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Diffstat (limited to 'js/src/builtin/Promise.cpp')
| -rw-r--r-- | js/src/builtin/Promise.cpp | 5911 |
1 files changed, 5911 insertions, 0 deletions
diff --git a/js/src/builtin/Promise.cpp b/js/src/builtin/Promise.cpp new file mode 100644 index 0000000000..1123555e2e --- /dev/null +++ b/js/src/builtin/Promise.cpp @@ -0,0 +1,5911 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "builtin/Promise.h" + +#include "mozilla/Atomics.h" +#include "mozilla/Maybe.h" +#include "mozilla/TimeStamp.h" + +#include "jsapi.h" +#include "jsexn.h" +#include "jsfriendapi.h" + +#include "js/Debug.h" +#include "js/experimental/JitInfo.h" // JSJitGetterOp, JSJitInfo +#include "js/ForOfIterator.h" // JS::ForOfIterator +#include "js/friend/ErrorMessages.h" // js::GetErrorMessage, JSMSG_* +#include "js/PropertySpec.h" +#include "vm/ArrayObject.h" +#include "vm/AsyncFunction.h" +#include "vm/AsyncIteration.h" +#include "vm/ErrorObject.h" +#include "vm/GeneratorObject.h" +#include "vm/Iteration.h" +#include "vm/JSContext.h" +#include "vm/JSObject.h" +#include "vm/PlainObject.h" // js::PlainObject +#include "vm/PromiseLookup.h" // js::PromiseLookup +#include "vm/PromiseObject.h" // js::PromiseObject, js::PromiseSlot_* +#include "vm/SelfHosting.h" +#include "vm/Warnings.h" // js::WarnNumberASCII + +#include "debugger/DebugAPI-inl.h" +#include "vm/Compartment-inl.h" +#include "vm/ErrorObject-inl.h" +#include "vm/JSContext-inl.h" // JSContext::check +#include "vm/JSObject-inl.h" +#include "vm/NativeObject-inl.h" + +using namespace js; + +static double MillisecondsSinceStartup() { + auto now = mozilla::TimeStamp::Now(); + return (now - mozilla::TimeStamp::ProcessCreation()).ToMilliseconds(); +} + +enum PromiseHandler { + PromiseHandlerIdentity = 0, + PromiseHandlerThrower, + + // ES 2018 draft 25.5.5.4-5. + PromiseHandlerAsyncFunctionAwaitedFulfilled, + PromiseHandlerAsyncFunctionAwaitedRejected, + + // ES2019 draft rev 49b781ec80117b60f73327ef3054703a3111e40c + // 6.2.3.1.1 Await Fulfilled Functions + // 6.2.3.1.2 Await Rejected Functions + PromiseHandlerAsyncGeneratorAwaitedFulfilled, + PromiseHandlerAsyncGeneratorAwaitedRejected, + + // ES2019 draft rev 49b781ec80117b60f73327ef3054703a3111e40c + // 25.5.3.5.1 AsyncGeneratorResumeNext Return Processor Fulfilled Functions + // 25.5.3.5.2 AsyncGeneratorResumeNext Return Processor Rejected Functions + PromiseHandlerAsyncGeneratorResumeNextReturnFulfilled, + PromiseHandlerAsyncGeneratorResumeNextReturnRejected, + + // ES2019 draft rev 49b781ec80117b60f73327ef3054703a3111e40c + // 25.5.3.7 AsyncGeneratorYield, steps 8.c-e. + PromiseHandlerAsyncGeneratorYieldReturnAwaitedFulfilled, + PromiseHandlerAsyncGeneratorYieldReturnAwaitedRejected, + + // ES2019 draft rev 49b781ec80117b60f73327ef3054703a3111e40c + // 25.1.4.2.5 Async-from-Sync Iterator Value Unwrap Functions + // + // Async-from-Sync iterator handlers take the resolved value and create new + // iterator objects. To do so it needs to forward whether the iterator is + // done. In spec, this is achieved via the [[Done]] internal slot. We + // enumerate both true and false cases here. + PromiseHandlerAsyncFromSyncIteratorValueUnwrapDone, + PromiseHandlerAsyncFromSyncIteratorValueUnwrapNotDone, + + // One past the maximum allowed PromiseHandler value. + PromiseHandlerLimit +}; + +enum ResolutionMode { ResolveMode, RejectMode }; + +enum ResolveFunctionSlots { + ResolveFunctionSlot_Promise = 0, + ResolveFunctionSlot_RejectFunction, +}; + +enum RejectFunctionSlots { + RejectFunctionSlot_Promise = 0, + RejectFunctionSlot_ResolveFunction, +}; + +enum PromiseCombinatorElementFunctionSlots { + PromiseCombinatorElementFunctionSlot_Data = 0, + PromiseCombinatorElementFunctionSlot_ElementIndex, +}; + +enum ReactionJobSlots { + ReactionJobSlot_ReactionRecord = 0, +}; + +enum ThenableJobSlots { + // The handler to use as the Promise reaction. It is a callable object + // that's guaranteed to be from the same compartment as the + // PromiseReactionJob. + ThenableJobSlot_Handler = 0, + + // JobData - a, potentially CCW-wrapped, dense list containing data + // required for proper execution of the reaction. + ThenableJobSlot_JobData, +}; + +enum ThenableJobDataIndices { + // The Promise to resolve using the given thenable. + ThenableJobDataIndex_Promise = 0, + + // The thenable to use as the receiver when calling the `then` function. + ThenableJobDataIndex_Thenable, + + ThenableJobDataLength, +}; + +enum BuiltinThenableJobSlots { + // The Promise to resolve using the given thenable. + BuiltinThenableJobSlot_Promise = 0, + + // The thenable to use as the receiver when calling the built-in `then` + // function. + BuiltinThenableJobSlot_Thenable, +}; + +struct PromiseCapability { + JSObject* promise = nullptr; + JSObject* resolve = nullptr; + JSObject* reject = nullptr; + + PromiseCapability() = default; + + void trace(JSTracer* trc); +}; + +void PromiseCapability::trace(JSTracer* trc) { + if (promise) { + TraceRoot(trc, &promise, "PromiseCapability::promise"); + } + if (resolve) { + TraceRoot(trc, &resolve, "PromiseCapability::resolve"); + } + if (reject) { + TraceRoot(trc, &reject, "PromiseCapability::reject"); + } +} + +namespace js { + +template <typename Wrapper> +class WrappedPtrOperations<PromiseCapability, Wrapper> { + const PromiseCapability& capability() const { + return static_cast<const Wrapper*>(this)->get(); + } + + public: + HandleObject promise() const { + return HandleObject::fromMarkedLocation(&capability().promise); + } + HandleObject resolve() const { + return HandleObject::fromMarkedLocation(&capability().resolve); + } + HandleObject reject() const { + return HandleObject::fromMarkedLocation(&capability().reject); + } +}; + +template <typename Wrapper> +class MutableWrappedPtrOperations<PromiseCapability, Wrapper> + : public WrappedPtrOperations<PromiseCapability, Wrapper> { + PromiseCapability& capability() { return static_cast<Wrapper*>(this)->get(); } + + public: + MutableHandleObject promise() { + return MutableHandleObject::fromMarkedLocation(&capability().promise); + } + MutableHandleObject resolve() { + return MutableHandleObject::fromMarkedLocation(&capability().resolve); + } + MutableHandleObject reject() { + return MutableHandleObject::fromMarkedLocation(&capability().reject); + } +}; + +} // namespace js + +struct PromiseCombinatorElements; + +class PromiseCombinatorDataHolder : public NativeObject { + enum { + Slot_Promise = 0, + Slot_RemainingElements, + Slot_ValuesArray, + Slot_ResolveOrRejectFunction, + SlotsCount, + }; + + public: + static const JSClass class_; + JSObject* promiseObj() { return &getFixedSlot(Slot_Promise).toObject(); } + JSObject* resolveOrRejectObj() { + return &getFixedSlot(Slot_ResolveOrRejectFunction).toObject(); + } + Value valuesArray() { return getFixedSlot(Slot_ValuesArray); } + int32_t remainingCount() { + return getFixedSlot(Slot_RemainingElements).toInt32(); + } + int32_t increaseRemainingCount() { + int32_t remainingCount = getFixedSlot(Slot_RemainingElements).toInt32(); + remainingCount++; + setFixedSlot(Slot_RemainingElements, Int32Value(remainingCount)); + return remainingCount; + } + int32_t decreaseRemainingCount() { + int32_t remainingCount = getFixedSlot(Slot_RemainingElements).toInt32(); + remainingCount--; + MOZ_ASSERT(remainingCount >= 0, "unpaired calls to decreaseRemainingCount"); + setFixedSlot(Slot_RemainingElements, Int32Value(remainingCount)); + return remainingCount; + } + + static PromiseCombinatorDataHolder* New( + JSContext* cx, HandleObject resultPromise, + Handle<PromiseCombinatorElements> elements, HandleObject resolveOrReject); +}; + +const JSClass PromiseCombinatorDataHolder::class_ = { + "PromiseCombinatorDataHolder", JSCLASS_HAS_RESERVED_SLOTS(SlotsCount)}; + +// Smart pointer to the "F.[[Values]]" part of the state of a Promise.all or +// Promise.allSettled invocation, or the "F.[[Errors]]" part of the state of a +// Promise.any invocation. Copes with compartment issues when setting an +// element. +struct MOZ_STACK_CLASS PromiseCombinatorElements final { + // Object value holding the elements array. The object can be a wrapper. + Value value; + + // Unwrapped elements array. May not belong to the current compartment! + ArrayObject* unwrappedArray = nullptr; + + // Set to true if the |setElement| method needs to wrap its input value. + bool setElementNeedsWrapping = false; + + PromiseCombinatorElements() = default; + + void trace(JSTracer* trc); +}; + +void PromiseCombinatorElements::trace(JSTracer* trc) { + TraceRoot(trc, &value, "PromiseCombinatorElements::value"); + if (unwrappedArray) { + TraceRoot(trc, &unwrappedArray, + "PromiseCombinatorElements::unwrappedArray"); + } +} + +namespace js { + +template <typename Wrapper> +class WrappedPtrOperations<PromiseCombinatorElements, Wrapper> { + const PromiseCombinatorElements& elements() const { + return static_cast<const Wrapper*>(this)->get(); + } + + public: + HandleValue value() const { + return HandleValue::fromMarkedLocation(&elements().value); + } + + HandleArrayObject unwrappedArray() const { + return HandleArrayObject::fromMarkedLocation(&elements().unwrappedArray); + } +}; + +template <typename Wrapper> +class MutableWrappedPtrOperations<PromiseCombinatorElements, Wrapper> + : public WrappedPtrOperations<PromiseCombinatorElements, Wrapper> { + PromiseCombinatorElements& elements() { + return static_cast<Wrapper*>(this)->get(); + } + + public: + MutableHandleValue value() { + return MutableHandleValue::fromMarkedLocation(&elements().value); + } + + MutableHandle<ArrayObject*> unwrappedArray() { + return MutableHandle<ArrayObject*>::fromMarkedLocation( + &elements().unwrappedArray); + } + + void initialize(ArrayObject* arrayObj) { + unwrappedArray().set(arrayObj); + value().setObject(*arrayObj); + + // |needsWrapping| isn't tracked here, because all modifications on the + // initial elements don't require any wrapping. + } + + void initialize(PromiseCombinatorDataHolder* data, ArrayObject* arrayObj, + bool needsWrapping) { + unwrappedArray().set(arrayObj); + value().set(data->valuesArray()); + elements().setElementNeedsWrapping = needsWrapping; + } + + MOZ_MUST_USE bool pushUndefined(JSContext* cx) { + // Helper for the AutoRealm we need to work with |array|. We mostly do this + // for performance; we could go ahead and do the define via a cross- + // compartment proxy instead... + AutoRealm ar(cx, unwrappedArray()); + + HandleArrayObject arrayObj = unwrappedArray(); + return js::NewbornArrayPush(cx, arrayObj, UndefinedValue()); + } + + // `Promise.all` Resolve Element Functions + // Step 9. Set values[index] to x. + // + // `Promise.allSettled` Resolve Element Functions + // `Promise.allSettled` Reject Element Functions + // Step 12. Set values[index] to obj. + // + // `Promise.any` Reject Element Functions + // Step 9. Set errors[index] to x. + // + // These handler functions are always created in the compartment of the + // Promise.all/allSettled/any function, which isn't necessarily the same + // compartment as unwrappedArray as explained in NewPromiseCombinatorElements. + // So before storing |val| we may need to enter unwrappedArray's compartment. + MOZ_MUST_USE bool setElement(JSContext* cx, uint32_t index, HandleValue val) { + // The index is guaranteed to be initialized to `undefined`. + MOZ_ASSERT(unwrappedArray()->getDenseElement(index).isUndefined()); + + if (elements().setElementNeedsWrapping) { + AutoRealm ar(cx, unwrappedArray()); + + RootedValue rootedVal(cx, val); + if (!cx->compartment()->wrap(cx, &rootedVal)) { + return false; + } + unwrappedArray()->setDenseElement(index, rootedVal); + } else { + unwrappedArray()->setDenseElement(index, val); + } + return true; + } +}; + +} // namespace js + +PromiseCombinatorDataHolder* PromiseCombinatorDataHolder::New( + JSContext* cx, HandleObject resultPromise, + Handle<PromiseCombinatorElements> elements, HandleObject resolveOrReject) { + auto* dataHolder = NewBuiltinClassInstance<PromiseCombinatorDataHolder>(cx); + if (!dataHolder) { + return nullptr; + } + + cx->check(resultPromise); + cx->check(elements.value()); + cx->check(resolveOrReject); + + dataHolder->setFixedSlot(Slot_Promise, ObjectValue(*resultPromise)); + dataHolder->setFixedSlot(Slot_RemainingElements, Int32Value(1)); + dataHolder->setFixedSlot(Slot_ValuesArray, elements.value()); + dataHolder->setFixedSlot(Slot_ResolveOrRejectFunction, + ObjectValue(*resolveOrReject)); + return dataHolder; +} + +namespace { +// Generator used by PromiseObject::getID. +mozilla::Atomic<uint64_t> gIDGenerator(0); +} // namespace + +class PromiseDebugInfo : public NativeObject { + private: + enum Slots { + Slot_AllocationSite, + Slot_ResolutionSite, + Slot_AllocationTime, + Slot_ResolutionTime, + Slot_Id, + SlotCount + }; + + public: + static const JSClass class_; + static PromiseDebugInfo* create(JSContext* cx, + Handle<PromiseObject*> promise) { + Rooted<PromiseDebugInfo*> debugInfo( + cx, NewBuiltinClassInstance<PromiseDebugInfo>(cx)); + if (!debugInfo) { + return nullptr; + } + + RootedObject stack(cx); + if (!JS::CaptureCurrentStack(cx, &stack, + JS::StackCapture(JS::AllFrames()))) { + return nullptr; + } + debugInfo->setFixedSlot(Slot_AllocationSite, ObjectOrNullValue(stack)); + debugInfo->setFixedSlot(Slot_ResolutionSite, NullValue()); + debugInfo->setFixedSlot(Slot_AllocationTime, + DoubleValue(MillisecondsSinceStartup())); + debugInfo->setFixedSlot(Slot_ResolutionTime, NumberValue(0)); + promise->setFixedSlot(PromiseSlot_DebugInfo, ObjectValue(*debugInfo)); + + return debugInfo; + } + + static PromiseDebugInfo* FromPromise(PromiseObject* promise) { + Value val = promise->getFixedSlot(PromiseSlot_DebugInfo); + if (val.isObject()) { + return &val.toObject().as<PromiseDebugInfo>(); + } + return nullptr; + } + + /** + * Returns the given PromiseObject's process-unique ID. + * The ID is lazily assigned when first queried, and then either stored + * in the DebugInfo slot if no debug info was recorded for this Promise, + * or in the Id slot of the DebugInfo object. + */ + static uint64_t id(PromiseObject* promise) { + Value idVal(promise->getFixedSlot(PromiseSlot_DebugInfo)); + if (idVal.isUndefined()) { + idVal.setDouble(++gIDGenerator); + promise->setFixedSlot(PromiseSlot_DebugInfo, idVal); + } else if (idVal.isObject()) { + PromiseDebugInfo* debugInfo = FromPromise(promise); + idVal = debugInfo->getFixedSlot(Slot_Id); + if (idVal.isUndefined()) { + idVal.setDouble(++gIDGenerator); + debugInfo->setFixedSlot(Slot_Id, idVal); + } + } + return uint64_t(idVal.toNumber()); + } + + double allocationTime() { + return getFixedSlot(Slot_AllocationTime).toNumber(); + } + double resolutionTime() { + return getFixedSlot(Slot_ResolutionTime).toNumber(); + } + JSObject* allocationSite() { + return getFixedSlot(Slot_AllocationSite).toObjectOrNull(); + } + JSObject* resolutionSite() { + return getFixedSlot(Slot_ResolutionSite).toObjectOrNull(); + } + + // The |unwrappedRejectionStack| parameter should only be set on promise + // rejections and should be the stack of the exception that caused the promise + // to be rejected. If the |unwrappedRejectionStack| is null, the current stack + // will be used instead. This is also the default behavior for fulfilled + // promises. + static void setResolutionInfo(JSContext* cx, Handle<PromiseObject*> promise, + HandleSavedFrame unwrappedRejectionStack) { + MOZ_ASSERT_IF(unwrappedRejectionStack, + promise->state() == JS::PromiseState::Rejected); + + if (!JS::IsAsyncStackCaptureEnabledForRealm(cx)) { + return; + } + + // If async stacks weren't enabled and the Promise's global wasn't a + // debuggee when the Promise was created, we won't have a debugInfo + // object. We still want to capture the resolution stack, so we + // create the object now and change it's slots' values around a bit. + Rooted<PromiseDebugInfo*> debugInfo(cx, FromPromise(promise)); + if (!debugInfo) { + RootedValue idVal(cx, promise->getFixedSlot(PromiseSlot_DebugInfo)); + debugInfo = create(cx, promise); + if (!debugInfo) { + cx->clearPendingException(); + return; + } + + // The current stack was stored in the AllocationSite slot, move + // it to ResolutionSite as that's what it really is. + debugInfo->setFixedSlot(Slot_ResolutionSite, + debugInfo->getFixedSlot(Slot_AllocationSite)); + debugInfo->setFixedSlot(Slot_AllocationSite, NullValue()); + + // There's no good default for a missing AllocationTime, so + // instead of resetting that, ensure that it's the same as + // ResolutionTime, so that the diff shows as 0, which isn't great, + // but bearable. + debugInfo->setFixedSlot(Slot_ResolutionTime, + debugInfo->getFixedSlot(Slot_AllocationTime)); + + // The Promise's ID might've been queried earlier, in which case + // it's stored in the DebugInfo slot. We saved that earlier, so + // now we can store it in the right place (or leave it as + // undefined if it wasn't ever initialized.) + debugInfo->setFixedSlot(Slot_Id, idVal); + return; + } + + RootedObject stack(cx, unwrappedRejectionStack); + if (stack) { + // The exception stack is always unwrapped so it might be in + // a different compartment. + if (!cx->compartment()->wrap(cx, &stack)) { + cx->clearPendingException(); + return; + } + } else { + if (!JS::CaptureCurrentStack(cx, &stack, + JS::StackCapture(JS::AllFrames()))) { + cx->clearPendingException(); + return; + } + } + + debugInfo->setFixedSlot(Slot_ResolutionSite, ObjectOrNullValue(stack)); + debugInfo->setFixedSlot(Slot_ResolutionTime, + DoubleValue(MillisecondsSinceStartup())); + } +}; + +const JSClass PromiseDebugInfo::class_ = { + "PromiseDebugInfo", JSCLASS_HAS_RESERVED_SLOTS(SlotCount)}; + +double PromiseObject::allocationTime() { + auto debugInfo = PromiseDebugInfo::FromPromise(this); + if (debugInfo) { + return debugInfo->allocationTime(); + } + return 0; +} + +double PromiseObject::resolutionTime() { + auto debugInfo = PromiseDebugInfo::FromPromise(this); + if (debugInfo) { + return debugInfo->resolutionTime(); + } + return 0; +} + +JSObject* PromiseObject::allocationSite() { + auto debugInfo = PromiseDebugInfo::FromPromise(this); + if (debugInfo) { + return debugInfo->allocationSite(); + } + return nullptr; +} + +JSObject* PromiseObject::resolutionSite() { + auto debugInfo = PromiseDebugInfo::FromPromise(this); + if (debugInfo) { + return debugInfo->resolutionSite(); + } + return nullptr; +} + +/** + * Wrapper for GetAndClearExceptionAndStack that handles cases where + * no exception is pending, but an error occurred. + * This can be the case if an OOM was encountered while throwing the error. + */ +static bool MaybeGetAndClearExceptionAndStack(JSContext* cx, + MutableHandleValue rval, + MutableHandleSavedFrame stack) { + if (!cx->isExceptionPending()) { + return false; + } + + return GetAndClearExceptionAndStack(cx, rval, stack); +} + +static MOZ_MUST_USE bool RunRejectFunction( + JSContext* cx, HandleObject onRejectedFunc, HandleValue result, + HandleObject promiseObj, HandleSavedFrame unwrappedRejectionStack, + UnhandledRejectionBehavior behavior); + +// ES2016, 25.4.1.1.1, Steps 1.a-b. +// Extracting all of this internal spec algorithm into a helper function would +// be tedious, so the check in step 1 and the entirety of step 2 aren't +// included. +static bool AbruptRejectPromise(JSContext* cx, CallArgs& args, + HandleObject promiseObj, HandleObject reject) { + // Step 1.a. + RootedValue reason(cx); + RootedSavedFrame stack(cx); + if (!MaybeGetAndClearExceptionAndStack(cx, &reason, &stack)) { + return false; + } + + if (!RunRejectFunction(cx, reject, reason, promiseObj, stack, + UnhandledRejectionBehavior::Report)) { + return false; + } + + // Step 1.b. + args.rval().setObject(*promiseObj); + return true; +} + +static bool AbruptRejectPromise(JSContext* cx, CallArgs& args, + Handle<PromiseCapability> capability) { + return AbruptRejectPromise(cx, args, capability.promise(), + capability.reject()); +} + +enum ReactionRecordSlots { + // This is the promise-like object that gets resolved with the result of this + // reaction, if any. If this reaction record was created with .then or .catch, + // this is the promise that .then or .catch returned. + // + // The spec says that a PromiseReaction record has a [[Capability]] field + // whose value is either undefined or a PromiseCapability record, but we just + // store the PromiseCapability's fields directly in this object. This is the + // capability's [[Promise]] field; its [[Resolve]] and [[Reject]] fields are + // stored in ReactionRecordSlot_Resolve and ReactionRecordSlot_Reject. + // + // This can be 'null' in reaction records created for a few situations: + // + // - When you resolve one promise to another. When you pass a promise P1 to + // the 'fulfill' function of a promise P2, so that resolving P1 resolves P2 + // in the same way, P1 gets a reaction record with the + // REACTION_FLAG_DEFAULT_RESOLVING_HANDLER flag set and whose + // ReactionRecordSlot_GeneratorOrPromiseToResolve slot holds P2. + // + // - When you await a promise. When an async function or generator awaits a + // value V, then the await expression generates an internal promise P, + // resolves it to V, and then gives P a reaction record with the + // REACTION_FLAG_ASYNC_FUNCTION or REACTION_FLAG_ASYNC_GENERATOR flag set + // and whose ReactionRecordSlot_GeneratorOrPromiseToResolve slot holds the + // generator object. (Typically V is a promise, so resolving P to V gives V + // a REACTION_FLAGS_DEFAULT_RESOLVING_HANDLER reaction record as described + // above.) + // + // - When JS::AddPromiseReactions{,IgnoringUnhandledRejection} cause the + // reaction to be created. (These functions act as if they had created a + // promise to invoke the appropriate provided reaction function, without + // actually allocating a promise for them.) + ReactionRecordSlot_Promise = 0, + + // The [[Handler]] field(s) of a PromiseReaction record. We create a + // single reaction record for fulfillment and rejection, therefore our + // PromiseReaction implementation needs two [[Handler]] fields. + // + // The slot value is either a callable object, an integer constant from + // the |PromiseHandler| enum, or null. If the value is null, either the + // REACTION_FLAG_DEBUGGER_DUMMY or the + // REACTION_FLAG_DEFAULT_RESOLVING_HANDLER flag must be set. + // + // After setting the target state for a PromiseReaction, the slot of the + // no longer used handler gets reused to store the argument of the active + // handler. + ReactionRecordSlot_OnFulfilled, + ReactionRecordSlot_OnRejectedArg = ReactionRecordSlot_OnFulfilled, + ReactionRecordSlot_OnRejected, + ReactionRecordSlot_OnFulfilledArg = ReactionRecordSlot_OnRejected, + + // The functions to resolve or reject the promise. Matches the + // [[Capability]].[[Resolve]] and [[Capability]].