/* -*- 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 "vm/ArrayBufferObject-inl.h" #include "vm/ArrayBufferObject.h" #include "mozilla/Assertions.h" #include "mozilla/Attributes.h" #include "mozilla/DebugOnly.h" #include "mozilla/Likely.h" #include "mozilla/Maybe.h" #include "mozilla/ScopeExit.h" #include "mozilla/TaggedAnonymousMemory.h" #include // std::max, std::min #include // std::uninitialized_copy_n #include #if !defined(XP_WIN) && !defined(__wasi__) # include #endif #include // std::tuple #include #ifdef MOZ_VALGRIND # include #endif #include "jsnum.h" #include "jstypes.h" #include "gc/Barrier.h" #include "gc/Memory.h" #include "js/ArrayBuffer.h" #include "js/Conversions.h" #include "js/experimental/TypedData.h" // JS_IsArrayBufferViewObject #include "js/friend/ErrorMessages.h" // js::GetErrorMessage, JSMSG_* #include "js/MemoryMetrics.h" #include "js/Prefs.h" #include "js/PropertySpec.h" #include "js/SharedArrayBuffer.h" #include "js/Wrapper.h" #include "util/WindowsWrapper.h" #include "vm/GlobalObject.h" #include "vm/JSContext.h" #include "vm/JSObject.h" #include "vm/SharedArrayObject.h" #include "vm/Warnings.h" // js::WarnNumberASCII #include "wasm/WasmConstants.h" #include "wasm/WasmLog.h" #include "wasm/WasmMemory.h" #include "wasm/WasmModuleTypes.h" #include "wasm/WasmProcess.h" #include "gc/GCContext-inl.h" #include "gc/Marking-inl.h" #include "vm/NativeObject-inl.h" #include "vm/Realm-inl.h" // js::AutoRealm using JS::ToInt32; using js::wasm::IndexType; using js::wasm::Pages; using mozilla::Atomic; using mozilla::CheckedInt; using mozilla::DebugOnly; using mozilla::Maybe; using mozilla::Nothing; using mozilla::Some; using namespace js; // Wasm allows large amounts of memory to be reserved at a time. On 64-bit // platforms (with "huge memories") we reserve around 4GB of virtual address // space for every wasm memory; on 32-bit platforms we usually do not, but users // often initialize memories in the hundreds of megabytes. // // If too many wasm memories remain live, we run up against system resource // exhaustion (address space or number of memory map descriptors) - see bug // 1068684, bug 1073934, bug 1517412, bug 1502733 for details. The limiting case // seems to be Android on ARM64, where the per-process address space is limited // to 4TB (39 bits) by the organization of the page tables. An earlier problem // was Windows Vista Home 64-bit, where the per-process address space is limited // to 8TB (40 bits). And 32-bit platforms only have 4GB of address space anyway. // // Thus we track the amount of memory reserved for wasm, and set a limit per // process. We trigger GC work when we approach the limit and we throw an OOM // error if the per-process limit is exceeded. The limit (WasmReservedBytesMax) // is specific to architecture, OS, and OS configuration. // // Since the WasmReservedBytesMax limit is not generally accounted for by // any existing GC-trigger heuristics, we need an extra heuristic for triggering // GCs when the caller is allocating memories rapidly without other garbage // (e.g. bug 1773225). Thus, once the reserved memory crosses the threshold // WasmReservedBytesStartTriggering, we start triggering GCs every // WasmReservedBytesPerTrigger bytes. Once we reach // WasmReservedBytesStartSyncFullGC bytes reserved, we perform expensive // non-incremental full GCs as a last-ditch effort to avoid unnecessary failure. // Once we reach WasmReservedBytesMax, we perform further full GCs before giving // up. // // (History: The original implementation only tracked the number of "huge // memories" allocated by WASM, but this was found to be insufficient because // 32-bit platforms have similar resource exhaustion issues. We now track // reserved bytes directly.) // // (We also used to reserve significantly more than 4GB for huge memories, but // this was reduced in bug 1442544.) // ASAN and TSAN use a ton of vmem for bookkeeping leaving a lot less for the // program so use a lower limit. #if defined(MOZ_TSAN) || defined(MOZ_ASAN) static const uint64_t WasmMemAsanOverhead = 2; #else static const uint64_t WasmMemAsanOverhead = 1; #endif // WasmReservedStartTriggering + WasmReservedPerTrigger must be well below // WasmReservedStartSyncFullGC in order to provide enough time for incremental // GC to do its job. #if defined(JS_CODEGEN_ARM64) && defined(ANDROID) static const uint64_t WasmReservedBytesMax = 75 * wasm::HugeMappedSize / WasmMemAsanOverhead; static const uint64_t WasmReservedBytesStartTriggering = 15 * wasm::HugeMappedSize; static const uint64_t WasmReservedBytesStartSyncFullGC = WasmReservedBytesMax - 15 * wasm::HugeMappedSize; static const uint64_t WasmReservedBytesPerTrigger = 15 * wasm::HugeMappedSize; #elif defined(WASM_SUPPORTS_HUGE_MEMORY) static const uint64_t WasmReservedBytesMax = 1000 * wasm::HugeMappedSize / WasmMemAsanOverhead; static const uint64_t WasmReservedBytesStartTriggering = 100 * wasm::HugeMappedSize; static const uint64_t WasmReservedBytesStartSyncFullGC = WasmReservedBytesMax - 100 * wasm::HugeMappedSize; static const uint64_t WasmReservedBytesPerTrigger = 100 * wasm::HugeMappedSize; #else // 32-bit (and weird 64-bit platforms without huge memory) static const uint64_t GiB = 1024 * 1024 * 1024; static const uint64_t WasmReservedBytesMax = (4 * GiB) / 2 / WasmMemAsanOverhead; static const uint64_t WasmReservedBytesStartTriggering = (4 * GiB) / 8; static const uint64_t WasmReservedBytesStartSyncFullGC = WasmReservedBytesMax - (4 * GiB) / 8; static const uint64_t WasmReservedBytesPerTrigger = (4 * GiB) / 8; #endif // The total number of bytes reserved for wasm memories. static Atomic wasmReservedBytes(0); // The number of bytes of wasm memory reserved since the last GC trigger. static Atomic wasmReservedBytesSinceLast(0); uint64_t js::WasmReservedBytes() { return wasmReservedBytes; } [[nodiscard]] static bool CheckArrayBufferTooLarge(JSContext* cx, uint64_t nbytes) { // Refuse to allocate too large buffers. if (MOZ_UNLIKELY(nbytes > ArrayBufferObject::ByteLengthLimit)) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH); return false; } return true; } void* js::MapBufferMemory(wasm::IndexType t, size_t mappedSize, size_t initialCommittedSize) { MOZ_ASSERT(mappedSize % gc::SystemPageSize() == 0); MOZ_ASSERT(initialCommittedSize % gc::SystemPageSize() == 0); MOZ_ASSERT(initialCommittedSize <= mappedSize); auto failed = mozilla::MakeScopeExit( [&] { wasmReservedBytes -= uint64_t(mappedSize); }); wasmReservedBytes += uint64_t(mappedSize); // Test >= to guard against the case where multiple extant runtimes // race to allocate. if (wasmReservedBytes >= WasmReservedBytesMax) { if (OnLargeAllocationFailure) { OnLargeAllocationFailure(); } if (wasmReservedBytes >= WasmReservedBytesMax) { return nullptr; } } #ifdef XP_WIN void* data = VirtualAlloc(nullptr, mappedSize, MEM_RESERVE, PAGE_NOACCESS); if (!data) { return nullptr; } if (!VirtualAlloc(data, initialCommittedSize, MEM_COMMIT, PAGE_READWRITE)) { VirtualFree(data, 0, MEM_RELEASE); return nullptr; } #elif defined(__wasi__) void* data = nullptr; if (int err = posix_memalign(&data, gc::SystemPageSize(), mappedSize)) { MOZ_ASSERT(err == ENOMEM); return nullptr; } MOZ_ASSERT(data); memset(data, 0, mappedSize); #else // !XP_WIN && !__wasi__ void* data = MozTaggedAnonymousMmap(nullptr, mappedSize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0, "wasm-reserved"); if (data == MAP_FAILED) { return nullptr; } // Note we will waste a page on zero-sized memories here if (mprotect(data, initialCommittedSize, PROT_READ | PROT_WRITE)) { munmap(data, mappedSize); return nullptr; } #endif // !XP_WIN && !