/*

 * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.lang.invoke;

import java.lang.invoke.MethodHandles.Lookup;

import java.lang.reflect.Field;

import static java.lang.invoke.MethodHandleNatives.Constants.*;

import static java.lang.invoke.MethodHandleStatics.*;

import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;

/**

 * The JVM interface for the method handles package is all here.

 * This is an interface internal and private to an implementation of JSR 292.

 * <em>This class is not part of the JSR 292 standard.</em>

 * @author jrose

 */

class MethodHandleNatives {

    private MethodHandleNatives() { } // static only

    /// MemberName support

    static native void init(MemberName self, Object ref);

    static native void expand(MemberName self);

    static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError;

    static native int getMembers(Class<?> defc, String matchName, String matchSig,

            int matchFlags, Class<?> caller, int skip, MemberName[] results);

    /// Field layout queries parallel to sun.misc.Unsafe:

    static native long objectFieldOffset(MemberName self);  // e.g., returns vmindex

    static native long staticFieldOffset(MemberName self);  // e.g., returns vmindex

    static native Object staticFieldBase(MemberName self);  // e.g., returns clazz

    static native Object getMemberVMInfo(MemberName self);  // returns {vmindex,vmtarget}

    /// CallSite support

    /** Tell the JVM that we need to change the target of a CallSite. */

    static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);

    static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);

    private static native void registerNatives();

    static {

        registerNatives();

        // The JVM calls MethodHandleNatives.<clinit>.  Cascade the <clinit> calls as needed:

        MethodHandleImpl.initStatics();

    }

    /**

     * Compile-time constants go here. This collection exists not only for

     * reference from clients, but also for ensuring the VM and JDK agree on the

     * values of these constants (see {@link #verifyConstants()}).

     */

    static class Constants {

        Constants() { } // static only

        static final int

            MN_IS_METHOD           = 0x00010000, // method (not constructor)

            MN_IS_CONSTRUCTOR      = 0x00020000, // constructor

            MN_IS_FIELD            = 0x00040000, // field

            MN_IS_TYPE             = 0x00080000, // nested type

            MN_CALLER_SENSITIVE    = 0x00100000, // @CallerSensitive annotation detected

            MN_REFERENCE_KIND_SHIFT = 24, // refKind

            MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,

            // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:

            MN_SEARCH_SUPERCLASSES = 0x00100000,

            MN_SEARCH_INTERFACES   = 0x00200000;

        /**

         * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.

         */

        static final byte

            REF_NONE                    = 0,  // null value

            REF_getField                = 1,

            REF_getStatic               = 2,

            REF_putField                = 3,

            REF_putStatic               = 4,

            REF_invokeVirtual           = 5,

            REF_invokeStatic            = 6,

            REF_invokeSpecial           = 7,

            REF_newInvokeSpecial        = 8,

            REF_invokeInterface         = 9,

            REF_LIMIT                  = 10;

    }

    static boolean refKindIsValid(int refKind) {

        return (refKind > REF_NONE && refKind < REF_LIMIT);

    }

    static boolean refKindIsField(byte refKind) {

        assert(refKindIsValid(refKind));

        return (refKind <= REF_putStatic);

    }

    static boolean refKindIsGetter(byte refKind) {

        assert(refKindIsValid(refKind));

        return (refKind <= REF_getStatic);

    }

    static boolean refKindIsSetter(byte refKind) {

        return refKindIsField(refKind) && !refKindIsGetter(refKind);

    }

    static boolean refKindIsMethod(byte refKind) {

        return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);

    }

    static boolean refKindIsConstructor(byte refKind) {

        return (refKind == REF_newInvokeSpecial);

    }

    static boolean refKindHasReceiver(byte refKind) {

        assert(refKindIsValid(refKind));

        return (refKind & 1) != 0;

    }

    static boolean refKindIsStatic(byte refKind) {

        return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);

    }

    static boolean refKindDoesDispatch(byte refKind) {

        assert(refKindIsValid(refKind));

        return (refKind == REF_invokeVirtual ||

                refKind == REF_invokeInterface);

