1 /*
2 * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import java.lang.invoke.MethodHandles.Lookup;
29 import java.lang.reflect.Field;
30 import static java.lang.invoke.MethodHandleNatives.Constants.*;
31 import static java.lang.invoke.MethodHandleStatics.*;
32 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
33
34 /**
35 * The JVM interface for the method handles package is all here.
36 * This is an interface internal and private to an implementation of JSR 292.
37 * <em>This class is not part of the JSR 292 standard.</em>
38 * @author jrose
39 */
40 class MethodHandleNatives {
41
42 private MethodHandleNatives() { } // static only
43
44 /// MemberName support
45
46 static native void init(MemberName self, Object ref);
47 static native void expand(MemberName self);
48 static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError;
49 static native int getMembers(Class<?> defc, String matchName, String matchSig,
50 int matchFlags, Class<?> caller, int skip, MemberName[] results);
51
52 /// Field layout queries parallel to sun.misc.Unsafe:
53 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
54 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
55 static native Object staticFieldBase(MemberName self); // e.g., returns clazz
56 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
57
58 /// CallSite support
59
60 /** Tell the JVM that we need to change the target of a CallSite. */
61 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
62 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
63
64 /** Invalidate CallSite context: clean up dependent nmethods and reset call site context to initial state (null). */
65 static native void invalidateDependentNMethods(CallSite site);
66
67 private static native void registerNatives();
68 static {
69 registerNatives();
70
71 // The JVM calls MethodHandleNatives.<clinit>. Cascade the <clinit> calls as needed:
72 MethodHandleImpl.initStatics();
73 }
74
75 /**
76 * Compile-time constants go here. This collection exists not only for
77 * reference from clients, but also for ensuring the VM and JDK agree on the
78 * values of these constants (see {@link #verifyConstants()}).
79 */
80 static class Constants {
81 Constants() { } // static only
82
83 static final int
84 MN_IS_METHOD = 0x00010000, // method (not constructor)
85 MN_IS_CONSTRUCTOR = 0x00020000, // constructor
86 MN_IS_FIELD = 0x00040000, // field
87 MN_IS_TYPE = 0x00080000, // nested type
88 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
89 MN_REFERENCE_KIND_SHIFT = 24, // refKind
90 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
91 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
92 MN_SEARCH_SUPERCLASSES = 0x00100000,
93 MN_SEARCH_INTERFACES = 0x00200000;
94
95 /**
96 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
97 */
98 static final byte
99 REF_NONE = 0, // null value
100 REF_getField = 1,
101 REF_getStatic = 2,
102 REF_putField = 3,
103 REF_putStatic = 4,
104 REF_invokeVirtual = 5,
105 REF_invokeStatic = 6,
106 REF_invokeSpecial = 7,
107 REF_newInvokeSpecial = 8,
108 REF_invokeInterface = 9,
109 REF_LIMIT = 10;
110 }
111
112 static boolean refKindIsValid(int refKind) {
113 return (refKind > REF_NONE && refKind < REF_LIMIT);
114 }
115 static boolean refKindIsField(byte refKind) {
116 assert(refKindIsValid(refKind));
117 return (refKind <= REF_putStatic);
118 }
119 static boolean refKindIsGetter(byte refKind) {
120 assert(refKindIsValid(refKind));
121 return (refKind <= REF_getStatic);
122 }
123 static boolean refKindIsSetter(byte refKind) {
124 return refKindIsField(refKind) && !refKindIsGetter(refKind);
125 }
126 static boolean refKindIsMethod(byte refKind) {
127 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
128 }
129 static boolean refKindIsConstructor(byte refKind) {
130 return (refKind == REF_newInvokeSpecial);
131 }
132 static boolean refKindHasReceiver(byte refKind) {
