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 private static native void registerNatives();
65 static {
66 registerNatives();
67
68 // The JVM calls MethodHandleNatives.<clinit>. Cascade the <clinit> calls as needed:
69 MethodHandleImpl.initStatics();
70 }
71
72 /**
73 * Compile-time constants go here. This collection exists not only for
74 * reference from clients, but also for ensuring the VM and JDK agree on the
75 * values of these constants (see {@link #verifyConstants()}).
76 */
77 static class Constants {
78 Constants() { } // static only
79
80
81 // The JVM uses values of -2 and above for vtable indexes.
82 // Field values are simple positive offsets.
83 // Ref: src/share/vm/oops/methodOop.hpp
84 // This value is negative enough to avoid such numbers,
85 // but not too negative.
86 static final int
87 MN_IS_METHOD = 0x00010000, // method (not constructor)
88 MN_IS_CONSTRUCTOR = 0x00020000, // constructor
89 MN_IS_FIELD = 0x00040000, // field
90 MN_IS_TYPE = 0x00080000, // nested type
91 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
92 MN_REFERENCE_KIND_SHIFT = 24, // refKind
93 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
94 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
95 MN_SEARCH_SUPERCLASSES = 0x00100000,
96 MN_SEARCH_INTERFACES = 0x00200000;
97
98 /**
99 * Basic types as encoded in the JVM. These code values are not
100 * intended for use outside this class. They are used as part of
101 * a private interface between the JVM and this class.
102 */
103 static final int
104 T_BOOLEAN = 4,
105 T_CHAR = 5,
106 T_FLOAT = 6,
107 T_DOUBLE = 7,
108 T_BYTE = 8,
109 T_SHORT = 9,
110 T_INT = 10,
111 T_LONG = 11,
112 T_OBJECT = 12,
113 //T_ARRAY = 13
114 T_VOID = 14,
115 //T_ADDRESS = 15
116 T_ILLEGAL = 99;
117
118 /**
119 * Constant pool entry types.
120 */
121 static final byte
122 CONSTANT_Utf8 = 1,
123 CONSTANT_Integer = 3,
124 CONSTANT_Float = 4,
125 CONSTANT_Long = 5,
126 CONSTANT_Double = 6,
127 CONSTANT_Class = 7,
128 CONSTANT_String = 8,
129 CONSTANT_Fieldref = 9,
130 CONSTANT_Methodref = 10,
131 CONSTANT_InterfaceMethodref = 11,
132 CONSTANT_NameAndType = 12,
133 CONSTANT_MethodHandle = 15, // JSR 292
134 CONSTANT_MethodType = 16, // JSR 292
135 CONSTANT_InvokeDynamic = 18,
136 CONSTANT_LIMIT = 19; // Limit to tags found in classfiles
137
138 /**
139 * Access modifier flags.
140 */
141 static final char
142 ACC_PUBLIC = 0x0001,
143 ACC_PRIVATE = 0x0002,
144 ACC_PROTECTED = 0x0004,
145 ACC_STATIC = 0x0008,
146 ACC_FINAL = 0x0010,
147 ACC_SYNCHRONIZED = 0x0020,
148 ACC_VOLATILE = 0x0040,
149 ACC_TRANSIENT = 0x0080,
150 ACC_NATIVE = 0x0100,
151 ACC_INTERFACE = 0x0200,
152 ACC_ABSTRACT = 0x0400,
153 ACC_STRICT = 0x0800,
154 ACC_SYNTHETIC = 0x1000,
155 ACC_ANNOTATION = 0x2000,
156 ACC_ENUM = 0x4000,
157 // aliases:
158 ACC_SUPER = ACC_SYNCHRONIZED,
159 ACC_BRIDGE = ACC_VOLATILE,
160 ACC_VARARGS = ACC_TRANSIENT;
161
162 /**
163 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
164 */
165 static final byte
166 REF_NONE = 0, // null value
167 REF_getField = 1,
168 REF_getStatic = 2,
169 REF_putField = 3,
170 REF_putStatic = 4,
171 REF_invokeVirtual = 5,
172 REF_invokeStatic = 6,
173 REF_invokeSpecial = 7,
