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Diffstat (limited to 'js/src/vm/Iteration.cpp')
| -rw-r--r-- | js/src/vm/Iteration.cpp | 1790 |
1 files changed, 1790 insertions, 0 deletions
diff --git a/js/src/vm/Iteration.cpp b/js/src/vm/Iteration.cpp new file mode 100644 index 0000000000..07386b1ca8 --- /dev/null +++ b/js/src/vm/Iteration.cpp @@ -0,0 +1,1790 @@ +/* -*- 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/. */ + +/* JavaScript iterators. */ + +#include "vm/Iteration.h" + +#include "mozilla/ArrayUtils.h" +#include "mozilla/DebugOnly.h" +#include "mozilla/Likely.h" +#include "mozilla/Maybe.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/PodOperations.h" +#include "mozilla/Unused.h" + +#include <algorithm> +#include <new> + +#include "jstypes.h" + +#include "builtin/Array.h" +#include "builtin/SelfHostingDefines.h" +#include "ds/Sort.h" +#include "gc/FreeOp.h" +#include "gc/Marking.h" +#include "js/friend/ErrorMessages.h" // js::GetErrorMessage, JSMSG_* +#include "js/PropertySpec.h" +#include "js/Proxy.h" +#include "util/DifferentialTesting.h" +#include "util/Poison.h" +#include "vm/BytecodeUtil.h" +#include "vm/GlobalObject.h" +#include "vm/Interpreter.h" +#include "vm/JSAtom.h" +#include "vm/JSContext.h" +#include "vm/JSObject.h" +#include "vm/JSScript.h" +#include "vm/NativeObject.h" // js::PlainObject +#include "vm/Shape.h" +#include "vm/TypedArrayObject.h" + +#include "vm/Compartment-inl.h" +#include "vm/JSScript-inl.h" +#include "vm/NativeObject-inl.h" +#include "vm/PlainObject-inl.h" // js::PlainObject::createWithTemplate +#include "vm/ReceiverGuard-inl.h" +#include "vm/Stack-inl.h" +#include "vm/StringType-inl.h" + +using namespace js; + +using mozilla::ArrayEqual; +using mozilla::DebugOnly; +using mozilla::Maybe; +using mozilla::PodCopy; + +using RootedPropertyIteratorObject = Rooted<PropertyIteratorObject*>; + +static const gc::AllocKind ITERATOR_FINALIZE_KIND = + gc::AllocKind::OBJECT2_BACKGROUND; + +// Beware! This function may have to trace incompletely-initialized +// |NativeIterator| allocations if the |IdToString| in that constructor recurs +// into this code. +void NativeIterator::trace(JSTracer* trc) { + TraceNullableEdge(trc, &objectBeingIterated_, "objectBeingIterated_"); + TraceNullableEdge(trc, &iterObj_, "iterObj"); + + // The limits below are correct at every instant of |NativeIterator| + // initialization, with the end-pointer incremented as each new guard is + // created, so they're safe to use here. + std::for_each(guardsBegin(), guardsEnd(), + [trc](HeapReceiverGuard& guard) { guard.trace(trc); }); + + // But as properties must be created *before* guards, |propertiesBegin()| + // that depends on |guardsEnd()| having its final value can't safely be + // used. Until this is fully initialized, use |propertyCursor_| instead, + // which points at the start of properties even in partially initialized + // |NativeIterator|s. (|propertiesEnd()| is safe at all times with respect + // to the properly-chosen beginning.) + // + // Note that we must trace all properties (not just those not yet visited, + // or just visited, due to |NativeIterator::previousPropertyWas|) for + // |NativeIterator|s to be reusable. + GCPtrLinearString* begin = + MOZ_LIKELY(isInitialized()) ? propertiesBegin() : propertyCursor_; + std::for_each(begin, propertiesEnd(), [trc](GCPtrLinearString& prop) { + // Properties begin life non-null and never *become* + // null. (Deletion-suppression will shift trailing + // properties over a deleted property in the properties + // array, but it doesn't null them out.) + TraceEdge(trc, &prop, "prop"); + }); +} + +using IdSet = GCHashSet<jsid, DefaultHasher<jsid>>; + +template <bool CheckForDuplicates> +static inline bool Enumerate(JSContext* cx, HandleObject pobj, jsid id, + bool enumerable, unsigned flags, + MutableHandle<IdSet> visited, + MutableHandleIdVector props) { + if (CheckForDuplicates) { + // If we've already seen this, we definitely won't add it. + IdSet::AddPtr p = visited.lookupForAdd(id); + if (MOZ_UNLIKELY(!!p)) { + return true; + } + + // It's not necessary to add properties to the hash set at the end of + // the prototype chain, but custom enumeration behaviors might return + // duplicated properties, so always add in such cases. + if (pobj->is<ProxyObject>() || pobj->staticPrototype() || + pobj->getClass()->getNewEnumerate()) { + if (!visited.add(p, id)) { + return false; + } + } + } + + if (!enumerable && !(flags & JSITER_HIDDEN)) { + return true; + } + + // Symbol-keyed properties and nonenumerable properties are skipped unless + // the caller specifically asks for them. A caller can also filter out + // non-symbols by asking for JSITER_SYMBOLSONLY. PrivateName symbols are + // skipped unless JSITER_PRIVATE is passed. + if (JSID_IS_SYMBOL(id)) { + if (!(flags & JSITER_SYMBOLS)) { + return true; + } + if (!(flags & JSITER_PRIVATE) && id.isPrivateName()) { + return true; + } + } else { + if ((flags & JSITER_SYMBOLSONLY)) { + return true; + } + } + + return props.append(id); +} + +static bool EnumerateExtraProperties(JSContext* cx, HandleObject obj, + unsigned flags, + MutableHandle<IdSet> visited, + MutableHandleIdVector props) { + MOZ_ASSERT(obj->getClass()->getNewEnumerate()); + + RootedIdVector properties(cx); + bool enumerableOnly = !(flags & JSITER_HIDDEN); + if (!obj->getClass()->getNewEnumerate()(cx, obj, &properties, + enumerableOnly)) { + return false; + } + + RootedId id(cx); + for (size_t n = 0; n < properties.length(); n++) { + id = properties[n]; + + // The enumerate hook does not indicate whether the properties + // it returns are enumerable or not. Since we already passed + // `enumerableOnly` to the hook to filter out non-enumerable + // properties, it doesn't really matter what we pass here. + bool enumerable = true; + if (!Enumerate<true>(cx, obj, id, enumerable, flags, visited, props)) { + return false; + } + } + + return true; +} + +static bool SortComparatorIntegerIds(jsid a, jsid b, bool* lessOrEqualp) { + uint32_t indexA, indexB; + MOZ_ALWAYS_TRUE(IdIsIndex(a, &indexA)); + MOZ_ALWAYS_TRUE(IdIsIndex(b, &indexB)); + *lessOrEqualp = (indexA <= indexB); + return true; +} + +template <bool CheckForDuplicates> +static bool EnumerateNativeProperties(JSContext* cx, HandleNativeObject pobj, + unsigned flags, + MutableHandle<IdSet> visited, + MutableHandleIdVector props) { + bool enumerateSymbols; + if (flags & JSITER_SYMBOLSONLY) { + enumerateSymbols = true; + } else { + // Collect any dense elements from this object. + size_t firstElemIndex = props.length(); + size_t initlen = pobj->getDenseInitializedLength(); + const Value* vp = pobj->getDenseElements(); + bool