js/src/jsapi.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* JavaScript API. */
   8
   9 #ifndef jsapi_h
  10 #define jsapi_h
  11
  12 #include "mozilla/AlreadyAddRefed.h"
  13 #include "mozilla/FloatingPoint.h"
  14 #include "mozilla/Maybe.h"
  15 #include "mozilla/MemoryReporting.h"
  16 #include "mozilla/RangedPtr.h"
  17 #include "mozilla/RefPtr.h"
  18 #include "mozilla/TimeStamp.h"
  19 #include "mozilla/Utf8.h"
  20 #include "mozilla/Variant.h"
  21
  22 #include <stdarg.h>
  23 #include <stddef.h>
  24 #include <stdint.h>
  25 #include <stdio.h>
  26
  27 #include "jspubtd.h"
  28
  29 #include "js/AllocPolicy.h"
  30 #include "js/CallAndConstruct.h"  // JS::Call, JS_CallFunction, JS_CallFunctionName, JS_CallFunctionValue
  31 #include "js/CallArgs.h"
  32 #include "js/CharacterEncoding.h"
  33 #include "js/Class.h"
  34 #include "js/CompileOptions.h"
  35 #include "js/Context.h"
  36 #include "js/Debug.h"
  37 #include "js/ErrorInterceptor.h"
  38 #include "js/ErrorReport.h"
  39 #include "js/Exception.h"
  40 #include "js/GCAPI.h"
  41 #include "js/GCVector.h"
  42 #include "js/GlobalObject.h"
  43 #include "js/HashTable.h"
  44 #include "js/Id.h"
  45 #include "js/Interrupt.h"
  46 #include "js/MapAndSet.h"
  47 #include "js/MemoryCallbacks.h"
  48 #include "js/MemoryFunctions.h"
  49 #include "js/OffThreadScriptCompilation.h"
  50 #include "js/Principals.h"
  51 #include "js/PropertyAndElement.h"  // JS_Enumerate
  52 #include "js/PropertyDescriptor.h"
  53 #include "js/PropertySpec.h"
  54 #include "js/Realm.h"
  55 #include "js/RealmIterators.h"
  56 #include "js/RealmOptions.h"
  57 #include "js/RefCounted.h"
  58 #include "js/RootingAPI.h"
  59 #include "js/ScriptPrivate.h"
  60 #include "js/Stack.h"
  61 #include "js/StreamConsumer.h"
  62 #include "js/String.h"
  63 #include "js/TelemetryTimers.h"
  64 #include "js/TracingAPI.h"
  65 #include "js/Transcoding.h"
  66 #include "js/UniquePtr.h"
  67 #include "js/Utility.h"
  68 #include "js/Value.h"
  69 #include "js/ValueArray.h"
  70 #include "js/Vector.h"
  71 #include "js/WaitCallbacks.h"
  72 #include "js/WeakMap.h"
  73 #include "js/WrapperCallbacks.h"
  74 #include "js/Zone.h"
  75
  76 /************************************************************************/
  77
  78 namespace JS {
  79 /**
  80  * Tell JS engine whether to use fdlibm for Math.sin, Math.cos, and Math.tan.
  81  * Using fdlibm ensures that we don't expose a math fingerprint.
  82  */
  83 extern JS_PUBLIC_API void SetUseFdlibmForSinCosTan(bool value);
  84 }  // namespace JS
  85
  86 /************************************************************************/
  87
  88 struct JSFunctionSpec;
  89 struct JSPropertySpec;
  90
  91 namespace JS {
  92
  93 template <typename UnitT>
  94 class SourceText;
  95
  96 class TwoByteChars;
  97
  98 using ValueVector = JS::GCVector<JS::Value>;
  99 using IdVector = JS::GCVector<jsid>;
 100 using ScriptVector = JS::GCVector<JSScript*>;
 101 using StringVector = JS::GCVector<JSString*>;
 102
 103 } /* namespace JS */
 104
 105 /************************************************************************/
 106
 107 static MOZ_ALWAYS_INLINE JS::Value JS_NumberValue(double d) {
 108   int32_t i;
 109   d = JS::CanonicalizeNaN(d);
 110   if (mozilla::NumberIsInt32(d, &i)) {
 111     return JS::Int32Value(i);
 112   }
 113   return JS::DoubleValue(d);
 114 }
 115
 116 /************************************************************************/
 117
 118 JS_PUBLIC_API bool JS_StringHasBeenPinned(JSContext* cx, JSString* str);
 119
 120 /************************************************************************/
 121
 122 /** Microseconds since the epoch, midnight, January 1, 1970 UTC. */
 123 extern JS_PUBLIC_API int64_t JS_Now(void);
 124
 125 extern JS_PUBLIC_API bool JS_ValueToObject(JSContext* cx, JS::HandleValue v,
 126                                            JS::MutableHandleObject objp);
 127
 128 extern JS_PUBLIC_API JSFunction* JS_ValueToFunction(JSContext* cx,
 129                                                     JS::HandleValue v);
 130
 131 extern JS_PUBLIC_API JSFunction* JS_ValueToConstructor(JSContext* cx,
 132                                                        JS::HandleValue v);
 133
 134 extern JS_PUBLIC_API JSString* JS_ValueToSource(JSContext* cx,
 135                                                 JS::Handle<JS::Value> v);
 136
 137 extern JS_PUBLIC_API bool JS_DoubleIsInt32(double d, int32_t* ip);
 138
 139 extern JS_PUBLIC_API JSType JS_TypeOfValue(JSContext* cx,
 140                                            JS::Handle<JS::Value> v);
 141
 142 namespace JS {
 143
 144 extern JS_PUBLIC_API const char* InformalValueTypeName(const JS::Value& v);
 145
 146 } /* namespace JS */
 147
 148 /** True iff fun is the global eval function. */
 149 extern JS_PUBLIC_API bool JS_IsBuiltinEvalFunction(JSFunction* fun);
 150
 151 /** True iff fun is the Function constructor. */
 152 extern JS_PUBLIC_API bool JS_IsBuiltinFunctionConstructor(JSFunction* fun);
 153
 154 extern JS_PUBLIC_API const char* JS_GetImplementationVersion(void);
 155
 156 extern JS_PUBLIC_API void JS_SetWrapObjectCallbacks(
 157     JSContext* cx, const JSWrapObjectCallbacks* callbacks);
 158
 159 // Examine a value to determine if it is one of the built-in Error types.