[[Reject]] fields from + // the spec. + // + // The slot values are either callable objects or null, but the latter + // case is only allowed if the promise is either a built-in Promise object + // or null. + ReactionRecordSlot_Resolve, + ReactionRecordSlot_Reject, + + // The incumbent global for this reaction record. Can be null. + ReactionRecordSlot_IncumbentGlobalObject, + + // Bitmask of the REACTION_FLAG values. + ReactionRecordSlot_Flags, + + // Additional slot to store extra data for specific reaction record types. + // + // - When the REACTION_FLAG_ASYNC_FUNCTION flag is set, this slot stores + // the (internal) generator object for this promise reaction. + // - When the REACTION_FLAG_ASYNC_GENERATOR flag is set, this slot stores + // the async generator object for this promise reaction. + // - When the REACTION_FLAG_DEFAULT_RESOLVING_HANDLER flag is set, this + // slot stores the promise to resolve when conceptually "calling" the + // OnFulfilled or OnRejected handlers. + ReactionRecordSlot_GeneratorOrPromiseToResolve, + + ReactionRecordSlots, +}; + +// ES2016, 25.4.1.2. +class PromiseReactionRecord : public NativeObject { + static constexpr uint32_t REACTION_FLAG_RESOLVED = 0x1; + static constexpr uint32_t REACTION_FLAG_FULFILLED = 0x2; + static constexpr uint32_t REACTION_FLAG_DEFAULT_RESOLVING_HANDLER = 0x4; + static constexpr uint32_t REACTION_FLAG_ASYNC_FUNCTION = 0x8; + static constexpr uint32_t REACTION_FLAG_ASYNC_GENERATOR = 0x10; + static constexpr uint32_t REACTION_FLAG_DEBUGGER_DUMMY = 0x20; + static constexpr uint32_t REACTION_FLAG_IGNORE_UNHANDLED_REJECTION = 0x40; + + void setFlagOnInitialState(uint32_t flag) { + int32_t flags = this->flags(); + MOZ_ASSERT(flags == 0, "Can't modify with non-default flags"); + flags |= flag; + setFixedSlot(ReactionRecordSlot_Flags, Int32Value(flags)); + } + + uint32_t handlerSlot() { + MOZ_ASSERT(targetState() != JS::PromiseState::Pending); + return targetState() == JS::PromiseState::Fulfilled + ? ReactionRecordSlot_OnFulfilled + : ReactionRecordSlot_OnRejected; + } + + uint32_t handlerArgSlot() { + MOZ_ASSERT(targetState() != JS::PromiseState::Pending); + return targetState() == JS::PromiseState::Fulfilled + ? ReactionRecordSlot_OnFulfilledArg + : ReactionRecordSlot_OnRejectedArg; + } + + public: + static const JSClass class_; + + JSObject* promise() { + return getFixedSlot(ReactionRecordSlot_Promise).toObjectOrNull(); + } + int32_t flags() const { + return getFixedSlot(ReactionRecordSlot_Flags).toInt32(); + } + JS::PromiseState targetState() { + int32_t flags = this->flags(); + if (!(flags & REACTION_FLAG_RESOLVED)) { + return JS::PromiseState::Pending; + } + return flags & REACTION_FLAG_FULFILLED ? JS::PromiseState::Fulfilled + : JS::PromiseState::Rejected; + } + void setTargetStateAndHandlerArg(JS::PromiseState state, const Value& arg) { + MOZ_ASSERT(targetState() == JS::PromiseState::Pending); + MOZ_ASSERT(state != JS::PromiseState::Pending, + "Can't revert a reaction to pending."); + + int32_t flags = this->flags(); + flags |= REACTION_FLAG_RESOLVED; + if (state == JS::PromiseState::Fulfilled) { + flags |= REACTION_FLAG_FULFILLED; + } + + setFixedSlot(ReactionRecordSlot_Flags, Int32Value(flags)); + setFixedSlot(handlerArgSlot(), arg); + } + + void setShouldIgnoreUnhandledRejection() { + setFlagOnInitialState(REACTION_FLAG_IGNORE_UNHANDLED_REJECTION); + } + UnhandledRejectionBehavior unhandledRejectionBehavior() const { + int32_t flags = this->flags(); + return (flags & REACTION_FLAG_IGNORE_UNHANDLED_REJECTION) + ? UnhandledRejectionBehavior::Ignore + : UnhandledRejectionBehavior::Report; + } + + void setIsDefaultResolvingHandler(PromiseObject* promiseToResolve) { + setFlagOnInitialState(REACTION_FLAG_DEFAULT_RESOLVING_HANDLER); + setFixedSlot(ReactionRecordSlot_GeneratorOrPromiseToResolve, + ObjectValue(*promiseToResolve)); + } + bool isDefaultResolvingHandler() { + int32_t flags = this->flags(); + return flags & REACTION_FLAG_DEFAULT_RESOLVING_HANDLER; + } + PromiseObject* defaultResolvingPromise() { + MOZ_ASSERT(isDefaultResolvingHandler()); + const Value& promiseToResolve = + getFixedSlot(ReactionRecordSlot_GeneratorOrPromiseToResolve); + return &promiseToResolve.toObject().as<PromiseObject>(); + } + void setIsAsyncFunction(AsyncFunctionGeneratorObject* genObj) { + setFlagOnInitialState(REACTION_FLAG_ASYNC_FUNCTION); + setFixedSlot(ReactionRecordSlot_GeneratorOrPromiseToResolve, + ObjectValue(*genObj)); + } + bool isAsyncFunction() { + int32_t flags = this->flags(); + return flags & REACTION_FLAG_ASYNC_FUNCTION; + } + AsyncFunctionGeneratorObject* asyncFunctionGenerator() { + MOZ_ASSERT(isAsyncFunction()); + const Value& generator = + getFixedSlot(ReactionRecordSlot_GeneratorOrPromiseToResolve); + return &generator.toObject().as<AsyncFunctionGeneratorObject>(); + } + void setIsAsyncGenerator(AsyncGeneratorObject* asyncGenObj) { + setFlagOnInitialState(REACTION_FLAG_ASYNC_GENERATOR); + setFixedSlot(ReactionRecordSlot_GeneratorOrPromiseToResolve, + ObjectValue(*asyncGenObj)); + } + bool isAsyncGenerator() { + int32_t flags = this->flags(); + return flags & REACTION_FLAG_ASYNC_GENERATOR; + } + AsyncGeneratorObject* asyncGenerator() { + MOZ_ASSERT(isAsyncGenerator()); + const Value& generator = + getFixedSlot(ReactionRecordSlot_GeneratorOrPromiseToResolve); + return &generator.toObject().as<AsyncGeneratorObject>(); + } + void setIsDebuggerDummy() { + setFlagOnInitialState(REACTION_FLAG_DEBUGGER_DUMMY); + } + bool isDebuggerDummy() { + int32_t flags = this->flags(); + return flags & REACTION_FLAG_DEBUGGER_DUMMY; + } + Value handler() { + MOZ_ASSERT(targetState() != JS::PromiseState::Pending); + return getFixedSlot(handlerSlot()); + } + Value handlerArg() { + MOZ_ASSERT(targetState() != JS::PromiseState::Pending); + return getFixedSlot(handlerArgSlot()); + } + JSObject* getAndClearIncumbentGlobalObject() { + JSObject* obj = + getFixedSlot(ReactionRecordSlot_IncumbentGlobalObject).toObjectOrNull(); + setFixedSlot(ReactionRecordSlot_IncumbentGlobalObject, UndefinedValue()); + return obj; + } +}; + +const JSClass PromiseReactionRecord::class_ = { + "PromiseReactionRecord", JSCLASS_HAS_RESERVED_SLOTS(ReactionRecordSlots)}; + +static void AddPromiseFlags(PromiseObject& promise, int32_t flag) { + int32_t flags = promise.flags(); + promise.setFixedSlot(PromiseSlot_Flags, Int32Value(flags | flag)); +} + +static void RemovePromiseFlags(PromiseObject& promise, int32_t flag) { + int32_t flags = promise.flags(); + promise.setFixedSlot(PromiseSlot_Flags, Int32Value(flags & ~flag)); +} + +static bool PromiseHasAnyFlag(PromiseObject& promise, int32_t flag) { + return promise.flags() & flag; +} + +static bool ResolvePromiseFunction(JSContext* cx, unsigned argc, Value* vp); +static bool RejectPromiseFunction(JSContext* cx, unsigned argc, Value* vp); + +// ES2016, 25.4.1.3. +static MOZ_MUST_USE MOZ_ALWAYS_INLINE bool CreateResolvingFunctions( + JSContext* cx, HandleObject promise, MutableHandleObject resolveFn, + MutableHandleObject rejectFn) { + HandlePropertyName funName = cx->names().empty; + resolveFn.set(NewNativeFunction(cx, ResolvePromiseFunction, 1, funName, + gc::AllocKind::FUNCTION_EXTENDED, + GenericObject)); + if (!resolveFn) { + return false; + } + + rejectFn.set(NewNativeFunction(cx, RejectPromiseFunction, 1, funName, + gc::AllocKind::FUNCTION_EXTENDED, + GenericObject)); + if (!rejectFn) { + return false; + } + + JSFunction* resolveFun = &resolveFn->as<JSFunction>(); + JSFunction* rejectFun = &rejectFn->as<JSFunction>(); + + resolveFun->initExtendedSlot(ResolveFunctionSlot_Promise, + ObjectValue(*promise)); + resolveFun->initExtendedSlot(ResolveFunctionSlot_RejectFunction, + ObjectValue(*rejectFun)); + + rejectFun->initExtendedSlot(RejectFunctionSlot_Promise, + ObjectValue(*promise)); + rejectFun->initExtendedSlot(RejectFunctionSlot_ResolveFunction, + ObjectValue(*resolveFun)); + + return true; +} + +static void ClearResolutionFunctionSlots(JSFunction* resolutionFun); + +static bool IsSettledMaybeWrappedPromise(JSObject* promise) { + if (IsProxy(promise)) { + promise = UncheckedUnwrap(promise); + + // Caller needs to handle dead wrappers. + if (JS_IsDeadWrapper(promise)) { + return false; + } + } + + return promise->as<PromiseObject>().state() != JS::PromiseState::Pending; +} + +// ES2016, 25.4.1.7. +static MOZ_MUST_USE bool RejectMaybeWrappedPromise( + JSContext* cx, HandleObject promiseObj, HandleValue reason, + HandleSavedFrame unwrappedRejectionStack); + +// ES2016, 25.4.1.7. +static MOZ_MUST_USE bool RejectPromiseInternal( + JSContext* cx, Handle<PromiseObject*> promise, HandleValue reason, + HandleSavedFrame unwrappedRejectionStack = nullptr); + +// ES2016, 25.4.1.3.1. +static bool RejectPromiseFunction(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + JSFunction* reject = &args.callee().as<JSFunction>(); + HandleValue reasonVal = args.get(0); + + // Steps 1-2. + const Value& promiseVal = reject->getExtendedSlot(RejectFunctionSlot_Promise); + + // Steps 3-4. + // If the Promise isn't available anymore, it has been resolved and the + // reference to it removed to make it eligible for collection. + if (promiseVal.isUndefined()) { + args.rval().setUndefined(); + return true; + } + + // Store the promise value in |promise| before ClearResolutionFunctionSlots + // removes the reference. + RootedObject promise(cx, &promiseVal.toObject()); + + // Step 5. + // Here, we only remove the Promise reference from the resolution + // functions. Actually marking it as fulfilled/rejected happens later. + ClearResolutionFunctionSlots(reject); + + // In some cases the Promise reference on the resolution function won't + // have been removed during resolution, so we need to check that here, + // too. + if (IsSettledMaybeWrappedPromise(promise)) { + args.rval().setUndefined(); + return true; + } + + // Step 6. + if (!RejectMaybeWrappedPromise(cx, promise, reasonVal, nullptr)) { + return false; + } + args.rval().setUndefined(); + return true; +} + +static MOZ_MUST_USE bool FulfillMaybeWrappedPromise(JSContext* cx, + HandleObject promiseObj, + HandleValue value_); + +static MOZ_MUST_USE bool EnqueuePromiseResolveThenableJob( + JSContext* cx, HandleValue promiseToResolve, HandleValue thenable, + HandleValue thenVal); + +static MOZ_MUST_USE bool EnqueuePromiseResolveThenableBuiltinJob( + JSContext* cx, HandleObject promiseToResolve, HandleObject thenable); + +static bool Promise_then_impl(JSContext* cx, HandleValue promiseVal, + HandleValue onFulfilled, HandleValue onRejected, + MutableHandleValue rval, bool rvalUsed); + +// ES2016, 25.4.1.3.2, steps 6-13. +static MOZ_MUST_USE bool ResolvePromiseInternal(JSContext* cx, + HandleObject promise, + HandleValue resolutionVal) { + cx->check(promise, resolutionVal); + MOZ_ASSERT(!IsSettledMaybeWrappedPromise(promise)); + + // Step 7 (reordered). + if (!resolutionVal.isObject()) { + return FulfillMaybeWrappedPromise(cx, promise, resolutionVal); + } + + RootedObject resolution(cx, &resolutionVal.toObject()); + + // Step 6. + if (resolution == promise) { + // Step 6.a. + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_CANNOT_RESOLVE_PROMISE_WITH_ITSELF); + RootedValue selfResolutionError(cx); + RootedSavedFrame stack(cx); + if (!MaybeGetAndClearExceptionAndStack(cx, &selfResolutionError, &stack)) { + return false; + } + + // Step 6.b. + return RejectMaybeWrappedPromise(cx, promise, selfResolutionError, stack); + } + + // Step 8. + RootedValue thenVal(cx); + bool status = + GetProperty(cx, resolution, resolution, cx->names().then, &thenVal); + + RootedValue error(cx); + RootedSavedFrame errorStack(cx); + if (!status) { + if (!MaybeGetAndClearExceptionAndStack(cx, &error, &errorStack)) { + return false; + } + } + + // Testing functions allow to directly settle a promise without going + // through the resolving functions. In that case the normal bookkeeping to + // ensure only pending promises can be resolved doesn't apply and we need + // to manually check for already settled promises. The exception is simply + // dropped when this case happens. + if (IsSettledMaybeWrappedPromise(promise)) { + return true; + } + + // Step 9. + if (!status) { + return RejectMaybeWrappedPromise(cx, promise, error, errorStack); + } + + // Step 10 (implicit). + + // Step 11. + if (!IsCallable(thenVal)) { + return FulfillMaybeWrappedPromise(cx, promise, resolutionVal); + } + + // If the resolution object is a built-in Promise object and the + // `then` property is the original Promise.prototype.then function + // from the current realm, we skip storing/calling it. + // Additionally we require that |promise| itself is also a built-in + // Promise object, so the fast path doesn't need to cope with wrappers. + bool isBuiltinThen = false; + if (resolution->is<PromiseObject>() && promise->is<PromiseObject>() && + IsNativeFunction(thenVal, Promise_then) && + thenVal.toObject().as<JSFunction>().realm() == cx->realm()) { + isBuiltinThen = true; + } + + // Step 12. + if (!isBuiltinThen) { + RootedValue promiseVal(cx, ObjectValue(*promise)); + if (!EnqueuePromiseResolveThenableJob(cx, promiseVal, resolutionVal, + thenVal)) { + return false; + } + } else { + if (!EnqueuePromiseResolveThenableBuiltinJob(cx, promise, resolution)) { + return false; + } + } + + // Step 13. + return true; +} + +// ES2016, 25.4.1.3.2. +static bool ResolvePromiseFunction(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + JSFunction* resolve = &args.callee().as<JSFunction>(); + HandleValue resolutionVal = args.get(0); + + // Steps 3-4 (reordered). + // We use the reference to the reject function as a signal for whether + // the resolve or reject function was already called, at which point + // the references on each of the functions are cleared. + if (!resolve->getExtendedSlot(ResolveFunctionSlot_RejectFunction) + .isObject()) { + args.rval().setUndefined(); + return true; + } + + // Steps 1-2 (reordered). + RootedObject promise( + cx, &resolve->getExtendedSlot(ResolveFunctionSlot_Promise).toObject()); + + // Step 5. + // Here, we only remove the Promise reference from the resolution + // functions. Actually marking it as fulfilled/rejected happens later. + ClearResolutionFunctionSlots(resolve); + + // In some cases the Promise reference on the resolution function won't + // have been removed during resolution, so we need to check that here, + // too. + if (IsSettledMaybeWrappedPromise(promise)) { + args.rval().setUndefined(); + return true; + } + + // Steps 6-13. + if (!ResolvePromiseInternal(cx, promise, resolutionVal)) { + return false; + } + args.rval().setUndefined(); + return true; +} + +static bool PromiseReactionJob(JSContext* cx, unsigned argc, Value* vp); + +/** + * Tells the embedding to enqueue a Promise reaction job, based on + * three parameters: + * reactionObj - The reaction record. + * handlerArg_ - The first and only argument to pass to the handler invoked by + * the job. This will be stored on the reaction record. + * targetState - The PromiseState this reaction job targets. This decides + * whether the onFulfilled or onRejected handler is called. + */ +MOZ_MUST_USE static bool EnqueuePromiseReactionJob( + JSContext* cx, HandleObject reactionObj, HandleValue handlerArg_, + JS::PromiseState targetState) { + MOZ_ASSERT(targetState == JS::PromiseState::Fulfilled || + targetState == JS::PromiseState::Rejected); + + // The reaction might have been stored on a Promise from another + // compartment, which means it would've been wrapped in a CCW. + // To properly handle that case here, unwrap it and enter its + // compartment, where the job creation should take place anyway. + Rooted<PromiseReactionRecord*> reaction(cx); + RootedValue handlerArg(cx, handlerArg_); + mozilla::Maybe<AutoRealm> ar; + if (!IsProxy(reactionObj)) { + MOZ_RELEASE_ASSERT(reactionObj->is<PromiseReactionRecord>()); + reaction = &reactionObj->as<PromiseReactionRecord>(); + if (cx->realm() != reaction->realm()) { + // If the compartment has multiple realms, create the job in the + // reaction's realm. This is consistent with the code in the else-branch + // and avoids problems with running jobs against a dying global (Gecko + // drops such jobs). + ar.emplace(cx, reaction); + } + } else { + JSObject* unwrappedReactionObj = UncheckedUnwrap(reactionObj); + if (JS_IsDeadWrapper(unwrappedReactionObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + reaction = &unwrappedReactionObj->as<PromiseReactionRecord>(); + MOZ_RELEASE_ASSERT(reaction->is<PromiseReactionRecord>()); + ar.emplace(cx, reaction); + if (!cx->compartment()->wrap(cx, &handlerArg)) { + return false; + } + } + + // Must not enqueue a reaction job more than once. + MOZ_ASSERT(reaction->targetState() == JS::PromiseState::Pending); + + cx->check(handlerArg); + reaction->setTargetStateAndHandlerArg(targetState, handlerArg); + + RootedValue reactionVal(cx, ObjectValue(*reaction)); + RootedValue handler(cx, reaction->handler()); + + // If we have a handler callback, we enter that handler's compartment so + // that the promise reaction job function is created in that compartment. + // That guarantees that the embedding ends up with the right entry global. + // This is relevant for some html APIs like fetch that derive information + // from said global. + mozilla::Maybe<AutoRealm> ar2; + if (handler.isObject()) { + // The unwrapping has to be unchecked because we specifically want to + // be able to use handlers with wrappers that would only allow calls. + // E.g., it's ok to have a handler from a chrome compartment in a + // reaction to a content compartment's Promise instance. + JSObject* handlerObj = UncheckedUnwrap(&handler.toObject()); + MOZ_ASSERT(handlerObj); + ar2.emplace(cx, handlerObj); + + // We need to wrap the reaction to store it on the job function. + if (!cx->compartment()->wrap(cx, &reactionVal)) { + return false; + } + } + + // Create the JS function to call when the job is triggered. + HandlePropertyName funName = cx->names().empty; + RootedFunction job( + cx, NewNativeFunction(cx, PromiseReactionJob, 0, funName, + gc::AllocKind::FUNCTION_EXTENDED, GenericObject)); + if (!job) { + return false; + } + + // Store the reaction on the reaction job. + job->setExtendedSlot(ReactionJobSlot_ReactionRecord, reactionVal); + + // When using JS::AddPromiseReactions{,IgnoringUnHandledRejection}, no actual + // promise is created, so we might not have one here. + // Additionally, we might have an object here that isn't an instance of + // Promise. This can happen if content overrides the value of + // Promise[@@species] (or invokes Promise#then on a Promise subclass + // instance with a non-default @@species value on the constructor) with a + // function that returns objects that're not Promise (subclass) instances. + // In that case, we just pretend we didn't have an object in the first + // place. + // If after all this we do have an object, wrap it in case we entered the + // handler's compartment above, because we should pass objects from a + // single compartment to the enqueuePromiseJob callback. + RootedObject promise(cx, reaction->promise()); + if (promise) { + if (promise->is<PromiseObject>()) { + if (!cx->compartment()->wrap(cx, &promise)) { + return false; + } + } else if (IsWrapper(promise)) { + // `promise` can be already-wrapped promise object at this point. + JSObject* unwrappedPromise = UncheckedUnwrap(promise); + if (unwrappedPromise->is<PromiseObject>()) { + if (!cx->compartment()->wrap(cx, &promise)) { + return false; + } + } else { + promise = nullptr; + } + } else { + promise = nullptr; + } + } + + // Using objectFromIncumbentGlobal, we can derive the incumbent global by + // unwrapping and then getting the global. This is very convoluted, but + // much better than having to store the original global as a private value + // because we couldn't wrap it to store it as a normal JS value. + Rooted<GlobalObject*> global(cx); + if (JSObject* objectFromIncumbentGlobal = + reaction->getAndClearIncumbentGlobalObject()) { + objectFromIncumbentGlobal = CheckedUnwrapStatic(objectFromIncumbentGlobal); + MOZ_ASSERT(objectFromIncumbentGlobal); + global = &objectFromIncumbentGlobal->nonCCWGlobal(); + } + + // Note: the global we pass here might be from a different compartment + // than job and promise. While it's somewhat unusual to pass objects + // from multiple compartments, in this case we specifically need the + // global to be unwrapped because wrapping and unwrapping aren't + // necessarily symmetric for globals. + return cx->runtime()->enqueuePromiseJob(cx, job, promise, global); +} + +static MOZ_MUST_USE bool TriggerPromiseReactions(JSContext* cx, + HandleValue reactionsVal, + JS::PromiseState state, + HandleValue valueOrReason); + +// ES2016, Commoned-out implementation of 25.4.1.4. and 25.4.1.7. +// +// This method takes an additional optional |unwrappedRejectionStack| parameter, +// which is only used for debugging purposes. +// It allows callers to to pass in the stack of some exception which +// triggered the rejection of the promise. +static MOZ_MUST_USE bool ResolvePromise( + JSContext* cx, Handle<PromiseObject*> promise, HandleValue valueOrReason, + JS::PromiseState state, + HandleSavedFrame unwrappedRejectionStack = nullptr) { + // Step 1. + MOZ_ASSERT(promise->state() == JS::PromiseState::Pending); + MOZ_ASSERT(state == JS::PromiseState::Fulfilled || + state == JS::PromiseState::Rejected); + MOZ_ASSERT_IF(unwrappedRejectionStack, state == JS::PromiseState::Rejected); + + // Step 2. + // We only have one list of reactions for both resolution types. So + // instead of getting the right list of reactions, we determine the + // resolution type to retrieve the right information from the + // reaction records. + RootedValue reactionsVal(cx, promise->reactions()); + + // Steps 3-5. + // The same slot is used for the reactions list and the result, so setting + // the result also removes the reactions list. + promise->setFixedSlot(PromiseSlot_ReactionsOrResult, valueOrReason); + + // Step 6. + int32_t flags = promise->flags(); + flags |= PROMISE_FLAG_RESOLVED; + if (state == JS::PromiseState::Fulfilled) { + flags |= PROMISE_FLAG_FULFILLED; + } + promise->setFixedSlot(PromiseSlot_Flags, Int32Value(flags)); + + // Also null out the resolve/reject functions so they can be GC'd. + promise->setFixedSlot(PromiseSlot_RejectFunction, UndefinedValue()); + + // Now that everything else is done, do the things the debugger needs. + // Step 7 of RejectPromise implemented in onSettled. + PromiseObject::onSettled(cx, promise, unwrappedRejectionStack); + + // Step 7 of FulfillPromise. + // Step 8 of RejectPromise. + return TriggerPromiseReactions(cx, reactionsVal, state, valueOrReason); +} + +// ES2016, 25.4.1.7. +static MOZ_MUST_USE bool RejectPromiseInternal( + JSContext* cx, Handle<PromiseObject*> promise, HandleValue reason, + HandleSavedFrame unwrappedRejectionStack) { + return ResolvePromise(cx, promise, reason, JS::PromiseState::Rejected, + unwrappedRejectionStack); +} + +// ES2016, 25.4.1.4. +static MOZ_MUST_USE bool FulfillMaybeWrappedPromise(JSContext* cx, + HandleObject promiseObj, + HandleValue value_) { + Rooted<PromiseObject*> promise(cx); + RootedValue value(cx, value_); + + mozilla::Maybe<AutoRealm> ar; + if (!IsProxy(promiseObj)) { + promise = &promiseObj->as<PromiseObject>(); + } else { + JSObject* unwrappedPromiseObj = UncheckedUnwrap(promiseObj); + if (JS_IsDeadWrapper(unwrappedPromiseObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + promise = &unwrappedPromiseObj->as<PromiseObject>(); + ar.emplace(cx, promise); + if (!cx->compartment()->wrap(cx, &value)) { + return false; + } + } + + return ResolvePromise(cx, promise, value, JS::PromiseState::Fulfilled); +} + +static bool GetCapabilitiesExecutor(JSContext* cx, unsigned argc, Value* vp); +static bool PromiseConstructor(JSContext* cx, unsigned argc, Value* vp); +static MOZ_MUST_USE PromiseObject* CreatePromiseObjectInternal( + JSContext* cx, HandleObject proto = nullptr, bool protoIsWrapped = false, + bool informDebugger = true); + +enum GetCapabilitiesExecutorSlots { + GetCapabilitiesExecutorSlots_Resolve, + GetCapabilitiesExecutorSlots_Reject +}; + +static MOZ_MUST_USE PromiseObject* +CreatePromiseObjectWithoutResolutionFunctions(JSContext* cx) { + PromiseObject* promise = CreatePromiseObjectInternal(cx); + if (!promise) { + return nullptr; + } + + AddPromiseFlags(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS); + return promise; +} + +static MOZ_MUST_USE PromiseObject* CreatePromiseWithDefaultResolutionFunctions( + JSContext* cx, MutableHandleObject resolve, MutableHandleObject reject) { + // ES2016, 25.4.3.1., as if called with GetCapabilitiesExecutor as the + // executor argument. + + // Steps 1-2 (Not applicable). + + // Steps 3-7. + Rooted<PromiseObject*> promise(cx, CreatePromiseObjectInternal(cx)); + if (!promise) { + return nullptr; + } + + // Step 8. + if (!CreateResolvingFunctions(cx, promise, resolve, reject)) { + return nullptr; + } + + promise->setFixedSlot(PromiseSlot_RejectFunction, ObjectValue(*reject)); + + // Steps 9-10 (Not