jdk-sandbox: comparison jdk/src/share/classes/java/lang/invoke/MethodHandles.java

equal deleted inserted replaced

-:05fc1bd20e10
+:9f284cf7836b
 */
 package java.lang.invoke;
 import java.lang.reflect.*;
-import java.security.AccessController;
-import java.security.PrivilegedAction;
 import java.util.List;
 import java.util.ArrayList;
 import java.util.Arrays;
 import sun.invoke.util.ValueConversions;
 * <li>Other factory methods to create method handles that emulate other common JVM operations or control flow patterns.
 * <li>Wrapper methods which can convert between method handles and interface types.
 * </ul>
 * <p>
 * @author John Rose, JSR 292 EG
+* @since 1.7
 */
 public class MethodHandles {
 private MethodHandles() { }  // do not instantiate
 * @return a lookup object which is trusted minimally
 */
 public static Lookup publicLookup() {
 return Lookup.PUBLIC_LOOKUP;
 }
+/**
+* Performs an unchecked "crack" of a direct method handle.
+* The result is as if the user had obtained a lookup object capable enough
+* to crack the target method handle, called
+* {@link java.lang.invoke.MethodHandles.Lookup#revealDirect Lookup.revealDirect}
+* on the target to obtain its symbolic reference, and then called
+* {@link java.lang.invoke.MethodHandleInfo#reflectAs MethodHandleInfo.reflectAs}
+* to resolve the symbolic reference to a member.
+* <p>
+* If there is a security manager, its {@code checkPermission} method
+* is called with a {@code ReflectPermission("suppressAccessChecks")} permission.
+* @param <T> the desired type of the result, either {@link Member} or a subtype
+* @param target a direct method handle to crack into symbolic reference components
+* @param expected a class object representing the desired result type {@code T}
+* @return a reference to the method, constructor, or field object
+* @exception SecurityException if the caller is not privileged to call {@code setAccessible}
+* @exception NullPointerException if either argument is {@code null}
+* @exception IllegalArgumentException if the target is not a direct method handle
+* @exception ClassCastException if the member is not of the expected type
+* @since 1.8
+*/
+public static <T extends Member> T
+reflectAs(Class<T> expected, MethodHandle target) {
+SecurityManager smgr = System.getSecurityManager();
+if (smgr != null)  smgr.checkPermission(ACCESS_PERMISSION);
+Lookup lookup = Lookup.IMPL_LOOKUP;  // use maximally privileged lookup
+return lookup.revealDirect(target).reflectAs(expected, lookup);
+}
+// Copied from AccessibleObject, as used by Method.setAccessible, etc.:
+static final private java.security.Permission ACCESS_PERMISSION =
+new ReflectPermission("suppressAccessChecks");
 /**
 * A <em>lookup object</em> is a factory for creating method handles,
 * when the creation requires access checking.
 * Method handles do not perform
 // these names require special lookups because of the implicit MethodType argument
 if ("invoke".equals(name))
 return invoker(type);
 if ("invokeExact".equals(name))
 return exactInvoker(type);
+assert(!MemberName.isMethodHandleInvokeName(name));
 return null;
 }
 /**
 * Produces a method handle which creates an object and initializes it, using
 *                                or if the method's variable arity modifier bit
 *                                is set and {@code asVarargsCollector} fails
 * @throws NullPointerException if the argument is null
 */
 public MethodHandle unreflect(Method m) throws IllegalAccessException {
+if (m.getDeclaringClass() == MethodHandle.class) {
+MethodHandle mh = unreflectForMH(m);
+if (mh != null)  return mh;
+}
 MemberName method = new MemberName(m);
 byte refKind = method.getReferenceKind();
 if (refKind == REF_invokeSpecial)
 refKind = REF_invokeVirtual;
 assert(method.isMethod());
 Lookup lookup = m.isAccessible() ? IMPL_LOOKUP : this;
 return lookup.getDirectMethod(refKind, method.getDeclaringClass(), method, findBoundCallerClass(method));
+}
+private MethodHandle unreflectForMH(Method m) {
+// these names require special lookups because they throw UnsupportedOperationException