 160 // If so, return the error type.
 161 extern JS_PUBLIC_API mozilla::Maybe<JSExnType> JS_GetErrorType(
 162     const JS::Value& val);
 163
 164 extern JS_PUBLIC_API bool JS_WrapObject(JSContext* cx,
 165                                         JS::MutableHandleObject objp);
 166
 167 extern JS_PUBLIC_API bool JS_WrapValue(JSContext* cx,
 168                                        JS::MutableHandleValue vp);
 169
 170 extern JS_PUBLIC_API JSObject* JS_TransplantObject(JSContext* cx,
 171                                                    JS::HandleObject origobj,
 172                                                    JS::HandleObject target);
 173
 174 /**
 175  * Resolve id, which must contain either a string or an int, to a standard
 176  * class name in obj if possible, defining the class's constructor and/or
 177  * prototype and storing true in *resolved.  If id does not name a standard
 178  * class or a top-level property induced by initializing a standard class,
 179  * store false in *resolved and just return true.  Return false on error,
 180  * as usual for bool result-typed API entry points.
 181  *
 182  * This API can be called directly from a global object class's resolve op,
 183  * to define standard classes lazily. The class should either have an enumerate
 184  * hook that calls JS_EnumerateStandardClasses, or a newEnumerate hook that
 185  * calls JS_NewEnumerateStandardClasses. newEnumerate is preferred because it's
 186  * faster (does not define all standard classes).
 187  */
 188 extern JS_PUBLIC_API bool JS_ResolveStandardClass(JSContext* cx,
 189                                                   JS::HandleObject obj,
 190                                                   JS::HandleId id,
 191                                                   bool* resolved);
 192
 193 extern JS_PUBLIC_API bool JS_MayResolveStandardClass(const JSAtomState& names,
 194                                                      jsid id,
 195                                                      JSObject* maybeObj);
 196
 197 extern JS_PUBLIC_API bool JS_EnumerateStandardClasses(JSContext* cx,
 198                                                       JS::HandleObject obj);
 199
 200 /**
 201  * Fill "properties" with a list of standard class names that have not yet been
 202  * resolved on "obj".  This can be used as (part of) a newEnumerate class hook
 203  * on a global.  Already-resolved things are excluded because they might have
 204  * been deleted by script after being resolved and enumeration considers
 205  * already-defined properties anyway.
 206  */
 207 extern JS_PUBLIC_API bool JS_NewEnumerateStandardClasses(
 208     JSContext* cx, JS::HandleObject obj, JS::MutableHandleIdVector properties,
 209     bool enumerableOnly);
 210
 211 /**
 212  * Fill "properties" with a list of standard class names.  This can be used for
 213  * proxies that want to define behavior that looks like enumerating a global
 214  * without touching the global itself.
 215  */
 216 extern JS_PUBLIC_API bool JS_NewEnumerateStandardClassesIncludingResolved(
 217     JSContext* cx, JS::HandleObject obj, JS::MutableHandleIdVector properties,
 218     bool enumerableOnly);
 219
 220 extern JS_PUBLIC_API bool JS_GetClassObject(JSContext* cx, JSProtoKey key,
 221                                             JS::MutableHandle<JSObject*> objp);
 222
 223 extern JS_PUBLIC_API bool JS_GetClassPrototype(
 224     JSContext* cx, JSProtoKey key, JS::MutableHandle<JSObject*> objp);
 225
 226 namespace JS {
 227
 228 /*
 229  * Determine if the given object is an instance/prototype/constructor for a
 230  * standard class. If so, return the associated JSProtoKey. If not, return
 231  * JSProto_Null.
 232  */
 233
 234 extern JS_PUBLIC_API JSProtoKey IdentifyStandardInstance(JSObject* obj);
 235
 236 extern JS_PUBLIC_API JSProtoKey IdentifyStandardPrototype(JSObject* obj);
 237
 238 extern JS_PUBLIC_API JSProtoKey
 239 IdentifyStandardInstanceOrPrototype(JSObject* obj);
 240
 241 extern JS_PUBLIC_API JSProtoKey IdentifyStandardConstructor(JSObject* obj);
 242
 243 extern JS_PUBLIC_API void ProtoKeyToId(JSContext* cx, JSProtoKey key,
 244                                        JS::MutableHandleId idp);
 245
 246 } /* namespace JS */
 247
 248 extern JS_PUBLIC_API JSProtoKey JS_IdToProtoKey(JSContext* cx, JS::HandleId id);
 249
 250 extern JS_PUBLIC_API JSObject* JS_GlobalLexicalEnvironment(JSObject* obj);
 251
 252 extern JS_PUBLIC_API bool JS_HasExtensibleLexicalEnvironment(JSObject* obj);
 253
 254 extern JS_PUBLIC_API JSObject* JS_ExtensibleLexicalEnvironment(JSObject* obj);
 255
 256 /**
 257  * Add 'Reflect.parse', a SpiderMonkey extension, to the Reflect object on the
 258  * given global.
 259  */
 260 extern JS_PUBLIC_API bool JS_InitReflectParse(JSContext* cx,
 261                                               JS::HandleObject global);
 262
 263 /**
 264  * Add various profiling-related functions as properties of the given object.
 265  * Defined in builtin/Profilers.cpp.
