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 }