+if (MemberName.isMethodHandleInvokeName(m.getName()))
+return MethodHandleImpl.fakeMethodHandleInvoke(new MemberName(m));
+return null;
 }
 /**
 * Produces a method handle for a reflected method.
 * It will bypass checks for overriding methods on the receiver,
 * @throws IllegalAccessException if access checking fails
 * @throws NullPointerException if the argument is null
 */
 public MethodHandle unreflectSetter(Field f) throws IllegalAccessException {
 return unreflectField(f, true);
+}
+/**
+* Cracks a direct method handle created by this lookup object or a similar one.
+* Security and access checks are performed to ensure that this lookup object
+* is capable of reproducing the target method handle.
+* This means that the cracking may fail if target is a direct method handle
+* but was created by an unrelated lookup object.
+* @param target a direct method handle to crack into symbolic reference components
+* @return a symbolic reference which can be used to reconstruct this method handle from this lookup object
+* @exception SecurityException if a security manager is present and it
+*                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
+* @throws IllegalArgumentException if the target is not a direct method handle or if access checking fails
+* @exception NullPointerException if the target is {@code null}
+* @since 1.8
+*/
+public MethodHandleInfo revealDirect(MethodHandle target) {
+MemberName member = target.internalMemberName();
+if (member == null || (!member.isResolved() && !member.isMethodHandleInvoke()))
+throw newIllegalArgumentException("not a direct method handle");
+Class<?> defc = member.getDeclaringClass();
+byte refKind = member.getReferenceKind();
+assert(MethodHandleNatives.refKindIsValid(refKind));
+if (refKind == REF_invokeSpecial && !target.isInvokeSpecial())
+// Devirtualized method invocation is usually formally virtual.
+// To avoid creating extra MemberName objects for this common case,
+// we encode this extra degree of freedom using MH.isInvokeSpecial.
+refKind = REF_invokeVirtual;
+if (refKind == REF_invokeVirtual && defc.isInterface())
+// Symbolic reference is through interface but resolves to Object method (toString, etc.)
+refKind = REF_invokeInterface;
+// Check SM permissions and member access before cracking.
+try {
+checkSecurityManager(defc, member);
+checkAccess(refKind, defc, member);
+} catch (IllegalAccessException ex) {
+throw new IllegalArgumentException(ex);
+}
+// Produce the handle to the results.
+return new InfoFromMemberName(this, member, refKind);
 }
 /// Helper methods, all package-private.
 MemberName resolveOrFail(byte refKind, Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {
 return getDirectMethodCommon(refKind, refc, method, false, callerClass);
 }
 private MethodHandle getDirectMethodCommon(byte refKind, Class<?> refc, MemberName method,
 boolean doRestrict, Class<?> callerClass) throws IllegalAccessException {
 checkMethod(refKind, refc, method);
-if (method.isMethodHandleInvoke())
+assert(!method.isMethodHandleInvoke());
-return fakeMethodHandleInvoke(method);
 Class<?> refcAsSuper;
 if (refKind == REF_invokeSpecial &&
 refc != lookupClass() &&
+!refc.isInterface() &&
 refc != (refcAsSuper = lookupClass().getSuperclass()) &&
 refc.isAssignableFrom(lookupClass())) {
 assert(!method.getName().equals("<init>"));  // not this code path
 // Per JVMS 6.5, desc. of invokespecial instruction:
 // If the method is in a superclass of the LC,
 mh = maybeBindCaller(method, mh, callerClass);
 mh = mh.setVarargs(method);
 if (doRestrict)
 mh = restrictReceiver(method, mh, lookupClass());
 return mh;
-}
-private MethodHandle fakeMethodHandleInvoke(MemberName method) {
-return throwException(method.getReturnType(), UnsupportedOperationException.class);
 }
 private MethodHandle maybeBindCaller(MemberName method, MethodHandle mh,
 Class<?> callerClass)
 throws IllegalAccessException {
 if (allowedModes == TRUSTED || !MethodHandleNatives.isCallerSensitive(method))

changeset 20851	9f284cf7836b
parent 20841	2b188911d712
parent 19804	83170920c07b
child 20853	505b28fe2b98