applicable). + + // Step 11. + return promise; +} + +// ES2016, 25.4.1.5. +static MOZ_MUST_USE bool NewPromiseCapability( + JSContext* cx, HandleObject C, MutableHandle<PromiseCapability> capability, + bool canOmitResolutionFunctions) { + RootedValue cVal(cx, ObjectValue(*C)); + + // Steps 1-2. + if (!IsConstructor(C)) { + ReportValueError(cx, JSMSG_NOT_CONSTRUCTOR, JSDVG_SEARCH_STACK, cVal, + nullptr); + return false; + } + + // If we'd call the original Promise constructor and know that the + // resolve/reject functions won't ever escape to content, we can skip + // creating and calling the executor function and instead return a Promise + // marked as having default resolve/reject functions. + // + // This can't be used in Promise.all and Promise.race because we have to + // pass the reject (and resolve, in the race case) function to thenables + // in the list passed to all/race, which (potentially) means exposing them + // to content. + // + // For Promise.all and Promise.race we can only optimize away the creation + // of the GetCapabilitiesExecutor function, and directly allocate the + // result promise instead of invoking the Promise constructor. + if (IsNativeFunction(cVal, PromiseConstructor) && + cVal.toObject().nonCCWRealm() == cx->realm()) { + PromiseObject* promise; + if (canOmitResolutionFunctions) { + promise = CreatePromiseObjectWithoutResolutionFunctions(cx); + } else { + promise = CreatePromiseWithDefaultResolutionFunctions( + cx, capability.resolve(), capability.reject()); + } + if (!promise) { + return false; + } + + capability.promise().set(promise); + return true; + } + + // Step 3 (omitted). + + // Step 4. + HandlePropertyName funName = cx->names().empty; + RootedFunction executor( + cx, NewNativeFunction(cx, GetCapabilitiesExecutor, 2, funName, + gc::AllocKind::FUNCTION_EXTENDED, GenericObject)); + if (!executor) { + return false; + } + + // Step 5 (omitted). + + // Step 6. + FixedConstructArgs<1> cargs(cx); + cargs[0].setObject(*executor); + if (!Construct(cx, cVal, cargs, cVal, capability.promise())) { + return false; + } + + // Step 7. + const Value& resolveVal = + executor->getExtendedSlot(GetCapabilitiesExecutorSlots_Resolve); + if (!IsCallable(resolveVal)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_PROMISE_RESOLVE_FUNCTION_NOT_CALLABLE); + return false; + } + + // Step 8. + const Value& rejectVal = + executor->getExtendedSlot(GetCapabilitiesExecutorSlots_Reject); + if (!IsCallable(rejectVal)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_PROMISE_REJECT_FUNCTION_NOT_CALLABLE); + return false; + } + + // Step 9 (well, the equivalent for all of promiseCapabilities' fields.) + capability.resolve().set(&resolveVal.toObject()); + capability.reject().set(&rejectVal.toObject()); + + // Step 10. + return true; +} + +// ES2016, 25.4.1.5.1. +static bool GetCapabilitiesExecutor(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + JSFunction* F = &args.callee().as<JSFunction>(); + + // Steps 1-2 (implicit). + + // Steps 3-4. + if (!F->getExtendedSlot(GetCapabilitiesExecutorSlots_Resolve).isUndefined() || + !F->getExtendedSlot(GetCapabilitiesExecutorSlots_Reject).isUndefined()) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_PROMISE_CAPABILITY_HAS_SOMETHING_ALREADY); + return false; + } + + // Step 5. + F->setExtendedSlot(GetCapabilitiesExecutorSlots_Resolve, args.get(0)); + + // Step 6. + F->setExtendedSlot(GetCapabilitiesExecutorSlots_Reject, args.get(1)); + + // Step 7. + args.rval().setUndefined(); + return true; +} + +// ES2016, 25.4.1.7. +static MOZ_MUST_USE bool RejectMaybeWrappedPromise( + JSContext* cx, HandleObject promiseObj, HandleValue reason_, + HandleSavedFrame unwrappedRejectionStack) { + Rooted<PromiseObject*> promise(cx); + RootedValue reason(cx, reason_); + + mozilla::Maybe<AutoRealm> ar; + if (!IsProxy(promiseObj)) { + promise = &promiseObj->as<PromiseObject>(); + } else { + JSObject* unwrappedPromiseObj = UncheckedUnwrap(promiseObj); + if (JS_IsDeadWrapper(unwrappedPromiseObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + promise = &unwrappedPromiseObj->as<PromiseObject>(); + ar.emplace(cx, promise); + + // The rejection reason might've been created in a compartment with higher + // privileges than the Promise's. In that case, object-type rejection + // values might be wrapped into a wrapper that throws whenever the + // Promise's reaction handler wants to do anything useful with it. To + // avoid that situation, we synthesize a generic error that doesn't + // expose any privileged information but can safely be used in the + // rejection handler. + if (!cx->compartment()->wrap(cx, &reason)) { + return false; + } + if (reason.isObject() && !CheckedUnwrapStatic(&reason.toObject())) { + // Report the existing reason, so we don't just drop it on the + // floor. + JSObject* realReason = UncheckedUnwrap(&reason.toObject()); + RootedValue realReasonVal(cx, ObjectValue(*realReason)); + Rooted<GlobalObject*> realGlobal(cx, &realReason->nonCCWGlobal()); + ReportErrorToGlobal(cx, realGlobal, realReasonVal); + + // Async stacks are only properly adopted if there's at least one + // interpreter frame active right now. If a thenable job with a + // throwing `then` function got us here, that'll not be the case, + // so we add one by throwing the error from self-hosted code. + if (!GetInternalError(cx, JSMSG_PROMISE_ERROR_IN_WRAPPED_REJECTION_REASON, + &reason)) { + return false; + } + } + } + + return ResolvePromise(cx, promise, reason, JS::PromiseState::Rejected, + unwrappedRejectionStack); +} + +// Apply f to a mutable handle on each member of a collection of reactions, like +// that stored in PromiseSlot_ReactionsOrResult on a pending promise. When the +// reaction record is wrapped, we pass the wrapper, without dereferencing it. If +// f returns false, then we stop the iteration immediately and return false. +// Otherwise, we return true. +// +// There are several different representations for collections: +// +// - We represent an empty collection of reactions as an 'undefined' value. +// +// - We represent a collection containing a single reaction simply as the given +// PromiseReactionRecord object, possibly wrapped. +// +// - We represent a collection of two or more reactions as a dense array of +// possibly-wrapped PromiseReactionRecords. +// +template <typename F> +static bool ForEachReaction(JSContext* cx, HandleValue reactionsVal, F f) { + if (reactionsVal.isUndefined()) { + return true; + } + + RootedObject reactions(cx, &reactionsVal.toObject()); + RootedObject reaction(cx); + + if (reactions->is<PromiseReactionRecord>() || IsWrapper(reactions) || + JS_IsDeadWrapper(reactions)) { + return f(&reactions); + } + + HandleNativeObject reactionsList = reactions.as<NativeObject>(); + uint32_t reactionsCount = reactionsList->getDenseInitializedLength(); + MOZ_ASSERT(reactionsCount > 1, "Reactions list should be created lazily"); + + for (uint32_t i = 0; i < reactionsCount; i++) { + const Value& reactionVal = reactionsList->getDenseElement(i); + MOZ_RELEASE_ASSERT(reactionVal.isObject()); + reaction = &reactionVal.toObject(); + if (!f(&reaction)) { + return false; + } + } + + return true; +} + +// ES2016, 25.4.1.8. +static MOZ_MUST_USE bool TriggerPromiseReactions(JSContext* cx, + HandleValue reactionsVal, + JS::PromiseState state, + HandleValue valueOrReason) { + MOZ_ASSERT(state == JS::PromiseState::Fulfilled || + state == JS::PromiseState::Rejected); + + return ForEachReaction(cx, reactionsVal, [&](MutableHandleObject reaction) { + return EnqueuePromiseReactionJob(cx, reaction, valueOrReason, state); + }); +} + +static MOZ_MUST_USE bool RunFulfillFunction(JSContext* cx, + HandleObject onFulfilledFunc, + HandleValue result, + HandleObject promiseObj); + +// Implements PromiseReactionJob optimized for the case when the reaction +// handler is one of the default resolving functions as created by the +// CreateResolvingFunctions abstract operation. +static MOZ_MUST_USE bool DefaultResolvingPromiseReactionJob( + JSContext* cx, Handle<PromiseReactionRecord*> reaction) { + MOZ_ASSERT(reaction->targetState() != JS::PromiseState::Pending); + + Rooted<PromiseObject*> promiseToResolve(cx, + reaction->defaultResolvingPromise()); + + // Testing functions allow to directly settle a promise without going + // through the resolving functions. In that case the normal bookkeeping to + // ensure only pending promises can be resolved doesn't apply and we need + // to manually check for already settled promises. We still call + // Run{Fulfill,Reject}Function for consistency with PromiseReactionJob. + ResolutionMode resolutionMode = ResolveMode; + RootedValue handlerResult(cx, UndefinedValue()); + RootedSavedFrame unwrappedRejectionStack(cx); + if (promiseToResolve->state() == JS::PromiseState::Pending) { + RootedValue argument(cx, reaction->handlerArg()); + + // Step 6. + bool ok; + if (reaction->targetState() == JS::PromiseState::Fulfilled) { + ok = ResolvePromiseInternal(cx, promiseToResolve, argument); + } else { + ok = RejectPromiseInternal(cx, promiseToResolve, argument); + } + + if (!ok) { + resolutionMode = RejectMode; + if (!MaybeGetAndClearExceptionAndStack(cx, &handlerResult, + &unwrappedRejectionStack)) { + return false; + } + } + } + + // Steps 7-9. + RootedObject promiseObj(cx, reaction->promise()); + RootedObject callee(cx); + if (resolutionMode == ResolveMode) { + callee = + reaction->getFixedSlot(ReactionRecordSlot_Resolve).toObjectOrNull(); + + return RunFulfillFunction(cx, callee, handlerResult, promiseObj); + } + + callee = reaction->getFixedSlot(ReactionRecordSlot_Reject).toObjectOrNull(); + + return RunRejectFunction(cx, callee, handlerResult, promiseObj, + unwrappedRejectionStack, + reaction->unhandledRejectionBehavior()); +} + +static MOZ_MUST_USE bool AsyncFunctionPromiseReactionJob( + JSContext* cx, Handle<PromiseReactionRecord*> reaction) { + MOZ_ASSERT(reaction->isAsyncFunction()); + + int32_t handler = reaction->handler().toInt32(); + RootedValue argument(cx, reaction->handlerArg()); + Rooted<AsyncFunctionGeneratorObject*> generator( + cx, reaction->asyncFunctionGenerator()); + + // Await's handlers don't return a value, nor throw any exceptions. + // They fail only on OOM. + + if (handler == PromiseHandlerAsyncFunctionAwaitedFulfilled) { + return AsyncFunctionAwaitedFulfilled(cx, generator, argument); + } + + MOZ_ASSERT(handler == PromiseHandlerAsyncFunctionAwaitedRejected); + return AsyncFunctionAwaitedRejected(cx, generator, argument); +} + +static MOZ_MUST_USE bool AsyncGeneratorPromiseReactionJob( + JSContext* cx, Handle<PromiseReactionRecord*> reaction) { + MOZ_ASSERT(reaction->isAsyncGenerator()); + + RootedValue argument(cx, reaction->handlerArg()); + Rooted<AsyncGeneratorObject*> asyncGenObj(cx, reaction->asyncGenerator()); + + // Await's handlers don't return a value, nor throw any exceptions. + // They fail only on OOM. + switch (int32_t handler = reaction->handler().toInt32(); handler) { + // ES2020 draft rev a09fc232c137800dbf51b6204f37fdede4ba1646 + // 6.2.3.1.1 Await Fulfilled Functions + case PromiseHandlerAsyncGeneratorAwaitedFulfilled: { + MOZ_ASSERT(asyncGenObj->isExecuting(), + "Await fulfilled when not in 'Executing' state"); + + return AsyncGeneratorAwaitedFulfilled(cx, asyncGenObj, argument); + } + + // ES2020 draft rev a09fc232c137800dbf51b6204f37fdede4ba1646 + // 6.2.3.1.2 Await Rejected Functions + case PromiseHandlerAsyncGeneratorAwaitedRejected: { + MOZ_ASSERT(asyncGenObj->isExecuting(), + "Await rejected when not in 'Executing' state"); + + return AsyncGeneratorAwaitedRejected(cx, asyncGenObj, argument); + } + + // ES2020 draft rev a09fc232c137800dbf51b6204f37fdede4ba1646 + // 25.5.3.5.1 AsyncGeneratorResumeNext Return Processor Fulfilled Functions + case PromiseHandlerAsyncGeneratorResumeNextReturnFulfilled: { + MOZ_ASSERT(asyncGenObj->isAwaitingReturn(), + "AsyncGeneratorResumeNext-Return fulfilled when not in " + "'AwaitingReturn' state"); + + // Steps 1-2. + asyncGenObj->setCompleted(); + + // Step 3. + return AsyncGeneratorResolve(cx, asyncGenObj, argument, true); + } + + // ES2020 draft rev a09fc232c137800dbf51b6204f37fdede4ba1646 + // 25.5.3.5.2 AsyncGeneratorResumeNext Return Processor Rejected Functions + case PromiseHandlerAsyncGeneratorResumeNextReturnRejected: { + MOZ_ASSERT(asyncGenObj->isAwaitingReturn(), + "AsyncGeneratorResumeNext-Return rejected when not in " + "'AwaitingReturn' state"); + + // Steps 1-2. + asyncGenObj->setCompleted(); + + // Step 3. + return AsyncGeneratorReject(cx, asyncGenObj, argument); + } + + // ES2020 draft rev a09fc232c137800dbf51b6204f37fdede4ba1646 + // 25.5.3.7 AsyncGeneratorYield + case PromiseHandlerAsyncGeneratorYieldReturnAwaitedFulfilled: { + MOZ_ASSERT(asyncGenObj->isAwaitingYieldReturn(), + "YieldReturn-Await fulfilled when not in " + "'AwaitingYieldReturn' state"); + + // We're using a separate 'AwaitingYieldReturn' state when awaiting a + // return completion in yield expressions, whereas the spec uses the + // 'Executing' state all along. So we now need to transition into the + // 'Executing' state. + asyncGenObj->setExecuting(); + + // Steps 8.d-e. + return AsyncGeneratorYieldReturnAwaitedFulfilled(cx, asyncGenObj, + argument); + } + + // ES2020 draft rev a09fc232c137800dbf51b6204f37fdede4ba1646 + // 25.5.3.7 AsyncGeneratorYield + case PromiseHandlerAsyncGeneratorYieldReturnAwaitedRejected: { + MOZ_ASSERT( + asyncGenObj->isAwaitingYieldReturn(), + "YieldReturn-Await rejected when not in 'AwaitingYieldReturn' state"); + + // We're using a separate 'AwaitingYieldReturn' state when awaiting a + // return completion in yield expressions, whereas the spec uses the + // 'Executing' state all along. So we now need to transition into the + // 'Executing' state. + asyncGenObj->setExecuting(); + + // Step 8.c. + return AsyncGeneratorYieldReturnAwaitedRejected(cx, asyncGenObj, + argument); + } + + default: + MOZ_CRASH("Bad handler in AsyncGeneratorPromiseReactionJob"); + } +} + +// ES2016, 25.4.2.1. +/** + * Callback triggering the fulfill/reject reaction for a resolved Promise, + * to be invoked by the embedding during its processing of the Promise job + * queue. + * + * See + * http://www.ecma-international.org/ecma-262/7.0/index.html#sec-jobs-and-job-queues + * + * A PromiseReactionJob is set as the native function of an extended + * JSFunction object, with all information required for the job's + * execution stored in in a reaction record in its first extended slot. + */ +static bool PromiseReactionJob(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + RootedFunction job(cx, &args.callee().as<JSFunction>()); + + // Promise reactions don't return any value. + args.rval().setUndefined(); + + RootedObject reactionObj( + cx, &job->getExtendedSlot(ReactionJobSlot_ReactionRecord).toObject()); + + // To ensure that the embedding ends up with the right entry global, we're + // guaranteeing that the reaction job function gets created in the same + // compartment as the handler function. That's not necessarily the global + // that the job was triggered from, though. + // We can find the triggering global via the job's reaction record. To go + // back, we check if the reaction is a wrapper and if so, unwrap it and + // enter its compartment. + mozilla::Maybe<AutoRealm> ar; + if (!IsProxy(reactionObj)) { + MOZ_RELEASE_ASSERT(reactionObj->is<PromiseReactionRecord>()); + } else { + reactionObj = UncheckedUnwrap(reactionObj); + if (JS_IsDeadWrapper(reactionObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + MOZ_RELEASE_ASSERT(reactionObj->is<PromiseReactionRecord>()); + ar.emplace(cx, reactionObj); + } + + // Steps 1-2. + Handle<PromiseReactionRecord*> reaction = + reactionObj.as<PromiseReactionRecord>(); + if (reaction->isDefaultResolvingHandler()) { + return DefaultResolvingPromiseReactionJob(cx, reaction); + } + if (reaction->isAsyncFunction()) { + return AsyncFunctionPromiseReactionJob(cx, reaction); + } + if (reaction->isAsyncGenerator()) { + return AsyncGeneratorPromiseReactionJob(cx, reaction); + } + if (reaction->isDebuggerDummy()) { + return true; + } + + // Step 3. + RootedValue handlerVal(cx, reaction->handler()); + + RootedValue argument(cx, reaction->handlerArg()); + + RootedValue handlerResult(cx); + ResolutionMode resolutionMode = ResolveMode; + + RootedSavedFrame unwrappedRejectionStack(cx); + + // Steps 4-6. + if (handlerVal.isInt32()) { + int32_t handlerNum = handlerVal.toInt32(); + + // Step 4. + if (handlerNum == PromiseHandlerIdentity) { + handlerResult = argument; + } else if (handlerNum == PromiseHandlerThrower) { + // Step 5. + resolutionMode = RejectMode; + handlerResult = argument; + } else { + MOZ_ASSERT( + handlerNum == PromiseHandlerAsyncFromSyncIteratorValueUnwrapDone || + handlerNum == PromiseHandlerAsyncFromSyncIteratorValueUnwrapNotDone); + + bool done = + handlerNum == PromiseHandlerAsyncFromSyncIteratorValueUnwrapDone; + // 25.1.4.2.5 Async-from-Sync Iterator Value Unwrap Functions, steps 1-2. + PlainObject* resultObj = CreateIterResultObject(cx, argument, done); + if (!resultObj) { + return false; + } + + handlerResult = ObjectValue(*resultObj); + } + } else { + MOZ_ASSERT(handlerVal.isObject()); + MOZ_ASSERT(IsCallable(handlerVal)); + + // Step 6. + if (!Call(cx, handlerVal, UndefinedHandleValue, argument, &handlerResult)) { + resolutionMode = RejectMode; + if (!MaybeGetAndClearExceptionAndStack(cx, &handlerResult, + &unwrappedRejectionStack)) { + return false; + } + } + } + + // Steps 7-9. + RootedObject promiseObj(cx, reaction->promise()); + RootedObject callee(cx); + if (resolutionMode == ResolveMode) { + callee = + reaction->getFixedSlot(ReactionRecordSlot_Resolve).toObjectOrNull(); + + return RunFulfillFunction(cx, callee, handlerResult, promiseObj); + } + + callee = reaction->getFixedSlot(ReactionRecordSlot_Reject).toObjectOrNull(); + + return RunRejectFunction(cx, callee, handlerResult, promiseObj, + unwrappedRejectionStack, + reaction->unhandledRejectionBehavior()); +} + +// ES2016, 25.4.2.2. +/** + * Callback for resolving a thenable, to be invoked by the embedding during + * its processing of the Promise job queue. + * + * See https://tc39.github.io/ecma262/#sec-jobs-and-job-queues + * + * A PromiseResolveThenableJob is set as the native function of an extended + * JSFunction object, with all information required for the job's + * execution stored in the function's extended slots. + * + * Usage of the function's extended slots is described in the ThenableJobSlots + * enum. + */ +static bool PromiseResolveThenableJob(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + RootedFunction job(cx, &args.callee().as<JSFunction>()); + RootedValue then(cx, job->getExtendedSlot(ThenableJobSlot_Handler)); + MOZ_ASSERT(then.isObject()); + MOZ_ASSERT(!IsWrapper(&then.toObject())); + RootedNativeObject jobArgs(cx, &job->getExtendedSlot(ThenableJobSlot_JobData) + .toObject() + .as<NativeObject>()); + + RootedObject promise( + cx, &jobArgs->getDenseElement(ThenableJobDataIndex_Promise).toObject()); + RootedValue thenable(cx, + jobArgs->getDenseElement(ThenableJobDataIndex_Thenable)); + + // Step 1. + RootedObject resolveFn(cx); + RootedObject rejectFn(cx); + if (!CreateResolvingFunctions(cx, promise, &resolveFn, &rejectFn)) { + return false; + } + + // Step 2. + FixedInvokeArgs<2> args2(cx); + args2[0].setObject(*resolveFn); + args2[1].setObject(*rejectFn); + + // In difference to the usual pattern, we return immediately on success. + RootedValue rval(cx); + if (Call(cx, then, thenable, args2, &rval)) { + return true; + } + + // Steps 3-4. + // Can't pass stack to a JS function. + RootedSavedFrame stack(cx); + if (!MaybeGetAndClearExceptionAndStack(cx, &rval, &stack)) { + return false; + } + + RootedValue rejectVal(cx, ObjectValue(*rejectFn)); + return Call(cx, rejectVal, UndefinedHandleValue, rval, &rval); +} + +static MOZ_MUST_USE bool OriginalPromiseThenWithoutSettleHandlers( + JSContext* cx, Handle<PromiseObject*> promise, + Handle<PromiseObject*> promiseToResolve); + +/** + * Specialization of PromiseResolveThenableJob when the `thenable` is a + * built-in Promise object and the `then` property is the built-in + * `Promise.prototype.then` function. + * + * A PromiseResolveBuiltinThenableJob is set as the native function of an + * extended JSFunction object, with all information required for the job's + * execution stored in the function's extended slots. + * + * Usage of the function's extended slots is described in the + * BuiltinThenableJobSlots enum. + */ +static bool PromiseResolveBuiltinThenableJob(JSContext* cx, unsigned argc, + Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + RootedFunction job(cx, &args.callee().as<JSFunction>()); + RootedObject promise( + cx, &job->getExtendedSlot(BuiltinThenableJobSlot_Promise).toObject()); + RootedObject thenable( + cx, &job->getExtendedSlot(BuiltinThenableJobSlot_Thenable).toObject()); + + cx->check(promise, thenable); + MOZ_ASSERT(promise->is<PromiseObject>()); + MOZ_ASSERT(thenable->is<PromiseObject>()); + + // Step 1 (Skipped). + + // Step 2. + // In difference to the usual pattern, we return immediately on success. + if (OriginalPromiseThenWithoutSettleHandlers(cx, thenable.as<PromiseObject>(), + promise.as<PromiseObject>())) { + return true; + } + + // Steps 3-4. + RootedValue exception(cx); + RootedSavedFrame stack(cx); + if (!MaybeGetAndClearExceptionAndStack(cx, &exception, &stack)) { + return false; + } + + // Testing functions allow to directly settle a promise without going + // through the resolving functions. In that case the normal bookkeeping to + // ensure only pending promises can be resolved doesn't apply and we need + // to manually check for already settled promises. The exception is simply + // dropped when this case happens. + if (promise->as<PromiseObject>().state() != JS::PromiseState::Pending) { + return true; + } + + return RejectPromiseInternal(cx, promise.as<PromiseObject>(), exception, + stack); +} + +/** + * Tells the embedding to enqueue a Promise resolve thenable job, based on + * three parameters: + * promiseToResolve_ - The promise to resolve, obviously. + * thenable_ - The thenable to resolve the Promise with. + * thenVal - The `then` function to invoke with the `thenable` as the receiver. + */ +static MOZ_MUST_USE bool EnqueuePromiseResolveThenableJob( + JSContext* cx, HandleValue promiseToResolve_, HandleValue thenable_, + HandleValue thenVal) { + // Need to re-root these to enable wrapping them below. + RootedValue promiseToResolve(cx, promiseToResolve_); + RootedValue thenable(cx, thenable_); + + // We enter the `then` callable's compartment so that the job function is + // created in that compartment. + // That guarantees that the embedding ends up with the right entry global. + // This is relevant for some html APIs like fetch that derive information + // from said global. + RootedObject then(cx, CheckedUnwrapStatic(&thenVal.toObject())); + AutoRealm ar(cx, then); + + // Wrap the `promiseToResolve` and `thenable` arguments. + if (!cx->compartment()->wrap(cx, &promiseToResolve)) { + return false; + } + + MOZ_ASSERT(thenable.isObject()); + if (!cx->compartment()->wrap(cx, &thenable)) { + return false; + } + + HandlePropertyName funName = cx->names().empty; + RootedFunction job( + cx, NewNativeFunction(cx, PromiseResolveThenableJob, 0, funName, + gc::AllocKind::FUNCTION_EXTENDED, GenericObject)); + if (!job) { + return false; + } + + // Store the `then` function on the callback. + job->setExtendedSlot(ThenableJobSlot_Handler, ObjectValue(*then)); + + // Create a dense array to hold the data needed for the reaction job to + // work. + // The layout is described in the ThenableJobDataIndices enum. + RootedArrayObject data( + cx, NewDenseFullyAllocatedArray(cx, ThenableJobDataLength)); + if (!data) { + return false; + } + + // Set the `promiseToResolve` and `thenable` arguments. + data->setDenseInitializedLength(ThenableJobDataLength); + data->initDenseElement(ThenableJobDataIndex_Promise, promiseToResolve); + data->initDenseElement(ThenableJobDataIndex_Thenable, thenable); + + // Store the data array on the reaction job. + job->setExtendedSlot(ThenableJobSlot_JobData, ObjectValue(*data)); + + // At this point the promise is guaranteed to be wrapped into the job's + // compartment. + RootedObject promise(cx, &promiseToResolve.toObject()); + + Rooted<GlobalObject*> incumbentGlobal(cx, + cx->runtime()->getIncumbentGlobal(cx)); + return cx->runtime()->enqueuePromiseJob(cx, job, promise, incumbentGlobal); +} + +/** + * Tells the embedding to enqueue a Promise resolve thenable built-in job, + * based on two parameters: + * promiseToResolve - The promise to resolve, obviously. + * thenable - The thenable to resolve the Promise with. + */ +static MOZ_MUST_USE bool EnqueuePromiseResolveThenableBuiltinJob( + JSContext* cx, HandleObject promiseToResolve, HandleObject thenable) { + cx->check(promiseToResolve, thenable); + MOZ_ASSERT(promiseToResolve->is<PromiseObject>()); + MOZ_ASSERT(thenable->is<PromiseObject>()); + + HandlePropertyName funName = cx->names().empty; + RootedFunction job( + cx, NewNativeFunction(cx, PromiseResolveBuiltinThenableJob, 0, funName, + gc::AllocKind::FUNCTION_EXTENDED, GenericObject)); + if (!job) { + return false; + } + + // Store the promise and the thenable on the reaction job. + job->setExtendedSlot(BuiltinThenableJobSlot_Promise, + ObjectValue(*promiseToResolve)); + job->setExtendedSlot(BuiltinThenableJobSlot_Thenable, ObjectValue(*thenable)); + + Rooted<GlobalObject*> incumbentGlobal(cx, + cx->runtime()->getIncumbentGlobal(cx)); + return cx->runtime()->enqueuePromiseJob(cx, job, promiseToResolve, + incumbentGlobal); +} + +static MOZ_MUST_USE bool AddDummyPromiseReactionForDebugger( + JSContext* cx, Handle<PromiseObject*> promise, + HandleObject dependentPromise); + +static MOZ_MUST_USE bool AddPromiseReaction( + JSContext* cx, Handle<PromiseObject*> promise, + Handle<PromiseReactionRecord*> reaction); + +static JSFunction* GetResolveFunctionFromReject(JSFunction* reject) { + MOZ_ASSERT(reject->maybeNative() == RejectPromiseFunction); + Value resolveFunVal = + reject->getExtendedSlot(RejectFunctionSlot_ResolveFunction); + MOZ_ASSERT(IsNativeFunction(resolveFunVal, ResolvePromiseFunction)); + return &resolveFunVal.toObject().as<JSFunction>(); +} + +static JSFunction* GetRejectFunctionFromResolve(JSFunction* resolve) { + MOZ_ASSERT(resolve->maybeNative() == ResolvePromiseFunction); + Value rejectFunVal = + resolve->getExtendedSlot(ResolveFunctionSlot_RejectFunction); + MOZ_ASSERT(IsNativeFunction(rejectFunVal, RejectPromiseFunction)); + return &rejectFunVal.toObject().as<JSFunction>(); +} + +static JSFunction* GetResolveFunctionFromPromise(PromiseObject* promise) { + Value rejectFunVal = promise->getFixedSlot(PromiseSlot_RejectFunction); + if (rejectFunVal.isUndefined()) { + return nullptr; + } + JSObject* rejectFunObj = &rejectFunVal.toObject(); + + // We can safely unwrap it because all we want is to get the resolve + // function. + if (IsWrapper(rejectFunObj)) { + rejectFunObj = UncheckedUnwrap(rejectFunObj); + } + + if (!rejectFunObj->is<JSFunction>()) { + return nullptr; + } + + JSFunction* rejectFun = &rejectFunObj->as<JSFunction>(); + + // Only the original RejectPromiseFunction has a reference to the resolve + // function. + if (rejectFun->maybeNative() != &RejectPromiseFunction) { + return nullptr; + } + + // The reject function was already called and cleared its resolve-function + // extended slot. + if (rejectFun->getExtendedSlot(RejectFunctionSlot_ResolveFunction) + .isUndefined()) { + return nullptr; + } + + return GetResolveFunctionFromReject(rejectFun); +} + +static void ClearResolutionFunctionSlots(JSFunction* resolutionFun) { + JSFunction* resolve; + JSFunction* reject; + if (resolutionFun->maybeNative() == ResolvePromiseFunction) { + resolve = resolutionFun; + reject = GetRejectFunctionFromResolve(resolutionFun); + } else { + resolve = GetResolveFunctionFromReject(resolutionFun); + reject = resolutionFun; + } + + resolve->setExtendedSlot(ResolveFunctionSlot_Promise, UndefinedValue()); + resolve->setExtendedSlot(ResolveFunctionSlot_RejectFunction, + UndefinedValue()); + + reject->setExtendedSlot(RejectFunctionSlot_Promise, UndefinedValue()); + reject->setExtendedSlot(RejectFunctionSlot_ResolveFunction, UndefinedValue()); +} + +// ES2016, 25.4.3.1. steps 3-7. +static MOZ_MUST_USE MOZ_ALWAYS_INLINE PromiseObject* +CreatePromiseObjectInternal(JSContext* cx, HandleObject proto /* = nullptr */, + bool protoIsWrapped /* = false */, + bool informDebugger /* = true */) { + // Step 3. + // Enter the unwrapped proto's compartment, if that's different from + // the current one. + // All state stored in a Promise's fixed slots must be created in the + // same compartment, so we get all of that out of the way here. + // (Except for the resolution functions, which are created below.) + mozilla::Maybe<AutoRealm> ar; + if (protoIsWrapped) { + ar.emplace(cx, proto); + } + + PromiseObject* promise = NewObjectWithClassProto<PromiseObject>(cx, proto); + if (!promise) { + return nullptr; + } + + // Step 4. + promise->initFixedSlot(PromiseSlot_Flags, Int32Value(0)); + + // Steps 5-6. + // Omitted, we allocate our single list of reaction records lazily. + + // Step 7. + // Implicit, the handled flag is unset by default. + + if (MOZ_LIKELY(!JS::IsAsyncStackCaptureEnabledForRealm(cx))) { + return promise; + } + + // Store an allocation stack so we can later figure out what the + // control flow was for some unexpected results. Frightfully expensive, + // but oh well. + + Rooted<PromiseObject*> promiseRoot(cx, promise); + + PromiseDebugInfo* debugInfo = PromiseDebugInfo::create(cx, promiseRoot); + if (!debugInfo) { + return nullptr; + } + + // Let the Debugger know about this Promise. + if (informDebugger) { + DebugAPI::onNewPromise(cx, promiseRoot); + } + + return promiseRoot; +} + +// ES2016, 25.4.3.1. +static bool PromiseConstructor(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + // Step 1. + if (!ThrowIfNotConstructing(cx, args, "Promise")) { + return false; + } + + // Step 2. + HandleValue executorVal = args.get(0); + if (!IsCallable(executorVal)) { + return ReportIsNotFunction(cx, executorVal); + } + RootedObject executor(cx, &executorVal.toObject()); + + // Steps 3-10. + RootedObject newTarget(cx, &args.newTarget().toObject()); + + // If the constructor is called via an Xray wrapper, then the newTarget + // hasn't been unwrapped. We want that because, while the actual instance + // should be created in the target compartment, the constructor's code + // should run in the wrapper's compartment. + // + // This is so that the resolve and reject callbacks get created in the + // wrapper's compartment, which is required for code in that compartment + // to freely interact with it, and, e.g., pass objects as arguments, which + // it wouldn't be able to if the callbacks were themselves wrapped in Xray + // wrappers. + // + // At the same time, just creating the Promise itself in the wrapper's + // compartment wouldn't be helpful: if the wrapper forbids interactions + // with objects except for specific actions, such as calling them, then + // the code we want to expose it to can't actually treat it as a Promise: + // calling .then on it would throw, for example. + // + // Another scenario where it's important to create the Promise in a + // different compartment from the resolution functions is when we want to + // give non-privileged code a Promise resolved with the result of a + // Promise from privileged code; as a return value of a JS-implemented + // API, say. If the resolution functions were unprivileged, then resolving + // with a privileged Promise would cause `resolve` to attempt accessing + // .then on the passed Promise, which would throw an exception, so we'd + // just end up with a rejected Promise. Really, we want to chain the two + // Promises, with the unprivileged one resolved with the resolution of the + // privileged one. + + bool needsWrapping = false; + RootedObject proto(cx); + if (IsWrapper(newTarget)) { + JSObject* unwrappedNewTarget = CheckedUnwrapStatic(newTarget); + MOZ_ASSERT(unwrappedNewTarget); + MOZ_ASSERT(unwrappedNewTarget != newTarget); + + newTarget = unwrappedNewTarget; + { + AutoRealm ar(cx, newTarget); + Handle<GlobalObject*> global = cx->global(); + JSObject* promiseCtor = + GlobalObject::getOrCreatePromiseConstructor(cx, global); + if (!promiseCtor) { + return false; + } + + // Promise subclasses don't get the special Xray treatment, so + // we only need to do the complex wrapping and unwrapping scheme + // described above for instances of Promise itself. + if (newTarget == promiseCtor) { + needsWrapping = true; + proto = GlobalObject::getOrCreatePromisePrototype(cx, cx->global()); + if (!proto) { + return false; + } + } + } + } + + if (needsWrapping) { + if (!cx->compartment()->wrap(cx, &proto)) { + return false; + } + } else { + if (!GetPrototypeFromBuiltinConstructor(cx, args, JSProto_Promise, + &proto)) { + return false; + } + } + PromiseObject* promise = + PromiseObject::create(cx, executor, proto, needsWrapping); + if (!promise) { + return false; + } + + // Step 11. + args.rval().setObject(*promise); + if (needsWrapping) { + return cx->compartment()->wrap(cx, args.rval()); + } + return true; +} + +// ES2016, 25.4.3.1. steps 3-11. +/* static */ +PromiseObject* PromiseObject::create(JSContext* cx, HandleObject executor, + HandleObject proto /* = nullptr */, + bool needsWrapping /* = false */) { + MOZ_ASSERT(executor->isCallable()); + + RootedObject usedProto(cx, proto); + // If the proto is wrapped, that means the current function is running + // with a different compartment active from the one the Promise instance + // is to be created in. + // See the comment in PromiseConstructor for details. + if (needsWrapping) { + MOZ_ASSERT(proto); + usedProto = CheckedUnwrapStatic(proto); + if (!usedProto) { + ReportAccessDenied(cx); + return nullptr; + } + } + + // Steps 3-7. + Rooted<PromiseObject*> promise( + cx, CreatePromiseObjectInternal(cx, usedProto, needsWrapping, false)); + if (!promise) { + return nullptr; + } + + RootedObject promiseObj(cx, promise); + if (needsWrapping && !cx->compartment()->wrap(cx, &promiseObj)) { + return nullptr; + } + + // Step 8. + // The resolving functions are created in the compartment active when the + // (maybe wrapped) Promise constructor was called. They contain checks and + // can unwrap the Promise if required. + RootedObject resolveFn(cx); + RootedObject rejectFn(cx); + if (!CreateResolvingFunctions(cx, promiseObj, &resolveFn, &rejectFn)) { + return nullptr; + } + + // Need to wrap the resolution functions before storing them on the Promise. + MOZ_ASSERT(promise->getFixedSlot(PromiseSlot_RejectFunction).isUndefined(), + "Slot must be undefined so initFixedSlot can be used"); + if (needsWrapping) { + AutoRealm ar(cx, promise); + RootedObject wrappedRejectFn(cx, rejectFn); + if (!cx->compartment()->wrap(cx, &wrappedRejectFn)) { + return nullptr; + } + promise->initFixedSlot(PromiseSlot_RejectFunction, + ObjectValue(*wrappedRejectFn)); + } else { + promise->initFixedSlot(PromiseSlot_RejectFunction, ObjectValue(*rejectFn)); + } + + // Step 9. + bool success; + { + FixedInvokeArgs<2> args(cx); + args[0].setObject(*resolveFn); + args[1].setObject(*rejectFn); + + RootedValue calleeOrRval(cx, ObjectValue(*executor)); + success = Call(cx, calleeOrRval, UndefinedHandleValue, args, &calleeOrRval); + } + + // Step 10. + if (!success) { + RootedValue exceptionVal(cx); + // Can't pass stack to a JS function. + RootedSavedFrame stack(cx); + if (!MaybeGetAndClearExceptionAndStack(cx, &exceptionVal, &stack)) { + return nullptr; + } + + RootedValue calleeOrRval(cx, ObjectValue(*rejectFn)); + if (!Call(cx, calleeOrRval, UndefinedHandleValue, exceptionVal, + &calleeOrRval)) { + return nullptr; + } + } + + // Let the Debugger know about this Promise. + DebugAPI::onNewPromise(cx, promise); + + // Step 11. + return promise; +} + +// ES2016, 25.4.3.1. skipping creation of resolution functions and executor +// function invocation. +/* static */ +PromiseObject* PromiseObject::createSkippingExecutor(JSContext* cx) { + return CreatePromiseObjectWithoutResolutionFunctions(cx); +} + +class MOZ_STACK_CLASS PromiseForOfIterator : public JS::ForOfIterator { + public: + using JS::ForOfIterator::ForOfIterator; + + bool isOptimizedDenseArrayIteration() { + MOZ_ASSERT(valueIsIterable()); + return index != NOT_ARRAY && IsPackedArray(iterator); + } +}; + +static MOZ_MUST_USE bool PerformPromiseAll( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done); + +static MOZ_MUST_USE bool PerformPromiseAllSettled( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done); + +static MOZ_MUST_USE bool PerformPromiseAny( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done); + +static MOZ_MUST_USE bool PerformPromiseRace( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done); + +enum class CombinatorKind { All, AllSettled, Any, Race }; + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// +// Unified implementation of +// 25.6.4.1 Promise.all ( iterable ) +// 25.6.4.2 Promise.allSettled ( iterable ) +// 25.6.4.4 Promise.race ( iterable ) +// +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// Promise.any ( iterable ) +static MOZ_MUST_USE bool CommonPromiseCombinator(JSContext* cx, CallArgs& args, + CombinatorKind kind) { + HandleValue iterable = args.get(0); + + // Step 2 (moved from NewPromiseCapability, step 1). + HandleValue CVal = args.thisv(); + if (!CVal.isObject()) { + const char* message; + switch (kind) { + case CombinatorKind::All: + message = "Receiver of Promise.all call"; + break; + case CombinatorKind::AllSettled: + message = "Receiver of Promise.allSettled call"; + break; + case CombinatorKind::Any: + message = "Receiver of Promise.any call"; + break; + case CombinatorKind::Race: + message = "Receiver of Promise.race call"; + break; + } + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_OBJECT_REQUIRED, message); + return false; + } + + // Step 1. + RootedObject C(cx, &CVal.toObject()); + + // Step 2. + Rooted<PromiseCapability> promiseCapability(cx); + if (!NewPromiseCapability(cx, C, &promiseCapability, false)) { + return false; + } + + RootedValue promiseResolve(cx, UndefinedValue()); + { + JSObject* promiseCtor = + GlobalObject::getOrCreatePromiseConstructor(cx, cx->global()); + if (!promiseCtor) { + return false; + } + + PromiseLookup& promiseLookup = cx->realm()->promiseLookup; + if (C != promiseCtor || !promiseLookup.isDefaultPromiseState(cx)) { + // 25.6.4.1, step 3. + // 25.6.4.2, step 3. + // 25.6.4.4, step 3. + if (!GetProperty(cx, C, C, cx->names().resolve, &promiseResolve)) { + return AbruptRejectPromise(cx, args, promiseCapability); + } + + // 25.6.4.1, step 4. + // 25.6.4.2, step 4. + // 25.6.4.4, step 4. + if (!IsCallable(promiseResolve)) { + ReportIsNotFunction(cx, promiseResolve); + return AbruptRejectPromise(cx, args, promiseCapability); + } + } + } + + // Steps 3-4. + PromiseForOfIterator iter(cx); + if (!iter.init(iterable, JS::ForOfIterator::AllowNonIterable)) { + return AbruptRejectPromise(cx, args, promiseCapability); + } + + if (!iter.valueIsIterable()) { + const char* message; + switch (kind) { + case CombinatorKind::All: + message = "Argument of Promise.all"; + break; + case CombinatorKind::AllSettled: + message = "Argument of Promise.allSettled"; + break; + case CombinatorKind::Any: + message = "Argument of Promise.any"; + break; + case CombinatorKind::Race: + message = "Argument of Promise.race"; + break; + } + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_NOT_ITERABLE, + message); + return AbruptRejectPromise(cx, args, promiseCapability); + } + + // Step 5. + bool done, result; + switch (kind) { + case CombinatorKind::All: + result = PerformPromiseAll(cx, iter, C, promiseCapability, promiseResolve, + &done); + break; + case CombinatorKind::AllSettled: + result = PerformPromiseAllSettled(cx, iter, C, promiseCapability, + promiseResolve, &done); + break; + case CombinatorKind::Any: + result = PerformPromiseAny(cx, iter, C, promiseCapability, promiseResolve, + &done); + break; + case CombinatorKind::Race: + result = PerformPromiseRace(cx, iter, C, promiseCapability, + promiseResolve, &done); + break; + } + + // Step 6. + if (!result) { + // Step 6.a. + if (!done) { + iter.closeThrow(); + } + + // Step 6.b. + return AbruptRejectPromise(cx, args, promiseCapability); + } + + // Step 7. + args.rval().setObject(*promiseCapability.promise()); + return true; +} + +// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9 +// 25.6.4.1 Promise.all ( iterable ) +static bool Promise_static_all(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + return CommonPromiseCombinator(cx, args, CombinatorKind::All); +} + +static MOZ_MUST_USE bool PerformPromiseThen( + JSContext* cx, Handle<PromiseObject*> promise, HandleValue onFulfilled_, + HandleValue onRejected_, Handle<PromiseCapability> resultCapability); + +static MOZ_MUST_USE bool PerformPromiseThenWithoutSettleHandlers( + JSContext* cx, Handle<PromiseObject*> promise, + Handle<PromiseObject*> promiseToResolve, + Handle<PromiseCapability> resultCapability); + +static JSFunction* NewPromiseCombinatorElementFunction( + JSContext* cx, Native native, + Handle<PromiseCombinatorDataHolder*> dataHolder, uint32_t index); + +static bool PromiseAllResolveElementFunction(JSContext* cx, unsigned argc, + Value* vp); + +// Unforgeable version of ES2016, 25.4.4.1. +MOZ_MUST_USE JSObject* js::GetWaitForAllPromise( + JSContext* cx, JS::HandleObjectVector promises) { +#ifdef DEBUG + for (size_t i = 0, len = promises.length(); i < len; i++) { + JSObject* obj = promises[i]; + cx->check(obj); + MOZ_ASSERT(UncheckedUnwrap(obj)->is<PromiseObject>()); + } +#endif + + // Step 1. + RootedObject C(cx, + GlobalObject::getOrCreatePromiseConstructor(cx, cx->global())); + if (!C) { + return nullptr; + } + + // Step 2 (omitted). + + // Step 3. + Rooted<PromiseCapability> resultCapability(cx); + if (!NewPromiseCapability(cx, C, &resultCapability, false)) { + return nullptr; + } + + // Steps 4-6 (omitted). + + // Step 7. + // Implemented as an inlined, simplied version of ES2016 25.4.4.1.1, + // PerformPromiseAll. + { + uint32_t promiseCount = promises.length(); + // Sub-steps 1-2 (omitted). + + // Sub-step 3. + Rooted<PromiseCombinatorElements> values(cx); + { + auto* valuesArray = NewDenseFullyAllocatedArray(cx, promiseCount); + if (!valuesArray) { + return nullptr; + } + valuesArray->ensureDenseInitializedLength(0, promiseCount); + + values.initialize(valuesArray); + } + + // Sub-step 4. + // Create our data holder that holds all the things shared across + // every step of the iterator. In particular, this holds the + // remainingElementsCount (as an integer reserved slot), the array of + // values, and the resolve function from our PromiseCapability. + Rooted<PromiseCombinatorDataHolder*> dataHolder(cx); + dataHolder = PromiseCombinatorDataHolder::New( + cx, resultCapability.promise(), values, resultCapability.resolve()); + if (!dataHolder) { + return nullptr; + } + + // Call PerformPromiseThen with resolve and reject set to nullptr. + Rooted<PromiseCapability> resultCapabilityWithoutResolving(cx); + resultCapabilityWithoutResolving.promise().set(resultCapability.promise()); + + // Sub-step 5 (inline in loop-header below). + + // Sub-step 6. + for (uint32_t index = 0; index < promiseCount; index++) { + // Steps a-c (omitted). + // Step d (implemented after the loop). + // Steps e-g (omitted). + + // Step h. + values.unwrappedArray()->setDenseElement(index, UndefinedHandleValue); + + // Step i, vastly simplified. + RootedObject nextPromiseObj(cx, promises[index]); + + // Steps j-o. + JSFunction* resolveFunc = NewPromiseCombinatorElementFunction( + cx, PromiseAllResolveElementFunction, dataHolder, index); + if (!resolveFunc) { + return nullptr; + } + + // Step p. + dataHolder->increaseRemainingCount(); + + // Step q, very roughly. + RootedValue resolveFunVal(cx, ObjectValue(*resolveFunc)); + RootedValue rejectFunVal(cx, ObjectValue(*resultCapability.reject())); + Rooted<PromiseObject*> nextPromise(cx); + + // GetWaitForAllPromise is used internally only and must not + // trigger content-observable effects when registering a reaction. + // It's also meant to work on wrapped Promises, potentially from + // compartments with principals inaccessible from the current + // compartment. To make that work, it unwraps promises with + // UncheckedUnwrap, + nextPromise = &UncheckedUnwrap(nextPromiseObj)->as<PromiseObject>(); + + if (!PerformPromiseThen(cx, nextPromise, resolveFunVal, rejectFunVal, + resultCapabilityWithoutResolving)) { + return nullptr; + } + + // Step r (inline in loop-header). + } + + // Sub-step d.i (implicit). + // Sub-step d.ii. + int32_t remainingCount = dataHolder->decreaseRemainingCount(); + + // Sub-step d.iii-iv. + if (remainingCount == 0) { + if (!ResolvePromiseInternal(cx, resultCapability.promise(), + values.value())) { + return nullptr; + } + } + } + + // Step 8 (omitted). + + // Step 9. + return resultCapability.promise(); +} + +static MOZ_MUST_USE bool RunFulfillFunction(JSContext* cx, + HandleObject onFulfilledFunc, + HandleValue result, + HandleObject promiseObj) { + cx->check(onFulfilledFunc); + cx->check(result); + cx->check(promiseObj); + + // If |onFulfilledFunc| couldn't be optimized away, just call it. + if (onFulfilledFunc) { + RootedValue calleeOrRval(cx, ObjectValue(*onFulfilledFunc)); + return Call(cx, calleeOrRval, UndefinedHandleValue, result, &calleeOrRval); + } + + // The promise itself may be optimized away. If so, we're done. + if (!promiseObj) { + return true; + } + + // Resolve the promise only if it's still pending. + Handle<PromiseObject*> promise = promiseObj.as<PromiseObject>(); + if (promise->state() != JS::PromiseState::Pending) { + return true; + } + + // If the promise has a default resolution function, perform its steps. + if (PromiseHasAnyFlag(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)) { + return ResolvePromiseInternal(cx, promise, result); + } + + // Otherwise we're done. + return true; +} + +static MOZ_MUST_USE bool RunRejectFunction( + JSContext* cx, HandleObject onRejectedFunc, HandleValue result, + HandleObject promiseObj, HandleSavedFrame unwrappedRejectionStack, + UnhandledRejectionBehavior behavior) { + cx->check(onRejectedFunc); + cx->check(result); + cx->check(promiseObj); + + // If |onRejectedFunc| couldn't be optimized away, just call it. + if (onRejectedFunc) { + RootedValue calleeOrRval(cx, ObjectValue(*onRejectedFunc)); + return Call(cx, calleeOrRval, UndefinedHandleValue, result, &calleeOrRval); + } + + // The promise itself may be optimized away. + if (!promiseObj) { + // Do nothing if unhandled rejections are to be ignored. + if (behavior == UnhandledRejectionBehavior::Ignore) { + return true; + } + + // Otherwise create and reject a promise on the fly. The promise's + // allocation time will be wrong. So it goes. + Rooted<PromiseObject*> temporaryPromise( + cx, CreatePromiseObjectWithoutResolutionFunctions(cx)); + if (!temporaryPromise) { + cx->clearPendingException(); + return true; + } + + return RejectPromiseInternal(cx, temporaryPromise, result, + unwrappedRejectionStack); + } + + // Reject the promise only if it's still pending. + Handle<PromiseObject*> promise = promiseObj.as<PromiseObject>(); + if (promise->state() != JS::PromiseState::Pending) { + return true; + } + + // If the promise has a default rejection function, perform its steps. + if (PromiseHasAnyFlag(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)) { + return RejectPromiseInternal(cx, promise, result, unwrappedRejectionStack); + } + + // Otherwise we're done. + return true; +} + +static MOZ_MUST_USE JSObject* CommonStaticResolveRejectImpl( + JSContext* cx, HandleValue thisVal, HandleValue