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 // All compile-time constants go here.
73 // There is an opportunity to check them against the JVM's idea of them.
74 static class Constants {
75 Constants() { } // static only
76
77 /**
78 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
79 */
80 static final byte
81 REF_NONE = 0, // null value
82 REF_getField = 1,
83 REF_getStatic = 2,
84 REF_putField = 3,
85 REF_putStatic = 4,
86 REF_invokeVirtual = 5,
87 REF_invokeStatic = 6,
88 REF_invokeSpecial = 7,
89 REF_newInvokeSpecial = 8,
90 REF_invokeInterface = 9,
91 REF_LIMIT = 10;
92 }
93
94 static boolean refKindIsValid(int refKind) {
95 return (refKind > REF_NONE && refKind < REF_LIMIT);
96 }
97 static boolean refKindIsField(byte refKind) {
98 assert(refKindIsValid(refKind));
99 return (refKind <= REF_putStatic);
100 }
101 static boolean refKindIsGetter(byte refKind) {
102 assert(refKindIsValid(refKind));
103 return (refKind <= REF_getStatic);
104 }
105 static boolean refKindIsSetter(byte refKind) {
106 return refKindIsField(refKind) && !refKindIsGetter(refKind);
107 }
108 static boolean refKindIsMethod(byte refKind) {
109 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
110 }
111 static boolean refKindIsConstructor(byte refKind) {
112 return (refKind == REF_newInvokeSpecial);
113 }
114 static boolean refKindHasReceiver(byte refKind) {
115 assert(refKindIsValid(refKind));
116 return (refKind & 1) != 0;
117 }
118 static boolean refKindIsStatic(byte refKind) {
119 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
120 }
121 static boolean refKindDoesDispatch(byte refKind) {
122 assert(refKindIsValid(refKind));
123 return (refKind == REF_invokeVirtual ||
124 refKind == REF_invokeInterface);
125 }
126 static {
127 final int HR_MASK = ((1 << REF_getField) |
128 (1 << REF_putField) |
129 (1 << REF_invokeVirtual) |
130 (1 << REF_invokeSpecial) |
131 (1 << REF_invokeInterface)
132 );
133 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
134 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
135 }
136 }
137 static String refKindName(byte refKind) {
138 assert(refKindIsValid(refKind));
139 switch (refKind) {
140 case REF_getField: return "getField";
141 case REF_getStatic: return "getStatic";
142 case REF_putField: return "putField";
143 case REF_putStatic: return "putStatic";
144 case REF_invokeVirtual: return "invokeVirtual";
145 case REF_invokeStatic: return "invokeStatic";
146 case REF_invokeSpecial: return "invokeSpecial";
147 case REF_newInvokeSpecial: return "newInvokeSpecial";
148 case REF_invokeInterface: return "invokeInterface";
149 default: return "REF_???";
150 }
151 }
152
153 private static native int getNamedCon(int which, Object[] name);
154 static boolean verifyConstants() {
155 Object[] box = { null };
156 for (int i = 0; ; i++) {
157 box[0] = null;
158 int vmval = getNamedCon(i, box);
159 if (box[0] == null) break;
160 String name = (String) box[0];
161 try {
162 Field con = Constants.class.getDeclaredField(name);
163 int jval = con.getInt(null);
164 if (jval == vmval) continue;
165 String err = (name+": JVM has "+vmval+" while Java has "+jval);
166 if (name.equals("CONV_OP_LIMIT")) {
167 System.err.println("warning: "+err);
168 continue;
169 }
170 throw new InternalError(err);
171 } catch (NoSuchFieldException | IllegalAccessException ex) {
172 String err = (name+": JVM has "+vmval+" which Java does not define");
173 // ignore exotic ops the JVM cares about; we just wont issue them
174 //System.err.println("warning: "+err);
175 continue;
176 }
177 }
178 return true;
179 }
180 static {
181 assert(verifyConstants());
182 }
183
184 // Up-calls from the JVM.
185 // These must NOT be public.