 266  */
 267 extern JS_PUBLIC_API bool JS_DefineProfilingFunctions(JSContext* cx,
 268                                                       JS::HandleObject obj);
 269
 270 namespace JS {
 271
 272 /**
 273  * Tell JS engine whether Profile Timeline Recording is enabled or not.
 274  * If Profile Timeline Recording is enabled, data shown there like stack won't
 275  * be optimized out.
 276  * This is global state and not associated with specific runtime or context.
 277  */
 278 extern JS_PUBLIC_API void SetProfileTimelineRecordingEnabled(bool enabled);
 279
 280 extern JS_PUBLIC_API bool IsProfileTimelineRecordingEnabled();
 281
 282 }  // namespace JS
 283
 284 /************************************************************************/
 285
 286 extern JS_PUBLIC_API bool JS_ValueToId(JSContext* cx, JS::HandleValue v,
 287                                        JS::MutableHandleId idp);
 288
 289 extern JS_PUBLIC_API bool JS_StringToId(JSContext* cx, JS::HandleString s,
 290                                         JS::MutableHandleId idp);
 291
 292 extern JS_PUBLIC_API bool JS_IdToValue(JSContext* cx, jsid id,
 293                                        JS::MutableHandle<JS::Value> vp);
 294
 295 namespace JS {
 296
 297 /**
 298  * Convert obj to a primitive value. On success, store the result in vp and
 299  * return true.
 300  *
 301  * The hint argument must be JSTYPE_STRING, JSTYPE_NUMBER, or
 302  * JSTYPE_UNDEFINED (no hint).
 303  *
 304  * Implements: ES6 7.1.1 ToPrimitive(input, [PreferredType]).
 305  */
 306 extern JS_PUBLIC_API bool ToPrimitive(JSContext* cx, JS::HandleObject obj,
 307                                       JSType hint, JS::MutableHandleValue vp);
 308
 309 /**
 310  * If args.get(0) is one of the strings "string", "number", or "default", set
 311  * result to JSTYPE_STRING, JSTYPE_NUMBER, or JSTYPE_UNDEFINED accordingly and
 312  * return true. Otherwise, return false with a TypeError pending.
 313  *
 314  * This can be useful in implementing a @@toPrimitive method.
 315  */
 316 extern JS_PUBLIC_API bool GetFirstArgumentAsTypeHint(JSContext* cx,
 317                                                      CallArgs args,
 318                                                      JSType* result);
 319
 320 } /* namespace JS */
 321
 322 /**
 323  * Defines a builtin constructor and prototype. Returns the prototype object.
 324  *
 325  * - Defines a property named `name` on `obj`, with its value set to a
 326  *   newly-created JS function that invokes the `constructor` JSNative. The
 327  *   `length` of the function is `nargs`.
 328  *
 329  * - Creates a prototype object with proto `protoProto` and class `protoClass`.
 330  *   If `protoProto` is `nullptr`, `Object.prototype` will be used instead.
 331  *   If `protoClass` is `nullptr`, the prototype object will be a plain JS
 332  *   object.
 333  *
 334  * - The `ps` and `fs` properties/functions will be defined on the prototype
 335  *   object.
 336  *
 337  * - The `static_ps` and `static_fs` properties/functions will be defined on the
 338  *   constructor.
 339  */
 340 extern JS_PUBLIC_API JSObject* JS_InitClass(
 341     JSContext* cx, JS::HandleObject obj, const JSClass* protoClass,
 342     JS::HandleObject protoProto, const char* name, JSNative constructor,
 343     unsigned nargs, const JSPropertySpec* ps, const JSFunctionSpec* fs,
 344     const JSPropertySpec* static_ps, const JSFunctionSpec* static_fs);
 345
 346 /**
 347  * Set up ctor.prototype = proto and proto.constructor = ctor with the
 348  * right property flags.
 349  */
 350 extern JS_PUBLIC_API bool JS_LinkConstructorAndPrototype(
 351     JSContext* cx, JS::Handle<JSObject*> ctor, JS::Handle<JSObject*> proto);
 352
 353 extern JS_PUBLIC_API bool JS_InstanceOf(JSContext* cx,
 354                                         JS::Handle<JSObject*> obj,
 355                                         const JSClass* clasp,
 356                                         JS::CallArgs* args);
 357
 358 extern JS_PUBLIC_API bool JS_HasInstance(JSContext* cx,
 359                                          JS::Handle<JSObject*> obj,
 360                                          JS::Handle<JS::Value> v, bool* bp);
 361
 362 namespace JS {
 363
 364 // Implementation of
 365 // http://www.ecma-international.org/ecma-262/6.0/#sec-ordinaryhasinstance.  If
 366 // you're looking for the equivalent of "instanceof", you want JS_HasInstance,
 367 // not this function.
 368 extern JS_PUBLIC_API bool OrdinaryHasInstance(JSContext* cx,
 369                                               HandleObject objArg,
 370                                               HandleValue v, bool* bp);
 371
 372 }  // namespace JS
 373
 374 extern JS_PUBLIC_API JSObject* JS_GetConstructor(JSContext* cx,
 375                                                  JS::Handle<JSObject*> proto);
 376
 377 extern JS_PUBLIC_API JSObject* JS_NewObject(JSContext* cx,
 378                                             const JSClass* clasp);
 379
 380 extern JS_PUBLIC_API bool JS_IsNative(JSObject* obj);
 381
 382 /**
 383  * Unlike JS_NewObject, JS_NewObjectWithGivenProto does not compute a default
 384  * proto. If proto is nullptr, the JS object will have `null` as [[Prototype]].
 385  */
 386 extern JS_PUBLIC_API JSObject* JS_NewObjectWithGivenProto(
 387     JSContext* cx, const JSClass* clasp, JS::Handle<JSObject*> proto);
 388
 389 /**
 390  * Creates a new plain object, like `new Object()`, with Object.prototype as
 391  * [[Prototype]].