hasHoles = false; + for (size_t i = 0; i < initlen; ++i, ++vp) { + if (vp->isMagic(JS_ELEMENTS_HOLE)) { + hasHoles = true; + } else { + // Dense arrays never get so large that i would not fit into an + // integer id. + if (!Enumerate<CheckForDuplicates>(cx, pobj, INT_TO_JSID(i), + /* enumerable = */ true, flags, + visited, props)) { + return false; + } + } + } + + // Collect any typed array or shared typed array elements from this + // object. + if (pobj->is<TypedArrayObject>()) { + size_t len = pobj->as<TypedArrayObject>().length().get(); + + // Fail early if the typed array is enormous, because this will be very + // slow and will likely report OOM. This also means we don't need to + // handle indices greater than JSID_INT_MAX in the loop below. + static_assert(JSID_INT_MAX == INT32_MAX); + if (len > INT32_MAX) { + ReportOutOfMemory(cx); + return false; + } + + for (size_t i = 0; i < len; i++) { + if (!Enumerate<CheckForDuplicates>(cx, pobj, INT_TO_JSID(i), + /* enumerable = */ true, flags, + visited, props)) { + return false; + } + } + } + + // Collect any sparse elements from this object. + bool isIndexed = pobj->isIndexed(); + if (isIndexed) { + // If the dense elements didn't have holes, we don't need to include + // them in the sort. + if (!hasHoles) { + firstElemIndex = props.length(); + } + + for (Shape::Range<NoGC> r(pobj->lastProperty()); !r.empty(); + r.popFront()) { + Shape& shape = r.front(); + jsid id = shape.propid(); + uint32_t dummy; + if (IdIsIndex(id, &dummy)) { + if (!Enumerate<CheckForDuplicates>(cx, pobj, id, shape.enumerable(), + flags, visited, props)) { + return false; + } + } + } + + MOZ_ASSERT(firstElemIndex <= props.length()); + + jsid* ids = props.begin() + firstElemIndex; + size_t n = props.length() - firstElemIndex; + + RootedIdVector tmp(cx); + if (!tmp.resize(n)) { + return false; + } + PodCopy(tmp.begin(), ids, n); + + if (!MergeSort(ids, n, tmp.begin(), SortComparatorIntegerIds)) { + return false; + } + } + + size_t initialLength = props.length(); + + /* Collect all unique property names from this object's shape. */ + bool symbolsFound = false; + Shape::Range<NoGC> r(pobj->lastProperty()); + for (; !r.empty(); r.popFront()) { + Shape& shape = r.front(); + jsid id = shape.propid(); + + if (JSID_IS_SYMBOL(id)) { + symbolsFound = true; + continue; + } + + uint32_t dummy; + if (isIndexed && IdIsIndex(id, &dummy)) { + continue; + } + + if (!Enumerate<CheckForDuplicates>(cx, pobj, id, shape.enumerable(), + flags, visited, props)) { + return false; + } + } + std::reverse(props.begin() + initialLength, props.end()); + + enumerateSymbols = symbolsFound && (flags & JSITER_SYMBOLS); + } + + if (enumerateSymbols) { + // Do a second pass to collect symbols. ES6 draft rev 25 (2014 May 22) + // 9.1.12 requires that all symbols appear after all strings in the + // result. + size_t initialLength = props.length(); + for (Shape::Range<NoGC> r(pobj->lastProperty()); !r.empty(); r.popFront()) { + Shape& shape = r.front(); + jsid id = shape.propid(); + if (JSID_IS_SYMBOL(id)) { + if (!Enumerate<CheckForDuplicates>(cx, pobj, id, shape.enumerable(), + flags, visited, props)) { + return false; + } + } + } + std::reverse(props.begin() + initialLength, props.end()); + } + + return true; +} + +static bool EnumerateNativeProperties(JSContext* cx, HandleNativeObject pobj, + unsigned flags, + MutableHandle<IdSet> visited, + MutableHandleIdVector props, + bool checkForDuplicates) { + if (checkForDuplicates) { + return EnumerateNativeProperties<true>(cx, pobj, flags, visited, props); + } + return EnumerateNativeProperties<false>(cx, pobj, flags, visited, props); +} + +template <bool CheckForDuplicates> +static bool EnumerateProxyProperties(JSContext* cx, HandleObject pobj, + unsigned flags, + MutableHandle<IdSet> visited, + MutableHandleIdVector props) { + MOZ_ASSERT(pobj->is<ProxyObject>()); + + RootedIdVector proxyProps(cx); + + if (flags & JSITER_HIDDEN || flags & JSITER_SYMBOLS) { + // This gets all property keys, both strings and symbols. The call to + // Enumerate in the loop below will filter out unwanted keys, per the + // flags. + if (!Proxy::ownPropertyKeys(cx, pobj, &proxyProps)) { + return false; + } + + Rooted<PropertyDescriptor> desc(cx); + for (size_t n = 0, len = proxyProps.length(); n < len; n++) { + bool enumerable = false; + + // We need to filter, if the caller just wants enumerable symbols. + if (!(flags & JSITER_HIDDEN)) { + if (!Proxy::getOwnPropertyDescriptor(cx, pobj, proxyProps[n], &desc)) { + return false; + } + enumerable = desc.enumerable(); + } + + if (!Enumerate<CheckForDuplicates>(cx, pobj, proxyProps[n], enumerable, + flags, visited, props)) { + return false; + } + } + + return true; + } + + // Returns enumerable property names (no symbols). + if (!Proxy::getOwnEnumerablePropertyKeys(cx, pobj, &proxyProps)) { + return false; + } + + for (size_t n = 0, len = proxyProps.length(); n < len; n++) { + if (!Enumerate<CheckForDuplicates>(cx, pobj, proxyProps[n], true, flags, + visited, props)) { + return false; + } + } + + return true; +} + +#ifdef DEBUG + +struct SortComparatorIds { + JSContext* const cx; + + explicit SortComparatorIds(JSContext* cx) : cx(cx) {} + + bool operator()(jsid aArg, jsid bArg, bool* lessOrEqualp) { + RootedId a(cx, aArg); + RootedId b(cx, bArg); + + // Pick an arbitrary order on jsids that is as stable as possible + // across executions. + if (a == b) { + *lessOrEqualp = true; + return true; + } + + size_t ta = JSID_BITS(a.get()) & JSID_TYPE_MASK; + size_t tb = JSID_BITS(b.get()) & JSID_TYPE_MASK; + if (ta != tb) { + *lessOrEqualp = (ta <= tb); + return true; + } + + if (JSID_IS_INT(a)) { + *lessOrEqualp = (JSID_TO_INT(a) <= JSID_TO_INT(b)); + return true; + } + + RootedString astr(cx), bstr(cx); + if (JSID_IS_SYMBOL(a)) { + MOZ_ASSERT(JSID_IS_SYMBOL(b)); + JS::SymbolCode ca = JSID_TO_SYMBOL(a)->code(); + JS::SymbolCode cb = JSID_TO_SYMBOL(b)->code(); + if (ca != cb) { + *lessOrEqualp = uint32_t(ca) <= uint32_t(cb); + return true; + } + MOZ_ASSERT(ca == JS::SymbolCode::InSymbolRegistry || + ca == JS::SymbolCode::UniqueSymbol); + astr = JSID_TO_SYMBOL(a)->description(); + bstr = JSID_TO_SYMBOL(b)->description(); + if (!astr || !bstr) { + *lessOrEqualp = !astr; + return true; + } + + // Fall through to string comparison on the descriptions. The sort + // order is nondeterministic if two different unique symbols have + // the same description. + } else { + astr = IdToString(cx, a); + if (!astr) { + return false; + } + bstr = IdToString(cx, b); + if (!bstr) { + return false; + } + } + + int32_t result; + if (!CompareStrings(cx, astr, bstr, &result)) { + return false; + } + + *lessOrEqualp = (result <= 0); + return true; + } +}; + +#endif /* DEBUG */ + +static bool Snapshot(JSContext* cx, HandleObject pobj_, unsigned flags, + MutableHandleIdVector props) { + Rooted<IdSet> visited(cx, IdSet(cx)); + RootedObject pobj(cx, pobj_); + + // Don't check for duplicates if we're only interested in own properties. + // This does the right thing for most objects: native objects don't have + // duplicate property ids and we allow the [[OwnPropertyKeys]] proxy trap to + // return duplicates. + // + // The only special case is when the object has a newEnumerate hook: it + // can return duplicate properties and we have to filter them. This is + // handled below. + bool checkForDuplicates = !