__wasi__ #if defined(MOZ_VALGRIND) && \ defined(VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE) VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE( (unsigned char*)data + initialCommittedSize, mappedSize - initialCommittedSize); #endif failed.release(); return data; } bool js::CommitBufferMemory(void* dataEnd, size_t delta) { MOZ_ASSERT(delta); MOZ_ASSERT(delta % gc::SystemPageSize() == 0); #ifdef XP_WIN if (!VirtualAlloc(dataEnd, delta, MEM_COMMIT, PAGE_READWRITE)) { return false; } #elif defined(__wasi__) // posix_memalign'd memory is already committed return true; #else if (mprotect(dataEnd, delta, PROT_READ | PROT_WRITE)) { return false; } #endif // XP_WIN #if defined(MOZ_VALGRIND) && \ defined(VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE) VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE((unsigned char*)dataEnd, delta); #endif return true; } bool js::ExtendBufferMapping(void* dataPointer, size_t mappedSize, size_t newMappedSize) { MOZ_ASSERT(mappedSize % gc::SystemPageSize() == 0); MOZ_ASSERT(newMappedSize % gc::SystemPageSize() == 0); MOZ_ASSERT(newMappedSize >= mappedSize); #ifdef XP_WIN void* mappedEnd = (char*)dataPointer + mappedSize; uint32_t delta = newMappedSize - mappedSize; if (!VirtualAlloc(mappedEnd, delta, MEM_RESERVE, PAGE_NOACCESS)) { return false; } return true; #elif defined(__wasi__) return false; #elif defined(XP_LINUX) // Note this will not move memory (no MREMAP_MAYMOVE specified) if (MAP_FAILED == mremap(dataPointer, mappedSize, newMappedSize, 0)) { return false; } return true; #else // No mechanism for remapping on MacOS and other Unices. Luckily // shouldn't need it here as most of these are 64-bit. return false; #endif } void js::UnmapBufferMemory(wasm::IndexType t, void* base, size_t mappedSize) { MOZ_ASSERT(mappedSize % gc::SystemPageSize() == 0); #ifdef XP_WIN VirtualFree(base, 0, MEM_RELEASE); #elif defined(__wasi__) free(base); #else munmap(base, mappedSize); #endif // XP_WIN #if defined(MOZ_VALGRIND) && \ defined(VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE) VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE((unsigned char*)base, mappedSize); #endif // Untrack reserved memory *after* releasing memory -- otherwise, a race // condition could enable the creation of unlimited buffers. wasmReservedBytes -= uint64_t(mappedSize); } /* * ArrayBufferObject * * This class holds the underlying raw buffer that the TypedArrayObject classes * access. It can be created explicitly and passed to a TypedArrayObject, or * can be created implicitly by constructing a TypedArrayObject with a size. */ /* * ArrayBufferObject (base) */ static const JSClassOps ArrayBufferObjectClassOps = { nullptr, // addProperty nullptr, // delProperty nullptr, // enumerate nullptr, // newEnumerate nullptr, // resolve nullptr, // mayResolve ArrayBufferObject::finalize, // finalize nullptr, // call nullptr, // construct nullptr, // trace }; static const JSFunctionSpec arraybuffer_functions[] = { JS_FN("isView", ArrayBufferObject::fun_isView, 1, 0), JS_FS_END, }; static const JSPropertySpec arraybuffer_properties[] = { JS_SELF_HOSTED_SYM_GET(species, "$ArrayBufferSpecies", 0), JS_PS_END, }; static const JSFunctionSpec arraybuffer_proto_functions[] = { JS_SELF_HOSTED_FN("slice", "ArrayBufferSlice", 2, 0), #ifdef NIGHTLY_BUILD JS_FN("resize", ArrayBufferObject::resize, 1, 0), #endif JS_FN("transfer", ArrayBufferObject::transfer, 0, 0), JS_FN("transferToFixedLength", ArrayBufferObject::transferToFixedLength, 0, 0), JS_FS_END, }; static const JSPropertySpec arraybuffer_proto_properties[] = { JS_PSG("byteLength", ArrayBufferObject::byteLengthGetter, 0), #ifdef NIGHTLY_BUILD JS_PSG("maxByteLength", ArrayBufferObject::maxByteLengthGetter, 0), JS_PSG("resizable", ArrayBufferObject::resizableGetter, 0), #endif JS_PSG("detached", ArrayBufferObject::detachedGetter, 0), JS_STRING_SYM_PS(toStringTag, "ArrayBuffer", JSPROP_READONLY), JS_PS_END, }; static JSObject* CreateArrayBufferPrototype(JSContext* cx, JSProtoKey key) { return GlobalObject::createBlankPrototype(cx, cx->global(), &ArrayBufferObject::protoClass_); } static const ClassSpec ArrayBufferObjectClassSpec = { GenericCreateConstructor, CreateArrayBufferPrototype, arraybuffer_functions, arraybuffer_properties, arraybuffer_proto_functions, arraybuffer_proto_properties, }; static const ClassExtension FixedLengthArrayBufferObjectClassExtension = { ArrayBufferObject::objectMoved< FixedLengthArrayBufferObject>, // objectMovedOp }; static const ClassExtension ResizableArrayBufferObjectClassExtension = { ArrayBufferObject::objectMoved< ResizableArrayBufferObject>, // objectMovedOp }; const JSClass ArrayBufferObject::protoClass_ = { "ArrayBuffer.prototype", JSCLASS_HAS_CACHED_PROTO(JSProto_ArrayBuffer), JS_NULL_CLASS_OPS, &ArrayBufferObjectClassSpec, }; const JSClass FixedLengthArrayBufferObject::class_ = { "ArrayBuffer", JSCLASS_DELAY_METADATA_BUILDER | JSCLASS_HAS_RESERVED_SLOTS(RESERVED_SLOTS) | JSCLASS_HAS_CACHED_PROTO(JSProto_ArrayBuffer) | JSCLASS_BACKGROUND_FINALIZE, &ArrayBufferObjectClassOps, &ArrayBufferObjectClassSpec, &FixedLengthArrayBufferObjectClassExtension, }; const JSClass ResizableArrayBufferObject::class_ = { "ArrayBuffer", JSCLASS_DELAY_METADATA_BUILDER | JSCLASS_HAS_RESERVED_SLOTS(RESERVED_SLOTS) | JSCLASS_HAS_CACHED_PROTO(JSProto_ArrayBuffer) | JSCLASS_BACKGROUND_FINALIZE, &ArrayBufferObjectClassOps, &ArrayBufferObjectClassSpec, &ResizableArrayBufferObjectClassExtension, }; static bool IsArrayBuffer(HandleValue v) { return v.isObject() && v.toObject().is(); } #ifdef NIGHTLY_BUILD static bool IsResizableArrayBuffer(HandleValue v) { return v.isObject() && v.toObject().is(); } #endif MOZ_ALWAYS_INLINE bool ArrayBufferObject::byteLengthGetterImpl( JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsArrayBuffer(args.thisv())); auto* buffer = &args.thisv().toObject().as(); args.rval().setNumber(buffer->byteLength()); return true; } bool ArrayBufferObject::byteLengthGetter(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } enum class PreserveResizability : bool { No, Yes }; /** * ArrayBufferCopyAndDetach ( arrayBuffer, newLength, preserveResizability ) * * https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffercopyanddetach */ static ArrayBufferObject* ArrayBufferCopyAndDetach( JSContext* cx, Handle arrayBuffer, Handle newLength, PreserveResizability preserveResizability) { // Steps 1-2. (Not applicable in our implementation.) // Steps 3-4. uint64_t newByteLength; if (newLength.isUndefined()) { // Step 3.a. newByteLength = arrayBuffer->byteLength(); } else { // Step 4.a. if (!ToIndex(cx, newLength, &newByteLength)) { return nullptr; } } // Step 5. if (arrayBuffer->isDetached()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED); return nullptr; } if (arrayBuffer->isLengthPinned()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_PINNED); return nullptr; } // Steps 6-7. mozilla::Maybe maxByteLength; if (preserveResizability == PreserveResizability::Yes && arrayBuffer->isResizable()) { auto* resizableBuffer = &arrayBuffer->as(); maxByteLength = mozilla::Some(resizableBuffer->maxByteLength()); } // Step 8. if (arrayBuffer->hasDefinedDetachKey()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_TRANSFER); return nullptr; } // Steps 9-16. // // 25.1.2.1 AllocateArrayBuffer, step 2. // 6.2.9.1 CreateByteDataBlock, step 2. if (!CheckArrayBufferTooLarge(cx, newByteLength)) { return nullptr; } if (maxByteLength) { if (size_t(newByteLength) > *maxByteLength) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_LARGER_THAN_MAXIMUM); return nullptr; } Rooted resizableBuffer( cx, &arrayBuffer->as()); return ResizableArrayBufferObject::copyAndDetach(cx, size_t(newByteLength), resizableBuffer); } return