argVal, + ResolutionMode mode); + +static bool IsPromiseSpecies(JSContext* cx, JSFunction* species); + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.1.1 Runtime Semantics: PerformPromiseAll, steps 5-6 and step 8. +// 25.6.4.2.1 Runtime Semantics: PerformPromiseAllSettled, steps 5-6 and step 8. +// 25.6.4.4.1 Runtime Semantics: PerformPromiseRace, steps 3-5. +// +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// Runtime Semantics: PerformPromiseAny, steps 6-8. +template <typename T> +static MOZ_MUST_USE bool CommonPerformPromiseCombinator( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + HandleObject resultPromise, HandleValue promiseResolve, bool* done, + bool resolveReturnsUndefined, T getResolveAndReject) { + RootedObject promiseCtor( + cx, GlobalObject::getOrCreatePromiseConstructor(cx, cx->global())); + if (!promiseCtor) { + return false; + } + + // Optimized dense array iteration ensures no side-effects take place + // during the iteration. + bool iterationMayHaveSideEffects = !iterator.isOptimizedDenseArrayIteration(); + + PromiseLookup& promiseLookup = cx->realm()->promiseLookup; + + // Try to optimize when the Promise object is in its default state, guarded + // by |C == promiseCtor| because we can only perform this optimization + // for the builtin Promise constructor. + bool isDefaultPromiseState = + C == promiseCtor && promiseLookup.isDefaultPromiseState(cx); + bool validatePromiseState = iterationMayHaveSideEffects; + + RootedValue CVal(cx, ObjectValue(*C)); + RootedValue resolveFunVal(cx); + RootedValue rejectFunVal(cx); + + // We're reusing rooted variables in the loop below, so we don't need to + // declare a gazillion different rooted variables here. Rooted variables + // which are reused include "Or" in their name. + RootedValue nextValueOrNextPromise(cx); + RootedObject nextPromiseObj(cx); + RootedValue thenVal(cx); + RootedObject thenSpeciesOrBlockedPromise(cx); + Rooted<PromiseCapability> thenCapability(cx); + + while (true) { + // Steps a-c, e-g. + RootedValue& nextValue = nextValueOrNextPromise; + if (!iterator.next(&nextValue, done)) { + // Steps b, f. + *done = true; + + // Steps c, g. + return false; + } + + // Step d. + if (*done) { + return true; + } + + // Set to false when we can skip the [[Get]] for "then" and instead + // use the built-in Promise.prototype.then function. + bool getThen = true; + + if (isDefaultPromiseState && validatePromiseState) { + isDefaultPromiseState = promiseLookup.isDefaultPromiseState(cx); + } + + RootedValue& nextPromise = nextValueOrNextPromise; + if (isDefaultPromiseState) { + PromiseObject* nextValuePromise = nullptr; + if (nextValue.isObject() && nextValue.toObject().is<PromiseObject>()) { + nextValuePromise = &nextValue.toObject().as<PromiseObject>(); + } + + if (nextValuePromise && + promiseLookup.isDefaultInstanceWhenPromiseStateIsSane( + cx, nextValuePromise)) { + // The below steps don't produce any side-effects, so we can + // skip the Promise state revalidation in the next iteration + // when the iterator itself also doesn't produce any + // side-effects. + validatePromiseState = iterationMayHaveSideEffects; + + // 25.6.4.1.1, step 8.i. + // 25.6.4.3.1, step 5.h. + // Promise.resolve is a no-op for the default case. + MOZ_ASSERT(&nextPromise.toObject() == nextValuePromise); + + // `nextPromise` uses the built-in `then` function. + getThen = false; + } else { + // Need to revalidate the Promise state in the next iteration, + // because CommonStaticResolveRejectImpl may have modified it. + validatePromiseState = true; + + // 25.6.4.1.1, step 8.i. + // 25.6.4.3.1, step 5.h. + // Inline the call to Promise.resolve. + JSObject* res = + CommonStaticResolveRejectImpl(cx, CVal, nextValue, ResolveMode); + if (!res) { + return false; + } + + nextPromise.setObject(*res); + } + } else if (promiseResolve.isUndefined()) { + // |promiseResolve| is undefined when the Promise constructor was + // initially in its default state, i.e. if it had been retrieved, it would + // have been set to |Promise.resolve|. + + // 25.6.4.1.1, step 8.i. + // 25.6.4.3.1, step 5.h. + // Inline the call to Promise.resolve. + JSObject* res = + CommonStaticResolveRejectImpl(cx, CVal, nextValue, ResolveMode); + if (!res) { + return false; + } + + nextPromise.setObject(*res); + } else { + // 25.6.4.1.1, step 8.i. + // 25.6.4.3.1, step 5.h. + if (!Call(cx, promiseResolve, CVal, nextValue, &nextPromise)) { + return false; + } + } + + // Get the resolving functions for this iteration. + // 25.6.4.1.1, steps 8.j-q. + if (!getResolveAndReject(&resolveFunVal, &rejectFunVal)) { + return false; + } + + // Call |nextPromise.then| with the provided hooks and add + // |resultPromise| to the list of dependent promises. + // + // If |nextPromise.then| is the original |Promise.prototype.then| + // function and the call to |nextPromise.then| would use the original + // |Promise| constructor to create the resulting promise, we skip the + // call to |nextPromise.then| and thus creating a new promise that + // would not be observable by content. + + // 25.6.4.1.1, step 8.r. + // 25.6.4.3.1, step 5.i. + nextPromiseObj = ToObject(cx, nextPromise); + if (!nextPromiseObj) { + return false; + } + + bool isBuiltinThen; + if (getThen) { + // We don't use the Promise lookup cache here, because this code + // is only called when we had a lookup cache miss, so it's likely + // we'd get another cache miss when trying to use the cache here. + if (!GetProperty(cx, nextPromiseObj, nextPromise, cx->names().then, + &thenVal)) { + return false; + } + + // |nextPromise| is an unwrapped Promise, and |then| is the + // original |Promise.prototype.then|, inline it here. + isBuiltinThen = nextPromiseObj->is<PromiseObject>() && + IsNativeFunction(thenVal, Promise_then); + } else { + isBuiltinThen = true; + } + + // By default, the blocked promise is added as an extra entry to the + // rejected promises list. + bool addToDependent = true; + + if (isBuiltinThen) { + MOZ_ASSERT(nextPromise.isObject()); + MOZ_ASSERT(&nextPromise.toObject() == nextPromiseObj); + + // 25.6.5.4, step 3. + RootedObject& thenSpecies = thenSpeciesOrBlockedPromise; + if (getThen) { + thenSpecies = SpeciesConstructor(cx, nextPromiseObj, JSProto_Promise, + IsPromiseSpecies); + if (!thenSpecies) { + return false; + } + } else { + thenSpecies = promiseCtor; + } + + // The fast path here and the one in NewPromiseCapability may not + // set the resolve and reject handlers, so we need to clear the + // fields in case they were set in the previous iteration. + thenCapability.resolve().set(nullptr); + thenCapability.reject().set(nullptr); + + // Skip the creation of a built-in Promise object if: + // 1. `thenSpecies` is the built-in Promise constructor. + // 2. `resolveFun` doesn't return an object, which ensures no side effects + // occur in ResolvePromiseInternal. + // 3. The result promise is a built-in Promise object. + // 4. The result promise doesn't use the default resolving functions, + // which in turn means Run{Fulfill,Reject}Function when called from + // PromiseReactionJob won't try to resolve the promise. + if (thenSpecies == promiseCtor && resolveReturnsUndefined && + resultPromise->is<PromiseObject>() && + !PromiseHasAnyFlag(resultPromise->as<PromiseObject>(), + PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)) { + thenCapability.promise().set(resultPromise); + addToDependent = false; + } else { + // 25.6.5.4, step 4. + if (!NewPromiseCapability(cx, thenSpecies, &thenCapability, true)) { + return false; + } + } + + // 25.6.5.4, step 5. + Handle<PromiseObject*> promise = nextPromiseObj.as<PromiseObject>(); + if (!PerformPromiseThen(cx, promise, resolveFunVal, rejectFunVal, + thenCapability)) { + return false; + } + } else { + // Optimization failed, do the normal call. + RootedValue& ignored = thenVal; + if (!Call(cx, thenVal, nextPromise, resolveFunVal, rejectFunVal, + &ignored)) { + return false; + } + + // In case the value to depend on isn't an object at all, there's + // nothing more to do here: we can only add reactions to Promise + // objects (potentially after unwrapping them), and non-object + // values can't be Promise objects. This can happen if Promise.all + // is called on an object with a `resolve` method that returns + // primitives. + if (!nextPromise.isObject()) { + addToDependent = false; + } + } + + // Adds |resultPromise| to the list of dependent promises. + if (addToDependent) { + // The object created by the |promise.then| call or the inlined + // version of it above is visible to content (either because + // |promise.then| was overridden by content and could leak it, + // or because a constructor other than the original value of + // |Promise| was used to create it). To have both that object and + // |resultPromise| show up as dependent promises in the debugger, + // add a dummy reaction to the list of reject reactions that + // contains |resultPromise|, but otherwise does nothing. + RootedObject& blockedPromise = thenSpeciesOrBlockedPromise; + blockedPromise = resultPromise; + + mozilla::Maybe<AutoRealm> ar; + if (IsProxy(nextPromiseObj)) { + nextPromiseObj = CheckedUnwrapStatic(nextPromiseObj); + if (!nextPromiseObj) { + ReportAccessDenied(cx); + return false; + } + if (JS_IsDeadWrapper(nextPromiseObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + ar.emplace(cx, nextPromiseObj); + if (!cx->compartment()->wrap(cx, &blockedPromise)) { + return false; + } + } + + // If either the object to depend on (`nextPromiseObj`) or the + // object that gets blocked (`resultPromise`) isn't a, + // maybe-wrapped, Promise instance, we ignore it. All this does is + // lose some small amount of debug information in scenarios that + // are highly unlikely to occur in useful code. + if (nextPromiseObj->is<PromiseObject>() && + resultPromise->is<PromiseObject>()) { + Handle<PromiseObject*> promise = nextPromiseObj.as<PromiseObject>(); + if (!AddDummyPromiseReactionForDebugger(cx, promise, blockedPromise)) { + return false; + } + } + } + } +} + +// Create the elements for the Promise combinators Promise.all and +// Promise.allSettled. +static MOZ_MUST_USE bool NewPromiseCombinatorElements( + JSContext* cx, Handle<PromiseCapability> resultCapability, + MutableHandle<PromiseCombinatorElements> elements) { + // We have to be very careful about which compartments we create things for + // the Promise combinators. In particular, we have to maintain the invariant + // that anything stored in a reserved slot is same-compartment with the object + // whose reserved slot it's in. But we want to create the values array in the + // compartment of the result capability's Promise, because that array can get + // exposed as the Promise's resolution value to code that has access to the + // Promise (in particular code from that compartment), and that should work, + // even if the Promise compartment is less-privileged than our caller + // compartment. + // + // So the plan is as follows: Create the values array in the promise + // compartment. Create the promise resolving functions and the data holder in + // our current compartment, i.e. the compartment of the Promise combinator + // function. Store a cross-compartment wrapper to the values array in the + // holder. This should be OK because the only things we hand the promise + // resolving functions to are the "then" calls we do and in the case when the + // Promise's compartment is not the current compartment those are happening + // over Xrays anyway, which means they get the canonical "then" function and + // content can't see our promise resolving functions. + + if (IsWrapper(resultCapability.promise())) { + JSObject* unwrappedPromiseObj = + CheckedUnwrapStatic(resultCapability.promise()); + MOZ_ASSERT(unwrappedPromiseObj); + + { + AutoRealm ar(cx, unwrappedPromiseObj); + auto* array = NewDenseEmptyArray(cx); + if (!array) { + return false; + } + elements.initialize(array); + } + + if (!cx->compartment()->wrap(cx, elements.value())) { + return false; + } + } else { + auto* array = NewDenseEmptyArray(cx); + if (!array) { + return false; + } + + elements.initialize(array); + } + return true; +} + +// Retrieve the combinator elements from the data holder. +static MOZ_MUST_USE bool GetPromiseCombinatorElements( + JSContext* cx, Handle<PromiseCombinatorDataHolder*> data, + MutableHandle<PromiseCombinatorElements> elements) { + bool needsWrapping = false; + JSObject* valuesObj = &data->valuesArray().toObject(); + if (IsProxy(valuesObj)) { + // See comment for NewPromiseCombinatorElements for why we unwrap here. + valuesObj = UncheckedUnwrap(valuesObj); + + if (JS_IsDeadWrapper(valuesObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + + needsWrapping = true; + } + + elements.initialize(data, &valuesObj->as<ArrayObject>(), needsWrapping); + return true; +} + +static JSFunction* NewPromiseCombinatorElementFunction( + JSContext* cx, Native native, + Handle<PromiseCombinatorDataHolder*> dataHolder, uint32_t index) { + JSFunction* fn = NewNativeFunction( + cx, native, 1, nullptr, gc::AllocKind::FUNCTION_EXTENDED, GenericObject); + if (!fn) { + return nullptr; + } + + fn->setExtendedSlot(PromiseCombinatorElementFunctionSlot_Data, + ObjectValue(*dataHolder)); + fn->setExtendedSlot(PromiseCombinatorElementFunctionSlot_ElementIndex, + Int32Value(index)); + return fn; +} + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.1.2 Promise.all Resolve Element Functions +// 25.6.4.2.2 Promise.allSettled Resolve Element Functions +// 25.6.4.2.3 Promise.allSettled Reject Element Functions +// +// Common implementation for Promise combinator element functions to check if +// they've already been called. +static bool PromiseCombinatorElementFunctionAlreadyCalled( + const CallArgs& args, MutableHandle<PromiseCombinatorDataHolder*> data, + uint32_t* index) { + // Step 1. + JSFunction* fn = &args.callee().as<JSFunction>(); + + // Step 2. + const Value& dataVal = + fn->getExtendedSlot(PromiseCombinatorElementFunctionSlot_Data); + + // Step 3. + // We use the existence of the data holder as a signal for whether the Promise + // combinator element function was already called. Upon resolution, it's reset + // to `undefined`. + if (dataVal.isUndefined()) { + return true; + } + + data.set(&dataVal.toObject().as<PromiseCombinatorDataHolder>()); + + // Step 4. + fn->setExtendedSlot(PromiseCombinatorElementFunctionSlot_Data, + UndefinedValue()); + + // Step 5. + int32_t idx = + fn->getExtendedSlot(PromiseCombinatorElementFunctionSlot_ElementIndex) + .toInt32(); + MOZ_ASSERT(idx >= 0); + *index = uint32_t(idx); + + return false; +} + +// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9 +// 25.6.4.1.1 PerformPromiseAll (iteratorRecord, constructor, resultCapability) +static MOZ_MUST_USE bool PerformPromiseAll( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done) { + *done = false; + + // Step 1. + MOZ_ASSERT(C->isConstructor()); + + // Step 2 (omitted). + + // Step 3. + Rooted<PromiseCombinatorElements> values(cx); + if (!NewPromiseCombinatorElements(cx, resultCapability, &values)) { + return false; + } + + // Step 4. + // Create our data holder that holds all the things shared across + // every step of the iterator. In particular, this holds the + // remainingElementsCount (as an integer reserved slot), the array of + // values, and the resolve function from our PromiseCapability. + Rooted<PromiseCombinatorDataHolder*> dataHolder(cx); + dataHolder = PromiseCombinatorDataHolder::New( + cx, resultCapability.promise(), values, resultCapability.resolve()); + if (!dataHolder) { + return false; + } + + // Step 7. + uint32_t index = 0; + + auto getResolveAndReject = [cx, &resultCapability, &values, &dataHolder, + &index](MutableHandleValue resolveFunVal, + MutableHandleValue rejectFunVal) { + // Step 8.h. + if (!values.pushUndefined(cx)) { + return false; + } + + // Steps 8.j-p. + JSFunction* resolveFunc = NewPromiseCombinatorElementFunction( + cx, PromiseAllResolveElementFunction, dataHolder, index); + if (!resolveFunc) { + return false; + } + + // Step 8.q. + dataHolder->increaseRemainingCount(); + + // Step 8.s. + index++; + MOZ_ASSERT(index > 0); + + resolveFunVal.setObject(*resolveFunc); + rejectFunVal.setObject(*resultCapability.reject()); + return true; + }; + + // Steps 5-6 and 8. + if (!CommonPerformPromiseCombinator( + cx, iterator, C, resultCapability.promise(), promiseResolve, done, + true, getResolveAndReject)) { + return false; + } + + // Step 8.d.ii. + int32_t remainingCount = dataHolder->decreaseRemainingCount(); + + // Steps 8.d.iii-iv. + if (remainingCount == 0) { + return RunFulfillFunction(cx, resultCapability.resolve(), values.value(), + resultCapability.promise()); + } + + return true; +} + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.1.2 Promise.all Resolve Element Functions +static bool PromiseAllResolveElementFunction(JSContext* cx, unsigned argc, + Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + HandleValue xVal = args.get(0); + + // Steps 1-5. + Rooted<PromiseCombinatorDataHolder*> data(cx); + uint32_t index; + if (PromiseCombinatorElementFunctionAlreadyCalled(args, &data, &index)) { + args.rval().setUndefined(); + return true; + } + + // Step 6. + Rooted<PromiseCombinatorElements> values(cx); + if (!GetPromiseCombinatorElements(cx, data, &values)) { + return false; + } + + // Step 7 (moved under step 11). + // Step 8 (moved to step 10). + + // Step 9. + if (!values.setElement(cx, index, xVal)) { + return false; + } + + // Steps 8,10. + uint32_t remainingCount = data->decreaseRemainingCount(); + + // Step 11. + if (remainingCount == 0) { + // Step 11.a. (Omitted, happened in PerformPromiseAll.) + // Step 11.b. + + // Step 7 (Adapted to work with PromiseCombinatorDataHolder's layout). + RootedObject resolveAllFun(cx, data->resolveOrRejectObj()); + RootedObject promiseObj(cx, data->promiseObj()); + if (!RunFulfillFunction(cx, resolveAllFun, values.value(), promiseObj)) { + return false; + } + } + + // Step 12. + args.rval().setUndefined(); + return true; +} + +// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9 +// 25.6.4.3 Promise.race ( iterable ) +static bool Promise_static_race(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + return CommonPromiseCombinator(cx, args, CombinatorKind::Race); +} + +// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9 +// 25.6.4.3.1 PerformPromiseRace (iteratorRecord, constructor, resultCapability) +static MOZ_MUST_USE bool PerformPromiseRace( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done) { + *done = false; + + // Step 1. + MOZ_ASSERT(C->isConstructor()); + + // Step 2 (omitted). + + // BlockOnPromise fast path requires the passed onFulfilled function + // doesn't return an object value, because otherwise the skipped promise + // creation is detectable due to missing property lookups. + bool isDefaultResolveFn = + IsNativeFunction(resultCapability.resolve(), ResolvePromiseFunction); + + auto getResolveAndReject = [&resultCapability]( + MutableHandleValue resolveFunVal, + MutableHandleValue rejectFunVal) { + resolveFunVal.setObject(*resultCapability.resolve()); + rejectFunVal.setObject(*resultCapability.reject()); + return true; + }; + + // Steps 3-5. + return CommonPerformPromiseCombinator( + cx, iterator, C, resultCapability.promise(), promiseResolve, done, + isDefaultResolveFn, getResolveAndReject); +} + +enum class PromiseAllSettledElementFunctionKind { Resolve, Reject }; + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.2 Promise.allSettled ( iterable ) +// +// Promise.allSettled Resolve Element Functions +// Promise.allSettled Reject Element Functions +template <PromiseAllSettledElementFunctionKind Kind> +static bool PromiseAllSettledElementFunction(JSContext* cx, unsigned argc, + Value* vp); + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.2 Promise.allSettled ( iterable ) +// +// Promise.allSettled ( iterable ) +static bool Promise_static_allSettled(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + return CommonPromiseCombinator(cx, args, CombinatorKind::AllSettled); +} + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.2 Promise.allSettled ( iterable ) +// +// PerformPromiseAllSettled ( iteratorRecord, constructor, resultCapability ) +static MOZ_MUST_USE bool PerformPromiseAllSettled( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done) { + *done = false; + + // Step 1. + MOZ_ASSERT(C->isConstructor()); + + // Step 2 (omitted). + + // Step 3. + Rooted<PromiseCombinatorElements> values(cx); + if (!NewPromiseCombinatorElements(cx, resultCapability, &values)) { + return false; + } + + // Step 4. + // Create our data holder that holds all the things shared across every step + // of the iterator. In particular, this holds the remainingElementsCount + // (as an integer reserved slot), the array of values, and the resolve + // function from our PromiseCapability. + Rooted<PromiseCombinatorDataHolder*> dataHolder(cx); + dataHolder = PromiseCombinatorDataHolder::New( + cx, resultCapability.promise(), values, resultCapability.resolve()); + if (!dataHolder) { + return false; + } + + // Step 7. + uint32_t index = 0; + + auto getResolveAndReject = [cx, &values, &dataHolder, &index]( + MutableHandleValue resolveFunVal, + MutableHandleValue rejectFunVal) { + // Step 8.h. + if (!values.pushUndefined(cx)) { + return false; + } + + auto PromiseAllSettledResolveElementFunction = + PromiseAllSettledElementFunction< + PromiseAllSettledElementFunctionKind::Resolve>; + auto PromiseAllSettledRejectElementFunction = + PromiseAllSettledElementFunction< + PromiseAllSettledElementFunctionKind::Reject>; + + // Steps 8.j-q. + JSFunction* resolveFunc = NewPromiseCombinatorElementFunction( + cx, PromiseAllSettledResolveElementFunction, dataHolder, index); + if (!resolveFunc) { + return false; + } + resolveFunVal.setObject(*resolveFunc); + + // Steps 8.r-x. + JSFunction* rejectFunc = NewPromiseCombinatorElementFunction( + cx, PromiseAllSettledRejectElementFunction, dataHolder, index); + if (!rejectFunc) { + return false; + } + rejectFunVal.setObject(*rejectFunc); + + // Step 8.y. + dataHolder->increaseRemainingCount(); + + // Step 8.aa. + index++; + MOZ_ASSERT(index > 0); + + return true; + }; + + // Steps 5-6 and 8. + if (!CommonPerformPromiseCombinator( + cx, iterator, C, resultCapability.promise(), promiseResolve, done, + true, getResolveAndReject)) { + return false; + } + + // Step 8.d.ii. + int32_t remainingCount = dataHolder->decreaseRemainingCount(); + + // Steps 8.d.iii-iv. + if (remainingCount == 0) { + return RunFulfillFunction(cx, resultCapability.resolve(), values.value(), + resultCapability.promise()); + } + + return true; +} + +// ES2020 draft rev e97c95d064750fb949b6778584702dd658cf5624 +// 25.6.4.2.2 Promise.allSettled Resolve Element Functions +// 25.6.4.2.3 Promise.allSettled Reject Element Functions +template <PromiseAllSettledElementFunctionKind Kind> +static bool PromiseAllSettledElementFunction(JSContext* cx, unsigned argc, + Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + HandleValue valueOrReason = args.get(0); + + // Steps 1-5. + Rooted<PromiseCombinatorDataHolder*> data(cx); + uint32_t index; + if (PromiseCombinatorElementFunctionAlreadyCalled(args, &data, &index)) { + args.rval().setUndefined(); + return true; + } + + // Step 6. + Rooted<PromiseCombinatorElements> values(cx); + if (!GetPromiseCombinatorElements(cx, data, &values)) { + return false; + } + + // Steps 2-3. + // The already-called check above only handles the case when |this| function + // is called repeatedly, so we still need to check if the other pair of this + // resolving function was already called: + // We use the element value as a signal for whether the Promise was already + // fulfilled. Upon resolution, it's set to the result object created below. + if (!values.unwrappedArray()->getDenseElement(index).isUndefined()) { + args.rval().setUndefined(); + return true; + } + + // Steps 7-8 (moved