174 REF_newInvokeSpecial = 8,
175 REF_invokeInterface = 9,
176 REF_LIMIT = 10;
177 }
178
179 static boolean refKindIsValid(int refKind) {
180 return (refKind > REF_NONE && refKind < REF_LIMIT);
181 }
182 static boolean refKindIsField(byte refKind) {
183 assert(refKindIsValid(refKind));
184 return (refKind <= REF_putStatic);
185 }
186 static boolean refKindIsGetter(byte refKind) {
187 assert(refKindIsValid(refKind));
188 return (refKind <= REF_getStatic);
189 }
190 static boolean refKindIsSetter(byte refKind) {
191 return refKindIsField(refKind) && !refKindIsGetter(refKind);
192 }
193 static boolean refKindIsMethod(byte refKind) {
194 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
195 }
196 static boolean refKindIsConstructor(byte refKind) {
197 return (refKind == REF_newInvokeSpecial);
198 }
199 static boolean refKindHasReceiver(byte refKind) {
200 assert(refKindIsValid(refKind));
201 return (refKind & 1) != 0;
202 }
203 static boolean refKindIsStatic(byte refKind) {
204 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
205 }
206 static boolean refKindDoesDispatch(byte refKind) {
207 assert(refKindIsValid(refKind));
208 return (refKind == REF_invokeVirtual ||
209 refKind == REF_invokeInterface);
210 }
211 static {
212 final int HR_MASK = ((1 << REF_getField) |
213 (1 << REF_putField) |
214 (1 << REF_invokeVirtual) |
215 (1 << REF_invokeSpecial) |
216 (1 << REF_invokeInterface)
217 );
218 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
219 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
220 }
221 }
222 static String refKindName(byte refKind) {
223 assert(refKindIsValid(refKind));
224 switch (refKind) {
225 case REF_getField: return "getField";
226 case REF_getStatic: return "getStatic";
227 case REF_putField: return "putField";
228 case REF_putStatic: return "putStatic";
229 case REF_invokeVirtual: return "invokeVirtual";
230 case REF_invokeStatic: return "invokeStatic";
231 case REF_invokeSpecial: return "invokeSpecial";
232 case REF_newInvokeSpecial: return "newInvokeSpecial";
233 case REF_invokeInterface: return "invokeInterface";
234 default: return "REF_???";
235 }
236 }
237
238 private static native int getNamedCon(int which, Object[] name);
239 static boolean verifyConstants() {
240 Object[] box = { null };
241 for (int i = 0; ; i++) {
242 box[0] = null;
243 int vmval = getNamedCon(i, box);
244 if (box[0] == null) break;
245 String name = (String) box[0];
246 try {
247 Field con = Constants.class.getDeclaredField(name);
248 int jval = con.getInt(null);
249 if (jval == vmval) continue;
250 String err = (name+": JVM has "+vmval+" while Java has "+jval);
251 if (name.equals("CONV_OP_LIMIT")) {
252 System.err.println("warning: "+err);
253 continue;
254 }
255 throw new InternalError(err);
256 } catch (NoSuchFieldException | IllegalAccessException ex) {
257 String err = (name+": JVM has "+vmval+" which Java does not define");
258 // ignore exotic ops the JVM cares about; we just wont issue them
259 //System.err.println("warning: "+err);
260 continue;
261 }
262 }
263 return true;
264 }
265 static {
266 assert(verifyConstants());
267 }
268
269 // Up-calls from the JVM.
270 // These must NOT be public.