133 assert(refKindIsValid(refKind));
134 return (refKind & 1) != 0;
135 }
136 static boolean refKindIsStatic(byte refKind) {
137 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
138 }
139 static boolean refKindDoesDispatch(byte refKind) {
140 assert(refKindIsValid(refKind));
141 return (refKind == REF_invokeVirtual ||
142 refKind == REF_invokeInterface);
143 }
144 static {
145 final int HR_MASK = ((1 << REF_getField) |
146 (1 << REF_putField) |
147 (1 << REF_invokeVirtual) |
148 (1 << REF_invokeSpecial) |
149 (1 << REF_invokeInterface)
150 );
151 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
152 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
153 }
154 }
155 static String refKindName(byte refKind) {
156 assert(refKindIsValid(refKind));
157 switch (refKind) {
158 case REF_getField: return "getField";
159 case REF_getStatic: return "getStatic";
160 case REF_putField: return "putField";
161 case REF_putStatic: return "putStatic";
162 case REF_invokeVirtual: return "invokeVirtual";
163 case REF_invokeStatic: return "invokeStatic";
164 case REF_invokeSpecial: return "invokeSpecial";
165 case REF_newInvokeSpecial: return "newInvokeSpecial";
166 case REF_invokeInterface: return "invokeInterface";
167 default: return "REF_???";
168 }
169 }
170
171 private static native int getNamedCon(int which, Object[] name);
172 static boolean verifyConstants() {
173 Object[] box = { null };
174 for (int i = 0; ; i++) {
175 box[0] = null;
176 int vmval = getNamedCon(i, box);
177 if (box[0] == null) break;
178 String name = (String) box[0];
179 try {
180 Field con = Constants.class.getDeclaredField(name);
181 int jval = con.getInt(null);
182 if (jval == vmval) continue;
183 String err = (name+": JVM has "+vmval+" while Java has "+jval);
184 if (name.equals("CONV_OP_LIMIT")) {
185 System.err.println("warning: "+err);
186 continue;
187 }
188 throw new InternalError(err);
189 } catch (NoSuchFieldException | IllegalAccessException ex) {
190 String err = (name+": JVM has "+vmval+" which Java does not define");
191 // ignore exotic ops the JVM cares about; we just wont issue them
192 //System.err.println("warning: "+err);
193 continue;
194 }
195 }
196 return true;
197 }
198 static {
199 assert(verifyConstants());
200 }
201
202 // Up-calls from the JVM.
203 // These must NOT be public.
204
205 /**
206 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
207 */
208 static MemberName linkCallSite(Object callerObj,
209 Object bootstrapMethodObj,
210 Object nameObj, Object typeObj,
211 Object staticArguments,
212 Object[] appendixResult) {
213 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
214 Class<?> caller = (Class<?>)callerObj;
215 String name = nameObj.toString().intern();
216 MethodType type = (MethodType)typeObj;
217 if (!TRACE_METHOD_LINKAGE)
218 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
219 staticArguments, appendixResult);
220 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
221 staticArguments, appendixResult);
222 }
223 static MemberName linkCallSiteImpl(Class<?> caller,
224 MethodHandle bootstrapMethod,
225 String name, MethodType type,
226 Object staticArguments,
227 Object[] appendixResult) {
228 CallSite callSite = CallSite.makeSite(bootstrapMethod,
229 name,
230 type,
231 staticArguments,
232 caller);
233 if (callSite instanceof ConstantCallSite) {
234 appendixResult[0] = callSite.dynamicInvoker();
235 return Invokers.linkToTargetMethod(type);
236 } else {
237 appendixResult[0] = callSite;
238 callSite.initContext(caller);
239 return Invokers.linkToCallSiteMethod(type);
240 }
241 }
242 // Tracing logic:
243 static MemberName linkCallSiteTracing(Class<?> caller,
244 MethodHandle bootstrapMethod,
245 String name, MethodType type,
246 Object staticArguments,
247 Object[] appendixResult) {
248 Object bsmReference = bootstrapMethod.internalMemberName();
249 if (bsmReference == null) bsmReference = bootstrapMethod;