 392  */
 393 extern JS_PUBLIC_API JSObject* JS_NewPlainObject(JSContext* cx);
 394
 395 /**
 396  * Freeze obj, and all objects it refers to, recursively. This will not recurse
 397  * through non-extensible objects, on the assumption that those are already
 398  * deep-frozen.
 399  */
 400 extern JS_PUBLIC_API bool JS_DeepFreezeObject(JSContext* cx,
 401                                               JS::Handle<JSObject*> obj);
 402
 403 /**
 404  * Freezes an object; see ES5's Object.freeze(obj) method.
 405  */
 406 extern JS_PUBLIC_API bool JS_FreezeObject(JSContext* cx,
 407                                           JS::Handle<JSObject*> obj);
 408
 409 /*** Standard internal methods **********************************************
 410  *
 411  * The functions below are the fundamental operations on objects.
 412  *
 413  * ES6 specifies 14 internal methods that define how objects behave.  The
 414  * standard is actually quite good on this topic, though you may have to read
 415  * it a few times. See ES6 sections 6.1.7.2 and 6.1.7.3.
 416  *
 417  * When 'obj' is an ordinary object, these functions have boring standard
 418  * behavior as specified by ES6 section 9.1; see the section about internal
 419  * methods in js/src/vm/NativeObject.h.
 420  *
 421  * Proxies override the behavior of internal methods. So when 'obj' is a proxy,
 422  * any one of the functions below could do just about anything. See
 423  * js/public/Proxy.h.
 424  */
 425
 426 /**
 427  * Get the prototype of |obj|, storing it in |proto|.
 428  *
 429  * Implements: ES6 [[GetPrototypeOf]] internal method.
 430  */
 431 extern JS_PUBLIC_API bool JS_GetPrototype(JSContext* cx, JS::HandleObject obj,
 432                                           JS::MutableHandleObject result);
 433
 434 /**
 435  * If |obj| (underneath any functionally-transparent wrapper proxies) has as
 436  * its [[GetPrototypeOf]] trap the ordinary [[GetPrototypeOf]] behavior defined
 437  * for ordinary objects, set |*isOrdinary = true| and store |obj|'s prototype
 438  * in |result|.  Otherwise set |*isOrdinary = false|.  In case of error, both
 439  * outparams have unspecified value.
 440  */
 441 extern JS_PUBLIC_API bool JS_GetPrototypeIfOrdinary(
 442     JSContext* cx, JS::HandleObject obj, bool* isOrdinary,
 443     JS::MutableHandleObject result);
 444
 445 /**
 446  * Change the prototype of obj.
 447  *
 448  * Implements: ES6 [[SetPrototypeOf]] internal method.
 449  *
 450  * In cases where ES6 [[SetPrototypeOf]] returns false without an exception,
 451  * JS_SetPrototype throws a TypeError and returns false.
 452  *
 453  * Performance warning: JS_SetPrototype is very bad for performance. It may
 454  * cause compiled jit-code to be invalidated. It also causes not only obj but
 455  * all other objects in the same "group" as obj to be permanently deoptimized.
 456  * It's better to create the object with the right prototype from the start.
 457  */
 458 extern JS_PUBLIC_API bool JS_SetPrototype(JSContext* cx, JS::HandleObject obj,
 459                                           JS::HandleObject proto);
 460
 461 /**
 462  * Determine whether obj is extensible. Extensible objects can have new
 463  * properties defined on them. Inextensible objects can't, and their
 464  * [[Prototype]] slot is fixed as well.
 465  *
 466  * Implements: ES6 [[IsExtensible]] internal method.
 467  */
 468 extern JS_PUBLIC_API bool JS_IsExtensible(JSContext* cx, JS::HandleObject obj,
 469                                           bool* extensible);
 470
 471 /**
 472  * Attempt to make |obj| non-extensible.
 473  *
 474  * Not all failures are treated as errors. See the comment on
 475  * JS::ObjectOpResult in js/public/Class.h.
 476  *
 477  * Implements: ES6 [[PreventExtensions]] internal method.
 478  */
 479 extern JS_PUBLIC_API bool JS_PreventExtensions(JSContext* cx,
 480                                                JS::HandleObject obj,
 481                                                JS::ObjectOpResult& result);
 482
 483 /**
 484  * Attempt to make the [[Prototype]] of |obj| immutable, such that any attempt
 485  * to modify it will fail.  If an error occurs during the attempt, return false
 486  * (with a pending exception set, depending upon the nature of the error).  If
 487  * no error occurs, return true with |*succeeded| set to indicate whether the
 488  * attempt successfully made the [[Prototype]] immutable.
 489  *
 490  * This is a nonstandard internal method.
 491  */
 492 extern JS_PUBLIC_API bool JS_SetImmutablePrototype(JSContext* cx,
 493                                                    JS::HandleObject obj,
 494                                                    bool* succeeded);
 495
 496 /**
 497  * Equivalent to `Object.assign(target, src)`: Copies the properties from the
 498  * `src` object (which must not be null) to `target` (which also must not be
 499  * null).
 500  */
 501 extern JS_PUBLIC_API bool JS_AssignObject(JSContext* cx,
 502                                           JS::HandleObject target,
 503                                           JS::HandleObject src);
 504
 505 namespace JS {
 506
 507 /**
 508  * On success, returns true, setting |*isMap| to true if |obj| is a Map object
 509  * or a wrapper around one, or to false if not.  Returns false on failure.
 510  *
 511  * This method returns true with |*isMap == false| when passed an ES6 proxy
 512  * whose target is a Map, or when passed a revoked proxy.
 513  */
 514 extern JS_PUBLIC_API bool IsMapObject(JSContext* cx, JS::HandleObject obj,
 515                                       bool* isMap);
 516
 517 /**
 518  * On success, returns true, setting |*isSet| to true if |obj| is a Set object
 519  * or a wrapper around one, or to false if not.  Returns false on failure.