below). + + // Step 9. + RootedPlainObject obj(cx, NewBuiltinClassInstance<PlainObject>(cx)); + if (!obj) { + return false; + } + + // Step 10. + RootedId id(cx, NameToId(cx->names().status)); + RootedValue statusValue(cx); + if (Kind == PromiseAllSettledElementFunctionKind::Resolve) { + statusValue.setString(cx->names().fulfilled); + } else { + statusValue.setString(cx->names().rejected); + } + if (!NativeDefineDataProperty(cx, obj, id, statusValue, JSPROP_ENUMERATE)) { + return false; + } + + // Step 11. + if (Kind == PromiseAllSettledElementFunctionKind::Resolve) { + id = NameToId(cx->names().value); + } else { + id = NameToId(cx->names().reason); + } + if (!NativeDefineDataProperty(cx, obj, id, valueOrReason, JSPROP_ENUMERATE)) { + return false; + } + + // Steps 4, 12. + RootedValue objVal(cx, ObjectValue(*obj)); + if (!values.setElement(cx, index, objVal)) { + return false; + } + + // Steps 8, 13. + uint32_t remainingCount = data->decreaseRemainingCount(); + + // Step 14. + if (remainingCount == 0) { + // Step 14.a. (Omitted, happened in PerformPromiseAllSettled.) + // Step 14.b. + + // Step 7 (Adapted to work with PromiseCombinatorDataHolder's layout). + RootedObject resolveAllFun(cx, data->resolveOrRejectObj()); + RootedObject promiseObj(cx, data->promiseObj()); + if (!RunFulfillFunction(cx, resolveAllFun, values.value(), promiseObj)) { + return false; + } + } + + // Step 15. + args.rval().setUndefined(); + return true; +} + +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// Promise.any ( iterable ) +static bool Promise_static_any(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + return CommonPromiseCombinator(cx, args, CombinatorKind::Any); +} + +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// Promise.any Reject Element Functions +static bool PromiseAnyRejectElementFunction(JSContext* cx, unsigned argc, + Value* vp); + +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// ThrowAggregateError ( errors ) +static void ThrowAggregateError(JSContext* cx, + Handle<PromiseCombinatorElements> errors, + HandleObject promise); + +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// PerformPromiseAny ( iteratorRecord, constructor, resultCapability ) +static MOZ_MUST_USE bool PerformPromiseAny( + JSContext* cx, PromiseForOfIterator& iterator, HandleObject C, + Handle<PromiseCapability> resultCapability, HandleValue promiseResolve, + bool* done) { + *done = false; + + // Step 1. + MOZ_ASSERT(C->isConstructor()); + + // Step 2 (omitted). + + // Step 3. + Rooted<PromiseCombinatorElements> errors(cx); + if (!NewPromiseCombinatorElements(cx, resultCapability, &errors)) { + return false; + } + + // Step 4. + // Create our data holder that holds all the things shared across every step + // of the iterator. In particular, this holds the remainingElementsCount (as + // an integer reserved slot), the array of errors, and the reject function + // from our PromiseCapability. + Rooted<PromiseCombinatorDataHolder*> dataHolder(cx); + dataHolder = PromiseCombinatorDataHolder::New( + cx, resultCapability.promise(), errors, resultCapability.reject()); + if (!dataHolder) { + return false; + } + + // Step 5. + uint32_t index = 0; + + auto getResolveAndReject = [cx, &resultCapability, &errors, &dataHolder, + &index](MutableHandleValue resolveFunVal, + MutableHandleValue rejectFunVal) { + // Step 8.h. + if (!errors.pushUndefined(cx)) { + return false; + } + + // Steps 8.j-p. + JSFunction* rejectFunc = NewPromiseCombinatorElementFunction( + cx, PromiseAnyRejectElementFunction, dataHolder, index); + if (!rejectFunc) { + return false; + } + + // Step 8.q. + dataHolder->increaseRemainingCount(); + + // Step 8.s. + index++; + MOZ_ASSERT(index > 0); + + resolveFunVal.setObject(*resultCapability.resolve()); + rejectFunVal.setObject(*rejectFunc); + return true; + }; + + // BlockOnPromise fast path requires the passed onFulfilled function doesn't + // return an object value, because otherwise the skipped promise creation is + // detectable due to missing property lookups. + bool isDefaultResolveFn = + IsNativeFunction(resultCapability.resolve(), ResolvePromiseFunction); + + // Steps 6-8. + if (!CommonPerformPromiseCombinator( + cx, iterator, C, resultCapability.promise(), promiseResolve, done, + isDefaultResolveFn, getResolveAndReject)) { + return false; + } + + // Step 8.d.ii. + int32_t remainingCount = dataHolder->decreaseRemainingCount(); + + // Step 8.d.iii. + if (remainingCount == 0) { + ThrowAggregateError(cx, errors, resultCapability.promise()); + return false; + } + + // Step 8.d.iv. + return true; +} + +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// Promise.any Reject Element Functions +static bool PromiseAnyRejectElementFunction(JSContext* cx, unsigned argc, + Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + HandleValue xVal = args.get(0); + + // Steps 1-5. + Rooted<PromiseCombinatorDataHolder*> data(cx); + uint32_t index; + if (PromiseCombinatorElementFunctionAlreadyCalled(args, &data, &index)) { + args.rval().setUndefined(); + return true; + } + + // Step 6. + Rooted<PromiseCombinatorElements> errors(cx); + if (!GetPromiseCombinatorElements(cx, data, &errors)) { + return false; + } + + // Step 9. + if (!errors.setElement(cx, index, xVal)) { + return false; + } + + // Steps 8, 10. + uint32_t remainingCount = data->decreaseRemainingCount(); + + // Step 11. + if (remainingCount == 0) { + // Step 7 (Adapted to work with PromiseCombinatorDataHolder's layout). + RootedObject rejectFun(cx, data->resolveOrRejectObj()); + RootedObject promiseObj(cx, data->promiseObj()); + + ThrowAggregateError(cx, errors, promiseObj); + + RootedValue reason(cx); + RootedSavedFrame stack(cx); + if (!MaybeGetAndClearExceptionAndStack(cx, &reason, &stack)) { + return false; + } + + if (!RunRejectFunction(cx, rejectFun, reason, promiseObj, stack, + UnhandledRejectionBehavior::Report)) { + return false; + } + } + + // Step 12. + args.rval().setUndefined(); + return true; +} + +// Promise.any (Stage 3 proposal) +// https://tc39.es/proposal-promise-any/ +// +// ThrowAggregateError ( errors ) +static void ThrowAggregateError(JSContext* cx, + Handle<PromiseCombinatorElements> errors, + HandleObject promise) { + MOZ_ASSERT(!cx->isExceptionPending()); + + // Create the AggregateError in the same realm as the array object. + AutoRealm ar(cx, errors.unwrappedArray()); + + RootedObject allocationSite(cx); + mozilla::Maybe<JS::AutoSetAsyncStackForNewCalls> asyncStack; + + // Provide a more useful error stack if possible: This function is typically + // called from Promise job queue, which doesn't have any JS frames on the + // stack. So when we create the AggregateError below, its stack property will + // be set to the empty string, which makes it harder to debug the error cause. + // To avoid this situation set-up an async stack based on the Promise + // allocation site, which should point to calling site of |Promise.any|. + if (promise->is<PromiseObject>()) { + allocationSite = promise->as<PromiseObject>().allocationSite(); + if (allocationSite) { + asyncStack.emplace( + cx, allocationSite, "Promise.any", + JS::AutoSetAsyncStackForNewCalls::AsyncCallKind::IMPLICIT); + } + } + + // AutoSetAsyncStackForNewCalls requires a new activation before it takes + // effect, so call into the self-hosting helper to set-up new call frames. + RootedValue error(cx); + if (!GetAggregateError(cx, JSMSG_PROMISE_ANY_REJECTION, &error)) { + return; + } + + // |error| isn't guaranteed to be an AggregateError in case of OOM or stack + // overflow. + RootedSavedFrame stack(cx); + if (error.isObject() && error.toObject().is<ErrorObject>()) { + Rooted<ErrorObject*> errorObj(cx, &error.toObject().as<ErrorObject>()); + if (errorObj->type() == JSEXN_AGGREGATEERR) { + RootedValue errorsVal(cx, JS::ObjectValue(*errors.unwrappedArray())); + if (!NativeDefineDataProperty(cx, errorObj, cx->names().errors, errorsVal, + 0)) { + return; + } + + // Adopt the existing saved frames when present. + if (JSObject* errorStack = errorObj->stack()) { + stack = &errorStack->as<SavedFrame>(); + } + } + } + + cx->setPendingException(error, stack); +} + +// https://tc39.github.io/ecma262/#sec-promise.reject +// +// Unified implementation of +// 25.6.4.4 Promise.reject ( r ) +// 25.6.4.5 Promise.resolve ( x ) +// 25.6.4.5.1 PromiseResolve ( C, x ) +static MOZ_MUST_USE JSObject* CommonStaticResolveRejectImpl( + JSContext* cx, HandleValue thisVal, HandleValue argVal, + ResolutionMode mode) { + // Steps 1-2 of Promise.reject and Promise.resolve. + // Step 1: Let C be the this value. + // Step 2: If Type(C) is not Object, throw a TypeError exception. + if (!thisVal.isObject()) { + const char* msg = mode == ResolveMode ? "Receiver of Promise.resolve call" + : "Receiver of Promise.reject call"; + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_OBJECT_REQUIRED, msg); + return nullptr; + } + RootedObject C(cx, &thisVal.toObject()); + + // Promise.resolve, step 3: Return ? PromiseResolve(C, x). + // PromiseResolve, step 1: Assert: Type(C) is Object (implicit). + // PromiseResolve, step 2: If IsPromise(x) is true, then + if (mode == ResolveMode && argVal.isObject()) { + RootedObject xObj(cx, &argVal.toObject()); + bool isPromise = false; + if (xObj->is<PromiseObject>()) { + isPromise = true; + } else if (IsWrapper(xObj)) { + // Treat instances of Promise from other compartments as Promises + // here, too. + // It's important to do the GetProperty for the `constructor` + // below through the wrapper, because wrappers can change the + // outcome, so instead of unwrapping and then performing the + // GetProperty, just check here and then operate on the original + // object again. + if (xObj->canUnwrapAs<PromiseObject>()) { + isPromise = true; + } + } + if (isPromise) { + // Step 2.a: Let xConstructor be ? Get(x, "constructor"). + RootedValue ctorVal(cx); + if (!GetProperty(cx, xObj, xObj, cx->names().constructor, &ctorVal)) { + return nullptr; + } + + // Step 2.b: If SameValue(xConstructor, C) is true, return x. + if (ctorVal == thisVal) { + return xObj; + } + } + } + + // The step numbers below happen to be the same for PromiseResolve and + // Promise.reject. + // Step 3: Let promiseCapability be ? NewPromiseCapability(C). + Rooted<PromiseCapability> capability(cx); + if (!NewPromiseCapability(cx, C, &capability, true)) { + return nullptr; + } + + HandleObject promise = capability.promise(); + if (mode == ResolveMode) { + // PromiseResolve, step 4: + // Perform ? Call(promiseCapability.[[Resolve]], undefined, « x »). + if (!RunFulfillFunction(cx, capability.resolve(), argVal, promise)) { + return nullptr; + } + } else { + // Promise.reject, step 4: + // Perform ? Call(promiseCapability.[[Reject]], undefined, « r »). + if (!RunRejectFunction(cx, capability.reject(), argVal, promise, nullptr, + UnhandledRejectionBehavior::Report)) { + return nullptr; + } + } + + // Step 5: Return promiseCapability.[[Promise]]. + return promise; +} + +MOZ_MUST_USE JSObject* js::PromiseResolve(JSContext* cx, + HandleObject constructor, + HandleValue value) { + RootedValue C(cx, ObjectValue(*constructor)); + return CommonStaticResolveRejectImpl(cx, C, value, ResolveMode); +} + +/** + * ES2016, 25.4.4.4, Promise.reject. + */ +static bool Promise_reject(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + HandleValue thisVal = args.thisv(); + HandleValue argVal = args.get(0); + JSObject* result = + CommonStaticResolveRejectImpl(cx, thisVal, argVal, RejectMode); + if (!result) { + return false; + } + args.rval().setObject(*result); + return true; +} + +/** + * Unforgeable version of ES2016, 25.4.4.4, Promise.reject. + */ +/* static */ +PromiseObject* PromiseObject::unforgeableReject(JSContext* cx, + HandleValue value) { + cx->check(value); + + Rooted<PromiseObject*> promise( + cx, CreatePromiseObjectWithoutResolutionFunctions(cx)); + if (!promise) { + return nullptr; + } + + MOZ_ASSERT(promise->state() == JS::PromiseState::Pending); + MOZ_ASSERT( + PromiseHasAnyFlag(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)); + + if (!RejectPromiseInternal(cx, promise, value)) { + return nullptr; + } + + return promise; +} + +/** + * ES2016, 25.4.4.5, Promise.resolve. + */ +bool js::Promise_static_resolve(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + HandleValue thisVal = args.thisv(); + HandleValue argVal = args.get(0); + JSObject* result = + CommonStaticResolveRejectImpl(cx, thisVal, argVal, ResolveMode); + if (!result) { + return false; + } + args.rval().setObject(*result); + return true; +} + +/** + * Unforgeable version of ES2016, 25.4.4.5, Promise.resolve. + */ +/* static */ +JSObject* PromiseObject::unforgeableResolve(JSContext* cx, HandleValue value) { + JSObject* promiseCtor = JS::GetPromiseConstructor(cx); + if (!promiseCtor) { + return nullptr; + } + RootedValue cVal(cx, ObjectValue(*promiseCtor)); + return CommonStaticResolveRejectImpl(cx, cVal, value, ResolveMode); +} + +/** + * Unforgeable version of ES2016, 25.4.4.5, Promise.resolve(value), where + * value is guaranteed not to be a promise. + */ +/* static */ +PromiseObject* PromiseObject::unforgeableResolveWithNonPromise( + JSContext* cx, HandleValue value) { + cx->check(value); + +#ifdef DEBUG + auto IsPromise = [](HandleValue value) { + if (!value.isObject()) { + return false; + } + + JSObject* obj = &value.toObject(); + if (obj->is<PromiseObject>()) { + return true; + } + + if (!IsWrapper(obj)) { + return false; + } + + return obj->canUnwrapAs<PromiseObject>(); + }; + MOZ_ASSERT(!IsPromise(value), "must use unforgeableResolve with this value"); +#endif + + Rooted<PromiseObject*> promise( + cx, CreatePromiseObjectWithoutResolutionFunctions(cx)); + if (!promise) { + return nullptr; + } + + MOZ_ASSERT(promise->state() == JS::PromiseState::Pending); + MOZ_ASSERT( + PromiseHasAnyFlag(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)); + + if (!ResolvePromiseInternal(cx, promise, value)) { + return nullptr; + } + + return promise; +} + +/** + * ES2016, 25.4.4.6 get Promise [ @@species ] + */ +bool js::Promise_static_species(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + // Step 1: Return the this value. + args.rval().set(args.thisv()); + return true; +} + +// ES2016, 25.4.5.1, implemented in Promise.js. + +enum class IncumbentGlobalObject { + // Do not use the incumbent global, this is a special case used by the + // debugger. + No, + + // Use incumbent global, this is the normal operation. + Yes +}; + +static PromiseReactionRecord* NewReactionRecord( + JSContext* cx, Handle<PromiseCapability> resultCapability, + HandleValue onFulfilled, HandleValue onRejected, + IncumbentGlobalObject incumbentGlobalObjectOption) { +#ifdef DEBUG + if (resultCapability.promise()) { + if (incumbentGlobalObjectOption == IncumbentGlobalObject::Yes) { + if (resultCapability.promise()->is<PromiseObject>()) { + // If `resultCapability.promise` is a Promise object, + // `resultCapability.{resolve,reject}` may be optimized out, + // but if they're not, they should be callable. + MOZ_ASSERT_IF(resultCapability.resolve(), + IsCallable(resultCapability.resolve())); + MOZ_ASSERT_IF(resultCapability.reject(), + IsCallable(resultCapability.reject())); + } else { + // If `resultCapability.promise` is a non-Promise object + // (including wrapped Promise object), + // `resultCapability.{resolve,reject}` should be callable. + MOZ_ASSERT(resultCapability.resolve()); + MOZ_ASSERT(IsCallable(resultCapability.resolve())); + MOZ_ASSERT(resultCapability.reject()); + MOZ_ASSERT(IsCallable(resultCapability.reject())); + } + } else { + // For debugger usage, `resultCapability.promise` should be a + // maybe-wrapped Promise object. The other fields are not used. + // + // This is the only case where we allow `resolve` and `reject` to + // be null when the `promise` field is not a PromiseObject. + JSObject* unwrappedPromise = UncheckedUnwrap(resultCapability.promise()); + MOZ_ASSERT(unwrappedPromise->is<PromiseObject>()); + MOZ_ASSERT(!resultCapability.resolve()); + MOZ_ASSERT(!resultCapability.reject()); + } + } else { + // `resultCapability.promise` is null for the following cases: + // * resulting Promise is known to be unused + // * Async Function + // * Async Generator + // In any case, other fields are also not used. + MOZ_ASSERT(!resultCapability.resolve()); + MOZ_ASSERT(!resultCapability.reject()); + MOZ_ASSERT(incumbentGlobalObjectOption == IncumbentGlobalObject::Yes); + } +#endif + + // Ensure the onFulfilled handler has the expected type. + MOZ_ASSERT(onFulfilled.isInt32() || onFulfilled.isObjectOrNull()); + MOZ_ASSERT_IF(onFulfilled.isObject(), IsCallable(onFulfilled)); + MOZ_ASSERT_IF(onFulfilled.isInt32(), + 0 <= onFulfilled.toInt32() && + onFulfilled.toInt32() < PromiseHandlerLimit); + + // Ensure the onRejected handler has the expected type. + MOZ_ASSERT(onRejected.isInt32() || onRejected.isObjectOrNull()); + MOZ_ASSERT_IF(onRejected.isObject(), IsCallable(onRejected)); + MOZ_ASSERT_IF( + onRejected.isInt32(), + 0 <= onRejected.toInt32() && onRejected.toInt32() < PromiseHandlerLimit); + + // Handlers must either both be present or both be absent. + MOZ_ASSERT(onFulfilled.isNull() == onRejected.isNull()); + + RootedObject incumbentGlobalObject(cx); + if (incumbentGlobalObjectOption == IncumbentGlobalObject::Yes) { + if (!GetObjectFromIncumbentGlobal(cx, &incumbentGlobalObject)) { + return nullptr; + } + } + + PromiseReactionRecord* reaction = + NewBuiltinClassInstance<PromiseReactionRecord>(cx); + if (!reaction) { + return nullptr; + } + + cx->check(resultCapability.promise()); + cx->check(onFulfilled); + cx->check(onRejected); + cx->check(resultCapability.resolve()); + cx->check(resultCapability.reject()); + cx->check(incumbentGlobalObject); + + reaction->setFixedSlot(ReactionRecordSlot_Promise, + ObjectOrNullValue(resultCapability.promise())); + reaction->setFixedSlot(ReactionRecordSlot_Flags, Int32Value(0)); + reaction->setFixedSlot(ReactionRecordSlot_OnFulfilled, onFulfilled); + reaction->setFixedSlot(ReactionRecordSlot_OnRejected, onRejected); + reaction->setFixedSlot(ReactionRecordSlot_Resolve, + ObjectOrNullValue(resultCapability.resolve())); + reaction->setFixedSlot(ReactionRecordSlot_Reject, + ObjectOrNullValue(resultCapability.reject())); + reaction->setFixedSlot(ReactionRecordSlot_IncumbentGlobalObject, + ObjectOrNullValue(incumbentGlobalObject)); + + return reaction; +} + +static bool IsPromiseSpecies(JSContext* cx, JSFunction* species) { + return species->maybeNative() == Promise_static_species; +} + +// Whether to create a promise as the return value of Promise#{then,catch}. +// If the return value is known to be unused, and if the operation is known +// to be unobservable, we can skip creating the promise. +enum class CreateDependentPromise { Always, SkipIfCtorUnobservable }; + +static bool PromiseThenNewPromiseCapability( + JSContext* cx, HandleObject promiseObj, + CreateDependentPromise createDependent, + MutableHandle<PromiseCapability> resultCapability) { + // Step 3. + RootedObject C(cx, SpeciesConstructor(cx, promiseObj, JSProto_Promise, + IsPromiseSpecies)); + if (!C) { + return false; + } + + if (createDependent == CreateDependentPromise::Always || + !IsNativeFunction(C, PromiseConstructor)) { + // Step 4. + if (!NewPromiseCapability(cx, C, resultCapability, true)) { + return false; + } + + RootedObject unwrappedPromise(cx, promiseObj); + if (IsWrapper(promiseObj)) { + unwrappedPromise = UncheckedUnwrap(promiseObj); + } + RootedObject unwrappedNewPromise(cx, resultCapability.promise()); + if (IsWrapper(resultCapability.promise())) { + unwrappedNewPromise = UncheckedUnwrap(resultCapability.promise()); + } + if (unwrappedPromise->is<PromiseObject>() && + unwrappedNewPromise->is<PromiseObject>()) { + unwrappedNewPromise->as<PromiseObject>().copyUserInteractionFlagsFrom( + *unwrappedPromise.as<PromiseObject>()); + } + } + + return true; +} + +// ES2016, 25.4.5.3., steps 3-5. +MOZ_MUST_USE PromiseObject* js::OriginalPromiseThen(JSContext* cx, + HandleObject promiseObj, + HandleObject onFulfilled, + HandleObject onRejected) { + cx->check(promiseObj); + cx->check(onFulfilled); + cx->check(onRejected); + + RootedValue promiseVal(cx, ObjectValue(*promiseObj)); + Rooted<PromiseObject*> unwrappedPromise( + cx, + UnwrapAndTypeCheckValue<PromiseObject>(cx, promiseVal, [cx, promiseObj] { + JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, + JSMSG_INCOMPATIBLE_PROTO, "Promise", "then", + promiseObj->getClass()->name); + })); + if (!unwrappedPromise) { + return nullptr; + } + + // Steps 3-4. + Rooted<PromiseObject*> newPromise( + cx, CreatePromiseObjectWithoutResolutionFunctions(cx)); + if (!newPromise) { + return nullptr; + } + newPromise->copyUserInteractionFlagsFrom(*unwrappedPromise); + + Rooted<PromiseCapability> resultCapability(cx); + resultCapability.promise().set(newPromise); + + // Step 5. + { + RootedValue onFulfilledVal(cx, ObjectOrNullValue(onFulfilled)); + RootedValue onRejectedVal(cx, ObjectOrNullValue(onRejected)); + if (!PerformPromiseThen(cx, unwrappedPromise, onFulfilledVal, onRejectedVal, + resultCapability)) { + return nullptr; + } + } + + return newPromise; +} + +static MOZ_MUST_USE bool OriginalPromiseThenWithoutSettleHandlers( + JSContext* cx, Handle<PromiseObject*> promise, + Handle<PromiseObject*> promiseToResolve) { + cx->check(promise); + + // Steps 3-4. + Rooted<PromiseCapability> resultCapability(cx); + if (!PromiseThenNewPromiseCapability( + cx, promise, CreateDependentPromise::SkipIfCtorUnobservable, + &resultCapability)) { + return false; + } + + // Step 5. + return PerformPromiseThenWithoutSettleHandlers(cx, promise, promiseToResolve, + resultCapability); +} + +static MOZ_MUST_USE bool PerformPromiseThenWithReaction( + JSContext* cx, Handle<PromiseObject*> promise, + Handle<PromiseReactionRecord*> reaction); + +MOZ_MUST_USE bool js::ReactToUnwrappedPromise( + JSContext* cx, Handle<PromiseObject*> unwrappedPromise, + HandleObject onFulfilled_, HandleObject onRejected_, + UnhandledRejectionBehavior behavior) { + cx->check(onFulfilled_); + cx->check(onRejected_); + + MOZ_ASSERT_IF(onFulfilled_, IsCallable(onFulfilled_)); + MOZ_ASSERT_IF(onRejected_, IsCallable(onRejected_)); + + RootedValue onFulfilled(cx, onFulfilled_ + ? ObjectValue(*onFulfilled_) + : Int32Value(PromiseHandlerIdentity)); + + RootedValue onRejected(cx, onRejected_ ? ObjectValue(*onRejected_) + : Int32Value(PromiseHandlerThrower)); + + Rooted<PromiseCapability> resultCapability(cx); + MOZ_ASSERT(!resultCapability.promise()); + + Rooted<PromiseReactionRecord*> reaction( + cx, NewReactionRecord(cx, resultCapability, onFulfilled, onRejected, + IncumbentGlobalObject::Yes)); + if (!reaction) { + return false; + } + + if (behavior == UnhandledRejectionBehavior::Ignore) { + reaction->setShouldIgnoreUnhandledRejection(); + } + + return PerformPromiseThenWithReaction(cx, unwrappedPromise, reaction); +} + +static bool CanCallOriginalPromiseThenBuiltin(JSContext* cx, + HandleValue promise) { + return promise.isObject() && promise.toObject().is<PromiseObject>() && + cx->realm()->promiseLookup.isDefaultInstance( + cx, &promise.toObject().as<PromiseObject>()); +} + +// ES2016, 25.4.5.3., steps 3-5. +static bool OriginalPromiseThenBuiltin(JSContext* cx, HandleValue promiseVal, + HandleValue onFulfilled, + HandleValue onRejected, + MutableHandleValue rval, bool rvalUsed) { + cx->check(promiseVal, onFulfilled, onRejected); + MOZ_ASSERT(CanCallOriginalPromiseThenBuiltin(cx, promiseVal)); + + Rooted<PromiseObject*> promise(cx, + &promiseVal.toObject().as<PromiseObject>()); + + // Steps 3-4. + Rooted<PromiseCapability> resultCapability(cx); + if (rvalUsed) { + PromiseObject* resultPromise = + CreatePromiseObjectWithoutResolutionFunctions(cx); + if (!resultPromise) { + return false; + } + + resultPromise->copyUserInteractionFlagsFrom( + promiseVal.toObject().as<PromiseObject>()); + resultCapability.promise().set(resultPromise); + } + + // Step 5. + if (!PerformPromiseThen(cx, promise, onFulfilled, onRejected, + resultCapability)) { + return false; + } + + if (rvalUsed) { + rval.setObject(*resultCapability.promise()); + } else { + rval.setUndefined(); + } + return true; +} + +MOZ_MUST_USE bool js::RejectPromiseWithPendingError( + JSContext* cx, Handle<PromiseObject*> promise) { + cx->check(promise); + + if (!cx->isExceptionPending()) { + // Reject the promise, but also propagate this uncatchable error. + mozilla::Unused << PromiseObject::reject(cx, promise, UndefinedHandleValue); + return false; + } + + RootedValue exn(cx); + if (!GetAndClearException(cx, &exn)) { + return false; + } + return PromiseObject::reject(cx, promise, exn); +} + +// Some async/await functions are implemented here instead of +// js/src/builtin/AsyncFunction.cpp, to call Promise internal functions. + +// ES 2018 draft 14.6.11 and 14.7.14 step 1. +MOZ_MUST_USE PromiseObject* js::CreatePromiseObjectForAsync(JSContext* cx) { + // Step 1. + PromiseObject* promise = CreatePromiseObjectWithoutResolutionFunctions(cx); + if (!promise) { + return nullptr; + } + + AddPromiseFlags(*promise, PROMISE_FLAG_ASYNC); + return promise; +} + +bool js::IsPromiseForAsyncFunctionOrGenerator(JSObject* promise) { + return promise->is<PromiseObject>() && + PromiseHasAnyFlag(promise->as<PromiseObject>(), PROMISE_FLAG_ASYNC); +} + +static MOZ_MUST_USE PromiseObject* CreatePromiseObjectForAsyncGenerator( + JSContext* cx) { + PromiseObject* promise = CreatePromiseObjectWithoutResolutionFunctions(cx); + if (!promise) { + return nullptr; + } + + AddPromiseFlags(*promise, PROMISE_FLAG_ASYNC); + return promise; +} + +// ES2019 draft rev 7428c89bef626548084cd4e697a19ece7168f24c +// 25.7.5.1 AsyncFunctionStart, steps 3.f-g. +MOZ_MUST_USE bool js::AsyncFunctionThrown(JSContext* cx, + Handle<PromiseObject*> resultPromise, + HandleValue reason) { + if (resultPromise->state() != JS::PromiseState::Pending) { + // OOM after resolving promise. + // Report a warning and ignore the result. + if (!WarnNumberASCII(cx, JSMSG_UNHANDLABLE_PROMISE_REJECTION_WARNING)) { + if (cx->isExceptionPending()) { + cx->clearPendingException(); + } + } + return true; + } + + return RejectPromiseInternal(cx, resultPromise, reason); +} + +// ES2019 draft rev 7428c89bef626548084cd4e697a19ece7168f24c +// 25.7.5.1 AsyncFunctionStart, steps 3.d-e, 3.g. +MOZ_MUST_USE bool js::AsyncFunctionReturned( + JSContext* cx, Handle<PromiseObject*> resultPromise, HandleValue value) { + return ResolvePromiseInternal(cx, resultPromise, value); +} + +// https://tc39.github.io/ecma262/#await +// +// Helper function that performs 6.2.3.1 Await(promise) steps 2 and 9. +// The same steps are also used in a few other places in the spec. +template <typename T> +static MOZ_MUST_USE bool InternalAwait(JSContext* cx, HandleValue value, + HandleObject resultPromise, + PromiseHandler onFulfilled, + PromiseHandler onRejected, T extraStep) { + // Step 2: Let promise be ? PromiseResolve(%Promise%, « value »). + RootedObject promise(cx, PromiseObject::unforgeableResolve(cx, value)); + if (!promise) { + return false; + } + + // This downcast is safe because unforgeableResolve either returns `value` + // (only if it is already a possibly-wrapped promise) or creates a new + // promise using the Promise constructor. + Rooted<PromiseObject*> unwrappedPromise( + cx, UnwrapAndDowncastObject<PromiseObject>(cx, promise)); + if (!unwrappedPromise) { + return false; + } + + // Steps 3-8 of the spec create onFulfilled and onRejected functions. + + // Step 9: Perform ! PerformPromiseThen(promise, onFulfilled, onRejected). + RootedValue onFulfilledValue(cx, Int32Value(onFulfilled)); + RootedValue onRejectedValue(cx, Int32Value(onRejected)); + Rooted<PromiseCapability> resultCapability(cx); + resultCapability.promise().set(resultPromise); + Rooted<PromiseReactionRecord*> reaction( + cx, NewReactionRecord(cx, resultCapability, onFulfilledValue, + onRejectedValue, IncumbentGlobalObject::Yes)); + if (!reaction) { + return false; + } + extraStep(reaction); + return PerformPromiseThenWithReaction(cx, unwrappedPromise, reaction); +} + +// https://tc39.github.io/ecma262/#await +// +// 6.2.3.1 Await(promise) steps 2-10 when the running execution context is +// evaluating an `await` expression in an async function. +MOZ_MUST_USE JSObject* js::AsyncFunctionAwait( + JSContext* cx, Handle<AsyncFunctionGeneratorObject*> genObj, + HandleValue value) { + auto extra = [&](Handle<PromiseReactionRecord*> reaction) { + reaction->setIsAsyncFunction(genObj); + }; + if (!InternalAwait(cx, value, nullptr, + PromiseHandlerAsyncFunctionAwaitedFulfilled, + PromiseHandlerAsyncFunctionAwaitedRejected, extra)) { + return nullptr; + } + return genObj->promise(); +} + +// 6.2.3.1 Await(promise) steps 2-10 when the running execution context is +// evaluating an `await` expression in an async generator. +MOZ_MUST_USE bool js::AsyncGeneratorAwait( + JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj, + HandleValue value) { + auto extra = [&](Handle<PromiseReactionRecord*> reaction) { + reaction->setIsAsyncGenerator(asyncGenObj); + }; + return InternalAwait(cx, value, nullptr, + PromiseHandlerAsyncGeneratorAwaitedFulfilled, + PromiseHandlerAsyncGeneratorAwaitedRejected, extra); +} + +// https://tc39.github.io/ecma262/#sec-%asyncfromsynciteratorprototype%.next +// 25.1.4.2.1 %AsyncFromSyncIteratorPrototype%.next +// 25.1.4.2.2 %AsyncFromSyncIteratorPrototype%.return +// 25.1.4.2.3 %AsyncFromSyncIteratorPrototype%.throw +bool js::AsyncFromSyncIteratorMethod(JSContext* cx, CallArgs& args, + CompletionKind completionKind) { + // Step 1: Let O be the this value. + HandleValue thisVal = args.thisv(); + + // Step 2: Let promiseCapability be ! NewPromiseCapability(%Promise%). + Rooted<PromiseObject*> resultPromise( + cx, CreatePromiseObjectWithoutResolutionFunctions(cx)); + if (!resultPromise) { + return false; + } + + // Step 3: If Type(O) is not Object, or if O does not have a + // [[SyncIteratorRecord]] internal slot, then + if (!thisVal.isObject() || + !thisVal.toObject().is<AsyncFromSyncIteratorObject>()) { + // NB: See https://github.com/tc39/proposal-async-iteration/issues/105 + // for why this check shouldn't be necessary as long as we can ensure + // the Async-from-Sync iterator can't be accessed directly by user + // code. + + // Step 3.a: Let invalidIteratorError be a newly created TypeError object. + RootedValue badGeneratorError(cx); + if (!GetTypeError(cx, JSMSG_NOT_AN_ASYNC_ITERATOR, &badGeneratorError)) { + return false; + } + + // Step 3.b: Perform ! Call(promiseCapability.[[Reject]], undefined, + // « invalidIteratorError »). + if (!RejectPromiseInternal(cx, resultPromise, badGeneratorError)) { + return false; + } + + // Step 3.c: Return promiseCapability.[[Promise]]. + args.rval().setObject(*resultPromise); + return true; + } + + Rooted<AsyncFromSyncIteratorObject*> asyncIter( + cx, &thisVal.toObject().as<AsyncFromSyncIteratorObject>()); + + // Step 4: Let syncIteratorRecord be O.[[SyncIteratorRecord]]. + RootedObject iter(cx, asyncIter->iterator()); + + RootedValue func(cx); + if (completionKind == CompletionKind::Normal) { + // next() preparing for steps 5-6. + func.set(asyncIter->nextMethod()); + } else if (completionKind == CompletionKind::Return) { + // return() steps 5-7. + // Step 5: Let return be GetMethod(syncIterator, "return"). + // Step 6: IfAbruptRejectPromise(return, promiseCapability). + if (!GetProperty(cx, iter, iter, cx->names().return_, &func)) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // Step 7: If return is undefined, then + // (Note: GetMethod contains a step that changes `null` to `undefined`; + // we omit that step above, and check for `null` here instead.) + if (func.isNullOrUndefined()) { + // Step 7.a: Let iterResult be ! CreateIterResultObject(value, true). + PlainObject* resultObj = CreateIterResultObject(cx, args.get(0), true); + if (!resultObj) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + RootedValue resultVal(cx, ObjectValue(*resultObj)); + + // Step 7.b: Perform ! Call(promiseCapability.[[Resolve]], undefined, + // « iterResult »). + if (!ResolvePromiseInternal(cx, resultPromise, resultVal)) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // Step 7.c: Return promiseCapability.[[Promise]]. + args.rval().setObject(*resultPromise); + return true; + } + } else { + // noexcept(true) steps 5-7. + MOZ_ASSERT(completionKind == CompletionKind::Throw); + + // Step 5: Let throw be GetMethod(syncIterator, "throw"). + // Step 6: IfAbruptRejectPromise(throw, promiseCapability). + if (!GetProperty(cx, iter, iter, cx->names().throw_, &func)) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // Step 7: If throw is undefined, then + // (Note: GetMethod contains a step that changes `null` to `undefined`; + // we omit that step above, and check for `null` here instead.) + if (func.isNullOrUndefined()) { + // Step 7.a: Perform ! Call(promiseCapability.[[Reject]], undefined, « + // value »). + if (!RejectPromiseInternal(cx, resultPromise, args.get(0))) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // Step 7.b: Return promiseCapability.[[Promise]]. + args.rval().setObject(*resultPromise); + return true; + } + } + + // next() steps 5-6. + // Step 5: Let result be IteratorNext(syncIteratorRecord, value). + // Step 6: IfAbruptRejectPromise(result, promiseCapability). + // return/throw() steps 8-9. + // Step 8: Let result be Call(throw, syncIterator, « value »). + // Step 9: IfAbruptRejectPromise(result, promiseCapability). + // + // Including the changes from: https://github.com/tc39/ecma262/pull/1776 + RootedValue iterVal(cx, ObjectValue(*iter)); + RootedValue resultVal(cx); + bool ok; + if (args.length() == 0) { + ok = Call(cx, func, iterVal, &resultVal); + } else { + ok = Call(cx, func, iterVal, args[0], &resultVal); + } + if (!ok) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // next() step 5 -> IteratorNext Step 3: + // If Type(result) is not Object, throw a TypeError exception. + // Followed by IfAbruptRejectPromise in step 6. + // + // return/throw() Step 10: If Type(result) is not Object, then + // Step 10.a: Perform ! Call(promiseCapability.[[Reject]], undefined, + // « a newly created TypeError object »). + // Step 10.b: Return promiseCapability.[[Promise]]. + if (!resultVal.isObject()) { + CheckIsObjectKind kind; + switch (completionKind) { + case CompletionKind::Normal: + kind = CheckIsObjectKind::IteratorNext; + break; + case CompletionKind::Throw: + kind = CheckIsObjectKind::IteratorThrow; + break; + case CompletionKind::Return: + kind = CheckIsObjectKind::IteratorReturn; + break; + } + MOZ_ALWAYS_FALSE(ThrowCheckIsObject(cx, kind)); + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + RootedObject resultObj(cx, &resultVal.toObject()); + + // next() Step 7, return/throw() Step 11: Return + // ! AsyncFromSyncIteratorContinuation(result, promiseCapability). + // + // The step numbers below are for + // 25.1.4.4 AsyncFromSyncIteratorContinuation ( result, promiseCapability ). + + // Step 1: Let done be IteratorComplete(result). + // Step 2: IfAbruptRejectPromise(done, promiseCapability). + RootedValue doneVal(cx); + if (!GetProperty(cx, resultObj, resultObj, cx->names().done, &doneVal)) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + bool done = ToBoolean(doneVal); + + // Step 3: Let value be IteratorValue(result). + // Step 4: IfAbruptRejectPromise(value, promiseCapability). + RootedValue value(cx); + if (!GetProperty(cx, resultObj, resultObj, cx->names().value, &value)) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // Step numbers below include the changes in + // <https://github.com/tc39/ecma262/pull/1470>, which inserted a new step 6. + // + // Steps 7-9 (reordered). + // Step 7: Let steps be the algorithm steps defined in Async-from-Sync + // Iterator Value Unwrap Functions. + // Step 8: Let onFulfilled be CreateBuiltinFunction(steps, « [[Done]] »). + // Step 9: Set onFulfilled.[[Done]] to done. + PromiseHandler onFulfilled = + done ? PromiseHandlerAsyncFromSyncIteratorValueUnwrapDone + : PromiseHandlerAsyncFromSyncIteratorValueUnwrapNotDone; + PromiseHandler onRejected = PromiseHandlerThrower; + + // Steps 5 and 10 are identical to some steps in Await; we have a utility + // function InternalAwait() that implements the idiom. + // + // Step 5: Let valueWrapper be PromiseResolve(%Promise%, « value »). + // Step 6: IfAbruptRejectPromise(valueWrapper, promiseCapability). + // Step 10: Perform ! PerformPromiseThen(valueWrapper, onFulfilled, + // undefined, promiseCapability). + auto extra = [](Handle<PromiseReactionRecord*> reaction) {}; + if (!InternalAwait(cx, value, resultPromise, onFulfilled, onRejected, + extra)) { + return AbruptRejectPromise(cx, args, resultPromise, nullptr); + } + + // Step 11: Return promiseCapability.[[Promise]]. + args.rval().setObject(*resultPromise); + return true; +} + +enum class ResumeNextKind { Enqueue, Reject, Resolve }; + +static MOZ_MUST_USE bool AsyncGeneratorResumeNext( + JSContext* cx, Handle<AsyncGeneratorObject*> generator, ResumeNextKind kind, + HandleValue valueOrException = UndefinedHandleValue, bool done = false); + +// 25.5.3.3 AsyncGeneratorResolve ( generator, value, done ) +MOZ_MUST_USE bool js::AsyncGeneratorResolve( + JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj, HandleValue value, + bool done) { + return AsyncGeneratorResumeNext(cx, asyncGenObj, ResumeNextKind::Resolve, + value, done); +} + +// 25.5.3.4 AsyncGeneratorReject ( generator, exception ) +MOZ_MUST_USE bool js::AsyncGeneratorReject( + JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj, + HandleValue exception) { + return AsyncGeneratorResumeNext(cx, asyncGenObj, ResumeNextKind::Reject, + exception); +} + +// Unified implementation of: +// 25.5.3.3 AsyncGeneratorResolve ( generator, value, done ) +// 25.5.3.4 AsyncGeneratorReject ( generator, exception ) +// 25.5.3.5 AsyncGeneratorResumeNext ( generator ) +static MOZ_MUST_USE bool AsyncGeneratorResumeNext( + JSContext* cx, Handle<AsyncGeneratorObject*> generator, ResumeNextKind kind, + HandleValue valueOrException_ /* = UndefinedHandleValue */, + bool done /* = false */) { + RootedValue valueOrException(cx, valueOrException_); + + // Many paths through the algorithm end in recursive tail-calls. + // We implement these with a loop. + while (true) { + switch (kind) { + case ResumeNextKind::Enqueue: + // No further action required. + break; + case ResumeNextKind::Reject: { + // 25.5.3.4 AsyncGeneratorReject ( generator, exception ) + HandleValue exception = valueOrException; + + // Step 1: Assert: generator is an AsyncGenerator instance (implicit). + // Step 2: Let queue be generator.[[AsyncGeneratorQueue]]. + // Step 3: Assert: queue is not an empty List. + MOZ_ASSERT(!generator->isQueueEmpty()); + + // Step 4: Remove the first element from queue and let next be the value + // of that element. + AsyncGeneratorRequest* request = + AsyncGeneratorObject::dequeueRequest(cx, generator); + if (!request) { + return false; + } + + // Step 5: Let promiseCapability be next.[[Capability]]. + Rooted<PromiseObject*> resultPromise(cx, request->promise()); + + generator->cacheRequest(request); + + // Step 6: Perform ! Call(promiseCapability.[[Reject]], undefined, + // « exception »). + if (!RejectPromiseInternal(cx, resultPromise, exception)) { + return false; + } + + // Step 7: Perform ! AsyncGeneratorResumeNext(generator). + // Step 8: Return undefined. + break; + } + case ResumeNextKind::Resolve: { + // 25.5.3.3 AsyncGeneratorResolve ( generator, value, done ) + HandleValue value = valueOrException; + + // Step 1: Assert: generator is an AsyncGenerator instance (implicit). + // Step 2: Let queue be generator.[[AsyncGeneratorQueue]]. + // Step 3: Assert: queue is not an empty List. + MOZ_ASSERT(!generator->isQueueEmpty()); + + // Step 4: Remove the first element from queue and let next be the value + // of that element. + AsyncGeneratorRequest* request = + AsyncGeneratorObject::dequeueRequest(cx, generator); + if (!request) { + return false; + } + + // Step 5: Let promiseCapability be next.[[Capability]]. + Rooted<PromiseObject*> resultPromise(cx, request->promise()); + + generator->cacheRequest(request); + + // Step 6: Let iteratorResult be ! CreateIterResultObject(value, done). + JSObject* resultObj = CreateIterResultObject(cx, value, done); + if (!resultObj) { + return false; + } + + RootedValue resultValue(cx, ObjectValue(*resultObj)); + + // Step 7: Perform ! Call(promiseCapability.[[Resolve]], undefined, + // « iteratorResult »). + if (!ResolvePromiseInternal(cx, resultPromise, resultValue)) { + return false; + } + + // Step 8: Perform ! AsyncGeneratorResumeNext(generator). + // Step 9: Return undefined. + break; + } + } + + // 25.5.3.5 AsyncGeneratorResumeNext ( generator ) + // Step 1: Assert: generator is an AsyncGenerator instance (implicit). + // Step 2: Let state be generator.[[AsyncGeneratorState]] (implicit). + // Step 3: Assert: state is not "executing". + MOZ_ASSERT(!generator->isExecuting()); + MOZ_ASSERT(!generator->isAwaitingYieldReturn()); + + // Step 4: If state is "awaiting-return", return undefined. + if (generator->isAwaitingReturn()) { + return true; + } + + // Step 5: Let queue be generator.[[AsyncGeneratorQueue]]. + // Step 6: If queue is an empty List, return undefined. + if (generator->isQueueEmpty()) { + return true; + } + + // Step 7: Let next be the value of the first element of queue. + // Step 8: Assert: next is an AsyncGeneratorRequest record. + Rooted<AsyncGeneratorRequest*> request( + cx, AsyncGeneratorObject::peekRequest(generator)); + if (!request) { + return false; + } + + // Step 9: Let completion be next.[[Completion]]. + CompletionKind completionKind = request->completionKind(); + + // Step 10: If completion is an abrupt completion, then + if (completionKind != CompletionKind::Normal) { + // Step 10.a: If state is "suspendedStart", then + if (generator->isSuspendedStart()) { + // Step 10.a.i: Set generator.[[AsyncGeneratorState]] to "completed". + // Step 10.a.ii: Set state to "completed". + generator->setCompleted(); + } + + // Step 10.b: If state is "completed", then + if (generator->isCompleted()) { + RootedValue value(cx, request->completionValue()); + + // Step 10.b.i: If completion.[[Type]] is return, then + if (completionKind == CompletionKind::Return) { + // Step 10.b.i.1: Set generator.[[AsyncGeneratorState]] to + // "awaiting-return". + generator->setAwaitingReturn(); + + // (reordered) + // Step 10.b.i.3: Let stepsFulfilled be the algorithm steps defined in + // AsyncGeneratorResumeNext Return Processor Fulfilled + // Functions. + // Step 10.b.i.4: Let onFulfilled be CreateBuiltinFunction( + // stepsFulfilled, « [[Generator]] »). + // Step 10.b.i.5: Set onFulfilled.[[Generator]] to generator. + // Step 10.b.i.6: Let stepsRejected be the algorithm steps defined in + // AsyncGeneratorResumeNext Return Processor Rejected + // Functions. + // Step 10.b.i.7: Let onRejected be CreateBuiltinFunction( + // stepsRejected, « [[Generator]] »). + // Step 10.b.i.8: Set onRejected.[[Generator]] to generator. + // + const PromiseHandler onFulfilled = + PromiseHandlerAsyncGeneratorResumeNextReturnFulfilled; + const PromiseHandler onRejected = + PromiseHandlerAsyncGeneratorResumeNextReturnRejected; + + // These steps are nearly identical to some steps in Await; + // InternalAwait() implements the idiom. + // + // Step 10.b.i.2: Let promise be ? PromiseResolve(%Promise%, + // « _completion_.[[Value]] »). + // Step 10.b.i.9: Perform ! PerformPromiseThen(promise, onFulfilled, + // onRejected). + // Step 10.b.i.10: Return undefined. + auto extra = [&](Handle<PromiseReactionRecord*> reaction) { + reaction->setIsAsyncGenerator(generator); + }; + return InternalAwait(cx, value, nullptr, onFulfilled, onRejected, + extra); + } + + // Step 10.b.ii: Else, + + // Step 10.b.ii.1: Assert: completion.[[Type]] is throw. + MOZ_ASSERT(completionKind == CompletionKind::Throw); + + // Step 10.b.ii.2: Perform ! AsyncGeneratorReject(generator, + // completion.[[Value]]). + // Step 10.b.ii.3: Return undefined. + kind = ResumeNextKind::Reject; + valueOrException.set(value); + continue; + } + } else if (generator->isCompleted()) { + // Step 11: Else if state is "completed", return + // ! AsyncGeneratorResolve(generator, undefined, true). + kind = ResumeNextKind::Resolve; + valueOrException.setUndefined(); + done = true; + continue; + } + + // Step 12: Assert: state is either "suspendedStart" or "suspendedYield". + MOZ_ASSERT(generator->isSuspendedStart() || generator->isSuspendedYield()); + + RootedValue argument(cx, request->completionValue()); + + if (completionKind == CompletionKind::Return) { + // 25.5.3.7 AsyncGeneratorYield steps 8.b-e. + // Since we don't have the place that handles return from yield + // inside the generator, handle the case here, with extra state + // State_AwaitingYieldReturn. + generator->setAwaitingYieldReturn(); + + const PromiseHandler onFulfilled = + PromiseHandlerAsyncGeneratorYieldReturnAwaitedFulfilled; + const PromiseHandler onRejected = + PromiseHandlerAsyncGeneratorYieldReturnAwaitedRejected; + + auto extra = [&](Handle<PromiseReactionRecord*> reaction) { + reaction->setIsAsyncGenerator(generator); + }; + return InternalAwait(cx, argument, nullptr, onFulfilled, onRejected, + extra); + } + + // Step 16 (reordered): Set generator.