271
272 /**
273 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
274 */
275 static MemberName linkCallSite(Object callerObj,
276 Object bootstrapMethodObj,
277 Object nameObj, Object typeObj,
278 Object staticArguments,
279 Object[] appendixResult) {
280 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
281 Class<?> caller = (Class<?>)callerObj;
282 String name = nameObj.toString().intern();
283 MethodType type = (MethodType)typeObj;
284 if (!TRACE_METHOD_LINKAGE)
285 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
286 staticArguments, appendixResult);
287 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
288 staticArguments, appendixResult);
289 }
290 static MemberName linkCallSiteImpl(Class<?> caller,
291 MethodHandle bootstrapMethod,
292 String name, MethodType type,
293 Object staticArguments,
294 Object[] appendixResult) {
295 CallSite callSite = CallSite.makeSite(bootstrapMethod,
296 name,
297 type,
298 staticArguments,
299 caller);
300 if (callSite instanceof ConstantCallSite) {
301 appendixResult[0] = callSite.dynamicInvoker();
302 return Invokers.linkToTargetMethod(type);
303 } else {
304 appendixResult[0] = callSite;
305 return Invokers.linkToCallSiteMethod(type);
306 }
307 }
308 // Tracing logic:
309 static MemberName linkCallSiteTracing(Class<?> caller,
310 MethodHandle bootstrapMethod,
311 String name, MethodType type,
312 Object staticArguments,
313 Object[] appendixResult) {
314 Object bsmReference = bootstrapMethod.internalMemberName();
315 if (bsmReference == null) bsmReference = bootstrapMethod;
316 Object staticArglist = (staticArguments instanceof Object[] ?
317 java.util.Arrays.asList((Object[]) staticArguments) :
318 staticArguments);
319 System.out.println("linkCallSite "+caller.getName()+" "+
320 bsmReference+" "+
321 name+type+"/"+staticArglist);
322 try {
323 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
324 staticArguments, appendixResult);
325 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
326 return res;
327 } catch (Throwable ex) {
328 System.out.println("linkCallSite => throw "+ex);
329 throw ex;
330 }
331 }
332
333 /**
334 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
335 */
336 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
337 return MethodType.makeImpl(rtype, ptypes, true);
338 }
339
340 /**
341 * The JVM wants to link a call site that requires a dynamic type check.
342 * Name is a type-checking invoker, invokeExact or invoke.
343 * Return a JVM method (MemberName) to handle the invoking.
344 * The method assumes the following arguments on the stack:
345 * 0: the method handle being invoked
346 * 1-N: the arguments to the method handle invocation
347 * N+1: an optional, implicitly added argument (typically the given MethodType)
348 * <p>
349 * The nominal method at such a call site is an instance of
350 * a signature-polymorphic method (see @PolymorphicSignature).
351 * Such method instances are user-visible entities which are
352 * "split" from the generic placeholder method in {@code MethodHandle}.
353 * (Note that the placeholder method is not identical with any of
354 * its instances. If invoked reflectively, is guaranteed to throw an
355 * {@code UnsupportedOperationException}.)
356 * If the signature-polymorphic method instance is ever reified,
357 * it appears as a "copy" of the original placeholder
358 * (a native final member of {@code MethodHandle}) except
359 * that its type descriptor has shape required by the instance,
360 * and the method instance is <em>not</em> varargs.
361 * The method instance is also marked synthetic, since the
362 * method (by definition) does not appear in Java source code.
363 * <p>
364 * The JVM is allowed to reify this method as instance metadata.
365 * For example, {@code invokeBasic} is always reified.
366 * But the JVM may instead call {@code linkMethod}.
367 * If the result is an * ordered pair of a {@code (method, appendix)},
368 * the method gets all the arguments (0..N inclusive)
369 * plus the appendix (N+1), and uses the appendix to complete the call.
370 * In this way, one reusable method (called a "linker method")
371 * can perform the function of any number of polymorphic instance
372 * methods.
373 * <p>
374 * Linker methods are allowed to be weakly typed, with any or
375 * all references rewritten to {@code Object} and any primitives
376 * (except {@code long}/{@code float}/{@code double})
377 * rewritten to {@code int}.
378 * A linker method is trusted to return a strongly typed result,
379 * according to the specific method type descriptor of the
380 * signature-polymorphic instance it is emulating.
381 * This can involve (as necessary) a dynamic check using
382 * data extracted from the appendix argument.
383 * <p>
384 * The JVM does not inspect the appendix, other than to pass
385 * it verbatim to the linker method at every call.
386 * This means that the JDK runtime has wide latitude
387 * for choosing the shape of each linker method and its
388 * corresponding appendix.
389 * Linker methods should be generated from {@code LambdaForm}s
390 * so that they do not become visible on stack traces.
391 * <p>
392 * The {@code linkMethod} call is free to omit the appendix
393 * (returning null) and instead emulate the required function
394 * completely in the linker method.
395 * As a corner case, if N==255, no appendix is possible.
396 * In this case, the method returned must be custom-generated to
397 * to perform any needed type checking.