(flags & JSITER_OWNONLY); + + do { + if (pobj->getClass()->getNewEnumerate()) { + if (!EnumerateExtraProperties(cx, pobj, flags, &visited, props)) { + return false; + } + + if (pobj->isNative()) { + if (!EnumerateNativeProperties(cx, pobj.as<NativeObject>(), flags, + &visited, props, true)) { + return false; + } + } + + } else if (pobj->isNative()) { + // Give the object a chance to resolve all lazy properties + if (JSEnumerateOp enumerate = pobj->getClass()->getEnumerate()) { + if (!enumerate(cx, pobj.as<NativeObject>())) { + return false; + } + } + if (!EnumerateNativeProperties(cx, pobj.as<NativeObject>(), flags, + &visited, props, checkForDuplicates)) { + return false; + } + } else if (pobj->is<ProxyObject>()) { + if (checkForDuplicates) { + if (!EnumerateProxyProperties<true>(cx, pobj, flags, &visited, props)) { + return false; + } + } else { + if (!EnumerateProxyProperties<false>(cx, pobj, flags, &visited, + props)) { + return false; + } + } + } else { + MOZ_CRASH("non-native objects must have an enumerate op"); + } + + if (flags & JSITER_OWNONLY) { + break; + } + + if (!GetPrototype(cx, pobj, &pobj)) { + return false; + } + + // The [[Prototype]] chain might be cyclic. + if (!CheckForInterrupt(cx)) { + return false; + } + } while (pobj != nullptr); + +#ifdef DEBUG + if (js::SupportDifferentialTesting()) { + /* + * In some cases the enumeration order for an object depends on the + * execution mode (interpreter vs. JIT), especially for native objects + * with a class enumerate hook (where resolving a property changes the + * resulting enumeration order). These aren't really bugs, but the + * differences can change the generated output and confuse correctness + * fuzzers, so we sort the ids if such a fuzzer is running. + * + * We don't do this in the general case because (a) doing so is slow, + * and (b) it also breaks the web, which expects enumeration order to + * follow the order in which properties are added, in certain cases. + * Since ECMA does not specify an enumeration order for objects, both + * behaviors are technically correct to do. + */ + + jsid* ids = props.begin(); + size_t n = props.length(); + + RootedIdVector tmp(cx); + if (!tmp.resize(n)) { + return false; + } + PodCopy(tmp.begin(), ids, n); + + if (!MergeSort(ids, n, tmp.begin(), SortComparatorIds(cx))) { + return false; + } + } +#endif + + return true; +} + +JS_FRIEND_API bool js::GetPropertyKeys(JSContext* cx, HandleObject obj, + unsigned flags, + MutableHandleIdVector props) { + return Snapshot(cx, obj, + flags & (JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS | + JSITER_SYMBOLSONLY | JSITER_PRIVATE), + props); +} + +static inline void RegisterEnumerator(ObjectRealm& realm, NativeIterator* ni) { + // Register non-escaping native enumerators (for-in) with the current + // context. + ni->link(realm.enumerators); + + MOZ_ASSERT(!ni->isActive()); + ni->markActive(); +} + +static PropertyIteratorObject* NewPropertyIteratorObject(JSContext* cx) { + RootedObjectGroup group( + cx, ObjectGroup::defaultNewGroup(cx, &PropertyIteratorObject::class_, + TaggedProto(nullptr))); + if (!group) { + return nullptr; + } + + const JSClass* clasp = &PropertyIteratorObject::class_; + RootedShape shape(cx, + EmptyShape::getInitialShape(cx, clasp, TaggedProto(nullptr), + ITERATOR_FINALIZE_KIND)); + if (!shape) { + return nullptr; + } + + JSObject* obj; + JS_TRY_VAR_OR_RETURN_NULL( + cx, obj, + NativeObject::create(cx, ITERATOR_FINALIZE_KIND, + GetInitialHeap(GenericObject, group), shape, group)); + + PropertyIteratorObject* res = &obj->as<PropertyIteratorObject>(); + + // CodeGenerator::visitIteratorStartO assumes the iterator object is not + // inside the nursery when deciding whether a barrier is necessary. + MOZ_ASSERT(!js::gc::IsInsideNursery(res)); + + MOZ_ASSERT(res->numFixedSlots() == PropertyIteratorObject::NUM_FIXED_SLOTS); + return res; +} + +static inline size_t ExtraStringCount(size_t propertyCount, size_t guardCount) { + static_assert(sizeof(ReceiverGuard) == 2 * sizeof(GCPtrLinearString), + "NativeIterators are allocated in space for 1) themselves, " + "2) the properties a NativeIterator iterates (as " + "GCPtrLinearStrings), and 3) |numGuards| HeapReceiverGuard " + "objects; the additional-length calculation below assumes " + "this size-relationship when determining the extra space to " + "allocate"); + + return propertyCount + guardCount * 2; +} + +static inline size_t AllocationSize(size_t propertyCount, size_t guardCount) { + return sizeof(NativeIterator) + (ExtraStringCount(propertyCount, guardCount) * + sizeof(GCPtrLinearString)); +} + +static PropertyIteratorObject* CreatePropertyIterator( + JSContext* cx, Handle<JSObject*> objBeingIterated, HandleIdVector props, + uint32_t numGuards, uint32_t guardKey) { + if (props.length() > NativeIterator::PropCountLimit) { + ReportAllocationOverflow(cx); + return nullptr; + } + + Rooted<PropertyIteratorObject*> propIter(cx, NewPropertyIteratorObject(cx)); + if (!propIter) { + return nullptr; + } + + void* mem = cx->pod_malloc_with_extra<NativeIterator, GCPtrLinearString>( + ExtraStringCount(props.length(), numGuards)); + if (!mem) { + return nullptr; + } + + // This also registers |ni| with |propIter|. + bool hadError = false; + NativeIterator* ni = new (mem) NativeIterator( + cx, propIter, objBeingIterated, props, numGuards, guardKey, &hadError); + if (hadError) { + return nullptr; + } + + ObjectRealm& realm = objBeingIterated ? ObjectRealm::get(objBeingIterated) + : ObjectRealm::get(propIter); + RegisterEnumerator(realm, ni); + + return propIter; +} + +/** + * Initialize a sentinel NativeIterator whose purpose is only to act as the + * start/end of the circular linked list of NativeIterators in + * ObjectRealm::enumerators. + */ +NativeIterator::NativeIterator() { + // Do our best to enforce that nothing in |this| except the two fields set + // below is ever observed. + AlwaysPoison(static_cast<void*>(this), JS_NEW_NATIVE_ITERATOR_PATTERN, + sizeof(*this), MemCheckKind::MakeUndefined); + + // These