250 Object staticArglist = (staticArguments instanceof Object[] ?
251 java.util.Arrays.asList((Object[]) staticArguments) :
252 staticArguments);
253 System.out.println("linkCallSite "+caller.getName()+" "+
254 bsmReference+" "+
255 name+type+"/"+staticArglist);
256 try {
257 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
258 staticArguments, appendixResult);
259 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
260 return res;
261 } catch (Throwable ex) {
262 System.out.println("linkCallSite => throw "+ex);
263 throw ex;
264 }
265 }
266
267 /**
268 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
269 */
270 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
271 return MethodType.makeImpl(rtype, ptypes, true);
272 }
273
274 /**
275 * The JVM wants to link a call site that requires a dynamic type check.
276 * Name is a type-checking invoker, invokeExact or invoke.
277 * Return a JVM method (MemberName) to handle the invoking.
278 * The method assumes the following arguments on the stack:
279 * 0: the method handle being invoked
280 * 1-N: the arguments to the method handle invocation
281 * N+1: an optional, implicitly added argument (typically the given MethodType)
282 * <p>
283 * The nominal method at such a call site is an instance of
284 * a signature-polymorphic method (see @PolymorphicSignature).
285 * Such method instances are user-visible entities which are
286 * "split" from the generic placeholder method in {@code MethodHandle}.
287 * (Note that the placeholder method is not identical with any of
288 * its instances. If invoked reflectively, is guaranteed to throw an
289 * {@code UnsupportedOperationException}.)
290 * If the signature-polymorphic method instance is ever reified,
291 * it appears as a "copy" of the original placeholder
292 * (a native final member of {@code MethodHandle}) except
293 * that its type descriptor has shape required by the instance,
294 * and the method instance is <em>not</em> varargs.
295 * The method instance is also marked synthetic, since the
296 * method (by definition) does not appear in Java source code.
297 * <p>
298 * The JVM is allowed to reify this method as instance metadata.
299 * For example, {@code invokeBasic} is always reified.
300 * But the JVM may instead call {@code linkMethod}.
301 * If the result is an * ordered pair of a {@code (method, appendix)},
302 * the method gets all the arguments (0..N inclusive)
303 * plus the appendix (N+1), and uses the appendix to complete the call.
304 * In this way, one reusable method (called a "linker method")
305 * can perform the function of any number of polymorphic instance
306 * methods.
307 * <p>
308 * Linker methods are allowed to be weakly typed, with any or
309 * all references rewritten to {@code Object} and any primitives
310 * (except {@code long}/{@code float}/{@code double})
311 * rewritten to {@code int}.
312 * A linker method is trusted to return a strongly typed result,
313 * according to the specific method type descriptor of the
314 * signature-polymorphic instance it is emulating.
315 * This can involve (as necessary) a dynamic check using
316 * data extracted from the appendix argument.
317 * <p>
318 * The JVM does not inspect the appendix, other than to pass
319 * it verbatim to the linker method at every call.
320 * This means that the JDK runtime has wide latitude
321 * for choosing the shape of each linker method and its
322 * corresponding appendix.
323 * Linker methods should be generated from {@code LambdaForm}s
324 * so that they do not become visible on stack traces.
325 * <p>
326 * The {@code linkMethod} call is free to omit the appendix
327 * (returning null) and instead emulate the required function
328 * completely in the linker method.
329 * As a corner case, if N==255, no appendix is possible.
330 * In this case, the method returned must be custom-generated to
331 * to perform any needed type checking.
332 * <p>
333 * If the JVM does not reify a method at a call site, but instead
334 * calls {@code linkMethod}, the corresponding call represented
335 * in the bytecodes may mention a valid method which is not
336 * representable with a {@code MemberName}.
337 * Therefore, use cases for {@code linkMethod} tend to correspond to
338 * special cases in reflective code such as {@code findVirtual}
339 * or {@code revealDirect}.
