/*

  * Copyright (c) 2008, 2013, 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

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 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 MemberName resolve(MemberName self, Class<?> caller) throws LinkageError {

         return self;

     }

     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}

     /// MethodHandle support

     /// 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);

     static {

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

         MethodHandleImpl.initStatics();

 }

     // All compile-time constants go here.

     // There is an opportunity to check them against the JVM's idea of them.

     static class Constants {

         Constants() { } // static only

         // MethodHandleImpl

         static final int // for getConstant

                 GC_COUNT_GWT = 4,

                 GC_LAMBDA_SUPPORT = 5;

         // MemberName

         // The JVM uses values of -2 and above for vtable indexes.

         // Field values are simple positive offsets.

         // Ref: src/share/vm/oops/methodOop.hpp

         // This value is negative enough to avoid such numbers,

         // but not too negative.

         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;

         /**

          * Basic types as encoded in the JVM.  These code values are not

          * intended for use outside this class.  They are used as part of

          * a private interface between the JVM and this class.

          */

         static final int

             T_BOOLEAN  =  4,

             T_CHAR     =  5,

             T_FLOAT    =  6,

             T_DOUBLE   =  7,

             T_BYTE     =  8,

             T_SHORT    =  9,

             T_INT      = 10,

             T_LONG     = 11,

             T_OBJECT   = 12,

             //T_ARRAY    = 13

             T_VOID     = 14,

             //T_ADDRESS  = 15

             T_ILLEGAL  = 99;

         /**

          * Constant pool entry types.

          */

         static final byte

             CONSTANT_Utf8                = 1,

             CONSTANT_Integer             = 3,

             CONSTANT_Float               = 4,

             CONSTANT_Long                = 5,

             CONSTANT_Double              = 6,

             CONSTANT_Class               = 7,

             CONSTANT_String              = 8,

             CONSTANT_Fieldref            = 9,

             CONSTANT_Methodref           = 10,

             CONSTANT_InterfaceMethodref  = 11,

             CONSTANT_NameAndType         = 12,

             CONSTANT_MethodHandle        = 15,  // JSR 292

             CONSTANT_MethodType          = 16,  // JSR 292

             CONSTANT_InvokeDynamic       = 18,

             CONSTANT_LIMIT               = 19;   // Limit to tags found in classfiles

         /**

          * Access modifier flags.

          */

         static final char

             ACC_PUBLIC                 = 0x0001,

             ACC_PRIVATE                = 0x0002,

             ACC_PROTECTED              = 0x0004,

             ACC_STATIC                 = 0x0008,

             ACC_FINAL                  = 0x0010,

             ACC_SYNCHRONIZED           = 0x0020,

             ACC_VOLATILE               = 0x0040,

             ACC_TRANSIENT              = 0x0080,

             ACC_NATIVE                 = 0x0100,

             ACC_INTERFACE              = 0x0200,

             ACC_ABSTRACT               = 0x0400,

             ACC_STRICT                 = 0x0800,

             ACC_SYNTHETIC              = 0x1000,

             ACC_ANNOTATION             = 0x2000,

             ACC_ENUM                   = 0x4000,

             // aliases:

             ACC_SUPER                  = ACC_SYNCHRONIZED,

             ACC_BRIDGE                 = ACC_VOLATILE,

             ACC_VARARGS                = ACC_TRANSIENT;

         /**

          * 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 (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;

         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);

         }

     }

     /**

      * 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 similer 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 true; //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

     }

 }