are the only two fields in sentinel NativeIterators that are + // examined, in ObjectRealm::traceWeakNativeIterators. Everything else is + // only examined *if* it's a NativeIterator being traced by a + // PropertyIteratorObject that owns it, and nothing owns this iterator. + prev_ = next_ = this; +} + +NativeIterator* NativeIterator::allocateSentinel(JSContext* cx) { + NativeIterator* ni = js_new<NativeIterator>(); + if (!ni) { + ReportOutOfMemory(cx); + return nullptr; + } + + return ni; +} + +/** + * Initialize a fresh NativeIterator. + * + * This definition is a bit tricky: some parts of initializing are fallible, so + * as we initialize, we must carefully keep this in GC-safe state (see + * NativeIterator::trace). + */ +NativeIterator::NativeIterator(JSContext* cx, + Handle<PropertyIteratorObject*> propIter, + Handle<JSObject*> objBeingIterated, + HandleIdVector props, uint32_t numGuards, + uint32_t guardKey, bool* hadError) + : objectBeingIterated_(objBeingIterated), + iterObj_(propIter), + // NativeIterator initially acts (before full initialization) as if it + // contains no guards... + guardsEnd_(guardsBegin()), + // ...and no properties. + propertyCursor_( + reinterpret_cast<GCPtrLinearString*>(guardsBegin() + numGuards)), + propertiesEnd_(propertyCursor_), + guardKey_(guardKey), + flagsAndCount_( + initialFlagsAndCount(props.length())) // note: no Flags::Initialized +{ + MOZ_ASSERT(!*hadError); + + // NOTE: This must be done first thing: The caller can't free `this` on error + // because it has GCPtr fields whose barriers have already fired; the + // store buffer has pointers to them. Only the GC can free `this` (via + // PropertyIteratorObject::finalize). + propIter->setNativeIterator(this); + + // The GC asserts on finalization that `this->allocationSize()` matches the + // `nbytes` passed to `AddCellMemory`. So once these lines run, we must make + // `this->allocationSize()` correct. That means infallibly initializing the + // guards. It's OK for the constructor to fail after that. + size_t nbytes = AllocationSize(props.length(), numGuards); + AddCellMemory(propIter, nbytes, MemoryUse::NativeIterator); + + if (numGuards > 0) { + // Construct guards into the guard array. Also recompute the guard key, + // which incorporates Shape* and ObjectGroup* addresses that could have + // changed during a GC triggered in (among other places) |IdToString| + // above. + JSObject* pobj = objBeingIterated; +#ifdef DEBUG + uint32_t i = 0; +#endif + uint32_t key = 0; + do { + ReceiverGuard guard(pobj); + new (guardsEnd_) HeapReceiverGuard(guard); + guardsEnd_++; +#ifdef DEBUG + i++; +#endif + + key = mozilla::AddToHash(key, guard.hash()); + + // The one caller of this method that passes |numGuards > 0|, does + // so only if the entire chain consists of cacheable objects (that + // necessarily have static prototypes). + pobj = pobj->staticPrototype(); + } while (pobj); + + guardKey_ = key; + MOZ_ASSERT(i == numGuards); + } + MOZ_ASSERT(static_cast<void*>(guardsEnd_) == propertyCursor_); + + for (size_t i = 0, len = props.length(); i < len; i++) { + JSLinearString* str = IdToString(cx, props[i]); + if (!str) { + *hadError = true; + return; + } + new (propertiesEnd_) GCPtrLinearString(str); + propertiesEnd_++; + } + + markInitialized(); + + MOZ_ASSERT(!*hadError); +} + +inline size_t NativeIterator::allocationSize() const { + size_t numGuards = guardsEnd() - guardsBegin(); + return AllocationSize(initialPropertyCount(), numGuards); +} + +/* static */ +bool IteratorHashPolicy::match(PropertyIteratorObject* obj, + const Lookup& lookup) { + NativeIterator* ni = obj->getNativeIterator(); + if (ni->guardKey() != lookup.key || ni->guardCount() != lookup.numGuards) { + return false; + } + + return ArrayEqual(reinterpret_cast<ReceiverGuard*>(ni->guardsBegin()), + lookup.guards, ni->guardCount()); +} + +static inline bool CanCompareIterableObjectToCache(JSObject* obj) { + if (obj->isNative()) { + return obj->as<NativeObject>().getDenseInitializedLength() == 0; + } + return false; +} + +using ReceiverGuardVector = Vector<ReceiverGuard, 8>; + +static MOZ_ALWAYS_INLINE PropertyIteratorObject* LookupInIteratorCache( + JSContext* cx, JSObject* obj, uint32_t* numGuards) { + MOZ_ASSERT(*numGuards == 0); + + ReceiverGuardVector guards(cx); + uint32_t key = 0; + JSObject* pobj = obj; + do { + if (!CanCompareIterableObjectToCache(pobj)) { + return nullptr; + } + + ReceiverGuard guard(pobj); + key = mozilla::AddToHash(key, guard.hash()); + + if (MOZ_UNLIKELY(!guards.append(guard))) { + cx->recoverFromOutOfMemory(); + return nullptr; + } + + pobj = pobj->staticPrototype(); + } while (pobj); + + MOZ_ASSERT(!guards.empty()); + *numGuards = guards.length(); + + IteratorHashPolicy::Lookup lookup(guards.begin(), guards.length(), key); + auto p = ObjectRealm::get(obj).iteratorCache.lookup(lookup); + if (!p) { + return nullptr; + } + + PropertyIteratorObject* iterobj = *p; + MOZ_ASSERT(iterobj->compartment() == cx->compartment()); + + NativeIterator* ni = iterobj->getNativeIterator(); + if (!ni->isReusable()) { + return nullptr; + } + + return iterobj; +} + +static bool CanStoreInIteratorCache(JSObject* obj) { + do { + MOZ_ASSERT(obj->isNative()); + + MOZ_ASSERT(obj->as<NativeObject>().getDenseInitializedLength() == 0); + + // Typed arrays have indexed properties not captured by the Shape guard. + // Enumerate hooks may add extra properties. + const JSClass* clasp = obj->getClass(); + if (MOZ_UNLIKELY(IsTypedArrayClass(clasp))) { + return false; + } + if (MOZ_UNLIKELY(clasp->getNewEnumerate() || clasp->getEnumerate())) { + return false; + } + + obj = obj->staticPrototype(); + } while (obj); + + return true; +} + +static MOZ_MUST_USE bool StoreInIteratorCache(JSContext* cx, JSObject* obj, + PropertyIteratorObject* iterobj) { + MOZ_ASSERT(CanStoreInIteratorCache(obj)); + + NativeIterator* ni = iterobj->getNativeIterator(); + MOZ_ASSERT(ni->guardCount() > 0); + + IteratorHashPolicy::Lookup lookup( + reinterpret_cast<ReceiverGuard*>(ni->guardsBegin()), ni->guardCount(), + ni->guardKey()); + + ObjectRealm::IteratorCache& cache = ObjectRealm::get(obj).iteratorCache; + bool ok; + auto p = cache.lookupForAdd(lookup); + if (MOZ_LIKELY(!p)) { + ok = cache.add(p, iterobj); + } else { + // If we weren't able to use an existing cached iterator, just + // replace it. + cache.remove(p); + ok = cache.relookupOrAdd(p, lookup, iterobj); + } + if (!ok) { + ReportOutOfMemory(cx); + return false; + } + + return true; +} + +bool js::EnumerateProperties(JSContext* cx, HandleObject obj, + MutableHandleIdVector props) { + MOZ_ASSERT(props.empty()); + + if (MOZ_UNLIKELY(obj->is<ProxyObject>())) { + return Proxy::enumerate(cx, obj, props); + } + + return Snapshot(cx, obj, 0, props); +} + +#ifdef DEBUG +static bool PrototypeMayHaveIndexedProperties(NativeObject* nobj) { + JSObject* proto = nobj->staticPrototype(); + if (!proto) { + return false; + } + + if (proto->is<NativeObject>() && + proto->as<NativeObject>().getDenseInitializedLength() > 0) { + return true; + } + + return ObjectMayHaveExtraIndexedProperties(proto); +} +#endif + +static JSObject* GetIterator(JSContext* cx, HandleObject obj) { + MOZ_ASSERT(!obj->is<PropertyIteratorObject>()); + MOZ_ASSERT(cx->compartment() == obj->compartment(), + "We may end up allocating shapes in the wrong zone!"); + + uint32_t numGuards = 0; + if (PropertyIteratorObject* iterobj = + LookupInIteratorCache(cx, obj, &numGuards)) { + NativeIterator* ni = iterobj->getNativeIterator(); + ni->changeObjectBeingIterated(*obj); + RegisterEnumerator(ObjectRealm::get(obj), ni); + return iterobj; + } + + if (numGuards > 0 && !CanStoreInIteratorCache(obj)) { + numGuards = 0; + } + + RootedIdVector keys(cx); + if (!EnumerateProperties(cx, obj, &keys)) { + return nullptr; + } + + // If the object has dense elements, mark the dense elements as + // maybe-in-iteration. + // + // The iterator is a snapshot so if indexed properties are added after this + // point we don't need to do anything. However, the object might have sparse + // elements now that can be densified later. To account for this, we set the + // maybe-in-iteration flag also in NativeObject::maybeDensifySparseElements. + // + // In debug builds, AssertDenseElementsNotIterated is used to check the flag + // is set correctly. + if (obj->is<NativeObject>() && + obj->as<NativeObject>().getDenseInitializedLength() > 0) { + obj->as<NativeObject>().markDenseElementsMaybeInIteration(); + } + + PropertyIteratorObject* iterobj = + CreatePropertyIterator(cx, obj, keys, numGuards, 0); + if (!iterobj) { + return nullptr; + } + + cx->check(iterobj); + +#ifdef DEBUG + if (obj->is<NativeObject>()) { + if (PrototypeMayHaveIndexedProperties(&obj->as<NativeObject>())) { + iterobj->getNativeIterator()->setMaybeHasIndexedPropertiesFromProto(); + } + } +#endif + + // Cache the iterator object. + if (numGuards > 0) { + if (!StoreInIteratorCache(cx, obj, iterobj)) { + return nullptr; + } + } + + return iterobj; +} + +PropertyIteratorObject* js::LookupInIteratorCache(JSContext* cx, + HandleObject obj) { + uint32_t numGuards = 0; + return LookupInIteratorCache(cx, obj, &numGuards); +} + +// ES 2017 draft 7.4.7. +PlainObject* js::CreateIterResultObject(JSContext* cx, HandleValue value, + bool done) { + // Step 1 (implicit). + + // Step 2. + Rooted<PlainObject*> templateObject( + cx, cx->realm()->getOrCreateIterResultTemplateObject(cx)); + if (!templateObject) { + return nullptr; + } + + PlainObject* resultObj; + JS_TRY_VAR_OR_RETURN_NULL( + cx, resultObj, PlainObject::createWithTemplate(cx, templateObject)); + + // Step 3. + resultObj->setSlot(Realm::IterResultObjectValueSlot, value); + + // Step 4. + resultObj->setSlot(Realm::IterResultObjectDoneSlot, + done ? TrueHandleValue : FalseHandleValue); + + // Step 5. + return resultObj; +} + +PlainObject* Realm::getOrCreateIterResultTemplateObject(JSContext* cx) { + MOZ_ASSERT(cx->realm() == this); + + if (iterResultTemplate_) { + return iterResultTemplate_; + } + + PlainObject* templateObj = + createIterResultTemplateObject(cx, WithObjectPrototype::Yes); + iterResultTemplate_.set(templateObj); + return iterResultTemplate_; +} + +PlainObject* Realm::getOrCreateIterResultWithoutPrototypeTemplateObject( + JSContext* cx) { + MOZ_ASSERT(cx->realm() == this); + + if (iterResultWithoutPrototypeTemplate_) { + return iterResultWithoutPrototypeTemplate_; + } + + PlainObject* templateObj = + createIterResultTemplateObject(cx, WithObjectPrototype::No); + iterResultWithoutPrototypeTemplate_.set(templateObj); + return iterResultWithoutPrototypeTemplate_; +} + +PlainObject* Realm::createIterResultTemplateObject( + JSContext* cx, WithObjectPrototype withProto) { + // Create template plain object + Rooted<PlainObject*> templateObject( + cx, withProto == WithObjectPrototype::Yes + ? NewTenuredBuiltinClassInstance<PlainObject>(cx) + : NewObjectWithGivenProto<PlainObject>(cx, nullptr)); + if (!templateObject) { + return nullptr; + } + + // Set dummy `value` property + if (!NativeDefineDataProperty(cx, templateObject, cx->names().value, + UndefinedHandleValue, JSPROP_ENUMERATE)) { + return nullptr; + } + + // Set dummy `done` property + if (!NativeDefineDataProperty(cx, templateObject, cx->names().done, + TrueHandleValue, JSPROP_ENUMERATE)) { + return nullptr; + } + + // Make sure that the properties are in the right slots. + DebugOnly<Shape*> shape = templateObject->lastProperty(); + MOZ_ASSERT(shape->previous()->slot() == Realm::IterResultObjectValueSlot && + shape->previous()->propidRef() == NameToId(cx->names().value)); + MOZ_ASSERT(shape->slot() == Realm::IterResultObjectDoneSlot && + shape->propidRef() == NameToId(cx->names().done)); + + return templateObject; +} + +/*** Iterator objects *******************************************************/ + +size_t PropertyIteratorObject::sizeOfMisc( + mozilla::MallocSizeOf mallocSizeOf) const { + return mallocSizeOf(getPrivate()); +} + +void PropertyIteratorObject::trace(JSTracer* trc, JSObject* obj) { + if (NativeIterator* ni = + obj->as<PropertyIteratorObject>().getNativeIterator()) { + ni->trace(trc); + } +} + +void PropertyIteratorObject::finalize(JSFreeOp* fop, JSObject* obj) { + if (NativeIterator* ni = + obj->as<PropertyIteratorObject>().getNativeIterator()) { + fop->free_(obj, ni, ni->allocationSize(), MemoryUse::NativeIterator); + } +} + +const JSClassOps PropertyIteratorObject::classOps_ = { + nullptr, // addProperty + nullptr, // delProperty + nullptr, // enumerate + nullptr, // newEnumerate + nullptr, // resolve + nullptr, // mayResolve + finalize, // finalize + nullptr, // call + nullptr, // hasInstance + nullptr, // construct + trace, // trace +}; + +const JSClass PropertyIteratorObject::class_ = { + "Iterator", JSCLASS_HAS_PRIVATE | JSCLASS_BACKGROUND_FINALIZE, + &PropertyIteratorObject::classOps_}; + +static const JSClass ArrayIteratorPrototypeClass = {"Array Iterator", 0}; + +enum { + ArrayIteratorSlotIteratedObject, + ArrayIteratorSlotNextIndex, + ArrayIteratorSlotItemKind, + ArrayIteratorSlotCount +}; + +const JSClass ArrayIteratorObject::class_ = { + "Array Iterator", JSCLASS_HAS_RESERVED_SLOTS(ArrayIteratorSlotCount)}; + +ArrayIteratorObject* js::NewArrayIteratorTemplate(JSContext* cx) { + RootedObject