSoFar = true;

            }

        }

        if (!successSoFar) {

            return false;

        }

        // Additional test for protected instance members

        // and protected constructors: JLS 6.6.2

        if (targetClass != null && Modifier.isProtected(modifiers) &&

            targetClass != currentClass)

        {

            if (!gotIsSameClassPackage) {

                isSameClassPackage = isSameClassPackage(currentClass, memberClass);

                gotIsSameClassPackage = true;

            }

            if (!isSameClassPackage) {

                if (!isSubclassOf(targetClass, currentClass)) {

                    return false;

                }

            }

        }

        return true;

    }

    /**

     * Returns {@code true} if memberClass's module exports memberClass's

     * package to currentModule.

     */

    public static boolean verifyModuleAccess(Module currentModule, Class<?> memberClass) {

        Module memberModule = memberClass.getModule();

        if (currentModule == memberModule) {

            // same module (named or unnamed) or both null if called

            // before module system is initialized, which means we are

            // dealing with java.base only.

            return true;

        } else {

            String pkg = memberClass.getPackageName();

            return memberModule.isExported(pkg, currentModule);

        }

    }

    /**

     * Returns true if two classes in the same package.

     */

    private static boolean isSameClassPackage(Class<?> c1, Class<?> c2) {

        if (c1.getClassLoader() != c2.getClassLoader())

            return false;

        return Objects.equals(c1.getPackageName(), c2.getPackageName());

    }

    static boolean isSubclassOf(Class<?> queryClass,

                                Class<?> ofClass)

    {

        while (queryClass != null) {

            if (queryClass == ofClass) {

                return true;

            }

            queryClass = queryClass.getSuperclass();

        }

        return false;

    }

    // fieldNames must contain only interned Strings

    public static synchronized void registerFieldsToFilter(Class<?> containingClass,

                                              String ... fieldNames) {

        fieldFilterMap =

            registerFilter(fieldFilterMap, containingClass, fieldNames);

    }

    // methodNames must contain only interned Strings

    public static synchronized void registerMethodsToFilter(Class<?> containingClass,

                                              String ... methodNames) {

        methodFilterMap =

            registerFilter(methodFilterMap, containingClass, methodNames);

    }

    private static Map<Class<?>,String[]> registerFilter(Map<Class<?>,String[]> map,

            Class<?> containingClass, String ... names) {

        if (map.get(containingClass) != null) {

            throw new IllegalArgumentException

                            ("Filter already registered: " + containingClass);

        }

        map = new HashMap<Class<?>,String[]>(map);

        map.put(containingClass, names);

        return map;

    }

    public static Field[] filterFields(Class<?> containingClass,

                                       Field[] fields) {

        if (fieldFilterMap == null) {

            // Bootstrapping

            return fields;

        }

        return (Field[])filter(fields, fieldFilterMap.get(containingClass));

    }

    public static Method[] filterMethods(Class<?> containingClass, Method[] methods) {

        if (methodFilterMap == null) {

            // Bootstrapping

            return methods;

        }

        return (Method[])filter(methods, methodFilterMap.get(containingClass));

    }

    private static Member[] filter(Member[] members, String[] filteredNames) {

        if ((filteredNames == null) || (members.length == 0)) {

            return members;

        }

        int numNewMembers = 0;

        for (Member member : members) {

            boolean shouldSkip = false;

            for (String filteredName : filteredNames) {

                if (member.getName() == filteredName) {

                    shouldSkip = true;

                    break;

                }

            }

            if (!shouldSkip) {

                ++numNewMembers;

            }

        }

        Member[] newMembers =

            (Member[])Array.newInstance(members[0].getClass(), numNewMembers);

        int destIdx = 0;

        for (Member member : members) {

            boolean shouldSkip = false;

            for (String filteredName : filteredNames) {

                if (member.getName() == filteredName) {

                    shouldSkip = true;

                    break;

                }

            }

            if (!shouldSkip) {

                newMembers[destIdx++] = member;

            }

        }

        return newMembers;

    }

    /**

     * Tests if the given method is caller-sensitive and the declaring class

     * is defined by either the bootstrap class loader or platform class loader.

     */

    public static boolean isCallerSensitive(Method m) {

        final ClassLoader loader = m.getDeclaringClass().getClassLoader();

        if (VM.isSystemDomainLoader(loader)) {

            return m.isAnnotationPresent(CallerSensitive.class);

        }

        return false;

    }

    /**

     * Returns an IllegalAccessException with an exception message based on

     * the access that is denied.

     */

    public static IllegalAccessException newIllegalAccessException(Class<?> currentClass,

                                                                   Class<?> memberClass,

                                                                   Class<?> targetClass,

                                                                   int modifiers)

        throws IllegalAccessException

    {

        String currentSuffix = "";

        String memberSuffix = "";

        Module m1 = currentClass.getModule();

        if (m1.isNamed())

            currentSuffix = " (in " + m1 + ")";

        Module m2 = memberClass.getModule();

        if (m2.isNamed())

            memberSuffix = " (in " + m2 + ")";

        String memberPackageName = memberClass.getPackageName();

        String msg = currentClass + currentSuffix + " cannot access ";

        if (m2.isExported(memberPackageName, m1)) {

            // module access okay so include the modifiers in the message

            msg += "a member of " + memberClass + memberSuffix +

                    " with modifiers \"" + Modifier.toString(modifiers) + "\"";

        } else {

            // module access failed

            msg += memberClass + memberSuffix+ " because "

                   + m2 + " does not export " + memberPackageName;

            if (m2.isNamed()) msg += " to " + m1;

        }

        return new IllegalAccessException(msg);

    }

}