186
187 /**
188 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
189 */
190 static MemberName linkCallSite(Object callerObj,
191 Object bootstrapMethodObj,
192 Object nameObj, Object typeObj,
193 Object staticArguments,
194 Object[] appendixResult) {
195 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
196 Class<?> caller = (Class<?>)callerObj;
197 String name = nameObj.toString().intern();
198 MethodType type = (MethodType)typeObj;
199 if (!TRACE_METHOD_LINKAGE)
200 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
201 staticArguments, appendixResult);
202 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
203 staticArguments, appendixResult);
204 }
205 static MemberName linkCallSiteImpl(Class<?> caller,
206 MethodHandle bootstrapMethod,
207 String name, MethodType type,
208 Object staticArguments,
209 Object[] appendixResult) {
210 CallSite callSite = CallSite.makeSite(bootstrapMethod,
211 name,
212 type,
213 staticArguments,
214 caller);
215 if (callSite instanceof ConstantCallSite) {
216 appendixResult[0] = callSite.dynamicInvoker();
217 return Invokers.linkToTargetMethod(type);
218 } else {
219 appendixResult[0] = callSite;
220 return Invokers.linkToCallSiteMethod(type);
221 }
222 }
223 // Tracing logic:
224 static MemberName linkCallSiteTracing(Class<?> caller,
225 MethodHandle bootstrapMethod,
226 String name, MethodType type,
227 Object staticArguments,
228 Object[] appendixResult) {
229 Object bsmReference = bootstrapMethod.internalMemberName();
230 if (bsmReference == null) bsmReference = bootstrapMethod;
231 Object staticArglist = (staticArguments instanceof Object[] ?
232 java.util.Arrays.asList((Object[]) staticArguments) :
233 staticArguments);
234 System.out.println("linkCallSite "+caller.getName()+" "+
235 bsmReference+" "+
236 name+type+"/"+staticArglist);
237 try {
238 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
239 staticArguments, appendixResult);
240 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
241 return res;
242 } catch (Throwable ex) {
243 System.out.println("linkCallSite => throw "+ex);
244 throw ex;
245 }
246 }
247
248 /**
249 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
250 */
251 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
252 return MethodType.makeImpl(rtype, ptypes, true);
253 }
254
255 /**
256 * The JVM wants to link a call site that requires a dynamic type check.
257 * Name is a type-checking invoker, invokeExact or invoke.
258 * Return a JVM method (MemberName) to handle the invoking.
259 * The method assumes the following arguments on the stack:
260 * 0: the method handle being invoked
261 * 1-N: the arguments to the method handle invocation
262 * N+1: an optional, implicitly added argument (typically the given MethodType)
263 * <p>
264 * The nominal method at such a call site is an instance of
265 * a signature-polymorphic method (see @PolymorphicSignature).
266 * Such method instances are user-visible entities which are
267 * "split" from the generic placeholder method in {@code MethodHandle}.
268 * (Note that the placeholder method is not identical with any of
269 * its instances. If invoked reflectively, is guaranteed to throw an
270 * {@code UnsupportedOperationException}.)
271 * If the signature-polymorphic method instance is ever reified,
272 * it appears as a "copy" of the original placeholder
273 * (a native final member of {@code MethodHandle}) except
274 * that its type descriptor has shape required by the instance,
275 * and the method instance is <em>not</em> varargs.
276 * The method instance is also marked synthetic, since the
277 * method (by definition) does not appear in Java source code.
278 * <p>
279 * The JVM is allowed to reify this method as instance metadata.
280 * For example, {@code invokeBasic} is always reified.
281 * But the JVM may instead call {@code linkMethod}.
282 * If the result is an * ordered pair of a {@code (method, appendix)},
283 * the method gets all the arguments (0..N inclusive)
284 * plus the appendix (N+1), and uses the appendix to complete the call.
285 * In this way, one reusable method (called a "linker method")
286 * can perform the function of any number of polymorphic instance
287 * methods.
288 * <p>
289 * Linker methods are allowed to be weakly typed, with any or
290 * all references rewritten to {@code Object} and any primitives
291 * (except {@code long}/{@code float}/{@code double})
292 * rewritten to {@code int}.
293 * A linker method is trusted to return a strongly typed result,
294 * according to the specific method type descriptor of the
295 * signature-polymorphic instance it is emulating.
296 * This can involve (as necessary) a dynamic check using
297 * data extracted from the appendix argument.
298 * <p>
299 * The JVM does not inspect the appendix, other than to pass
300 * it verbatim to the linker method at every call.
301 * This means that the JDK runtime has wide latitude
302 * for choosing the shape of each linker method and its
303 * corresponding appendix.
304 * Linker methods should be generated from {@code LambdaForm}s
305 * so that they do not become visible on stack traces.
306 * <p>
307 * The {@code linkMethod} call is free to omit the appendix
308 * (returning null) and instead emulate the required function
309 * completely in the linker method.