    }

    static {

        final int HR_MASK = ((1 << REF_getField) |

                             (1 << REF_putField) |

                             (1 << REF_invokeVirtual) |

                             (1 << REF_invokeSpecial) |

                             (1 << REF_invokeInterface)

                            );

        for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {

            assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;

        }

    }

    static String refKindName(byte refKind) {

        assert(refKindIsValid(refKind));

        switch (refKind) {

        case REF_getField:          return "getField";

        case REF_getStatic:         return "getStatic";

        case REF_putField:          return "putField";

        case REF_putStatic:         return "putStatic";

        case REF_invokeVirtual:     return "invokeVirtual";

        case REF_invokeStatic:      return "invokeStatic";

        case REF_invokeSpecial:     return "invokeSpecial";

        case REF_newInvokeSpecial:  return "newInvokeSpecial";

        case REF_invokeInterface:   return "invokeInterface";

        default:                    return "REF_???";

        }

    }

    private static native int getNamedCon(int which, Object[] name);

    static boolean verifyConstants() {

        Object[] box = { null };

        for (int i = 0; ; i++) {

            box[0] = null;

            int vmval = getNamedCon(i, box);

            if (box[0] == null)  break;

            String name = (String) box[0];

            try {

                Field con = Constants.class.getDeclaredField(name);

                int jval = con.getInt(null);

                if (jval == vmval)  continue;

                String err = (name+": JVM has "+vmval+" while Java has "+jval);

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

                    System.err.println("warning: "+err);

                    continue;

                }

                throw new InternalError(err);

            } catch (NoSuchFieldException | IllegalAccessException ex) {

                String err = (name+": JVM has "+vmval+" which Java does not define");

                // ignore exotic ops the JVM cares about; we just wont issue them

                //System.err.println("warning: "+err);

                continue;

            }

        }

        return true;

    }

    static {

        assert(verifyConstants());

    }

    // Up-calls from the JVM.

    // These must NOT be public.

    /**

     * The JVM is linking an invokedynamic instruction.  Create a reified call site for it.

     */

    static MemberName linkCallSite(Object callerObj,

                                   Object bootstrapMethodObj,

                                   Object nameObj, Object typeObj,

                                   Object staticArguments,

                                   Object[] appendixResult) {

        MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;

        Class<?> caller = (Class<?>)callerObj;

        String name = nameObj.toString().intern();

        MethodType type = (MethodType)typeObj;

        if (!TRACE_METHOD_LINKAGE)

            return linkCallSiteImpl(caller, bootstrapMethod, name, type,

                                    staticArguments, appendixResult);

        return linkCallSiteTracing(caller, bootstrapMethod, name, type,

                                   staticArguments, appendixResult);

    }

    static MemberName linkCallSiteImpl(Class<?> caller,

                                       MethodHandle bootstrapMethod,

                                       String name, MethodType type,

                                       Object staticArguments,

                                       Object[] appendixResult) {

        CallSite callSite = CallSite.makeSite(bootstrapMethod,

                                              name,

                                              type,

                                              staticArguments,

                                              caller);

        if (callSite instanceof ConstantCallSite) {

            appendixResult[0] = callSite.dynamicInvoker();

            return Invokers.linkToTargetMethod(type);

        } else {

            appendixResult[0] = callSite;

            return Invokers.linkToCallSiteMethod(type);

        }

    }

    // Tracing logic:

    static MemberName linkCallSiteTracing(Class<?> caller,

                                          MethodHandle bootstrapMethod,

                                          String name, MethodType type,

                                          Object staticArguments,

                                          Object[] appendixResult) {

        Object bsmReference = bootstrapMethod.internalMemberName();

        if (bsmReference == null)  bsmReference = bootstrapMethod;

        Object staticArglist = (staticArguments instanceof Object[] ?