ArrayBufferObject::copyAndDetach(cx, size_t(newByteLength), arrayBuffer); } #ifdef NIGHTLY_BUILD /** * get ArrayBuffer.prototype.maxByteLength * * https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.maxbytelength */ bool ArrayBufferObject::maxByteLengthGetterImpl(JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsArrayBuffer(args.thisv())); auto* buffer = &args.thisv().toObject().as(); // Steps 4-6. size_t maxByteLength = buffer->maxByteLength(); MOZ_ASSERT_IF(buffer->isDetached(), maxByteLength == 0); // Step 7. args.rval().setNumber(maxByteLength); return true; } /** * get ArrayBuffer.prototype.maxByteLength * * https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.maxbytelength */ bool ArrayBufferObject::maxByteLengthGetter(JSContext* cx, unsigned argc, Value* vp) { // Steps 1-3. CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } /** * get ArrayBuffer.prototype.resizable * * https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.resizable */ bool ArrayBufferObject::resizableGetterImpl(JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsArrayBuffer(args.thisv())); // Step 4. auto* buffer = &args.thisv().toObject().as(); args.rval().setBoolean(buffer->isResizable()); return true; } /** * get ArrayBuffer.prototype.resizable * * https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.resizable */ bool ArrayBufferObject::resizableGetter(JSContext* cx, unsigned argc, Value* vp) { // Steps 1-3. CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } #endif /** * get ArrayBuffer.prototype.detached * * https://tc39.es/proposal-arraybuffer-transfer/#sec-get-arraybuffer.prototype.detached */ bool ArrayBufferObject::detachedGetterImpl(JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsArrayBuffer(args.thisv())); // Step 4. auto* buffer = &args.thisv().toObject().as(); args.rval().setBoolean(buffer->isDetached()); return true; } /** * get ArrayBuffer.prototype.detached * * https://tc39.es/proposal-arraybuffer-transfer/#sec-get-arraybuffer.prototype.detached */ bool ArrayBufferObject::detachedGetter(JSContext* cx, unsigned argc, Value* vp) { // Steps 1-3. CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } /** * ArrayBuffer.prototype.transfer ( [ newLength ] ) * * https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffer.prototype.transfer */ bool ArrayBufferObject::transferImpl(JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsArrayBuffer(args.thisv())); // Steps 1-2. Rooted buffer( cx, &args.thisv().toObject().as()); auto* newBuffer = ArrayBufferCopyAndDetach(cx, buffer, args.get(0), PreserveResizability::Yes); if (!newBuffer) { return false; } args.rval().setObject(*newBuffer); return true; } /** * ArrayBuffer.prototype.transfer ( [ newLength ] ) * * https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffer.prototype.transfer */ bool ArrayBufferObject::transfer(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } /** * ArrayBuffer.prototype.transferToFixedLength ( [ newLength ] ) * * https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffer.prototype.transfertofixedlength */ bool ArrayBufferObject::transferToFixedLengthImpl(JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsArrayBuffer(args.thisv())); // Steps 1-2. Rooted buffer( cx, &args.thisv().toObject().as()); auto* newBuffer = ArrayBufferCopyAndDetach(cx, buffer, args.get(0), PreserveResizability::No); if (!newBuffer) { return false; } args.rval().setObject(*newBuffer); return true; } /** * ArrayBuffer.prototype.transferToFixedLength ( [ newLength ] ) * * https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffer.prototype.transfertofixedlength */ bool ArrayBufferObject::transferToFixedLength(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } #ifdef NIGHTLY_BUILD /** * ArrayBuffer.prototype.resize ( newLength ) * * https://tc39.es/ecma262/#sec-arraybuffer.prototype.resize */ bool ArrayBufferObject::resizeImpl(JSContext* cx, const CallArgs& args) { MOZ_ASSERT(IsResizableArrayBuffer(args.thisv())); Rooted obj( cx, &args.thisv().toObject().as()); // Step 4. uint64_t newByteLength; if (!ToIndex(cx, args.get(0), &newByteLength)) { return false; } // Step 5. if (obj->isDetached()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED); return false; } if (obj->isLengthPinned()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_PINNED); return false; } // Step 6. if (newByteLength > obj->maxByteLength()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_LARGER_THAN_MAXIMUM); return false; } // Steps 7-15. obj->resize(size_t(newByteLength)); // Step 16. args.rval().setUndefined(); return true; } /** * ArrayBuffer.prototype.resize ( newLength ) * * https://tc39.es/ecma262/#sec-arraybuffer.prototype.resize */ bool ArrayBufferObject::resize(JSContext* cx, unsigned argc, Value* vp) { // Steps 1-3. CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } #endif /* * ArrayBuffer.isView(obj); ES6 (Dec 2013 draft) 24.1.3.1 */ bool ArrayBufferObject::fun_isView(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); args.rval().setBoolean(args.get(0).isObject() && JS_IsArrayBufferViewObject(&args.get(0).toObject())); return true; } // ES2024 draft rev 3a773fc9fae58be023228b13dbbd402ac18eeb6b // 25.1.4.1 ArrayBuffer ( length [ , options ] ) bool ArrayBufferObject::class_constructor(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); // Step 1. if (!ThrowIfNotConstructing(cx, args, "ArrayBuffer")) { return false; } // Step 2. uint64_t byteLength; if (!ToIndex(cx, args.get(0), &byteLength)) { return false; } // Step 3. mozilla::Maybe maxByteLength; #ifdef NIGHTLY_BUILD if (JS::Prefs::experimental_arraybuffer_resizable()) { // Inline call to GetArrayBufferMaxByteLengthOption. if (args.get(1).isObject()) { Rooted options(cx, &args[1].toObject()); Rooted val(cx); if (!GetProperty(cx, options, options, cx->names().maxByteLength, &val)) { return false; } if (!val.isUndefined()) { uint64_t maxByteLengthInt; if (!ToIndex(cx, val, &maxByteLengthInt)) { return false; } // 25.1.3.1 AllocateArrayBuffer, step 3.a. if (byteLength > maxByteLengthInt) { JS_ReportErrorNumberASCII( cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_LARGER_THAN_MAXIMUM); return false; } maxByteLength = mozilla::Some(maxByteLengthInt); } } } #endif // Step 4 (Inlined 25.1.3.1 AllocateArrayBuffer). // 25.1.3.1, step 4 (Inlined 10.1.13 OrdinaryCreateFromConstructor, step 2). RootedObject proto(cx); if (!GetPrototypeFromBuiltinConstructor(cx, args, JSProto_ArrayBuffer, &proto)) { return false; } // 25.1.3.1, step 5 (Inlined 6.2.9.1 CreateByteDataBlock, step 2). if (!CheckArrayBufferTooLarge(cx, byteLength)) { return false; } if (maxByteLength) { // 25.1.3.1, step 8.a. if (!CheckArrayBufferTooLarge(cx, *maxByteLength)) { return false; } // 25.1.3.1, remaining steps. auto* bufobj = ResizableArrayBufferObject::createZeroed( cx, byteLength, *maxByteLength, proto); if (!bufobj) { return false; } args.rval().setObject(*bufobj); return true; } // 25.1.3.1, remaining steps. JSObject* bufobj = createZeroed(cx, byteLength, proto); if (!bufobj) { return false; } args.rval().setObject(*bufobj); return true; } using ArrayBufferContents = UniquePtr; static ArrayBufferContents AllocateUninitializedArrayBufferContents( JSContext* cx, size_t nbytes) { // First attempt a normal allocation. uint8_t* p = cx->maybe_pod_arena_malloc(js::ArrayBufferContentsArena, nbytes); if (MOZ_UNLIKELY(!p)) { // Otherwise attempt a large allocation, calling the // large-allocation-failure callback if necessary. p = static_cast(cx->runtime()->onOutOfMemoryCanGC( js::AllocFunction::Malloc, js::ArrayBufferContentsArena, nbytes)); if (!p) { ReportOutOfMemory(cx); } } return ArrayBufferContents(p); } static ArrayBufferContents