398 * <p>
399 * If the JVM does not reify a method at a call site, but instead
400 * calls {@code linkMethod}, the corresponding call represented
401 * in the bytecodes may mention a valid method which is not
402 * representable with a {@code MemberName}.
403 * Therefore, use cases for {@code linkMethod} tend to correspond to
404 * special cases in reflective code such as {@code findVirtual}
405 * or {@code revealDirect}.
406 */
407 static MemberName linkMethod(Class<?> callerClass, int refKind,
408 Class<?> defc, String name, Object type,
409 Object[] appendixResult) {
410 if (!TRACE_METHOD_LINKAGE)
411 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
412 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
413 }
414 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
415 Class<?> defc, String name, Object type,
416 Object[] appendixResult) {
417 try {
418 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
419 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
420 }
421 } catch (Throwable ex) {
422 if (ex instanceof LinkageError)
423 throw (LinkageError) ex;
424 else
425 throw new LinkageError(ex.getMessage(), ex);
426 }
427 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
428 }
429 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
430 if (type instanceof MethodType)
431 return (MethodType) type;
432 else
433 return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());
434 }
435 // Tracing logic:
436 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
437 Class<?> defc, String name, Object type,
438 Object[] appendixResult) {
439 System.out.println("linkMethod "+defc.getName()+"."+
440 name+type+"/"+Integer.toHexString(refKind));
441 try {
442 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
443 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
444 return res;
445 } catch (Throwable ex) {
446 System.out.println("linkMethod => throw "+ex);
447 throw ex;
448 }
449 }
450
451
452 /**
453 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
454 * It will make an up-call to this method. (Do not change the name or signature.)
455 * The type argument is a Class for field requests and a MethodType for non-fields.
456 * <p>
457 * Recent versions of the JVM may also pass a resolved MemberName for the type.
458 * In that case, the name is ignored and may be null.
459 */
460 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
461 Class<?> defc, String name, Object type) {
462 try {
463 Lookup lookup = IMPL_LOOKUP.in(callerClass);
464 assert(refKindIsValid(refKind));
465 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
466 } catch (IllegalAccessException ex) {
467 Throwable cause = ex.getCause();
468 if (cause instanceof AbstractMethodError) {
469 throw (AbstractMethodError) cause;
470 } else {
471 Error err = new IllegalAccessError(ex.getMessage());
472 throw initCauseFrom(err, ex);
473 }
474 } catch (NoSuchMethodException ex) {
475 Error err = new NoSuchMethodError(ex.getMessage());
476 throw initCauseFrom(err, ex);
477 } catch (NoSuchFieldException ex) {
478 Error err = new NoSuchFieldError(ex.getMessage());
479 throw initCauseFrom(err, ex);
480 } catch (ReflectiveOperationException ex) {
481 Error err = new IncompatibleClassChangeError();
482 throw initCauseFrom(err, ex);
483 }
484 }
485
486 /**
487 * Use best possible cause for err.initCause(), substituting the
488 * cause for err itself if the cause has the same (or better) type.
489 */
490 static private Error initCauseFrom(Error err, Exception ex) {
491 Throwable th = ex.getCause();
492 if (err.getClass().isInstance(th))
493 return (Error) th;
494 err.initCause(th == null ? ex : th);
495 return err;
496 }
497
498 /**
499 * Is this method a caller-sensitive method?
500 * I.e., does it call Reflection.getCallerClass or a similar method
501 * to ask about the identity of its caller?
502 */
503 static boolean isCallerSensitive(MemberName mem) {
504 if (!mem.isInvocable()) return false; // fields are not caller sensitive
505
506 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
507 }
508
509 static boolean canBeCalledVirtual(MemberName mem) {
510 assert(mem.isInvocable());
511 Class<?> defc = mem.getDeclaringClass();
512 switch (mem.getName()) {
513 case "checkMemberAccess":
514 return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
515 case "getContextClassLoader":
516 return canBeCalledVirtual(mem, java.lang.Thread.class);
517 }
518 return false;
519 }
520
521 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
522 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
523 if (symbolicRefClass == definingClass) return true;
524 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
525 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
526 symbolicRefClass.isInterface()); // Mdef implements Msym
527 }
528 }