                                java.util.Arrays.asList((Object[]) staticArguments) :

                                staticArguments);

        System.out.println("linkCallSite "+caller.getName()+" "+

                           bsmReference+" "+

                           name+type+"/"+staticArglist);

        try {

            MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,

                                              staticArguments, appendixResult);

            System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);

            return res;

        } catch (Throwable ex) {

            System.out.println("linkCallSite => throw "+ex);

            throw ex;

        }

    }

    /**

     * The JVM wants a pointer to a MethodType.  Oblige it by finding or creating one.

     */

    static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {

        return MethodType.makeImpl(rtype, ptypes, true);

    }

    /**

     * The JVM wants to link a call site that requires a dynamic type check.

     * Name is a type-checking invoker, invokeExact or invoke.

     * Return a JVM method (MemberName) to handle the invoking.

     * The method assumes the following arguments on the stack:

     * 0: the method handle being invoked

     * 1-N: the arguments to the method handle invocation

     * N+1: an optional, implicitly added argument (typically the given MethodType)

     * <p>

     * The nominal method at such a call site is an instance of

     * a signature-polymorphic method (see @PolymorphicSignature).

     * Such method instances are user-visible entities which are

     * "split" from the generic placeholder method in {@code MethodHandle}.

     * (Note that the placeholder method is not identical with any of

     * its instances.  If invoked reflectively, is guaranteed to throw an

     * {@code UnsupportedOperationException}.)

     * If the signature-polymorphic method instance is ever reified,

     * it appears as a "copy" of the original placeholder

     * (a native final member of {@code MethodHandle}) except

     * that its type descriptor has shape required by the instance,

     * and the method instance is <em>not</em> varargs.

     * The method instance is also marked synthetic, since the

     * method (by definition) does not appear in Java source code.

     * <p>

     * The JVM is allowed to reify this method as instance metadata.

     * For example, {@code invokeBasic} is always reified.

     * But the JVM may instead call {@code linkMethod}.

     * If the result is an * ordered pair of a {@code (method, appendix)},

     * the method gets all the arguments (0..N inclusive)

     * plus the appendix (N+1), and uses the appendix to complete the call.

     * In this way, one reusable method (called a "linker method")

     * can perform the function of any number of polymorphic instance

     * methods.

     * <p>

     * Linker methods are allowed to be weakly typed, with any or

     * all references rewritten to {@code Object} and any primitives

     * (except {@code long}/{@code float}/{@code double})

     * rewritten to {@code int}.

     * A linker method is trusted to return a strongly typed result,

     * according to the specific method type descriptor of the

     * signature-polymorphic instance it is emulating.

     * This can involve (as necessary) a dynamic check using

     * data extracted from the appendix argument.

     * <p>

     * The JVM does not inspect the appendix, other than to pass

     * it verbatim to the linker method at every call.

     * This means that the JDK runtime has wide latitude

     * for choosing the shape of each linker method and its

     * corresponding appendix.

     * Linker methods should be generated from {@code LambdaForm}s

     * so that they do not become visible on stack traces.

     * <p>

     * The {@code linkMethod} call is free to omit the appendix

     * (returning null) and instead emulate the required function

     * completely in the linker method.

     * As a corner case, if N==255, no appendix is possible.

     * In this case, the method returned must be custom-generated to

     * to perform any needed type checking.

     * <p>

     * If the JVM does not reify a method at a call site, but instead

     * calls {@code linkMethod}, the corresponding call represented

     * in the bytecodes may mention a valid method which is not

     * representable with a {@code MemberName}.

     * Therefore, use cases for {@code linkMethod} tend to correspond to

     * special cases in reflective code such as {@code findVirtual}

     * or {@code revealDirect}.