AllocateArrayBufferContents(JSContext* cx, size_t nbytes) { // First attempt a normal allocation. uint8_t* p = cx->maybe_pod_arena_calloc(js::ArrayBufferContentsArena, nbytes); if (MOZ_UNLIKELY(!p)) { // Otherwise attempt a large allocation, calling the // large-allocation-failure callback if necessary. p = static_cast(cx->runtime()->onOutOfMemoryCanGC( js::AllocFunction::Calloc, js::ArrayBufferContentsArena, nbytes)); if (!p) { ReportOutOfMemory(cx); } } return ArrayBufferContents(p); } static ArrayBufferContents ReallocateArrayBufferContents(JSContext* cx, uint8_t* old, size_t oldSize, size_t newSize) { // First attempt a normal reallocation. uint8_t* p = cx->maybe_pod_arena_realloc( js::ArrayBufferContentsArena, old, oldSize, newSize); if (MOZ_UNLIKELY(!p)) { // Otherwise attempt a large allocation, calling the // large-allocation-failure callback if necessary. p = static_cast(cx->runtime()->onOutOfMemoryCanGC( js::AllocFunction::Realloc, js::ArrayBufferContentsArena, newSize, old)); if (!p) { ReportOutOfMemory(cx); } } return ArrayBufferContents(p); } static ArrayBufferContents NewCopiedBufferContents( JSContext* cx, Handle buffer) { ArrayBufferContents dataCopy = AllocateUninitializedArrayBufferContents(cx, buffer->byteLength()); if (dataCopy) { if (auto count = buffer->byteLength()) { memcpy(dataCopy.get(), buffer->dataPointer(), count); } } return dataCopy; } /* static */ void ArrayBufferObject::detach(JSContext* cx, Handle buffer) { cx->check(buffer); MOZ_ASSERT(!buffer->isPreparedForAsmJS()); MOZ_ASSERT(!buffer->isLengthPinned()); // Update all views of the buffer to account for the buffer having been // detached, and clear the buffer's data and list of views. auto& innerViews = ObjectRealm::get(buffer).innerViews.get(); if (InnerViewTable::ViewVector* views = innerViews.maybeViewsUnbarriered(buffer)) { for (size_t i = 0; i < views->length(); i++) { JSObject* view = (*views)[i]; view->as().notifyBufferDetached(); } innerViews.removeViews(buffer); } if (JSObject* view = buffer->firstView()) { view->as().notifyBufferDetached(); buffer->setFirstView(nullptr); } if (buffer->dataPointer()) { buffer->releaseData(cx->gcContext()); buffer->setDataPointer(BufferContents::createNoData()); } buffer->setByteLength(0); buffer->setIsDetached(); if (buffer->isResizable()) { buffer->as().setMaxByteLength(0); } } void ResizableArrayBufferObject::resize(size_t newByteLength) { MOZ_ASSERT(!isPreparedForAsmJS()); MOZ_ASSERT(!isWasm()); MOZ_ASSERT(!isDetached()); MOZ_ASSERT(!isLengthPinned()); MOZ_ASSERT(isResizable()); MOZ_ASSERT(newByteLength <= maxByteLength()); // Clear the bytes between `data[newByteLength..oldByteLength]` when // shrinking the buffer. We don't need to clear any bytes when growing the // buffer, because the new space was either initialized to zero when creating // the buffer, or a prior shrink zeroed it out here. size_t oldByteLength = byteLength(); if (newByteLength < oldByteLength) { size_t nbytes = oldByteLength - newByteLength; memset(dataPointer() + newByteLength, 0, nbytes); } setByteLength(newByteLength); // Update all views of the buffer to account for the buffer having been // resized. auto& innerViews = ObjectRealm::get(this).innerViews.get(); if (InnerViewTable::ViewVector* views = innerViews.maybeViewsUnbarriered(this)) { for (auto& view : *views) { view->notifyBufferResized(); } } if (auto* view = firstView()) { view->as().notifyBufferResized(); } } /* clang-format off */ /* * [SMDOC] WASM Linear Memory structure * * Wasm Raw Buf Linear Memory Structure * * The linear heap in Wasm is an mmaped array buffer. Several constants manage * its lifetime: * * - byteLength - the wasm-visible current length of the buffer in * bytes. Accesses in the range [0, byteLength] succeed. May only increase. * * - boundsCheckLimit - the size against which we perform bounds checks. The * value of this depends on the bounds checking strategy chosen for the array * buffer and the specific bounds checking semantics. For asm.js code and * for wasm code running with explicit bounds checking, it is the always the * same as the byteLength. For wasm code using the huge-memory trick, it is * always wasm::GuardSize smaller than mappedSize. * * See also "Linear memory addresses and bounds checking" in * wasm/WasmMemory.cpp. * * See also WasmMemoryObject::boundsCheckLimit(). * * - sourceMaxSize - the optional declared limit on how far byteLength can grow * in pages. This is the unmodified maximum size from the source module or * JS-API invocation. This may not be representable in byte lengths, nor * feasible for a module to actually grow to due to implementation limits. * It is used for correct linking checks and js-types reflection. * * - clampedMaxSize - the maximum size on how far the byteLength can grow in * pages. This value respects implementation limits and is always * representable as a byte length. Every memory has a clampedMaxSize, even if * no maximum was specified in source. When a memory has no sourceMaxSize, * the clampedMaxSize will be the maximum amount of memory that can be grown * to while still respecting implementation limits. * * - mappedSize - the actual mmapped size. Access in the range [0, mappedSize] * will either succeed, or be handled by the wasm signal handlers. If * sourceMaxSize is present at initialization, then we attempt to map the * whole clampedMaxSize. Otherwise we only map the region needed for the * initial size. * * The below diagram shows the layout of the wasm heap. The wasm-visible portion * of the heap starts at 0. There is one extra page prior to the start of the * wasm heap which contains the WasmArrayRawBuffer struct at its end (i.e. right * before the start of the WASM heap). * * WasmArrayRawBuffer * \ ArrayBufferObject::dataPointer() * \ / * \ | * ______|_|______________________________________________________ * |______|_|______________|___________________|___________________| * 0 byteLength clampedMaxSize mappedSize * * \_______________________/ * COMMITED * \_____________________________________/ * SLOP * \______________________________________________________________/ * MAPPED * * Invariants on byteLength, clampedMaxSize, and mappedSize: * - byteLength only increases * - 0 <= byteLength <= clampedMaxSize <= mappedSize * - if sourceMaxSize is not specified, mappedSize may grow. * It is otherwise constant. * - initialLength <= clampedMaxSize <= sourceMaxSize (if present) * - clampedMaxSize <= wasm::MaxMemoryPages() * * Invariants on boundsCheckLimit: * - for wasm code with the huge-memory trick, * clampedMaxSize <= boundsCheckLimit <= mappedSize * - for asm.js code or wasm with explicit bounds checking, * byteLength == boundsCheckLimit <= clampedMaxSize * - on ARM, boundsCheckLimit must be a valid ARM immediate. * - if sourceMaxSize is not specified, boundsCheckLimit may grow as * mappedSize grows. They are otherwise constant. * NOTE: For asm.js on 32-bit platforms and on all platforms when running with * explicit bounds checking, we guarantee that * * byteLength == maxSize == boundsCheckLimit == mappedSize * * That is, signal handlers will not be invoked. * * The region between byteLength and mappedSize is the SLOP - an area where we use * signal handlers to catch things that slip by bounds checks. Logically it has * two parts: * * - from byteLength to boundsCheckLimit - this part of the SLOP serves to catch * accesses to memory we have reserved but not yet grown into. This allows us * to grow memory up to max (when present) without having to patch/update the * bounds checks. * * - from boundsCheckLimit to mappedSize - this part of the SLOP allows us to * bounds check against base pointers and fold some constant offsets inside * loads. This enables better Bounds Check Elimination. See "Linear memory * addresses and bounds checking" in wasm/WasmMemory.cpp. * */ /* clang-format on */ [[nodiscard]] bool WasmArrayRawBuffer::growToPagesInPlace(Pages newPages) { size_t newSize = newPages.byteLength(); size_t oldSize = byteLength(); MOZ_ASSERT(newSize >= oldSize); MOZ_ASSERT(newPages <= clampedMaxPages()); MOZ_ASSERT(newSize <= mappedSize()); size_t delta = newSize - oldSize; MOZ_ASSERT(delta % wasm::PageSize == 0); uint8_t* dataEnd = dataPointer() + oldSize; MOZ_ASSERT(uintptr_t(dataEnd) % gc::SystemPageSize() == 0); if (delta && !CommitBufferMemory(dataEnd, delta)) { return false; } length_ = newSize; return true; } bool WasmArrayRawBuffer::extendMappedSize(Pages maxPages) { size_t newMappedSize = wasm::ComputeMappedSize(maxPages); MOZ_ASSERT(mappedSize_ <= newMappedSize); if (mappedSize_ == newMappedSize) { return true; } if (!ExtendBufferMapping(dataPointer(), mappedSize_, newMappedSize)) { return false; } mappedSize_ = newMappedSize; return true; } void WasmArrayRawBuffer::tryGrowMaxPagesInPlace(Pages deltaMaxPages) { Pages newMaxPages = clampedMaxPages_; DebugOnly valid = newMaxPages.checkedIncrement(deltaMaxPages); // Caller must ensure increment does not overflow or increase over the // specified maximum pages. MOZ_ASSERT(valid); MOZ_ASSERT_IF(sourceMaxPages_.isSome(), newMaxPages <= *sourceMaxPages_); if (!extendMappedSize(newMaxPages)) { return; } clampedMaxPages_ = newMaxPages; } void WasmArrayRawBuffer::discard(size_t byteOffset, size_t byteLen) { uint8_t* memBase = dataPointer(); // The caller is responsible for ensuring these conditions are met; see this // function's comment in ArrayBufferObject.h. MOZ_ASSERT(byteOffset % wasm::PageSize == 0); MOZ_ASSERT(byteLen % wasm::PageSize == 0); MOZ_ASSERT(wasm::MemoryBoundsCheck(uint64_t(byteOffset), uint64_t(byteLen), byteLength())); // Discarding zero bytes "succeeds" with no effect. if (byteLen == 0) { return; } void* addr = memBase + uintptr_t(byteOffset); // On POSIX-ish platforms, we discard memory by overwriting previously-mapped // pages with freshly-mapped pages (which are all zeroed). The operating // system recognizes this and decreases the process RSS, and eventually // collects the abandoned physical pages. // // On Windows, committing over previously-committed pages has no effect, and // the memory must be explicitly decommitted first. This is not the same as an // munmap; the address space is still reserved. #ifdef XP_WIN if (!VirtualFree(addr, byteLen, MEM_DECOMMIT)) { MOZ_CRASH("wasm discard: failed to decommit memory"); } if (!VirtualAlloc(addr, byteLen, MEM_COMMIT, PAGE_READWRITE)) { MOZ_CRASH("wasm discard: decommitted memory but failed to recommit"); }; #elif defined(__wasi__) memset(addr, 0, byteLen); #else // !XP_WIN void* data = MozTaggedAnonymousMmap(addr, byteLen, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0, "wasm-reserved"); if (data == MAP_FAILED) { MOZ_CRASH("failed to discard wasm memory; memory mappings may be broken"); } #endif } /* static */ WasmArrayRawBuffer* WasmArrayRawBuffer::AllocateWasm( IndexType indexType, Pages initialPages, Pages clampedMaxPages, const Maybe& sourceMaxPages, const Maybe& mapped) { // Prior code has asserted that initial pages is within our implementation // limits (wasm::MaxMemoryPages) and we can assume it is a valid size_t. MOZ_ASSERT(initialPages.hasByteLength()); size_t numBytes = initialPages.byteLength(); // If there is a specified maximum, attempt to map the whole range for // clampedMaxPages. Or else map only what's required for initialPages. Pages initialMappedPages = sourceMaxPages.isSome() ? clampedMaxPages : initialPages; // Use an override mapped size, or else compute the mapped size from // initialMappedPages. size_t mappedSize = mapped.isSome() ? *mapped : wasm::ComputeMappedSize(initialMappedPages); MOZ_RELEASE_ASSERT(mappedSize <= SIZE_MAX - gc::SystemPageSize()); MOZ_RELEASE_ASSERT(numBytes <= SIZE_MAX - gc::SystemPageSize()); MOZ_RELEASE_ASSERT(initialPages <= clampedMaxPages); MOZ_ASSERT(numBytes % gc::SystemPageSize() == 0); MOZ_ASSERT(mappedSize % gc::SystemPageSize() == 0); uint64_t mappedSizeWithHeader = mappedSize + gc::SystemPageSize(); uint64_t numBytesWithHeader = numBytes + gc::SystemPageSize(); void* data = MapBufferMemory(indexType, (size_t)mappedSizeWithHeader, (size_t)numBytesWithHeader); if (!data) { return nullptr; } uint8_t* base = reinterpret_cast(data) + gc::SystemPageSize(); uint8_t* header = base - sizeof(WasmArrayRawBuffer); auto rawBuf = new (header) WasmArrayRawBuffer( indexType, base, clampedMaxPages, sourceMaxPages, mappedSize, numBytes); return rawBuf; } /* static */ void WasmArrayRawBuffer::Release(void* mem) { WasmArrayRawBuffer* header = (WasmArrayRawBuffer*)((uint8_t*)mem - sizeof(WasmArrayRawBuffer)); MOZ_RELEASE_ASSERT(header->mappedSize() <= SIZE_MAX - gc::SystemPageSize()); size_t mappedSizeWithHeader = header->mappedSize() + gc::SystemPageSize(); static_assert(std::is_trivially_destructible_v, "no need to call the destructor"); UnmapBufferMemory(header->indexType(), header->basePointer(), mappedSizeWithHeader); } WasmArrayRawBuffer* ArrayBufferObject::BufferContents::wasmBuffer() const { MOZ_RELEASE_ASSERT(kind_ == WASM); return (WasmArrayRawBuffer*)(data_ - sizeof(WasmArrayRawBuffer)); } template static ArrayBufferObjectMaybeShared* CreateSpecificWasmBuffer( JSContext* cx, const wasm::MemoryDesc& memory) { bool useHugeMemory = wasm::IsHugeMemoryEnabled(memory.indexType()); Pages initialPages = memory.initialPages(); Maybe sourceMaxPages = memory.maximumPages(); Pages clampedMaxPages = wasm::ClampedMaxPages( memory.indexType(), initialPages, sourceMaxPages, useHugeMemory); Maybe mappedSize; #ifdef WASM_SUPPORTS_HUGE_MEMORY // Override the mapped size if we are using huge memory. If we are not, then // it will be calculated by the raw buffer we are using. if (useHugeMemory) { mappedSize = Some(wasm::HugeMappedSize); } #endif RawbufT* buffer = RawbufT::AllocateWasm(memory.limits.indexType, initialPages, clampedMaxPages, sourceMaxPages, mappedSize); if (!buffer) { if (useHugeMemory) { WarnNumberASCII(cx, JSMSG_WASM_HUGE_MEMORY_FAILED); if (cx->isExceptionPending()) { cx->clearPendingException(); } ReportOutOfMemory(cx); return nullptr; } // If we fail, and have a sourceMaxPages, try to reserve the biggest // chunk in the range [initialPages, clampedMaxPages) using log backoff. if (!sourceMaxPages) { wasm::Log(cx, "new Memory({initial=%" PRIu64 " pages}) failed", initialPages.value()); ReportOutOfMemory(cx); return nullptr; } uint64_t cur = clampedMaxPages.value() / 2; for (; Pages(cur) > initialPages; cur /= 2) { buffer = RawbufT::AllocateWasm(memory.limits.indexType, initialPages, Pages(cur), sourceMaxPages, mappedSize); if (buffer) { break; } } if (!buffer) { wasm::Log(cx, "new Memory({initial=%" PRIu64 " pages}) failed", initialPages.value()); ReportOutOfMemory(cx); return nullptr; } // Try to grow our chunk as much as possible. for (size_t d = cur / 2; d >= 1; d /= 2) { buffer->tryGrowMaxPagesInPlace(Pages(d)); } } // ObjT::createFromNewRawBuffer assumes ownership of |buffer| even in case // of failure. Rooted object( cx, ObjT::createFromNewRawBuffer(cx, buffer, initialPages.byteLength())); if (!object) { return nullptr; } // See MaximumLiveMappedBuffers comment above. if (wasmReservedBytes > WasmReservedBytesStartSyncFullGC) { JS::PrepareForFullGC(cx); JS::NonIncrementalGC(cx, JS::GCOptions::Normal, JS::GCReason::TOO_MUCH_WASM_MEMORY); wasmReservedBytesSinceLast = 0; } else if (wasmReservedBytes > WasmReservedBytesStartTriggering) { wasmReservedBytesSinceLast += uint64_t(buffer->mappedSize()); if (wasmReservedBytesSinceLast > WasmReservedBytesPerTrigger) { (void)cx->runtime()->gc.triggerGC(JS::GCReason::TOO_MUCH_WASM_MEMORY); wasmReservedBytesSinceLast = 0; } } else { wasmReservedBytesSinceLast = 0; } // Log the result with details on the memory allocation if (sourceMaxPages) { if (useHugeMemory) { wasm::Log(cx, "new Memory({initial:%" PRIu64 " pages, maximum:%" PRIu64 " pages}) succeeded", initialPages.value(), sourceMaxPages->value()); } else { wasm::Log(cx, "new Memory({initial:%" PRIu64 " pages, maximum:%" PRIu64 " pages}) succeeded " "with internal maximum of %" PRIu64 " pages", initialPages.value(), sourceMaxPages->value(), object->wasmClampedMaxPages().value()); } } else { wasm::Log(cx, "new Memory({initial:%" PRIu64 " pages}) succeeded", initialPages.value()); } return object; } ArrayBufferObjectMaybeShared* js::CreateWasmBuffer( JSContext* cx, const wasm::MemoryDesc& memory) { MOZ_RELEASE_ASSERT(memory.initialPages() <= wasm::MaxMemoryPages(memory.indexType())); MOZ_RELEASE_ASSERT(cx->wasm().haveSignalHandlers); if (memory.isShared()) { if (!cx->realm()->creationOptions().getSharedMemoryAndAtomicsEnabled()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_SHMEM_LINK); return nullptr; } return CreateSpecificWasmBuffer(cx, memory); } return CreateSpecificWasmBuffer( cx, memory); } bool ArrayBufferObject::prepareForAsmJS() { MOZ_ASSERT(byteLength() % wasm::PageSize == 0, "prior size checking should have guaranteed page-size multiple"); MOZ_ASSERT(byteLength() > 0, "prior size checking should have excluded empty buffers"); MOZ_ASSERT(!isResizable(), "prior checks should have excluded resizable buffers"); switch (bufferKind()) { case MALLOCED_ARRAYBUFFER_CONTENTS_ARENA: case MALLOCED_UNKNOWN_ARENA: case MAPPED: case EXTERNAL: // It's okay if this uselessly sets the flag a second time. setIsPreparedForAsmJS(); return true; case INLINE_DATA: static_assert( wasm::PageSize > FixedLengthArrayBufferObject::MaxInlineBytes, "inline data must be too small to be a page size multiple"); MOZ_ASSERT_UNREACHABLE( "inline-data buffers should be implicitly excluded by size checks"); return false; case NO_DATA: MOZ_ASSERT_UNREACHABLE( "size checking should have excluded detached or empty buffers"); return false; // asm.js code and associated buffers are potentially long-lived. Yet a // buffer of user-owned data *must* be detached by the user before the // user-owned data is disposed. No caller wants to use a user-owned // ArrayBuffer with asm.js, so just don't support this and avoid a mess of // complexity. case USER_OWNED: // wasm buffers can be detached at any time. case WASM: MOZ_ASSERT(!isPreparedForAsmJS()); return false; } MOZ_ASSERT_UNREACHABLE("non-exhaustive kind-handling switch?"); return false; } ArrayBufferObject::BufferContents ArrayBufferObject::createMappedContents( int fd, size_t offset, size_t length) { void* data = gc::AllocateMappedContent(fd, offset, length, ARRAY_BUFFER_ALIGNMENT); return BufferContents::createMapped(data); } uint8_t* FixedLengthArrayBufferObject::inlineDataPointer() const { return static_cast(fixedData(JSCLASS_RESERVED_SLOTS(&class_))); } uint8_t* ResizableArrayBufferObject::inlineDataPointer() const { return static_cast(fixedData(JSCLASS_RESERVED_SLOTS(&class_))); } uint8_t* ArrayBufferObject::dataPointer() const { return static_cast(getFixedSlot(DATA_SLOT).toPrivate()); } SharedMem ArrayBufferObject::dataPointerShared() const { return SharedMem::unshared(getFixedSlot(DATA_SLOT).toPrivate()); } ArrayBufferObject::FreeInfo* ArrayBufferObject::freeInfo() const { MOZ_ASSERT(isExternal()); MOZ_ASSERT(!isResizable()); auto* data = as().inlineDataPointer(); return reinterpret_cast(data); } void ArrayBufferObject::releaseData(JS::GCContext* gcx) { switch (bufferKind()) { case INLINE_DATA: // Inline data doesn't require releasing. break; case MALLOCED_ARRAYBUFFER_CONTENTS_ARENA: case MALLOCED_UNKNOWN_ARENA: gcx->free_(this, dataPointer(), associatedBytes(), MemoryUse::ArrayBufferContents); break; case NO_DATA: // There's nothing to release if there's no data. MOZ_ASSERT(dataPointer() == nullptr); break; case USER_OWNED: // User-owned data is released by, well, the user. break; case MAPPED: gc::DeallocateMappedContent(dataPointer(), byteLength()); gcx->removeCellMemory(this, associatedBytes(), MemoryUse::ArrayBufferContents); break; case WASM: WasmArrayRawBuffer::Release(dataPointer()); gcx->removeCellMemory(this, byteLength(), MemoryUse::ArrayBufferContents); break; case EXTERNAL: MOZ_ASSERT(freeInfo()->freeFunc); { // The analyzer can't know for sure whether the embedder-supplied // free function will GC. We give the analyzer a hint here. // (Doing a GC in the free function is considered a programmer // error.) JS::AutoSuppressGCAnalysis nogc; freeInfo()->freeFunc(dataPointer(), freeInfo()->freeUserData); } break; } } void ArrayBufferObject::setDataPointer(BufferContents contents) { setFixedSlot(DATA_SLOT, PrivateValue(contents.data())); setFlags((flags() & ~KIND_MASK) | contents.kind()); if (isExternal()) { auto info = freeInfo(); info->freeFunc = contents.freeFunc(); info->freeUserData = contents.freeUserData(); } } size_t ArrayBufferObject::byteLength() const { return size_t(getFixedSlot(BYTE_LENGTH_SLOT).toPrivate()); } inline size_t ArrayBufferObject::associatedBytes() const { if (isMalloced()) { return maxByteLength(); } if (isMapped()) { return RoundUp(byteLength(), js::gc::SystemPageSize()); } MOZ_CRASH("Unexpected buffer kind"); } void ArrayBufferObject::setByteLength(size_t length) { MOZ_ASSERT(length <= ArrayBufferObject::ByteLengthLimit); setFixedSlot(BYTE_LENGTH_SLOT, PrivateValue(length)); } size_t ArrayBufferObject::wasmMappedSize() const { if (isWasm()) { return contents().wasmBuffer()->mappedSize(); } return byteLength(); } IndexType ArrayBufferObject::wasmIndexType() const { if (isWasm()) { return contents().wasmBuffer()->indexType(); } MOZ_ASSERT(isPreparedForAsmJS()); return wasm::IndexType::I32; } Pages ArrayBufferObject::wasmPages() const { if (isWasm()) { return contents().wasmBuffer()->pages(); } MOZ_ASSERT(isPreparedForAsmJS()); return Pages::fromByteLengthExact(byteLength()); } Pages ArrayBufferObject::wasmClampedMaxPages() const { if (isWasm()) { return contents().wasmBuffer()->clampedMaxPages(); } MOZ_ASSERT(isPreparedForAsmJS()); return Pages::fromByteLengthExact(byteLength()); } Maybe ArrayBufferObject::wasmSourceMaxPages() const { if (isWasm()) { return contents().wasmBuffer()->sourceMaxPages(); } MOZ_ASSERT(isPreparedForAsmJS()); return Some(Pages::fromByteLengthExact(byteLength())); } size_t js::WasmArrayBufferMappedSize(const ArrayBufferObjectMaybeShared* buf) { if (buf->is()) { return buf->as().wasmMappedSize(); } return buf->as().wasmMappedSize(); } IndexType js::WasmArrayBufferIndexType( const ArrayBufferObjectMaybeShared* buf) { if (buf->is()) { return buf->as().wasmIndexType(); } return buf->as().wasmIndexType(); } Pages js::WasmArrayBufferPages(const ArrayBufferObjectMaybeShared* buf) { if (buf->is()) { return buf->as().wasmPages(); } return buf->as().volatileWasmPages(); } Pages js::WasmArrayBufferClampedMaxPages( const ArrayBufferObjectMaybeShared* buf) { if (buf->is()) { return buf->as().wasmClampedMaxPages(); } return buf->as().wasmClampedMaxPages(); } Maybe js::WasmArrayBufferSourceMaxPages( const ArrayBufferObjectMaybeShared* buf) { if (buf->is()) { return buf->as().wasmSourceMaxPages(); } return Some(buf->as().wasmSourceMaxPages()); } static void CheckStealPreconditions(Handle buffer, JSContext* cx) { cx->check(buffer); MOZ_ASSERT(!buffer->isDetached(), "can't steal from a detached buffer"); MOZ_ASSERT(!buffer->isLengthPinned(), "can't steal from a buffer with a pinned