1 /*
2 * Copyright (c) 2008, 2013, 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 /// MethodHandle support
59
60 /** Fetch MH-related JVM parameter.
61 * which=0 retrieves MethodHandlePushLimit
62 * which=1 retrieves stack slot push size (in address units)
63 */
64 static native int getConstant(int which);
65
66 static final boolean COUNT_GWT;
67
68 /// CallSite support
69
70 /** Tell the JVM that we need to change the target of a CallSite. */
71 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
72 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
73
74 private static native void registerNatives();
75 static {
76 registerNatives();
77 COUNT_GWT = getConstant(Constants.GC_COUNT_GWT) != 0;
78
79 // The JVM calls MethodHandleNatives.<clinit>. Cascade the <clinit> calls as needed:
80 MethodHandleImpl.initStatics();
81 }
82
83 // All compile-time constants go here.
84 // There is an opportunity to check them against the JVM's idea of them.
85 static class Constants {
86 Constants() { } // static only
87 // MethodHandleImpl
88 static final int // for getConstant
89 GC_COUNT_GWT = 4,
90 GC_LAMBDA_SUPPORT = 5;
91
92 // MemberName
93 // The JVM uses values of -2 and above for vtable indexes.
94 // Field values are simple positive offsets.
95 // Ref: src/share/vm/oops/methodOop.hpp
96 // This value is negative enough to avoid such numbers,
97 // but not too negative.
98 static final int
99 MN_IS_METHOD = 0x00010000, // method (not constructor)
100 MN_IS_CONSTRUCTOR = 0x00020000, // constructor
101 MN_IS_FIELD = 0x00040000, // field
102 MN_IS_TYPE = 0x00080000, // nested type
103 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
104 MN_REFERENCE_KIND_SHIFT = 24, // refKind
105 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
106 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
107 MN_SEARCH_SUPERCLASSES = 0x00100000,
108 MN_SEARCH_INTERFACES = 0x00200000;
109
110 /**
111 * Basic types as encoded in the JVM. These code values are not
112 * intended for use outside this class. They are used as part of
113 * a private interface between the JVM and this class.
114 */
115 static final int
116 T_BOOLEAN = 4,
117 T_CHAR = 5,
118 T_FLOAT = 6,
119 T_DOUBLE = 7,
120 T_BYTE = 8,
121 T_SHORT = 9,
122 T_INT = 10,
123 T_LONG = 11,
124 T_OBJECT = 12,
125 //T_ARRAY = 13
126 T_VOID = 14,
127 //T_ADDRESS = 15
128 T_ILLEGAL = 99;
129
130 /**
131 * Constant pool entry types.
132 */
133 static final byte
134 CONSTANT_Utf8 = 1,
135 CONSTANT_Integer = 3,
136 CONSTANT_Float = 4,
137 CONSTANT_Long = 5,
138 CONSTANT_Double = 6,
139 CONSTANT_Class = 7,
140 CONSTANT_String = 8,
141 CONSTANT_Fieldref = 9,
142 CONSTANT_Methodref = 10,
143 CONSTANT_InterfaceMethodref = 11,
144 CONSTANT_NameAndType = 12,
145 CONSTANT_MethodHandle = 15, // JSR 292
146 CONSTANT_MethodType = 16, // JSR 292
147 CONSTANT_InvokeDynamic = 18,
148 CONSTANT_LIMIT = 19; // Limit to tags found in classfiles
149
150 /**
151 * Access modifier flags.