 520  *
 521  * This method returns true with |*isSet == false| when passed an ES6 proxy
 522  * whose target is a Set, or when passed a revoked proxy.
 523  */
 524 extern JS_PUBLIC_API bool IsSetObject(JSContext* cx, JS::HandleObject obj,
 525                                       bool* isSet);
 526
 527 } /* namespace JS */
 528
 529 /**
 530  * Assign 'undefined' to all of the object's non-reserved slots. Note: this is
 531  * done for all slots, regardless of the associated property descriptor.
 532  */
 533 JS_PUBLIC_API void JS_SetAllNonReservedSlotsToUndefined(JS::HandleObject obj);
 534
 535 extern JS_PUBLIC_API void JS_SetReservedSlot(JSObject* obj, uint32_t index,
 536                                              const JS::Value& v);
 537
 538 extern JS_PUBLIC_API void JS_InitReservedSlot(JSObject* obj, uint32_t index,
 539                                               void* ptr, size_t nbytes,
 540                                               JS::MemoryUse use);
 541
 542 template <typename T>
 543 void JS_InitReservedSlot(JSObject* obj, uint32_t index, T* ptr,
 544                          JS::MemoryUse use) {
 545   JS_InitReservedSlot(obj, index, ptr, sizeof(T), use);
 546 }
 547
 548 /************************************************************************/
 549
 550 /* native that can be called as a ctor */
 551 static constexpr unsigned JSFUN_CONSTRUCTOR = 0x400;
 552
 553 /* | of all the JSFUN_* flags */
 554 static constexpr unsigned JSFUN_FLAGS_MASK = 0x400;
 555
 556 static_assert((JSPROP_FLAGS_MASK & JSFUN_FLAGS_MASK) == 0,
 557               "JSFUN_* flags do not overlap JSPROP_* flags, because bits from "
 558               "the two flag-sets appear in the same flag in some APIs");
 559
 560 /*
 561  * Functions and scripts.
 562  */
 563 extern JS_PUBLIC_API JSFunction* JS_NewFunction(JSContext* cx, JSNative call,
 564                                                 unsigned nargs, unsigned flags,
 565                                                 const char* name);
 566
 567 namespace JS {
 568
 569 extern JS_PUBLIC_API JSFunction* GetSelfHostedFunction(
 570     JSContext* cx, const char* selfHostedName, HandleId id, unsigned nargs);
 571
 572 /**
 573  * Create a new function based on the given JSFunctionSpec, *fs.
 574  * id is the result of a successful call to
 575  * `PropertySpecNameToId(cx, fs->name, &id)` or
 576    `PropertySpecNameToPermanentId(cx, fs->name, &id)`.
 577  *
 578  * Unlike JS_DefineFunctions, this does not treat fs as an array.
 579  * *fs must not be JS_FS_END.
 580  */
 581 extern JS_PUBLIC_API JSFunction* NewFunctionFromSpec(JSContext* cx,
 582                                                      const JSFunctionSpec* fs,
 583                                                      HandleId id);
 584
 585 /**
 586  * Same as above, but without an id arg, for callers who don't have
 587  * the id already.
 588  */
 589 extern JS_PUBLIC_API JSFunction* NewFunctionFromSpec(JSContext* cx,
 590                                                      const JSFunctionSpec* fs);
 591
 592 } /* namespace JS */
 593
 594 extern JS_PUBLIC_API JSObject* JS_GetFunctionObject(JSFunction* fun);
 595
 596 /**
 597  * Return the function's identifier as a JSString, or null if fun is unnamed.
 598  * The returned string lives as long as fun, so you don't need to root a saved
 599  * reference to it if fun is well-connected or rooted, and provided you bound
 600  * the use of the saved reference by fun's lifetime.
 601  */
 602 extern JS_PUBLIC_API JSString* JS_GetFunctionId(JSFunction* fun);
 603
 604 /**
 605  * Return a function's display name. This is the defined name if one was given
 606  * where the function was defined, or it could be an inferred name by the JS
 607  * engine in the case that the function was defined to be anonymous. This can
 608  * still return nullptr if a useful display name could not be inferred. The
 609  * same restrictions on rooting as those in JS_GetFunctionId apply.
 610  */
 611 extern JS_PUBLIC_API JSString* JS_GetFunctionDisplayId(JSFunction* fun);
 612
 613 /*
 614  * Return the arity of fun, which includes default parameters and rest
 615  * parameter.  This can be used as `nargs` parameter for other functions.
 616  */
 617 extern JS_PUBLIC_API uint16_t JS_GetFunctionArity(JSFunction* fun);
 618
 619 /*
 620  * Return the length of fun, which is the original value of .length property.
 621  */
 622 JS_PUBLIC_API bool JS_GetFunctionLength(JSContext* cx, JS::HandleFunction fun,
 623                                         uint16_t* length);
 624
 625 /**
 626  * Infallible predicate to test whether obj is a function object (faster than
 627  * comparing obj's class name to "Function", but equivalent unless someone has
 628  * overwritten the "Function" identifier with a different constructor and then
 629  * created instances using that constructor that might be passed in as obj).