proto( + cx, GlobalObject::getOrCreateArrayIteratorPrototype(cx, cx->global())); + if (!proto) { + return nullptr; + } + + return NewTenuredObjectWithGivenProto<ArrayIteratorObject>(cx, proto); +} + +ArrayIteratorObject* js::NewArrayIterator(JSContext* cx) { + RootedObject proto( + cx, GlobalObject::getOrCreateArrayIteratorPrototype(cx, cx->global())); + if (!proto) { + return nullptr; + } + + return NewObjectWithGivenProto<ArrayIteratorObject>(cx, proto); +} + +static const JSFunctionSpec array_iterator_methods[] = { + JS_SELF_HOSTED_FN("next", "ArrayIteratorNext", 0, 0), JS_FS_END}; + +static const JSClass StringIteratorPrototypeClass = {"String Iterator", 0}; + +enum { + StringIteratorSlotIteratedObject, + StringIteratorSlotNextIndex, + StringIteratorSlotCount +}; + +const JSClass StringIteratorObject::class_ = { + "String Iterator", JSCLASS_HAS_RESERVED_SLOTS(StringIteratorSlotCount)}; + +static const JSFunctionSpec string_iterator_methods[] = { + JS_SELF_HOSTED_FN("next", "StringIteratorNext", 0, 0), JS_FS_END}; + +StringIteratorObject* js::NewStringIteratorTemplate(JSContext* cx) { + RootedObject proto( + cx, GlobalObject::getOrCreateStringIteratorPrototype(cx, cx->global())); + if (!proto) { + return nullptr; + } + + return NewTenuredObjectWithGivenProto<StringIteratorObject>(cx, proto); +} + +StringIteratorObject* js::NewStringIterator(JSContext* cx) { + RootedObject proto( + cx, GlobalObject::getOrCreateStringIteratorPrototype(cx, cx->global())); + if (!proto) { + return nullptr; + } + + return NewObjectWithGivenProto<StringIteratorObject>(cx, proto); +} + +static const JSClass RegExpStringIteratorPrototypeClass = { + "RegExp String Iterator", 0}; + +enum { + // The regular expression used for iteration. May hold the original RegExp + // object when it is reused instead of a new RegExp object. + RegExpStringIteratorSlotRegExp, + + // The String value being iterated upon. + RegExpStringIteratorSlotString, + + // The source string of the original RegExp object. Used to validate we can + // reuse the original RegExp object for matching. + RegExpStringIteratorSlotSource, + + // The flags of the original RegExp object. + RegExpStringIteratorSlotFlags, + + // When non-negative, this slot holds the current lastIndex position when + // reusing the original RegExp object for matching. When set to |-1|, the + // iterator has finished. When set to any other negative value, the + // iterator is not yet exhausted and we're not on the fast path and we're + // not reusing the input RegExp object. + RegExpStringIteratorSlotLastIndex, + + RegExpStringIteratorSlotCount +}; + +static_assert(RegExpStringIteratorSlotRegExp == + REGEXP_STRING_ITERATOR_REGEXP_SLOT, + "RegExpStringIteratorSlotRegExp must match self-hosting define " + "for regexp slot."); +static_assert(RegExpStringIteratorSlotString == + REGEXP_STRING_ITERATOR_STRING_SLOT, + "RegExpStringIteratorSlotString must match self-hosting define " + "for string slot."); +static_assert(RegExpStringIteratorSlotSource == + REGEXP_STRING_ITERATOR_SOURCE_SLOT, + "RegExpStringIteratorSlotString must match self-hosting define " + "for source slot."); +static_assert(RegExpStringIteratorSlotFlags == + REGEXP_STRING_ITERATOR_FLAGS_SLOT, + "RegExpStringIteratorSlotFlags must match self-hosting define " + "for flags slot."); +static_assert(RegExpStringIteratorSlotLastIndex == + REGEXP_STRING_ITERATOR_LASTINDEX_SLOT, + "RegExpStringIteratorSlotLastIndex must match self-hosting " + "define for lastIndex slot."); + +const JSClass RegExpStringIteratorObject::class_ = { + "RegExp String Iterator", + JSCLASS_HAS_RESERVED_SLOTS(RegExpStringIteratorSlotCount)}; + +static const JSFunctionSpec regexp_string_iterator_methods[] = { + JS_SELF_HOSTED_FN("next", "RegExpStringIteratorNext", 0, 0), + + JS_FS_END}; + +RegExpStringIteratorObject* js::NewRegExpStringIteratorTemplate(JSContext* cx) { + RootedObject proto(cx, GlobalObject::getOrCreateRegExpStringIteratorPrototype( + cx, cx->global())); + if (!proto) { + return nullptr; + } + + return NewTenuredObjectWithGivenProto<RegExpStringIteratorObject>(cx, proto); +} + +RegExpStringIteratorObject* js::NewRegExpStringIterator(JSContext* cx) { + RootedObject proto(cx, GlobalObject::getOrCreateRegExpStringIteratorPrototype( + cx, cx->global())); + if (!proto) { + return nullptr; + } + + return NewObjectWithGivenProto<RegExpStringIteratorObject>(cx, proto); +} + +JSObject* js::ValueToIterator(JSContext* cx, HandleValue vp) { + RootedObject obj(cx); + if (vp.isObject()) { + /* Common case. */ + obj = &vp.toObject(); + } else if (vp.isNullOrUndefined()) { + /* + * Enumerating over null and undefined gives an empty enumerator, so + * that |for (var p in <null or undefined>) <loop>;| never executes + * <loop>, per ES5 12.6.4. + */ + RootedIdVector props(cx); // Empty + return CreatePropertyIterator(cx, nullptr, props, 0, 0); + } else { + obj = ToObject(cx, vp); + if (!obj) { + return nullptr; + } + } + + return GetIterator(cx, obj); +} + +void js::CloseIterator(JSObject* obj) { + if (obj->is<PropertyIteratorObject>()) { + /* Remove enumerators from the active list, which is a stack. */ + NativeIterator* ni = obj->as<PropertyIteratorObject>().getNativeIterator(); + + ni->unlink(); + + MOZ_ASSERT(ni->isActive()); + ni->markInactive(); + + // Reset the enumerator; it may still be in the cached iterators for + // this thread and can be reused. + ni->resetPropertyCursorForReuse(); + } +} + +bool js::IteratorCloseForException(JSContext* cx, HandleObject obj) { + MOZ_ASSERT(cx->isExceptionPending()); + + bool isClosingGenerator = cx->isClosingGenerator(); + JS::AutoSaveExceptionState savedExc(cx); + + // Implements IteratorClose (ES 7.4.6) for exception unwinding. See + // also the bytecode generated by BytecodeEmitter::emitIteratorClose. + + // Step 3. + // + // Get the "return" method. + RootedValue returnMethod(cx); + if (!GetProperty(cx, obj, obj, cx->names().return_, &returnMethod)) { + return false; + } + + // Step 4. + // + // Do nothing if "return" is null or undefined. Throw a TypeError if the + // method is not IsCallable. + if (returnMethod.isNullOrUndefined()) { + return true; + } + if (!IsCallable(returnMethod)) { + return ReportIsNotFunction(cx, returnMethod); + } + + // Step 5, 6, 8. + // + // Call "return" if it is not null or undefined. + RootedValue rval(cx); + bool ok = Call(cx, returnMethod, obj, &rval); + if (isClosingGenerator) { + // Closing an iterator is implemented as an exception, but in spec + // terms it is a Completion value with [[Type]] return. In this case + // we *do* care if the call threw and if it returned an object. + if (!ok) { + return false; + } + if (!rval.isObject()) { + return