[[AsyncGeneratorState]] to + // "executing". + generator->setExecuting(); + + // Steps 13-15, 17-21. + return AsyncGeneratorResume(cx, generator, completionKind, argument); + } +} + +// 25.5.3.6 AsyncGeneratorEnqueue ( generator, completion ) +MOZ_MUST_USE bool js::AsyncGeneratorEnqueue(JSContext* cx, + HandleValue asyncGenVal, + CompletionKind completionKind, + HandleValue completionValue, + MutableHandleValue result) { + // Step 1 (implicit). + + // Step 3. + if (!asyncGenVal.isObject() || + !asyncGenVal.toObject().canUnwrapAs<AsyncGeneratorObject>()) { + // Step 2. + Rooted<PromiseObject*> resultPromise( + cx, CreatePromiseObjectForAsyncGenerator(cx)); + if (!resultPromise) { + return false; + } + + // Step 3.a. + RootedValue badGeneratorError(cx); + if (!GetTypeError(cx, JSMSG_NOT_AN_ASYNC_GENERATOR, &badGeneratorError)) { + return false; + } + + // Step 3.b. + if (!RejectPromiseInternal(cx, resultPromise, badGeneratorError)) { + return false; + } + + // Step 3.c. + result.setObject(*resultPromise); + return true; + } + + Rooted<AsyncGeneratorObject*> asyncGenObj( + cx, &asyncGenVal.toObject().unwrapAs<AsyncGeneratorObject>()); + + bool wrapResult = false; + { + // The |resultPromise| must be same-compartment with |asyncGenObj|, because + // it is stored in AsyncGeneratorRequest, which in turn is stored in a + // reserved slot of |asyncGenObj|. + // So we first enter the realm of |asyncGenObj|, then create the result + // promise and resume the generator, and finally wrap the result promise to + // match the original compartment. + + mozilla::Maybe<AutoRealm> ar; + RootedValue completionVal(cx, completionValue); + if (asyncGenObj->compartment() != cx->compartment()) { + ar.emplace(cx, asyncGenObj); + wrapResult = true; + + if (!cx->compartment()->wrap(cx, &completionVal)) { + return false; + } + } + + // Step 2. + Rooted<PromiseObject*> resultPromise( + cx, CreatePromiseObjectForAsyncGenerator(cx)); + if (!resultPromise) { + return false; + } + + // Step 5 (reordered). + Rooted<AsyncGeneratorRequest*> request( + cx, AsyncGeneratorObject::createRequest(cx, asyncGenObj, completionKind, + completionVal, resultPromise)); + if (!request) { + return false; + } + + // Steps 4, 6. + if (!AsyncGeneratorObject::enqueueRequest(cx, asyncGenObj, request)) { + return false; + } + + // Step 7. + if (!asyncGenObj->isExecuting() && !asyncGenObj->isAwaitingYieldReturn()) { + // Step 8. + if (!AsyncGeneratorResumeNext(cx, asyncGenObj, ResumeNextKind::Enqueue)) { + return false; + } + } + + // Step 9. + result.setObject(*resultPromise); + } + + return !wrapResult || cx->compartment()->wrap(cx, result); +} + +static bool Promise_catch_impl(JSContext* cx, unsigned argc, Value* vp, + bool rvalUsed) { + CallArgs args = CallArgsFromVp(argc, vp); + + HandleValue thisVal = args.thisv(); + HandleValue onFulfilled = UndefinedHandleValue; + HandleValue onRejected = args.get(0); + + // Fast path when the default Promise state is intact. + if (CanCallOriginalPromiseThenBuiltin(cx, thisVal)) { + return OriginalPromiseThenBuiltin(cx, thisVal, onFulfilled, onRejected, + args.rval(), rvalUsed); + } + + // Step 1. + RootedValue thenVal(cx); + if (!GetProperty(cx, thisVal, cx->names().then, &thenVal)) { + return false; + } + + if (IsNativeFunction(thenVal, &Promise_then) && + thenVal.toObject().nonCCWRealm() == cx->realm()) { + return Promise_then_impl(cx, thisVal, onFulfilled, onRejected, args.rval(), + rvalUsed); + } + + return Call(cx, thenVal, thisVal, UndefinedHandleValue, onRejected, + args.rval()); +} + +static MOZ_ALWAYS_INLINE bool IsPromiseThenOrCatchRetValImplicitlyUsed( + JSContext* cx) { + // The returned promise of Promise#then and Promise#catch contains + // stack info if async stack is enabled. Even if their return value is not + // used explicitly in the script, the stack info is observable in devtools + // and profilers. We shouldn't apply the optimization not to allocate the + // returned Promise object if the it's implicitly used by them. + if (!cx->options().asyncStack()) { + return false; + } + + // If devtools is opened, the current realm will become debuggee. + if (cx->realm()->isDebuggee()) { + return true; + } + + // There are 2 profilers, and they can be independently enabled. + if (cx->runtime()->geckoProfiler().enabled()) { + return true; + } + if (JS::IsProfileTimelineRecordingEnabled()) { + return true; + } + + // The stack is also observable from Error#stack, but we don't care since + // it's nonstandard feature. + return false; +} + +// ES2016, 25.4.5.3. +static bool Promise_catch_noRetVal(JSContext* cx, unsigned argc, Value* vp) { + return Promise_catch_impl(cx, argc, vp, + IsPromiseThenOrCatchRetValImplicitlyUsed(cx)); +} + +// ES2016, 25.4.5.3. +static bool Promise_catch(JSContext* cx, unsigned argc, Value* vp) { + return Promise_catch_impl(cx, argc, vp, true); +} + +static bool Promise_then_impl(JSContext* cx, HandleValue promiseVal, + HandleValue onFulfilled, HandleValue onRejected, + MutableHandleValue rval, bool rvalUsed) { + // Step 1 (implicit). + // Step 2. + if (!promiseVal.isObject()) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_OBJECT_REQUIRED, + "Receiver of Promise.prototype.then call"); + return false; + } + + // Fast path when the default Promise state is intact. + if (CanCallOriginalPromiseThenBuiltin(cx, promiseVal)) { + return OriginalPromiseThenBuiltin(cx, promiseVal, onFulfilled, onRejected, + rval, rvalUsed); + } + + RootedObject promiseObj(cx, &promiseVal.toObject()); + Rooted<PromiseObject*> unwrappedPromise( + cx, + UnwrapAndTypeCheckValue<PromiseObject>(cx, promiseVal, [cx, &promiseVal] { + JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, + JSMSG_INCOMPATIBLE_PROTO, "Promise", "then", + InformalValueTypeName(promiseVal)); + })); + if (!unwrappedPromise) { + return false; + } + + // Steps 3-4. + CreateDependentPromise createDependent = + rvalUsed ? CreateDependentPromise::Always + : CreateDependentPromise::SkipIfCtorUnobservable; + Rooted<PromiseCapability> resultCapability(cx); + if (!PromiseThenNewPromiseCapability(cx, promiseObj, createDependent, + &resultCapability)) { + return false; + } + + // Step 5. + if (!PerformPromiseThen(cx, unwrappedPromise, onFulfilled, onRejected, + resultCapability)) { + return false; + } + + if (rvalUsed) { + rval.setObject(*resultCapability.promise()); + } else { + rval.setUndefined(); + } + return true; +} + +// ES2016, 25.4.5.3. +bool Promise_then_noRetVal(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + return Promise_then_impl(cx, args.thisv(), args.get(0), args.get(1), + args.rval(), + IsPromiseThenOrCatchRetValImplicitlyUsed(cx)); +} + +// ES2016, 25.4.5.3. +bool js::Promise_then(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + return Promise_then_impl(cx, args.thisv(), args.get(0), args.get(1), + args.rval(), true); +} + +// ES2016, 25.4.5.3.1. +static MOZ_MUST_USE bool PerformPromiseThen( + JSContext* cx, Handle<PromiseObject*> promise, HandleValue onFulfilled_, + HandleValue onRejected_, Handle<PromiseCapability> resultCapability) { + // Step 1 (implicit). + // Step 2 (implicit). + + // Step 3. + RootedValue onFulfilled(cx, onFulfilled_); + if (!IsCallable(onFulfilled)) { + onFulfilled = Int32Value(PromiseHandlerIdentity); + } + + // Step 4. + RootedValue onRejected(cx, onRejected_); + if (!IsCallable(onRejected)) { + onRejected = Int32Value(PromiseHandlerThrower); + } + + // Step 7. + Rooted<PromiseReactionRecord*> reaction( + cx, NewReactionRecord(cx, resultCapability, onFulfilled, onRejected, + IncumbentGlobalObject::Yes)); + if (!reaction) { + return false; + } + + return PerformPromiseThenWithReaction(cx, promise, reaction); +} + +static MOZ_MUST_USE bool PerformPromiseThenWithoutSettleHandlers( + JSContext* cx, Handle<PromiseObject*> promise, + Handle<PromiseObject*> promiseToResolve, + Handle<PromiseCapability> resultCapability) { + // Step 1 (implicit). + // Step 2 (implicit). + + // Step 3. + HandleValue onFulfilled = NullHandleValue; + + // Step 4. + HandleValue onRejected = NullHandleValue; + + // Step 7. + Rooted<PromiseReactionRecord*> reaction( + cx, NewReactionRecord(cx, resultCapability, onFulfilled, onRejected, + IncumbentGlobalObject::Yes)); + if (!reaction) { + return false; + } + + reaction->setIsDefaultResolvingHandler(promiseToResolve); + + return PerformPromiseThenWithReaction(cx, promise, reaction); +} + +// https://tc39.github.io/ecma262/#sec-performpromisethen +// 25.6.5.4.1 PerformPromiseThen steps 8-11. +static MOZ_MUST_USE bool PerformPromiseThenWithReaction( + JSContext* cx, Handle<PromiseObject*> unwrappedPromise, + Handle<PromiseReactionRecord*> reaction) { + // Step 8: If promise.[[PromiseState]] is "pending", then + JS::PromiseState state = unwrappedPromise->state(); + int32_t flags = unwrappedPromise->flags(); + if (state == JS::PromiseState::Pending) { + // Step 8.a: Append fulfillReaction as the last element of the List that is + // promise.[[PromiseFulfillReactions]]. + // Step 8.b: Append rejectReaction as the last element of the List that is + // promise.[[PromiseRejectReactions]]. + // + // Instead of creating separate reaction records for fulfillment and + // rejection, we create a combined record. All places we use the record + // can handle that. + if (!AddPromiseReaction(cx, unwrappedPromise, reaction)) { + return false; + } + } + + // Steps 9-10. In the spec, step 9 runs if the promise is fulfilled, step 10 + // if it is rejected. This implementation unifies the two paths. + else { + // Step 10.a. + MOZ_ASSERT_IF(state != JS::PromiseState::Fulfilled, + state == JS::PromiseState::Rejected); + + // Step 9.a: Let value be promise.[[PromiseResult]]. + // Step 10.b: Let reason be promise.[[PromiseResult]]. + RootedValue valueOrReason(cx, unwrappedPromise->valueOrReason()); + + // We might be operating on a promise from another compartment. In that + // case, we need to wrap the result/reason value before using it. + if (!cx->compartment()->wrap(cx, &valueOrReason)) { + return false; + } + + // Step 10.c: If promise.[[PromiseIsHandled]] is false, + // perform HostPromiseRejectionTracker(promise, "handle"). + if (state == JS::PromiseState::Rejected && + !(flags & PROMISE_FLAG_HANDLED)) { + cx->runtime()->removeUnhandledRejectedPromise(cx, unwrappedPromise); + } + + // Step 9.b: Perform EnqueueJob("PromiseJobs", PromiseReactionJob, + // « fulfillReaction, value »). + // Step 10.d: Perform EnqueueJob("PromiseJobs", PromiseReactionJob, + // « rejectReaction, reason »). + if (!EnqueuePromiseReactionJob(cx, reaction, valueOrReason, state)) { + return false; + } + } + + // Step 11: Set promise.[[PromiseIsHandled]] to true. + unwrappedPromise->setHandled(); + + return true; +} + +static MOZ_MUST_USE bool AddPromiseReaction( + JSContext* cx, Handle<PromiseObject*> unwrappedPromise, + Handle<PromiseReactionRecord*> reaction) { + MOZ_RELEASE_ASSERT(reaction->is<PromiseReactionRecord>()); + RootedValue reactionVal(cx, ObjectValue(*reaction)); + + // The code that creates Promise reactions can handle wrapped Promises, + // unwrapping them as needed. That means that the `promise` and `reaction` + // objects we have here aren't necessarily from the same compartment. In + // order to store the reaction on the promise, we have to ensure that it + // is properly wrapped. + mozilla::Maybe<AutoRealm> ar; + if (unwrappedPromise->compartment() != cx->compartment()) { + ar.emplace(cx, unwrappedPromise); + if (!cx->compartment()->wrap(cx, &reactionVal)) { + return false; + } + } + Handle<PromiseObject*> promise = unwrappedPromise; + + // 25.4.5.3.1 steps 7.a,b. + RootedValue reactionsVal(cx, promise->reactions()); + + if (reactionsVal.isUndefined()) { + // If no reactions existed so far, just store the reaction record directly. + promise->setFixedSlot(PromiseSlot_ReactionsOrResult, reactionVal); + return true; + } + + RootedObject reactionsObj(cx, &reactionsVal.toObject()); + + // If only a single reaction exists, it's stored directly instead of in a + // list. In that case, `reactionsObj` might be a wrapper, which we can + // always safely unwrap. + if (IsProxy(reactionsObj)) { + reactionsObj = UncheckedUnwrap(reactionsObj); + if (JS_IsDeadWrapper(reactionsObj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + MOZ_RELEASE_ASSERT(reactionsObj->is<PromiseReactionRecord>()); + } + + if (reactionsObj->is<PromiseReactionRecord>()) { + // If a single reaction existed so far, create a list and store the + // old and the new reaction in it. + ArrayObject* reactions = NewDenseFullyAllocatedArray(cx, 2); + if (!reactions) { + return false; + } + + reactions->setDenseInitializedLength(2); + reactions->initDenseElement(0, reactionsVal); + reactions->initDenseElement(1, reactionVal); + + promise->setFixedSlot(PromiseSlot_ReactionsOrResult, + ObjectValue(*reactions)); + } else { + // Otherwise, just store the new reaction. + MOZ_RELEASE_ASSERT(reactionsObj->is<NativeObject>()); + HandleNativeObject reactions = reactionsObj.as<NativeObject>(); + uint32_t len = reactions->getDenseInitializedLength(); + DenseElementResult result = reactions->ensureDenseElements(cx, len, 1); + if (result != DenseElementResult::Success) { + MOZ_ASSERT(result == DenseElementResult::Failure); + return false; + } + reactions->setDenseElement(len, reactionVal); + } + + return true; +} + +static MOZ_MUST_USE bool AddDummyPromiseReactionForDebugger( + JSContext* cx, Handle<PromiseObject*> promise, + HandleObject dependentPromise) { + if (promise->state() != JS::PromiseState::Pending) { + return true; + } + + // `dependentPromise` should be a maybe-wrapped Promise. + MOZ_ASSERT(UncheckedUnwrap(dependentPromise)->is<PromiseObject>()); + + // Leave resolve and reject as null. + Rooted<PromiseCapability> capability(cx); + capability.promise().set(dependentPromise); + + Rooted<PromiseReactionRecord*> reaction( + cx, NewReactionRecord(cx, capability, NullHandleValue, NullHandleValue, + IncumbentGlobalObject::No)); + if (!reaction) { + return false; + } + + reaction->setIsDebuggerDummy(); + + return AddPromiseReaction(cx, promise, reaction); +} + +uint64_t PromiseObject::getID() { return PromiseDebugInfo::id(this); } + +double PromiseObject::lifetime() { + return MillisecondsSinceStartup() - allocationTime(); +} + +/** + * Returns all promises that directly depend on this one. That means those + * created by calling `then` on this promise, or the promise returned by + * `Promise.all(iterable)` or `Promise.race(iterable)`, with this promise + * being a member of the passed-in `iterable`. + * + * Per spec, we should have separate lists of reaction records for the + * fulfill and reject cases. As an optimization, we have only one of those, + * containing the required data for both cases. So we just walk that list + * and extract the dependent promises from all reaction records. + */ +bool PromiseObject::dependentPromises(JSContext* cx, + MutableHandle<GCVector<Value>> values) { + if (state() != JS::PromiseState::Pending) { + return true; + } + + uint32_t valuesIndex = 0; + RootedValue reactionsVal(cx, reactions()); + + return ForEachReaction(cx, reactionsVal, [&](MutableHandleObject obj) { + if (IsProxy(obj)) { + obj.set(UncheckedUnwrap(obj)); + } + + if (JS_IsDeadWrapper(obj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + + MOZ_RELEASE_ASSERT(obj->is<PromiseReactionRecord>()); + Rooted<PromiseReactionRecord*> reaction(cx, + &obj->as<PromiseReactionRecord>()); + + // Not all reactions have a Promise on them. + RootedObject promiseObj(cx, reaction->promise()); + if (promiseObj) { + if (!values.growBy(1)) { + return false; + } + + values[valuesIndex++].setObject(*promiseObj); + } + return true; + }); +} + +bool PromiseObject::forEachReactionRecord( + JSContext* cx, PromiseReactionRecordBuilder& builder) { + if (state() != JS::PromiseState::Pending) { + // Promise was resolved, so no reaction records are present. + return true; + } + + RootedValue reactionsVal(cx, reactions()); + if (reactionsVal.isNullOrUndefined()) { + // No reaction records are attached to this promise. + return true; + } + + return ForEachReaction(cx, reactionsVal, [&](MutableHandleObject obj) { + if (IsProxy(obj)) { + obj.set(UncheckedUnwrap(obj)); + } + + if (JS_IsDeadWrapper(obj)) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_DEAD_OBJECT); + return false; + } + + Rooted<PromiseReactionRecord*> reaction(cx, + &obj->as<PromiseReactionRecord>()); + MOZ_ASSERT(reaction->targetState() == JS::PromiseState::Pending); + + if (reaction->isAsyncFunction()) { + Rooted<AsyncFunctionGeneratorObject*> generator( + cx, reaction->asyncFunctionGenerator()); + if (!builder.asyncFunction(cx, generator)) { + return false; + } + } else if (reaction->isAsyncGenerator()) { + Rooted<AsyncGeneratorObject*> generator(cx, reaction->asyncGenerator()); + if (!builder.asyncGenerator(cx, generator)) { + return false; + } + } else if (reaction->isDefaultResolvingHandler()) { + Rooted<PromiseObject*> promise(cx, reaction->defaultResolvingPromise()); + if (!builder.direct(cx, promise)) { + return false; + } + } else { + RootedObject resolve(cx); + RootedObject reject(cx); + RootedObject result(cx, reaction->promise()); + + Value v = reaction->getFixedSlot(ReactionRecordSlot_OnFulfilled); + if (v.isObject()) { + resolve = &v.toObject(); + } + + v = reaction->getFixedSlot(ReactionRecordSlot_OnRejected); + if (v.isObject()) { + reject = &v.toObject(); + } + + if (!builder.then(cx, resolve, reject, result)) { + return false; + } + } + + return true; + }); +} + +/* static */ +bool PromiseObject::resolve(JSContext* cx, Handle<PromiseObject*> promise, + HandleValue resolutionValue) { + MOZ_ASSERT(!PromiseHasAnyFlag(*promise, PROMISE_FLAG_ASYNC)); + if (promise->state() != JS::PromiseState::Pending) { + return true; + } + + if (PromiseHasAnyFlag(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)) { + return ResolvePromiseInternal(cx, promise, resolutionValue); + } + + JSFunction* resolveFun = GetResolveFunctionFromPromise(promise); + if (!resolveFun) { + return true; + } + + RootedValue funVal(cx, ObjectValue(*resolveFun)); + + // For xray'd Promises, the resolve fun may have been created in another + // compartment. For the call below to work in that case, wrap the + // function into the current compartment. + if (!cx->compartment()->wrap(cx, &funVal)) { + return false; + } + + RootedValue dummy(cx); + return Call(cx, funVal, UndefinedHandleValue, resolutionValue, &dummy); +} + +/* static */ +bool PromiseObject::reject(JSContext* cx, Handle<PromiseObject*> promise, + HandleValue rejectionValue) { + MOZ_ASSERT(!PromiseHasAnyFlag(*promise, PROMISE_FLAG_ASYNC)); + if (promise->state() != JS::PromiseState::Pending) { + return true; + } + + if (PromiseHasAnyFlag(*promise, PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS)) { + return ResolvePromise(cx, promise, rejectionValue, + JS::PromiseState::Rejected); + } + + RootedValue funVal(cx, promise->getFixedSlot(PromiseSlot_RejectFunction)); + MOZ_ASSERT(IsCallable(funVal)); + + RootedValue dummy(cx); + return Call(cx, funVal, UndefinedHandleValue, rejectionValue, &dummy); +} + +/* static */ +void PromiseObject::onSettled(JSContext* cx, Handle<PromiseObject*> promise, + HandleSavedFrame unwrappedRejectionStack) { + PromiseDebugInfo::setResolutionInfo(cx, promise, unwrappedRejectionStack); + + if (promise->state() == JS::PromiseState::Rejected && + promise->isUnhandled()) { + cx->runtime()->addUnhandledRejectedPromise(cx, promise); + } + + DebugAPI::onPromiseSettled(cx, promise); +} + +void PromiseObject::setRequiresUserInteractionHandling(bool state) { + if (state) { + AddPromiseFlags(*this, PROMISE_FLAG_REQUIRES_USER_INTERACTION_HANDLING); + } else { + RemovePromiseFlags(*this, PROMISE_FLAG_REQUIRES_USER_INTERACTION_HANDLING); + } +} + +void PromiseObject::setHadUserInteractionUponCreation(bool state) { + if (state) { + AddPromiseFlags(*this, PROMISE_FLAG_HAD_USER_INTERACTION_UPON_CREATION); + } else { + RemovePromiseFlags(*this, PROMISE_FLAG_HAD_USER_INTERACTION_UPON_CREATION); + } +} + +void PromiseObject::copyUserInteractionFlagsFrom(PromiseObject& rhs) { + setRequiresUserInteractionHandling(rhs.requiresUserInteractionHandling()); + setHadUserInteractionUponCreation(rhs.hadUserInteractionUponCreation()); +} + +// We can skip `await` with an already resolved value only if the current frame +// is the topmost JS frame and the current job is the last job in the job queue. +// This guarantees that any new job enqueued in the current turn will be +// executed immediately after the current job. +// +// Currently we only support skipping jobs when the async function is resumed +// at least once. +static MOZ_MUST_USE bool IsTopMostAsyncFunctionCall(JSContext* cx) { + FrameIter iter(cx); + + // The current frame should be the async function. + if (iter.done()) { + return false; + } + + if (!iter.isFunctionFrame() && iter.isModuleFrame()) { + // The iterator is not a function frame, it is a module frame. + // Ignore this optimization for now. + return true; + } + + MOZ_ASSERT(iter.calleeTemplate()->isAsync()); + +#ifdef DEBUG + bool isGenerator = iter.calleeTemplate()->isGenerator(); +#endif + + ++iter; + + // The parent frame should be the `next` function of the generator that is + // internally called in AsyncFunctionResume resp. AsyncGeneratorResume. + if (iter.done()) { + return false; + } + // The initial call into an async function can happen from top-level code, so + // the parent frame isn't required to be a function frame. Contrary to that, + // the parent frame for an async generator function is always a function + // frame, because async generators can't directly fall through to an `await` + // expression from their initial call. + if (!iter.isFunctionFrame()) { + MOZ_ASSERT(!isGenerator); + return false; + } + + // Always skip InterpretGeneratorResume if present. + JSFunction* fun = iter.calleeTemplate(); + if (IsSelfHostedFunctionWithName(fun, cx->names().InterpretGeneratorResume)) { + ++iter; + + if (iter.done()) { + return false; + } + + MOZ_ASSERT(iter.isFunctionFrame()); + fun = iter.calleeTemplate(); + } + + if (!IsSelfHostedFunctionWithName(fun, cx->names().AsyncFunctionNext) && + !IsSelfHostedFunctionWithName(fun, cx->names().AsyncGeneratorNext)) { + return false; + } + + ++iter; + + // There should be no more frames. + if (iter.done()) { + return true; + } + + return false; +} + +MOZ_MUST_USE bool js::CanSkipAwait(JSContext* cx, HandleValue val, + bool* canSkip) { + if (!cx->canSkipEnqueuingJobs) { + *canSkip = false; + return true; + } + + if (!IsTopMostAsyncFunctionCall(cx)) { + *canSkip = false; + return true; + } + + // Primitive values cannot be 'thenables', so we can trivially skip the + // await operation. + if (!val.isObject()) { + *canSkip = true; + return true; + } + + JSObject* obj = &val.toObject(); + if (!obj->is<PromiseObject>()) { + *canSkip = false; + return true; + } + + PromiseObject* promise = &obj->as<PromiseObject>(); + + if (promise->state() == JS::PromiseState::Pending) { + *canSkip = false; + return true; + } + + PromiseLookup& promiseLookup = cx->realm()->promiseLookup; + if (!promiseLookup.isDefaultInstance(cx, promise)) { + *canSkip = false; + return true; + } + + if (promise->state() == JS::PromiseState::Rejected) { + // We don't optimize rejected Promises for now. + *canSkip = false; + return true; + } + + *canSkip = true; + return true; +} + +MOZ_MUST_USE bool js::ExtractAwaitValue(JSContext* cx, HandleValue val, + MutableHandleValue resolved) { +// Ensure all callers of this are jumping past the +// extract if it's not possible to extract. +#ifdef DEBUG + bool canSkip; + if (!CanSkipAwait(cx, val, &canSkip)) { + return false; + } + MOZ_ASSERT(canSkip == true); +#endif + + // Primitive values cannot be 'thenables', so we can trivially skip the + // await operation. + if (!val.isObject()) { + resolved.set(val); + return true; + } + + JSObject* obj = &val.toObject(); + PromiseObject* promise = &obj->as<PromiseObject>(); + resolved.set(promise->value()); + + return true; +} + +JS::AutoDebuggerJobQueueInterruption::AutoDebuggerJobQueueInterruption() + : cx(nullptr) {} + +JS::AutoDebuggerJobQueueInterruption::~AutoDebuggerJobQueueInterruption() { + MOZ_ASSERT_IF(initialized(), cx->jobQueue->empty()); +} + +bool JS::AutoDebuggerJobQueueInterruption::init(JSContext* cx) { + MOZ_ASSERT(cx->jobQueue); + this->cx = cx; + saved = cx->jobQueue->saveJobQueue(cx); + return !!saved; +} + +void JS::AutoDebuggerJobQueueInterruption::runJobs() { + JS::AutoSaveExceptionState ases(cx); + cx->jobQueue->runJobs(cx); +} + +const JSJitInfo promise_then_info = { + {(JSJitGetterOp)Promise_then_noRetVal}, + {0}, /* unused */ + {0}, /* unused */ + JSJitInfo::IgnoresReturnValueNative, + JSJitInfo::AliasEverything, + JSVAL_TYPE_UNDEFINED, +}; + +const JSJitInfo promise_catch_info = { + {(JSJitGetterOp)Promise_catch_noRetVal}, + {0}, /* unused */ + {0}, /* unused */ + JSJitInfo::IgnoresReturnValueNative, + JSJitInfo::AliasEverything, + JSVAL_TYPE_UNDEFINED, +}; + +static const JSFunctionSpec promise_methods[] = { + JS_FNINFO("then", js::Promise_then, &promise_then_info, 2, 0), + JS_FNINFO("catch", Promise_catch, &promise_catch_info, 1, 0), + JS_SELF_HOSTED_FN("finally", "Promise_finally", 1, 0), JS_FS_END}; + +static const JSPropertySpec promise_properties[] = { + JS_STRING_SYM_PS(toStringTag, "Promise", JSPROP_READONLY), JS_PS_END}; + +static const JSFunctionSpec promise_static_methods[] = { + JS_FN("all", Promise_static_all, 1, 0), + JS_FN("allSettled", Promise_static_allSettled, 1, 0), + JS_FN("any", Promise_static_any, 1, 0), + JS_FN("race", Promise_static_race, 1, 0), + JS_FN("reject", Promise_reject, 1, 0), + JS_FN("resolve", js::Promise_static_resolve, 1, 0), + JS_FS_END}; + +static const JSPropertySpec promise_static_properties[] = { + JS_SYM_GET(species, js::Promise_static_species, 0), JS_PS_END}; + +static const ClassSpec PromiseObjectClassSpec = { + GenericCreateConstructor<PromiseConstructor, 1, gc::AllocKind::FUNCTION>, + GenericCreatePrototype<PromiseObject>, + promise_static_methods, + promise_static_properties, + promise_methods, + promise_properties}; + +const JSClass PromiseObject::class_ = { + "Promise", + JSCLASS_HAS_RESERVED_SLOTS(RESERVED_SLOTS) | + JSCLASS_HAS_CACHED_PROTO(JSProto_Promise) | + JSCLASS_HAS_XRAYED_CONSTRUCTOR, + JS_NULL_CLASS_OPS, &PromiseObjectClassSpec}; + +const JSClass PromiseObject::protoClass_ = { + "Promise.prototype", JSCLASS_HAS_CACHED_PROTO(JSProto_Promise), + JS_NULL_CLASS_OPS, &PromiseObjectClassSpec}; |