152 */
153 static final char
154 ACC_PUBLIC = 0x0001,
155 ACC_PRIVATE = 0x0002,
156 ACC_PROTECTED = 0x0004,
157 ACC_STATIC = 0x0008,
158 ACC_FINAL = 0x0010,
159 ACC_SYNCHRONIZED = 0x0020,
160 ACC_VOLATILE = 0x0040,
161 ACC_TRANSIENT = 0x0080,
162 ACC_NATIVE = 0x0100,
163 ACC_INTERFACE = 0x0200,
164 ACC_ABSTRACT = 0x0400,
165 ACC_STRICT = 0x0800,
166 ACC_SYNTHETIC = 0x1000,
167 ACC_ANNOTATION = 0x2000,
168 ACC_ENUM = 0x4000,
169 // aliases:
170 ACC_SUPER = ACC_SYNCHRONIZED,
171 ACC_BRIDGE = ACC_VOLATILE,
172 ACC_VARARGS = ACC_TRANSIENT;
173
174 /**
175 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
176 */
177 static final byte
178 REF_NONE = 0, // null value
179 REF_getField = 1,
180 REF_getStatic = 2,
181 REF_putField = 3,
182 REF_putStatic = 4,
183 REF_invokeVirtual = 5,
184 REF_invokeStatic = 6,
185 REF_invokeSpecial = 7,
186 REF_newInvokeSpecial = 8,
187 REF_invokeInterface = 9,
188 REF_LIMIT = 10;
189 }
190
191 static boolean refKindIsValid(int refKind) {
192 return (refKind > REF_NONE && refKind < REF_LIMIT);
193 }
194 static boolean refKindIsField(byte refKind) {
195 assert(refKindIsValid(refKind));
196 return (refKind <= REF_putStatic);
197 }
198 static boolean refKindIsGetter(byte refKind) {
199 assert(refKindIsValid(refKind));
200 return (refKind <= REF_getStatic);
201 }
202 static boolean refKindIsSetter(byte refKind) {
203 return refKindIsField(refKind) && !refKindIsGetter(refKind);
204 }
205 static boolean refKindIsMethod(byte refKind) {
206 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
207 }
208 static boolean refKindIsConstructor(byte refKind) {
209 return (refKind == REF_newInvokeSpecial);
210 }
211 static boolean refKindHasReceiver(byte refKind) {
212 assert(refKindIsValid(refKind));
213 return (refKind & 1) != 0;
214 }
215 static boolean refKindIsStatic(byte refKind) {
216 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
217 }
218 static boolean refKindDoesDispatch(byte refKind) {
219 assert(refKindIsValid(refKind));
220 return (refKind == REF_invokeVirtual ||
221 refKind == REF_invokeInterface);
222 }
223 static {
224 final int HR_MASK = ((1 << REF_getField) |
225 (1 << REF_putField) |
226 (1 << REF_invokeVirtual) |
227 (1 << REF_invokeSpecial) |
228 (1 << REF_invokeInterface)
229 );
230 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
231 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
232 }
233 }
234 static String refKindName(byte refKind) {
235 assert(refKindIsValid(refKind));
236 switch (refKind) {
237 case REF_getField: return "getField";
238 case REF_getStatic: return "getStatic";
239 case REF_putField: return "putField";
240 case REF_putStatic: return "putStatic";
241 case REF_invokeVirtual: return "invokeVirtual";
242 case REF_invokeStatic: return "invokeStatic";
243 case REF_invokeSpecial: return "invokeSpecial";
244 case REF_newInvokeSpecial: return "newInvokeSpecial";
245 case REF_invokeInterface: return "invokeInterface";
246 default: return "REF_???";
247 }
248 }
249
250 private static native int getNamedCon(int which, Object[] name);
251 static boolean verifyConstants() {
252 Object[] box = { null };
253 for (int i = 0; ; i++) {
254 box[0] = null;
255 int vmval = getNamedCon(i, box);
256 if (box[0] == null) break;
257 String name = (String) box[0];
258 try {
259 Field con = Constants.class.getDeclaredField(name);
260 int jval = con.getInt(null);
261 if (jval == vmval) continue;
262 String err = (name+": JVM has "+vmval+" while Java has "+jval);
263 if (name.equals("CONV_OP_LIMIT")) {
264 System.err.println("warning: "+err);
265 continue;
266 }
267 throw new InternalError(err);
268 } catch (NoSuchFieldException | IllegalAccessException ex) {
269 String err = (name+": JVM has "+vmval+" which Java does not define");
270 // ignore exotic ops the JVM cares about; we just wont issue them
271 //System.err.println("warning: "+err);
272 continue;
273 }
274 }
275 return true;
276 }
277 static {
278 assert(verifyConstants());
279 }
280
281 // Up-calls from the JVM.