ThrowCheckIsObject(cx, CheckIsObjectKind::IteratorReturn); + } + } else { + // We don't care if the call threw or that it returned an Object, as + // Step 6 says if IteratorClose is being called during a throw, the + // original throw has primacy. + savedExc.restore(); + } + + return true; +} + +void js::UnwindIteratorForUncatchableException(JSObject* obj) { + if (obj->is<PropertyIteratorObject>()) { + NativeIterator* ni = obj->as<PropertyIteratorObject>().getNativeIterator(); + ni->unlink(); + } +} + +static bool SuppressDeletedProperty(JSContext* cx, NativeIterator* ni, + HandleObject obj, + Handle<JSLinearString*> str) { + if (ni->objectBeingIterated() != obj) { + return true; + } + + // Optimization for the following common case: + // + // for (var p in o) { + // delete o[p]; + // } + // + // Note that usually both strings will be atoms so we only check for pointer + // equality here. + if (ni->previousPropertyWas(str)) { + return true; + } + + while (true) { + bool restart = false; + + // Check whether id is still to come. + GCPtrLinearString* const cursor = ni->nextProperty(); + GCPtrLinearString* const end = ni->propertiesEnd(); + for (GCPtrLinearString* idp = cursor; idp < end; ++idp) { + // Common case: both strings are atoms. + if ((*idp)->isAtom() && str->isAtom()) { + if (*idp != str) { + continue; + } + } else { + if (!EqualStrings(*idp, str)) { + continue; + } + } + + // Check whether another property along the prototype chain became + // visible as a result of this deletion. + RootedObject proto(cx); + if (!GetPrototype(cx, obj, &proto)) { + return false; + } + if (proto) { + RootedId id(cx); + RootedValue idv(cx, StringValue(*idp)); + if (!PrimitiveValueToId<CanGC>(cx, idv, &id)) { + return false; + } + + Rooted<PropertyDescriptor> desc(cx); + if (!GetPropertyDescriptor(cx, proto, id, &desc)) { + return false; + } + + if (desc.object() && desc.enumerable()) { + continue; + } + } + + // If GetPropertyDescriptor above removed a property from ni, start + // over. + if (end != ni->propertiesEnd() || cursor != ni->nextProperty()) { + restart = true; + break; + } + + // No property along the prototype chain stepped in to take the + // property's place, so go ahead and delete id from the list. + // If it is the next property to be enumerated, just skip it. + if (idp == cursor) { + ni->incCursor(); + } else { + for (GCPtrLinearString* p = idp; p + 1 != end; p++) { + *p = *(p + 1); + } + + ni->trimLastProperty(); + } + + ni->markHasUnvisitedPropertyDeletion(); + return true; + } + + if (!restart) { + return true; + } + } +} + +/* + * Suppress enumeration of deleted properties. This function must be called + * when a property is deleted and there might be active enumerators. + * + * We maintain a list of active non-escaping for-in enumerators. To suppress + * a property, we check whether each active enumerator contains the (obj, id) + * pair and has not yet enumerated |id|. If so, and |id| is the next property, + * we simply advance the cursor. Otherwise, we delete |id| from the list. + * + * We do not suppress enumeration of a property deleted along an object's + * prototype chain. Only direct deletions on the object are handled. + */ +static bool SuppressDeletedPropertyHelper(JSContext* cx, HandleObject obj, + Handle<JSLinearString*> str) { + NativeIterator* enumeratorList = ObjectRealm::get(obj).enumerators; + NativeIterator* ni = enumeratorList->next(); + + while (ni != enumeratorList) { + if (!SuppressDeletedProperty(cx, ni, obj, str)) { + return false; + } + ni = ni->next(); + } + + return true; +} + +bool js::SuppressDeletedProperty(JSContext* cx, HandleObject obj, jsid id) { + if (MOZ_LIKELY(!ObjectRealm::get(obj).objectMaybeInIteration(obj))) { + return true; + } + + if (JSID_IS_SYMBOL(id)) { + return true; + } + + Rooted<JSLinearString*> str(cx, IdToString(cx, id)); + if (!str) { + return false; + } + return SuppressDeletedPropertyHelper(cx, obj, str); +} + +bool js::SuppressDeletedElement(JSContext* cx, HandleObject obj, + uint32_t index) { + if (MOZ_LIKELY(!ObjectRealm::get(obj).objectMaybeInIteration(obj))) { + return true; + } + + RootedId id(cx); + if (!IndexToId(cx, index, &id)) { + return false; + } + + Rooted<JSLinearString*> str(cx, IdToString(cx, id)); + if (!str) { + return false; + } + return SuppressDeletedPropertyHelper(cx, obj, str); +} + +#ifdef DEBUG +void js::AssertDenseElementsNotIterated(NativeObject* obj) { + // Search for active iterators for |obj| and assert they don't contain any + // property keys that are dense elements. This is used to check correctness + // of the MAYBE_IN_ITERATION flag on ObjectElements. + // + // Ignore iterators that may contain indexed properties from objects on the + // prototype chain, as that can result in false positives. See bug 1656744. + + // Limit the number of properties we check to avoid slowing down debug builds + // too much. + static constexpr uint32_t MaxPropsToCheck = 10; + uint32_t propsChecked = 0; + + NativeIterator* enumeratorList = ObjectRealm::get(obj).enumerators; + NativeIterator* ni = enumeratorList->next(); + + while (ni != enumeratorList) { + if (ni->objectBeingIterated() == obj && + !ni->maybeHasIndexedPropertiesFromProto()) { + for (GCPtrLinearString* idp = ni->nextProperty(); + idp < ni->propertiesEnd(); ++idp) { + uint32_t index; + if (idp->get()->isIndex(&index)) { + MOZ_ASSERT(!obj->containsDenseElement(index)); + } + if (++propsChecked > MaxPropsToCheck) { + return; + } + } + } + ni = ni->next(); + } +} +#endif + +static const JSFunctionSpec iterator_methods[] = { + JS_SELF_HOSTED_SYM_FN(iterator, "IteratorIdentity", 0, 0), JS_FS_END}; + +static const JSFunctionSpec iterator_static_methods[] = { + JS_SELF_HOSTED_FN("from", "IteratorFrom", 1, 0), JS_FS_END}; + +// These methods are only attached to Iterator.prototype when the +// Iterator Helpers feature is enabled. +static const JSFunctionSpec iterator_methods_with_helpers[] = { + JS_SELF_HOSTED_FN("map", "IteratorMap", 1, 0), + JS_SELF_HOSTED_FN("filter", "IteratorFilter", 1, 0), + JS_SELF_HOSTED_FN("take", "IteratorTake", 1, 0), + JS_SELF_HOSTED_FN("drop", "IteratorDrop", 1, 0), + JS_SELF_HOSTED_FN("asIndexedPairs", "IteratorAsIndexedPairs", 0, 0), + JS_SELF_HOSTED_FN("flatMap", "IteratorFlatMap", 1, 0), + JS_SELF_HOSTED_FN("reduce", "IteratorReduce", 1, 0), + JS_SELF_HOSTED_FN("toArray", "IteratorToArray", 0, 0), + JS_SELF_HOSTED_FN("forEach", "IteratorForEach", 1, 0), + JS_SELF_HOSTED_FN("some", "IteratorSome", 1, 0), + JS_SELF_HOSTED_FN("every", "IteratorEvery", 1, 0), + JS_SELF_HOSTED_FN("find", "IteratorFind", 1, 0), + JS_SELF_HOSTED_SYM_FN(iterator, "IteratorIdentity", 0, 0), + JS_FS_END}; + +/* static */ +bool GlobalObject::initIteratorProto(JSContext* cx, + Handle<GlobalObject*> global) { + if (global->getReservedSlot(ITERATOR_PROTO).isObject()) { + return true; + } + + RootedObject proto( + cx, GlobalObject::createBlankPrototype<PlainObject>(cx, global)); + if (!proto) { + return false; + } + + // %IteratorPrototype%.map.