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