 630  */
 631 extern JS_PUBLIC_API bool JS_ObjectIsFunction(JSObject* obj);
 632
 633 extern JS_PUBLIC_API bool JS_IsNativeFunction(JSObject* funobj, JSNative call);
 634
 635 /** Return whether the given function is a valid constructor. */
 636 extern JS_PUBLIC_API bool JS_IsConstructor(JSFunction* fun);
 637
 638 extern JS_PUBLIC_API bool JS_ObjectIsBoundFunction(JSObject* obj);
 639
 640 extern JS_PUBLIC_API JSObject* JS_GetBoundFunctionTarget(JSObject* obj);
 641
 642 extern JS_PUBLIC_API JSObject* JS_GetGlobalFromScript(JSScript* script);
 643
 644 extern JS_PUBLIC_API const char* JS_GetScriptFilename(JSScript* script);
 645
 646 extern JS_PUBLIC_API unsigned JS_GetScriptBaseLineNumber(JSContext* cx,
 647                                                          JSScript* script);
 648
 649 extern JS_PUBLIC_API JSScript* JS_GetFunctionScript(JSContext* cx,
 650                                                     JS::HandleFunction fun);
 651
 652 extern JS_PUBLIC_API JSString* JS_DecompileScript(JSContext* cx,
 653                                                   JS::Handle<JSScript*> script);
 654
 655 extern JS_PUBLIC_API JSString* JS_DecompileFunction(
 656     JSContext* cx, JS::Handle<JSFunction*> fun);
 657
 658 namespace JS {
 659
 660 /**
 661  * Supply an alternative stack to incorporate into captured SavedFrame
 662  * backtraces as the imputed caller of asynchronous JavaScript calls, like async
 663  * function resumptions and DOM callbacks.
 664  *
 665  * When one async function awaits the result of another, it's natural to think
 666  * of that as a sort of function call: just as execution resumes from an
 667  * ordinary call expression when the callee returns, with the return value
 668  * providing the value of the call expression, execution resumes from an 'await'
 669  * expression after the awaited asynchronous function call returns, passing the
 670  * return value along.
 671  *
 672  * Call the two async functions in such a situation the 'awaiter' and the
 673  * 'awaitee'.
 674  *
 675  * As an async function, the awaitee contains 'await' expressions of its own.
 676  * Whenever it executes after its first 'await', there are never any actual
 677  * frames on the JavaScript stack under it; its awaiter is certainly not there.
 678  * An await expression's continuation is invoked as a promise callback, and
 679  * those are always called directly from the event loop in their own microtick.
 680  * (Ignore unusual cases like nested event loops.)
 681  *
 682  * But because await expressions bear such a strong resemblance to calls (and
 683  * deliberately so!), it would be unhelpful for stacks captured within the
 684  * awaitee to be empty; instead, they should present the awaiter as the caller.
 685  *
 686  * The AutoSetAsyncStackForNewCalls RAII class supplies a SavedFrame stack to
 687  * treat as the caller of any JavaScript invocations that occur within its
 688  * lifetime. Any SavedFrame stack captured during such an invocation uses the
 689  * SavedFrame passed to the constructor's 'stack' parameter as the 'asyncParent'
 690  * property of the SavedFrame for the invocation's oldest frame. Its 'parent'
 691  * property will be null, so stack-walking code can distinguish this
 692  * awaiter/awaitee transition from an ordinary caller/callee transition.
 693  *
 694  * The constructor's 'asyncCause' parameter supplies a string explaining what
 695  * sort of asynchronous call caused 'stack' to be spliced into the backtrace;
 696  * for example, async function resumptions use the string "async". This appears
 697  * as the 'asyncCause' property of the 'asyncParent' SavedFrame.
 698  *
 699  * Async callers are distinguished in the string form of a SavedFrame chain by
 700  * including the 'asyncCause' string in the frame. It appears before the
 701  * function name, with the two separated by a '*'.
 702  *
 703  * Note that, as each compartment has its own set of SavedFrames, the
 704  * 'asyncParent' may actually point to a copy of 'stack', rather than the exact
 705  * SavedFrame object passed.
 706  *
 707  * The youngest frame of 'stack' is not mutated to take the asyncCause string as
 708  * its 'asyncCause' property; SavedFrame objects are immutable. Rather, a fresh
 709  * clone of the frame is created with the needed 'asyncCause' property.
 710  *
 711  * The 'kind' argument specifies how aggressively 'stack' supplants any
 712  * JavaScript frames older than this AutoSetAsyncStackForNewCalls object. If
 713  * 'kind' is 'EXPLICIT', then all captured SavedFrame chains take on 'stack' as
 714  * their 'asyncParent' where the chain crosses this object's scope. If 'kind' is
 715  * 'IMPLICIT', then 'stack' is only included in captured chains if there are no
 716  * other JavaScript frames on the stack --- that is, only if the stack would
 717  * otherwise end at that point.
 718  *
 719  * AutoSetAsyncStackForNewCalls affects only SavedFrame chains; it does not
 720  * affect Debugger.Frame or js::FrameIter. SavedFrame chains are used for
 721  * Error.stack, allocation profiling, Promise debugging, and so on.
 722  *
 723  * See also `js/src/doc/SavedFrame/SavedFrame.md` for documentation on async
 724  * stack frames.
 725  */
 726 class MOZ_STACK_CLASS JS_PUBLIC_API AutoSetAsyncStackForNewCalls {
 727   JSContext* cx;
 728   RootedObject oldAsyncStack;
 729   const char* oldAsyncCause;
 730   bool oldAsyncCallIsExplicit;
 731
 732  public:
 733   enum class AsyncCallKind {
 734     // The ordinary kind of call, where we may apply an async
 735     // parent if there is no ordinary parent.
 736     IMPLICIT,
 737     // An explicit async parent, e.g., callFunctionWithAsyncStack,
 738     // where we always want to override any ordinary parent.
 739     EXPLICIT
 740   };
 741
 742   // The stack parameter cannot be null by design, because it would be
 743   // ambiguous whether that would clear any scheduled async stack and make the
 744   // normal stack reappear in the new call, or just keep the async stack
 745   // already scheduled for the new call, if any.
 746   //
 747   // asyncCause is owned by the caller and its lifetime must outlive the
 748   // lifetime of the AutoSetAsyncStackForNewCalls object. It is strongly
 749   // encouraged that asyncCause be a string constant or similar statically
 750   // allocated string.