282 // These must NOT be public.
283
284 /**
285 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
286 */
287 static MemberName linkCallSite(Object callerObj,
288 Object bootstrapMethodObj,
289 Object nameObj, Object typeObj,
290 Object staticArguments,
291 Object[] appendixResult) {
292 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
293 Class<?> caller = (Class<?>)callerObj;
294 String name = nameObj.toString().intern();
295 MethodType type = (MethodType)typeObj;
296 CallSite callSite = CallSite.makeSite(bootstrapMethod,
297 name,
298 type,
299 staticArguments,
300 caller);
301 if (callSite instanceof ConstantCallSite) {
302 appendixResult[0] = callSite.dynamicInvoker();
303 return Invokers.linkToTargetMethod(type);
304 } else {
305 appendixResult[0] = callSite;
306 return Invokers.linkToCallSiteMethod(type);
307 }
308 }
309
310 /**
311 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
312 */
313 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
314 return MethodType.makeImpl(rtype, ptypes, true);
315 }
316
317 /**
318 * The JVM wants to link a call site that requires a dynamic type check.
319 * Name is a type-checking invoker, invokeExact or invoke.
320 * Return a JVM method (MemberName) to handle the invoking.
321 * The method assumes the following arguments on the stack:
322 * 0: the method handle being invoked
323 * 1-N: the arguments to the method handle invocation
324 * N+1: an optional, implicitly added argument (typically the given MethodType)
325 * <p>
326 * The nominal method at such a call site is an instance of
327 * a signature-polymorphic method (see @PolymorphicSignature).
328 * Such method instances are user-visible entities which are
329 * "split" from the generic placeholder method in {@code MethodHandle}.
330 * (Note that the placeholder method is not identical with any of
331 * its instances. If invoked reflectively, is guaranteed to throw an
332 * {@code UnsupportedOperationException}.)
333 * If the signature-polymorphic method instance is ever reified,
334 * it appears as a "copy" of the original placeholder
335 * (a native final member of {@code MethodHandle}) except
336 * that its type descriptor has shape required by the instance,
337 * and the method instance is <em>not</em> varargs.
338 * The method instance is also marked synthetic, since the
339 * method (by definition) does not appear in Java source code.
340 * <p>
341 * The JVM is allowed to reify this method as instance metadata.
342 * For example, {@code invokeBasic} is always reified.
343 * But the JVM may instead call {@code linkMethod}.
344 * If the result is an * ordered pair of a {@code (method, appendix)},
345 * the method gets all the arguments (0..N inclusive)
346 * plus the appendix (N+1), and uses the appendix to complete the call.
347 * In this way, one reusable method (called a "linker method")
348 * can perform the function of any number of polymorphic instance
349 * methods.
350 * <p>
351 * Linker methods are allowed to be weakly typed, with any or
352 * all references rewritten to {@code Object} and any primitives
353 * (except {@code long}/{@code float}/{@code double})
354 * rewritten to {@code int}.
355 * A linker method is trusted to return a strongly typed result,
356 * according to the specific method type descriptor of the
357 * signature-polymorphic instance it is emulating.
358 * This can involve (as necessary) a dynamic check using
359 * data extracted from the appendix argument.
360 * <p>
361 * The JVM does not inspect the appendix, other than to pass
362 * it verbatim to the linker method at every call.
363 * This means that the JDK runtime has wide latitude
364 * for choosing the shape of each linker method and its
365 * corresponding appendix.
366 * Linker methods should be generated from {@code LambdaForm}s
367 * so that they do not become visible on stack traces.
368 * <p>
369 * The {@code linkMethod} call is free to omit the appendix
370 * (returning null) and instead emulate the required function
371 * completely in the linker method.
372 * As a corner case, if N==255, no appendix is possible.
373 * In this case, the method returned must be custom-generated to
374 * to perform any needed type checking.
375 * <p>
376 * If the JVM does not reify a method at a call site, but instead
377 * calls {@code linkMethod}, the corresponding call represented
378 * in the bytecodes may mention a valid method which is not
379 * representable with a {@code MemberName}.