340 */
341 static MemberName linkMethod(Class<?> callerClass, int refKind,
342 Class<?> defc, String name, Object type,
343 Object[] appendixResult) {
344 if (!TRACE_METHOD_LINKAGE)
345 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
346 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
347 }
348 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
349 Class<?> defc, String name, Object type,
350 Object[] appendixResult) {
351 try {
352 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
353 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
354 }
355 } catch (Throwable ex) {
356 if (ex instanceof LinkageError)
357 throw (LinkageError) ex;
358 else
359 throw new LinkageError(ex.getMessage(), ex);
360 }
361 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
362 }
363 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
364 if (type instanceof MethodType)
365 return (MethodType) type;
366 else
367 return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());
368 }
369 // Tracing logic:
370 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
371 Class<?> defc, String name, Object type,
372 Object[] appendixResult) {
373 System.out.println("linkMethod "+defc.getName()+"."+
374 name+type+"/"+Integer.toHexString(refKind));
375 try {
376 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
377 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
378 return res;
379 } catch (Throwable ex) {
380 System.out.println("linkMethod => throw "+ex);
381 throw ex;
382 }
383 }
384
385
386 /**
387 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
388 * It will make an up-call to this method. (Do not change the name or signature.)
389 * The type argument is a Class for field requests and a MethodType for non-fields.
390 * <p>
391 * Recent versions of the JVM may also pass a resolved MemberName for the type.
392 * In that case, the name is ignored and may be null.
393 */
394 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
395 Class<?> defc, String name, Object type) {
396 try {
397 Lookup lookup = IMPL_LOOKUP.in(callerClass);
398 assert(refKindIsValid(refKind));
399 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
400 } catch (IllegalAccessException ex) {
401 Throwable cause = ex.getCause();
402 if (cause instanceof AbstractMethodError) {
403 throw (AbstractMethodError) cause;
404 } else {
405 Error err = new IllegalAccessError(ex.getMessage());
406 throw initCauseFrom(err, ex);
407 }
408 } catch (NoSuchMethodException ex) {
409 Error err = new NoSuchMethodError(ex.getMessage());
410 throw initCauseFrom(err, ex);
411 } catch (NoSuchFieldException ex) {
412 Error err = new NoSuchFieldError(ex.getMessage());
413 throw initCauseFrom(err, ex);
414 } catch (ReflectiveOperationException ex) {
415 Error err = new IncompatibleClassChangeError();
416 throw initCauseFrom(err, ex);
417 }
418 }
419
420 /**
421 * Use best possible cause for err.initCause(), substituting the
422 * cause for err itself if the cause has the same (or better) type.
423 */
424 static private Error initCauseFrom(Error err, Exception ex) {
425 Throwable th = ex.getCause();
426 if (err.getClass().isInstance(th))
427 return (Error) th;
428 err.initCause(th == null ? ex : th);
429 return err;
430 }
431
432 /**
433 * Is this method a caller-sensitive method?
434 * I.e., does it call Reflection.getCallerClass or a similar method
435 * to ask about the identity of its caller?
436 */
437 static boolean isCallerSensitive(MemberName mem) {
438 if (!mem.isInvocable()) return false; // fields are not caller sensitive
439
440 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
441 }
442
443 static boolean canBeCalledVirtual(MemberName mem) {
444 assert(mem.isInvocable());
445 Class<?> defc = mem.getDeclaringClass();
446 switch (mem.getName()) {
447 case "checkMemberAccess":
448 return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
449 case "getContextClassLoader":
450 return canBeCalledVirtual(mem, java.lang.Thread.class);
451 }
452 return false;
453 }
454
455 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
456 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
457 if (symbolicRefClass == definingClass) return true;
458 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
459 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
460 symbolicRefClass.isInterface()); // Mdef implements Msym
461 }
462 }