 751   AutoSetAsyncStackForNewCalls(JSContext* cx, HandleObject stack,
 752                                const char* asyncCause,
 753                                AsyncCallKind kind = AsyncCallKind::IMPLICIT);
 754   ~AutoSetAsyncStackForNewCalls();
 755 };
 756
 757 }  // namespace JS
 758
 759 /************************************************************************/
 760
 761 namespace JS {
 762
 763 JS_PUBLIC_API bool PropertySpecNameEqualsId(JSPropertySpec::Name name,
 764                                             HandleId id);
 765
 766 /**
 767  * Create a jsid that does not need to be marked for GC.
 768  *
 769  * 'name' is a JSPropertySpec::name or JSFunctionSpec::name value. The
 770  * resulting jsid, on success, is either an interned string or a well-known
 771  * symbol; either way it is immune to GC so there is no need to visit *idp
 772  * during GC marking.
 773  */
 774 JS_PUBLIC_API bool PropertySpecNameToPermanentId(JSContext* cx,
 775                                                  JSPropertySpec::Name name,
 776                                                  jsid* idp);
 777
 778 } /* namespace JS */
 779
 780 /************************************************************************/
 781
 782 /**
 783  * A JS context always has an "owner thread". The owner thread is set when the
 784  * context is created (to the current thread) and practically all entry points
 785  * into the JS engine check that a context (or anything contained in the
 786  * context: runtime, compartment, object, etc) is only touched by its owner
 787  * thread. Embeddings may check this invariant outside the JS engine by calling
 788  * JS_AbortIfWrongThread (which will abort if not on the owner thread, even for
 789  * non-debug builds).
 790  */
 791
 792 extern JS_PUBLIC_API void JS_AbortIfWrongThread(JSContext* cx);
 793
 794 /************************************************************************/
 795
 796 /**
 797  * A constructor can request that the JS engine create a default new 'this'
 798  * object of the given class, using the callee to determine parentage and
 799  * [[Prototype]].
 800  */
 801 extern JS_PUBLIC_API JSObject* JS_NewObjectForConstructor(
 802     JSContext* cx, const JSClass* clasp, const JS::CallArgs& args);
 803
 804 /************************************************************************/
 805
 806 extern JS_PUBLIC_API void JS_SetParallelParsingEnabled(JSContext* cx,
 807                                                        bool enabled);
 808
 809 extern JS_PUBLIC_API void JS_SetOffthreadIonCompilationEnabled(JSContext* cx,
 810                                                                bool enabled);
 811
 812 // clang-format off
 813 #define JIT_COMPILER_OPTIONS(Register) \
 814   Register(BASELINE_INTERPRETER_WARMUP_TRIGGER, "blinterp.warmup.trigger") \
 815   Register(BASELINE_WARMUP_TRIGGER, "baseline.warmup.trigger") \
 816   Register(IC_FORCE_MEGAMORPHIC, "ic.force-megamorphic") \
 817   Register(ION_NORMAL_WARMUP_TRIGGER, "ion.warmup.trigger") \
 818   Register(ION_GVN_ENABLE, "ion.gvn.enable") \
 819   Register(ION_FORCE_IC, "ion.forceinlineCaches") \
 820   Register(ION_ENABLE, "ion.enable") \
 821   Register(JIT_TRUSTEDPRINCIPALS_ENABLE, "jit_trustedprincipals.enable") \
 822   Register(ION_CHECK_RANGE_ANALYSIS, "ion.check-range-analysis") \
 823   Register(ION_FREQUENT_BAILOUT_THRESHOLD, "ion.frequent-bailout-threshold") \
 824   Register(BASE_REG_FOR_LOCALS, "base-reg-for-locals") \
 825   Register(INLINING_BYTECODE_MAX_LENGTH, "inlining.bytecode-max-length") \
 826   Register(BASELINE_INTERPRETER_ENABLE, "blinterp.enable") \
 827   Register(BASELINE_ENABLE, "baseline.enable") \
 828   Register(OFFTHREAD_COMPILATION_ENABLE, "offthread-compilation.enable")  \
 829   Register(FULL_DEBUG_CHECKS, "jit.full-debug-checks") \
 830   Register(JUMP_THRESHOLD, "jump-threshold") \
 831   Register(NATIVE_REGEXP_ENABLE, "native_regexp.enable") \
 832   Register(JIT_HINTS_ENABLE, "jitHints.enable") \
 833   Register(SIMULATOR_ALWAYS_INTERRUPT, "simulator.always-interrupt")      \
 834   Register(SPECTRE_INDEX_MASKING, "spectre.index-masking") \
 835   Register(SPECTRE_OBJECT_MITIGATIONS, "spectre.object-mitigations") \
 836   Register(SPECTRE_STRING_MITIGATIONS, "spectre.string-mitigations") \
 837   Register(SPECTRE_VALUE_MASKING, "spectre.value-masking") \
 838   Register(SPECTRE_JIT_TO_CXX_CALLS, "spectre.jit-to-cxx-calls") \
 839   Register(WRITE_PROTECT_CODE, "write-protect-code") \
 840   Register(WATCHTOWER_MEGAMORPHIC, "watchtower.megamorphic") \
 841   Register(WASM_FOLD_OFFSETS, "wasm.fold-offsets") \
 842   Register(WASM_DELAY_TIER2, "wasm.delay-tier2") \
 843   Register(WASM_JIT_BASELINE, "wasm.baseline") \
 844   Register(WASM_JIT_OPTIMIZING, "wasm.optimizing")
 845 // clang-format on
 846
 847 typedef enum JSJitCompilerOption {
 848 #define JIT_COMPILER_DECLARE(key, str) JSJITCOMPILER_##key,
 849
 850   JIT_COMPILER_OPTIONS(JIT_COMPILER_DECLARE)
 851 #undef JIT_COMPILER_DECLARE
 852
 853       JSJITCOMPILER_NOT_AN_OPTION
 854 } JSJitCompilerOption;
 855
 856 extern JS_PUBLIC_API void JS_SetGlobalJitCompilerOption(JSContext* cx,
 857                                                         JSJitCompilerOption opt,
 858                                                         uint32_t value);
 859 extern JS_PUBLIC_API bool JS_GetGlobalJitCompilerOption(JSContext* cx,
 860                                                         JSJitCompilerOption opt,
 861                                                         uint32_t* valueOut);
 862
 863 namespace JS {
 864
 865 // Disable all Spectre mitigations for this process after creating the initial
 866 // JSContext. Must be called on this context's thread.