[[Prototype]] is %Generator% and + // %Generator%.prototype.[[Prototype]] is %IteratorPrototype%. + // Populate the slot early, to prevent runaway mutual recursion. + global->setReservedSlot(ITERATOR_PROTO, ObjectValue(*proto)); + + if (!DefinePropertiesAndFunctions(cx, proto, nullptr, iterator_methods)) { + // In this case, we leave a partially initialized object in the + // slot. There's no obvious way to do better, since this object may already + // be in the prototype chain of %GeneratorPrototype%. + return false; + } + + return true; +} + +/* static */ +template <unsigned Slot, const JSClass* ProtoClass, + const JSFunctionSpec* Methods> +bool GlobalObject::initObjectIteratorProto(JSContext* cx, + Handle<GlobalObject*> global, + HandleAtom tag) { + if (global->getReservedSlot(Slot).isObject()) { + return true; + } + + RootedObject iteratorProto( + cx, GlobalObject::getOrCreateIteratorPrototype(cx, global)); + if (!iteratorProto) { + return false; + } + + RootedObject proto(cx, GlobalObject::createBlankPrototypeInheriting( + cx, ProtoClass, iteratorProto)); + if (!proto || !DefinePropertiesAndFunctions(cx, proto, nullptr, Methods) || + (tag && !DefineToStringTag(cx, proto, tag))) { + return false; + } + + global->setReservedSlot(Slot, ObjectValue(*proto)); + return true; +} + +/* static */ +NativeObject* GlobalObject::getOrCreateArrayIteratorPrototype( + JSContext* cx, Handle<GlobalObject*> global) { + return MaybeNativeObject(getOrCreateObject( + cx, global, ARRAY_ITERATOR_PROTO, cx->names().ArrayIterator.toHandle(), + initObjectIteratorProto<ARRAY_ITERATOR_PROTO, + &ArrayIteratorPrototypeClass, + array_iterator_methods>)); +} + +/* static */ +JSObject* GlobalObject::getOrCreateStringIteratorPrototype( + JSContext* cx, Handle<GlobalObject*> global) { + return getOrCreateObject( + cx, global, STRING_ITERATOR_PROTO, cx->names().StringIterator.toHandle(), + initObjectIteratorProto<STRING_ITERATOR_PROTO, + &StringIteratorPrototypeClass, + string_iterator_methods>); +} + +/* static */ +JSObject* GlobalObject::getOrCreateRegExpStringIteratorPrototype( + JSContext* cx, Handle<GlobalObject*> global) { + return getOrCreateObject( + cx, global, REGEXP_STRING_ITERATOR_PROTO, + cx->names().RegExpStringIterator.toHandle(), + initObjectIteratorProto<REGEXP_STRING_ITERATOR_PROTO, + &RegExpStringIteratorPrototypeClass, + regexp_string_iterator_methods>); +} + +// Iterator Helper Proposal 2.1.3.1 Iterator() +// https://tc39.es/proposal-iterator-helpers/#sec-iterator as of revision +// ed6e15a +static bool IteratorConstructor(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + + // Step 1. + if (!ThrowIfNotConstructing(cx, args, js_Iterator_str)) { + return false; + } + // Throw TypeError if NewTarget is the active function object, preventing the + // Iterator constructor from being used directly. + if (args.callee() == args.newTarget().toObject()) { + JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, + JSMSG_BOGUS_CONSTRUCTOR, js_Iterator_str); + return false; + } + + // Step 2. + RootedObject proto(cx); + if (!GetPrototypeFromBuiltinConstructor(cx, args, JSProto_Iterator, &proto)) { + return false; + } + + JSObject* obj = NewObjectWithClassProto<IteratorObject>(cx, proto); + if (!obj) { + return false; + } + + args.rval().setObject(*obj); + return true; +} + +static const ClassSpec IteratorObjectClassSpec = { + GenericCreateConstructor<IteratorConstructor, 0, gc::AllocKind::FUNCTION>, + GenericCreatePrototype<IteratorObject>, + iterator_static_methods, + nullptr, + iterator_methods_with_helpers, + nullptr, + nullptr, +}; + +const JSClass IteratorObject::class_ = { + js_Iterator_str, + JSCLASS_HAS_CACHED_PROTO(JSProto_Iterator), + JS_NULL_CLASS_OPS, + &IteratorObjectClassSpec, +}; + +const JSClass IteratorObject::protoClass_ = { + "Iterator.prototype", + JSCLASS_HAS_CACHED_PROTO(JSProto_Iterator), + JS_NULL_CLASS_OPS, + &IteratorObjectClassSpec, +}; + +// Set up WrapForValidIteratorObject class and its prototype. +static const JSFunctionSpec wrap_for_valid_iterator_methods[] = { + JS_SELF_HOSTED_FN("next", "WrapForValidIteratorNext", 1, 0), + JS_SELF_HOSTED_FN("return", "WrapForValidIteratorReturn", 1, 0), + JS_SELF_HOSTED_FN("throw", "WrapForValidIteratorThrow", 1, 0), + JS_FS_END, +}; + +static const JSClass WrapForValidIteratorPrototypeClass = { + "Wrap For Valid Iterator", 0}; + +const JSClass WrapForValidIteratorObject::class_ = { + "Wrap For Valid Iterator", + JSCLASS_HAS_RESERVED_SLOTS(WrapForValidIteratorObject::SlotCount), +}; + +/* static */ +NativeObject* GlobalObject::getOrCreateWrapForValidIteratorPrototype( + JSContext* cx, Handle<GlobalObject*> global) { + return MaybeNativeObject(getOrCreateObject( + cx, global, WRAP_FOR_VALID_ITERATOR_PROTO, HandleAtom(nullptr), + initObjectIteratorProto<WRAP_FOR_VALID_ITERATOR_PROTO, + &WrapForValidIteratorPrototypeClass, + wrap_for_valid_iterator_methods>)); +} + +WrapForValidIteratorObject* js::NewWrapForValidIterator(JSContext* cx) { + RootedObject proto(cx, GlobalObject::getOrCreateWrapForValidIteratorPrototype( + cx, cx->global())); + if (!proto) { + return nullptr; + } + return NewObjectWithGivenProto<WrapForValidIteratorObject>(cx, proto); +} + +// Common iterator object returned by Iterator Helper methods. +static const JSFunctionSpec iterator_helper_methods[] = { + JS_SELF_HOSTED_FN("next", "IteratorHelperNext", 1, 0), + JS_SELF_HOSTED_FN("return", "IteratorHelperReturn", 1, 0), + JS_SELF_HOSTED_FN("throw", "IteratorHelperThrow", 1, 0), JS_FS_END}; + +static const JSClass IteratorHelperPrototypeClass = {"Iterator Helper", 0}; + +const JSClass IteratorHelperObject::class_ = { + "Iterator Helper", + JSCLASS_HAS_RESERVED_SLOTS(IteratorHelperObject::SlotCount), +}; + +/* static */ +NativeObject* GlobalObject::getOrCreateIteratorHelperPrototype( + JSContext* cx, Handle<GlobalObject*> global) { + return MaybeNativeObject( + getOrCreateObject(cx, global, ITERATOR_HELPER_PROTO, HandleAtom(nullptr), + initObjectIteratorProto<ITERATOR_HELPER_PROTO, + &IteratorHelperPrototypeClass, + iterator_helper_methods>)); +} + +IteratorHelperObject* js::NewIteratorHelper(JSContext* cx) { + RootedObject proto( + cx, GlobalObject::getOrCreateIteratorHelperPrototype(cx, cx->global())); + if (!proto) { + return nullptr; + } + return NewObjectWithGivenProto<IteratorHelperObject>(cx, proto); +} |