     */

    static MemberName linkMethod(Class<?> callerClass, int refKind,

                                 Class<?> defc, String name, Object type,

                                 Object[] appendixResult) {

        if (!TRACE_METHOD_LINKAGE)

            return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);

        return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);

    }

    static MemberName linkMethodImpl(Class<?> callerClass, int refKind,

                                     Class<?> defc, String name, Object type,

                                     Object[] appendixResult) {

        try {

            if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {

                return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);

            }

        } catch (Throwable ex) {

            if (ex instanceof LinkageError)

                throw (LinkageError) ex;

            else

                throw new LinkageError(ex.getMessage(), ex);

        }

        throw new LinkageError("no such method "+defc.getName()+"."+name+type);

    }

    private static MethodType fixMethodType(Class<?> callerClass, Object type) {

        if (type instanceof MethodType)

            return (MethodType) type;

        else

            return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());

    }

    // Tracing logic:

    static MemberName linkMethodTracing(Class<?> callerClass, int refKind,

                                        Class<?> defc, String name, Object type,

                                        Object[] appendixResult) {

        System.out.println("linkMethod "+defc.getName()+"."+

                           name+type+"/"+Integer.toHexString(refKind));

        try {

            MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);

            System.out.println("linkMethod => "+res+" + "+appendixResult[0]);

            return res;

        } catch (Throwable ex) {

            System.out.println("linkMethod => throw "+ex);

            throw ex;

        }

    }

    /**

     * The JVM is resolving a CONSTANT_MethodHandle CP entry.  And it wants our help.

     * It will make an up-call to this method.  (Do not change the name or signature.)

     * The type argument is a Class for field requests and a MethodType for non-fields.

     * <p>

     * Recent versions of the JVM may also pass a resolved MemberName for the type.

     * In that case, the name is ignored and may be null.

     */

    static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,

                                                 Class<?> defc, String name, Object type) {

        try {

            Lookup lookup = IMPL_LOOKUP.in(callerClass);

            assert(refKindIsValid(refKind));

            return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);

        } catch (IllegalAccessException ex) {

            Throwable cause = ex.getCause();

            if (cause instanceof AbstractMethodError) {

                throw (AbstractMethodError) cause;

            } else {

                Error err = new IllegalAccessError(ex.getMessage());

                throw initCauseFrom(err, ex);

            }

        } catch (NoSuchMethodException ex) {

            Error err = new NoSuchMethodError(ex.getMessage());

            throw initCauseFrom(err, ex);

        } catch (NoSuchFieldException ex) {

            Error err = new NoSuchFieldError(ex.getMessage());

            throw initCauseFrom(err, ex);

        } catch (ReflectiveOperationException ex) {

            Error err = new IncompatibleClassChangeError();

            throw initCauseFrom(err, ex);

        }

    }

    /**

     * Use best possible cause for err.initCause(), substituting the

     * cause for err itself if the cause has the same (or better) type.

     */

    static private Error initCauseFrom(Error err, Exception ex) {

        Throwable th = ex.getCause();

        if (err.getClass().isInstance(th))

           return (Error) th;

        err.initCause(th == null ? ex : th);

        return err;

    }

    /**

     * Is this method a caller-sensitive method?

     * I.e., does it call Reflection.getCallerClass or a similar method

     * to ask about the identity of its caller?

     */

    static boolean isCallerSensitive(MemberName mem) {

        if (!mem.isInvocable())  return false;  // fields are not caller sensitive

        return mem.isCallerSensitive() || canBeCalledVirtual(mem);

    }

    static boolean canBeCalledVirtual(MemberName mem) {

        assert(mem.isInvocable());

        Class<?> defc = mem.getDeclaringClass();

        switch (mem.getName()) {

        case "checkMemberAccess":

            return canBeCalledVirtual(mem, java.lang.SecurityManager.class);

        case "getContextClassLoader":

            return canBeCalledVirtual(mem, java.lang.Thread.class);

        }

        return false;

    }

    static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {

        Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();

        if (symbolicRefClass == definingClass)  return true;

        if (symbolicRef.isStatic() || symbolicRef.isPrivate())  return false;

        return (definingClass.isAssignableFrom(symbolicRefClass) ||  // Msym overrides Mdef

                symbolicRefClass.isInterface());                     // Mdef implements Msym

    }

}