 867 extern JS_PUBLIC_API void DisableSpectreMitigationsAfterInit();
 868
 869 };  // namespace JS
 870
 871 /**
 872  * Convert a uint32_t index into a jsid.
 873  */
 874 extern JS_PUBLIC_API bool JS_IndexToId(JSContext* cx, uint32_t index,
 875                                        JS::MutableHandleId);
 876
 877 /**
 878  * Convert chars into a jsid.
 879  *
 880  * |chars| may not be an index.
 881  */
 882 extern JS_PUBLIC_API bool JS_CharsToId(JSContext* cx, JS::TwoByteChars chars,
 883                                        JS::MutableHandleId);
 884
 885 /**
 886  *  Test if the given string is a valid ECMAScript identifier
 887  */
 888 extern JS_PUBLIC_API bool JS_IsIdentifier(JSContext* cx, JS::HandleString str,
 889                                           bool* isIdentifier);
 890
 891 /**
 892  * Test whether the given chars + length are a valid ECMAScript identifier.
 893  * This version is infallible, so just returns whether the chars are an
 894  * identifier.
 895  */
 896 extern JS_PUBLIC_API bool JS_IsIdentifier(const char16_t* chars, size_t length);
 897
 898 namespace js {
 899 class ScriptSource;
 900 }  // namespace js
 901
 902 namespace JS {
 903
 904 class MOZ_RAII JS_PUBLIC_API AutoFilename {
 905  private:
 906   js::ScriptSource* ss_;
 907   mozilla::Variant<const char*, UniqueChars> filename_;
 908
 909   AutoFilename(const AutoFilename&) = delete;
 910   AutoFilename& operator=(const AutoFilename&) = delete;
 911
 912  public:
 913   AutoFilename()
 914       : ss_(nullptr), filename_(mozilla::AsVariant<const char*>(nullptr)) {}
 915
 916   ~AutoFilename() { reset(); }
 917
 918   void reset();
 919
 920   void setOwned(UniqueChars&& filename);
 921   void setUnowned(const char* filename);
 922   void setScriptSource(js::ScriptSource* ss);
 923
 924   const char* get() const;
 925 };
 926
 927 /**
 928  * Return the current filename, line number and column number of the most
 929  * currently running frame. Returns true if a scripted frame was found, false
 930  * otherwise.
 931  *
 932  * If a the embedding has hidden the scripted caller for the topmost activation
 933  * record, this will also return false.
 934  */
 935 extern JS_PUBLIC_API bool DescribeScriptedCaller(
 936     JSContext* cx, AutoFilename* filename = nullptr, unsigned* lineno = nullptr,
 937     unsigned* column = nullptr);
 938
 939 extern JS_PUBLIC_API JSObject* GetScriptedCallerGlobal(JSContext* cx);
 940
 941 /**
 942  * Informs the JS engine that the scripted caller should be hidden. This can be
 943  * used by the embedding to maintain an override of the scripted caller in its
 944  * calculations, by hiding the scripted caller in the JS engine and pushing data
 945  * onto a separate stack, which it inspects when DescribeScriptedCaller returns
 946  * null.
 947  *
 948  * We maintain a counter on each activation record. Add() increments the counter
 949  * of the topmost activation, and Remove() decrements it. The count may never
 950  * drop below zero, and must always be exactly zero when the activation is
 951  * popped from the stack.
 952  */
 953 extern JS_PUBLIC_API void HideScriptedCaller(JSContext* cx);
 954
 955 extern JS_PUBLIC_API void UnhideScriptedCaller(JSContext* cx);
 956
 957 class MOZ_RAII AutoHideScriptedCaller {
 958  public:
 959   explicit AutoHideScriptedCaller(JSContext* cx) : mContext(cx) {
 960     HideScriptedCaller(mContext);
 961   }
 962   ~AutoHideScriptedCaller() { UnhideScriptedCaller(mContext); }
 963
 964  protected:
 965   JSContext* mContext;
 966 };
 967
 968 /**
 969  * Attempt to disable Wasm's usage of reserving a large virtual memory
 970  * allocation to avoid bounds checking overhead. This must be called before any
 971  * Wasm module or memory is created in this process, or else this function will
 972  * fail.
 973  */
 974 [[nodiscard]] extern JS_PUBLIC_API bool DisableWasmHugeMemory();
 975
 976 /**
 977  * Return true iff the given object is either a SavedFrame object or wrapper
 978  * around a SavedFrame object, and it is not the SavedFrame.prototype object.
 979  */
 980 extern JS_PUBLIC_API bool IsMaybeWrappedSavedFrame(JSObject* obj);
 981
 982 /**
 983  * Return true iff the given object is a SavedFrame object and not the
 984  * SavedFrame.prototype object.
 985  */
 986 extern JS_PUBLIC_API bool IsUnwrappedSavedFrame(JSObject* obj);
 987
 988 } /* namespace JS */
 989
 990 namespace js {
 991
 992 /**
 993  * Hint that we expect a crash. Currently, the only thing that cares is the
 994  * breakpad injector, which (if loaded) will suppress minidump generation.
 995  */
 996 extern JS_PUBLIC_API void NoteIntentionalCrash();
 997
 998 } /* namespace js */
 999
1000 #ifdef DEBUG
1001 namespace JS {
1002
1003 extern JS_PUBLIC_API void SetSupportDifferentialTesting(bool value);
1004
1005 }
1006 #endif /* DEBUG */
1007
1008 #endif /* jsapi_h */