310 * As a corner case, if N==255, no appendix is possible.
311 * In this case, the method returned must be custom-generated to
312 * to perform any needed type checking.
313 * <p>
314 * If the JVM does not reify a method at a call site, but instead
315 * calls {@code linkMethod}, the corresponding call represented
316 * in the bytecodes may mention a valid method which is not
317 * representable with a {@code MemberName}.
318 * Therefore, use cases for {@code linkMethod} tend to correspond to
319 * special cases in reflective code such as {@code findVirtual}
320 * or {@code revealDirect}.
321 */
322 static MemberName linkMethod(Class<?> callerClass, int refKind,
323 Class<?> defc, String name, Object type,
324 Object[] appendixResult) {
325 if (!TRACE_METHOD_LINKAGE)
326 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
327 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
328 }
329 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
330 Class<?> defc, String name, Object type,
331 Object[] appendixResult) {
332 try {
333 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
334 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
335 }
336 } catch (Throwable ex) {
337 if (ex instanceof LinkageError)
338 throw (LinkageError) ex;
339 else
340 throw new LinkageError(ex.getMessage(), ex);
341 }
342 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
343 }
344 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
345 if (type instanceof MethodType)
346 return (MethodType) type;
347 else
348 return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());
349 }
350 // Tracing logic:
351 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
352 Class<?> defc, String name, Object type,
353 Object[] appendixResult) {
354 System.out.println("linkMethod "+defc.getName()+"."+
355 name+type+"/"+Integer.toHexString(refKind));
356 try {
357 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
358 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
359 return res;
360 } catch (Throwable ex) {
361 System.out.println("linkMethod => throw "+ex);
362 throw ex;
363 }
364 }
365
366
367 /**
368 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
369 * It will make an up-call to this method. (Do not change the name or signature.)
370 * The type argument is a Class for field requests and a MethodType for non-fields.
371 * <p>
372 * Recent versions of the JVM may also pass a resolved MemberName for the type.
373 * In that case, the name is ignored and may be null.
374 */
375 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
376 Class<?> defc, String name, Object type) {
377 try {
378 Lookup lookup = IMPL_LOOKUP.in(callerClass);
379 assert(refKindIsValid(refKind));
380 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
381 } catch (IllegalAccessException ex) {
382 Throwable cause = ex.getCause();
383 if (cause instanceof AbstractMethodError) {
384 throw (AbstractMethodError) cause;
385 } else {
386 Error err = new IllegalAccessError(ex.getMessage());
387 throw initCauseFrom(err, ex);
388 }
389 } catch (NoSuchMethodException ex) {
390 Error err = new NoSuchMethodError(ex.getMessage());
391 throw initCauseFrom(err, ex);
392 } catch (NoSuchFieldException ex) {
393 Error err = new NoSuchFieldError(ex.getMessage());
394 throw initCauseFrom(err, ex);
395 } catch (ReflectiveOperationException ex) {
396 Error err = new IncompatibleClassChangeError();
397 throw initCauseFrom(err, ex);
398 }
399 }
400
401 /**
402 * Use best possible cause for err.initCause(), substituting the
403 * cause for err itself if the cause has the same (or better) type.
404 */
405 static private Error initCauseFrom(Error err, Exception ex) {
406 Throwable th = ex.getCause();
407 if (err.getClass().isInstance(th))
408 return (Error) th;
409 err.initCause(th == null ? ex : th);
410 return err;
411 }
412
413 /**
414 * Is this method a caller-sensitive method?
415 * I.e., does it call Reflection.getCallerClass or a similar method
416 * to ask about the identity of its caller?
417 */
418 static boolean isCallerSensitive(MemberName mem) {
419 if (!mem.isInvocable()) return false; // fields are not caller sensitive
420
421 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
422 }
423
424 static boolean canBeCalledVirtual(MemberName mem) {
425 assert(mem.isInvocable());
426 Class<?> defc = mem.getDeclaringClass();
427 switch (mem.getName()) {
428 case "checkMemberAccess":
429 return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
430 case "getContextClassLoader":
431 return canBeCalledVirtual(mem, java.lang.Thread.class);
432 }
433 return false;
434 }
435
436 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
437 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
438 if (symbolicRefClass == definingClass) return true;
439 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
440 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
441 symbolicRefClass.isInterface()); // Mdef implements Msym
442 }
443 }