380 * Therefore, use cases for {@code linkMethod} tend to correspond to
381 * special cases in reflective code such as {@code findVirtual}
382 * or {@code revealDirect}.
383 */
384 static MemberName linkMethod(Class<?> callerClass, int refKind,
385 Class<?> defc, String name, Object type,
386 Object[] appendixResult) {
387 if (!TRACE_METHOD_LINKAGE)
388 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
389 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
390 }
391 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
392 Class<?> defc, String name, Object type,
393 Object[] appendixResult) {
394 try {
395 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
396 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
397 }
398 } catch (Throwable ex) {
399 if (ex instanceof LinkageError)
400 throw (LinkageError) ex;
401 else
402 throw new LinkageError(ex.getMessage(), ex);
403 }
404 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
405 }
406 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
407 if (type instanceof MethodType)
408 return (MethodType) type;
409 else
410 return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());
411 }
412 // Tracing logic:
413 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
414 Class<?> defc, String name, Object type,
415 Object[] appendixResult) {
416 System.out.println("linkMethod "+defc.getName()+"."+
417 name+type+"/"+Integer.toHexString(refKind));
418 try {
419 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
420 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
421 return res;
422 } catch (Throwable ex) {
423 System.out.println("linkMethod => throw "+ex);
424 throw ex;
425 }
426 }
427
428
429 /**
430 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
431 * It will make an up-call to this method. (Do not change the name or signature.)
432 * The type argument is a Class for field requests and a MethodType for non-fields.
433 * <p>
434 * Recent versions of the JVM may also pass a resolved MemberName for the type.
435 * In that case, the name is ignored and may be null.
436 */
437 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
438 Class<?> defc, String name, Object type) {
439 try {
440 Lookup lookup = IMPL_LOOKUP.in(callerClass);
441 assert(refKindIsValid(refKind));
442 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
443 } catch (IllegalAccessException ex) {
444 Throwable cause = ex.getCause();
445 if (cause instanceof AbstractMethodError) {
446 throw (AbstractMethodError) cause;
447 } else {
448 Error err = new IllegalAccessError(ex.getMessage());
449 throw initCauseFrom(err, ex);
450 }
451 } catch (NoSuchMethodException ex) {
452 Error err = new NoSuchMethodError(ex.getMessage());
453 throw initCauseFrom(err, ex);
454 } catch (NoSuchFieldException ex) {
455 Error err = new NoSuchFieldError(ex.getMessage());
456 throw initCauseFrom(err, ex);
457 } catch (ReflectiveOperationException ex) {
458 Error err = new IncompatibleClassChangeError();
459 throw initCauseFrom(err, ex);
460 }
461 }
462
463 /**
464 * Use best possible cause for err.initCause(), substituting the
465 * cause for err itself if the cause has the same (or better) type.
466 */
467 static private Error initCauseFrom(Error err, Exception ex) {
468 Throwable th = ex.getCause();
469 if (err.getClass().isInstance(th))
470 return (Error) th;
471 err.initCause(th == null ? ex : th);
472 return err;
473 }
474
475 /**
476 * Is this method a caller-sensitive method?
477 * I.e., does it call Reflection.getCallerClass or a similer method
478 * to ask about the identity of its caller?
479 */
480 static boolean isCallerSensitive(MemberName mem) {
481 if (!mem.isInvocable()) return false; // fields are not caller sensitive
482
483 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
484 }
485
486 static boolean canBeCalledVirtual(MemberName mem) {
487 assert(mem.isInvocable());
488 Class<?> defc = mem.getDeclaringClass();
489 switch (mem.getName()) {
490 case "checkMemberAccess":
491 return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
492 case "getContextClassLoader":
493 return canBeCalledVirtual(mem, java.lang.Thread.class);
494 }
495 return false;
496 }
497
498 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
499 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
500 if (symbolicRefClass == definingClass) return true;
501 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
502 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
503 symbolicRefClass.isInterface()); // Mdef implements Msym
504 }
505 }