length"); MOZ_ASSERT(!buffer->isPreparedForAsmJS(), "asm.js-prepared buffers don't have detachable/stealable data"); } /* static */ ArrayBufferObject* ArrayBufferObject::wasmGrowToPagesInPlace( wasm::IndexType t, Pages newPages, Handle oldBuf, JSContext* cx) { if (oldBuf->isLengthPinned()) { return nullptr; } CheckStealPreconditions(oldBuf, cx); MOZ_ASSERT(oldBuf->isWasm()); // Check that the new pages is within our allowable range. This will // simultaneously check against the maximum specified in source and our // implementation limits. if (newPages > oldBuf->wasmClampedMaxPages()) { return nullptr; } MOZ_ASSERT(newPages <= wasm::MaxMemoryPages(t) && newPages.byteLength() <= ArrayBufferObject::ByteLengthLimit); // We have checked against the clamped maximum and so we know we can convert // to byte lengths now. size_t newSize = newPages.byteLength(); // On failure, do not throw and ensure that the original buffer is // unmodified and valid. After WasmArrayRawBuffer::growToPagesInPlace(), the // wasm-visible length of the buffer has been increased so it must be the // last fallible operation. auto* newBuf = ArrayBufferObject::createEmpty(cx); if (!newBuf) { cx->clearPendingException(); return nullptr; } MOZ_ASSERT(newBuf->isNoData()); if (!oldBuf->contents().wasmBuffer()->growToPagesInPlace(newPages)) { return nullptr; } // Extract the grown contents from |oldBuf|. BufferContents oldContents = oldBuf->contents(); // Overwrite |oldBuf|'s data pointer *without* releasing old data. oldBuf->setDataPointer(BufferContents::createNoData()); // Detach |oldBuf| now that doing so won't release |oldContents|. RemoveCellMemory(oldBuf, oldBuf->byteLength(), MemoryUse::ArrayBufferContents); ArrayBufferObject::detach(cx, oldBuf); // Set |newBuf|'s contents to |oldBuf|'s original contents. newBuf->initialize(newSize, oldContents); AddCellMemory(newBuf, newSize, MemoryUse::ArrayBufferContents); return newBuf; } /* static */ ArrayBufferObject* ArrayBufferObject::wasmMovingGrowToPages( IndexType t, Pages newPages, Handle oldBuf, JSContext* cx) { // On failure, do not throw and ensure that the original buffer is // unmodified and valid. if (oldBuf->isLengthPinned()) { return nullptr; } // Check that the new pages is within our allowable range. This will // simultaneously check against the maximum specified in source and our // implementation limits. if (newPages > oldBuf->wasmClampedMaxPages()) { return nullptr; } MOZ_ASSERT(newPages <= wasm::MaxMemoryPages(t) && newPages.byteLength() < ArrayBufferObject::ByteLengthLimit); // We have checked against the clamped maximum and so we know we can convert // to byte lengths now. size_t newSize = newPages.byteLength(); if (wasm::ComputeMappedSize(newPages) <= oldBuf->wasmMappedSize() || oldBuf->contents().wasmBuffer()->extendMappedSize(newPages)) { return wasmGrowToPagesInPlace(t, newPages, oldBuf, cx); } Rooted newBuf(cx, ArrayBufferObject::createEmpty(cx)); if (!newBuf) { cx->clearPendingException(); return nullptr; } Pages clampedMaxPages = wasm::ClampedMaxPages(t, newPages, Nothing(), /* hugeMemory */ false); WasmArrayRawBuffer* newRawBuf = WasmArrayRawBuffer::AllocateWasm( oldBuf->wasmIndexType(), newPages, clampedMaxPages, Nothing(), Nothing()); if (!newRawBuf) { return nullptr; } AddCellMemory(newBuf, newSize, MemoryUse::ArrayBufferContents); BufferContents contents = BufferContents::createWasm(newRawBuf->dataPointer()); newBuf->initialize(newSize, contents); memcpy(newBuf->dataPointer(), oldBuf->dataPointer(), oldBuf->byteLength()); ArrayBufferObject::detach(cx, oldBuf); return newBuf; } /* static */ void ArrayBufferObject::wasmDiscard(Handle buf, uint64_t byteOffset, uint64_t byteLen) { MOZ_ASSERT(buf->isWasm()); buf->contents().wasmBuffer()->discard(byteOffset, byteLen); } uint32_t ArrayBufferObject::flags() const { return uint32_t(getFixedSlot(FLAGS_SLOT).toInt32()); } void ArrayBufferObject::setFlags(uint32_t flags) { setFixedSlot(FLAGS_SLOT, Int32Value(flags)); } static constexpr js::gc::AllocKind GetArrayBufferGCObjectKind(size_t numSlots) { if (numSlots <= 4) { return js::gc::AllocKind::ARRAYBUFFER4; } if (numSlots <= 8) { return js::gc::AllocKind::ARRAYBUFFER8; } if (numSlots <= 12) { return js::gc::AllocKind::ARRAYBUFFER12; } return js::gc::AllocKind::ARRAYBUFFER16; } template static ArrayBufferType* NewArrayBufferObject(JSContext* cx, HandleObject proto_, gc::AllocKind allocKind) { MOZ_ASSERT(allocKind == gc::AllocKind::ARRAYBUFFER4 || allocKind == gc::AllocKind::ARRAYBUFFER8 || allocKind == gc::AllocKind::ARRAYBUFFER12 || allocKind == gc::AllocKind::ARRAYBUFFER16); static_assert(std::is_same_v || std::is_same_v); RootedObject proto(cx, proto_); if (!proto) { proto = GlobalObject::getOrCreatePrototype(cx, JSProto_ArrayBuffer); if (!proto) { return nullptr; } } const JSClass* clasp = &ArrayBufferType::class_; // Array buffers can store data inline so we only use fixed slots to cover the // reserved slots, ignoring the AllocKind. MOZ_ASSERT(ClassCanHaveFixedData(clasp)); constexpr size_t nfixed = ArrayBufferType::RESERVED_SLOTS; static_assert(nfixed <= NativeObject::MAX_FIXED_SLOTS); Rooted shape( cx, SharedShape::getInitialShape(cx, clasp, cx->realm(), AsTaggedProto(proto), nfixed, ObjectFlags())); if (!shape) { return nullptr; } // Array buffers can't be nursery allocated but can be background-finalized. MOZ_ASSERT(IsBackgroundFinalized(allocKind)); MOZ_ASSERT(!CanNurseryAllocateFinalizedClass(clasp)); constexpr gc::Heap heap = gc::Heap::Tenured; return NativeObject::create(cx, allocKind, heap, shape); } // Creates a new ArrayBufferObject with %ArrayBuffer.prototype% as proto and no // space for inline data. static ArrayBufferObject* NewArrayBufferObject(JSContext* cx) { constexpr auto allocKind = GetArrayBufferGCObjectKind(FixedLengthArrayBufferObject::RESERVED_SLOTS); return NewArrayBufferObject(cx, nullptr, allocKind); } static ResizableArrayBufferObject* NewResizableArrayBufferObject( JSContext* cx) { constexpr auto allocKind = GetArrayBufferGCObjectKind(ResizableArrayBufferObject::RESERVED_SLOTS); return NewArrayBufferObject(cx, nullptr, allocKind); } ArrayBufferObject* ArrayBufferObject::createForContents( JSContext* cx, size_t nbytes, BufferContents contents) { MOZ_ASSERT(contents); MOZ_ASSERT(contents.kind() != INLINE_DATA); MOZ_ASSERT(contents.kind() != NO_DATA); MOZ_ASSERT(contents.kind() != WASM); // 24.1.1.1, step 3 (Inlined 6.2.6.1 CreateByteDataBlock, step 2). if (!CheckArrayBufferTooLarge(cx, nbytes)) { return nullptr; } // Some |contents| kinds need to store extra data in the ArrayBuffer beyond a // data pointer. If needed for the particular kind, add extra fixed slots to // the ArrayBuffer for use as raw storage to store such information. constexpr size_t reservedSlots = FixedLengthArrayBufferObject::RESERVED_SLOTS; size_t nAllocated = 0; size_t nslots = reservedSlots; if (contents.kind() == USER_OWNED) { // No accounting to do in this case. } else if (contents.kind() == EXTERNAL) { // Store the FreeInfo in the inline data slots so that we // don't use up slots for it in non-refcounted array buffers. constexpr size_t freeInfoSlots = HowMany(sizeof(FreeInfo), sizeof(Value)); static_assert( reservedSlots + freeInfoSlots <= NativeObject::MAX_FIXED_SLOTS, "FreeInfo must fit in inline slots"); nslots += freeInfoSlots; } else { // The ABO is taking ownership, so account the bytes against the zone. nAllocated = nbytes; if (contents.kind() == MAPPED) { nAllocated = RoundUp(nbytes, js::gc::SystemPageSize()); } else { MOZ_ASSERT(contents.kind() == MALLOCED_ARRAYBUFFER_CONTENTS_ARENA || contents.kind() == MALLOCED_UNKNOWN_ARENA, "should have handled all possible callers' kinds"); } } gc::AllocKind allocKind = GetArrayBufferGCObjectKind(nslots); AutoSetNewObjectMetadata metadata(cx); Rooted buffer( cx, NewArrayBufferObject(cx, nullptr, allocKind)); if (!buffer) { return nullptr; } MOZ_ASSERT(!gc::IsInsideNursery(buffer), "ArrayBufferObject has a finalizer that must be called to not " "leak in some cases, so it can't be nursery-allocated"); buffer->initialize(nbytes, contents); if (contents.kind() == MAPPED || contents.kind() == MALLOCED_ARRAYBUFFER_CONTENTS_ARENA || contents.kind() == MALLOCED_UNKNOWN_ARENA) { AddCellMemory(buffer, nAllocated, MemoryUse::ArrayBufferContents); } return buffer; } template /* static */ std::tuple ArrayBufferObject::createUninitializedBufferAndData( JSContext* cx, size_t nbytes, AutoSetNewObjectMetadata&, JS::Handle proto) { MOZ_ASSERT(nbytes <= ArrayBufferObject::ByteLengthLimit, "caller must validate the byte count it passes"); static_assert(std::is_same_v || std::is_same_v); // Try fitting the data inline with the object by repurposing fixed-slot // storage. Add extra fixed slots if necessary to accomplish this, but don't // exceed the maximum number of fixed slots! size_t nslots = ArrayBufferType::RESERVED_SLOTS; ArrayBufferContents data; if (nbytes <= ArrayBufferType::MaxInlineBytes) { int newSlots = HowMany(nbytes, sizeof(Value)); MOZ_ASSERT(int(nbytes) <= newSlots * int(sizeof(Value))); nslots += newSlots; } else { data = FillType == FillContents::Uninitialized ? AllocateUninitializedArrayBufferContents(cx, nbytes) : AllocateArrayBufferContents(cx, nbytes); if (!data) { return {nullptr, nullptr}; } } gc::AllocKind allocKind = GetArrayBufferGCObjectKind(nslots); auto* buffer = NewArrayBufferObject(cx, proto, allocKind); if (!buffer) { return {nullptr, nullptr}; } MOZ_ASSERT(!gc::IsInsideNursery(buffer), "ArrayBufferObject has a finalizer that must be called to not " "leak in some cases, so it can't be nursery-allocated"); if (data) { return {buffer, data.release()}; } if constexpr (FillType == FillContents::Zero) { memset(buffer->inlineDataPointer(), 0, nbytes); } return {buffer, nullptr}; } template /* static */ std::tuple ArrayBufferObject::createBufferAndData( JSContext* cx, size_t nbytes, AutoSetNewObjectMetadata& metadata, JS::Handle proto /* = nullptr */) { MOZ_ASSERT(nbytes <= ArrayBufferObject::ByteLengthLimit, "caller must validate the byte count it passes"); auto [buffer, data] = createUninitializedBufferAndData( cx, nbytes, metadata, proto); if (!buffer) { return {nullptr, nullptr}; } if (data) { buffer->initialize( nbytes, BufferContents::createMallocedArrayBufferContentsArena(data)); AddCellMemory(buffer, nbytes, MemoryUse::ArrayBufferContents); } else { data = buffer->inlineDataPointer(); buffer->initialize(nbytes, BufferContents::createInlineData(data)); } return {buffer, data}; } template /* static */ std::tuple ResizableArrayBufferObject::createBufferAndData( JSContext* cx, size_t byteLength, size_t maxByteLength, AutoSetNewObjectMetadata& metadata, Handle proto) { MOZ_ASSERT(byteLength <= maxByteLength); MOZ_ASSERT(maxByteLength <= ArrayBufferObject::ByteLengthLimit, "caller must validate the byte count it passes"); // NOTE: The spec proposal for resizable ArrayBuffers suggests to use a // virtual memory based approach to avoid eagerly allocating the maximum byte // length. We don't yet support this and instead are allocating the maximum // byte length direct from the start. size_t nbytes = maxByteLength; auto [buffer, data] = createUninitializedBufferAndData( cx, nbytes, metadata, proto); if (!buffer) { return {nullptr, nullptr}; } if (data) { buffer->initialize( byteLength, maxByteLength, BufferContents::createMallocedArrayBufferContentsArena(data)); AddCellMemory(buffer, nbytes, MemoryUse::ArrayBufferContents); } else { data = buffer->inlineDataPointer(); buffer->initialize(byteLength, maxByteLength, BufferContents::createInlineData(data)); } return {buffer, data}; } /* static */ ArrayBufferObject* ArrayBufferObject::copy( JSContext* cx, size_t newByteLength, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(newByteLength <= ArrayBufferObject::ByteLengthLimit, "caller must validate the byte count it passes"); size_t sourceByteLength = source->byteLength(); if (newByteLength > sourceByteLength) { // Copy into a larger buffer. AutoSetNewObjectMetadata metadata(cx); auto [buffer, toFill] = createBufferAndData( cx, newByteLength, metadata, nullptr); if (!buffer) { return nullptr; } std::copy_n(source->dataPointer(), sourceByteLength, toFill); return buffer; } // Copy into a smaller or same size buffer. AutoSetNewObjectMetadata metadata(cx); auto [buffer, toFill] = createBufferAndData( cx, newByteLength, metadata, nullptr); if (!buffer) { return nullptr; } std::uninitialized_copy_n(source->dataPointer(), newByteLength, toFill); return buffer; } /* static */ ResizableArrayBufferObject* ResizableArrayBufferObject::copy( JSContext* cx, size_t newByteLength, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(newByteLength <= source->maxByteLength()); size_t sourceByteLength = source->byteLength(); size_t newMaxByteLength = source->maxByteLength(); if (newByteLength > sourceByteLength) { // Copy into a larger buffer. AutoSetNewObjectMetadata metadata(cx); auto [buffer, toFill] = createBufferAndData( cx, newByteLength, newMaxByteLength, metadata, nullptr); if (!buffer) { return nullptr; } // The `createBufferAndData()` call first zero-initializes the complete // buffer and then we copy over |sourceByteLength| bytes from |source|. It // seems prudent to only zero-initialize the trailing bytes of |toFill| // to avoid writing twice to `toFill[0..newByteLength]`. We don't yet // implement this optimization, because this method is only called for // small, inline buffers, so any write optimizations probably won't make // much of a difference. std::copy_n(source->dataPointer(), sourceByteLength, toFill); return buffer; } // Copy into a smaller or same size buffer. AutoSetNewObjectMetadata metadata(cx); auto [buffer, toFill] = createBufferAndData( cx, newByteLength, newMaxByteLength, metadata, nullptr); if (!buffer) { return nullptr; } std::uninitialized_copy_n(source->dataPointer(), newByteLength, toFill); return buffer; } /* static */ ArrayBufferObject* ArrayBufferObject::copyAndDetach( JSContext* cx, size_t newByteLength, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(!source->isLengthPinned()); MOZ_ASSERT(newByteLength <= ArrayBufferObject::ByteLengthLimit, "caller must validate the byte count it passes"); if (newByteLength > FixedLengthArrayBufferObject::MaxInlineBytes && source->isMalloced()) { if (newByteLength == source->associatedBytes()) { return copyAndDetachSteal(cx, source); } if (source->bufferKind() == ArrayBufferObject::MALLOCED_ARRAYBUFFER_CONTENTS_ARENA) { return copyAndDetachRealloc(cx, newByteLength, source); } } auto* newBuffer = ArrayBufferObject::copy(cx, newByteLength, source); if (!newBuffer) { return nullptr; } ArrayBufferObject::detach(cx, source); return newBuffer; } /* static */ ArrayBufferObject* ArrayBufferObject::copyAndDetachSteal( JSContext* cx, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(!source->isLengthPinned()); MOZ_ASSERT(source->isMalloced()); size_t newByteLength = source->associatedBytes(); MOZ_ASSERT(newByteLength > FixedLengthArrayBufferObject::MaxInlineBytes, "prefer copying small buffers"); MOZ_ASSERT(source->byteLength() <= newByteLength, "source length is less-or-equal to |newByteLength|"); auto* newBuffer = ArrayBufferObject::createEmpty(cx); if (!newBuffer) { return nullptr; } // Extract the contents from |source|. BufferContents contents = source->contents(); MOZ_ASSERT(contents); MOZ_ASSERT(contents.kind() == MALLOCED_ARRAYBUFFER_CONTENTS_ARENA || contents.kind() == MALLOCED_UNKNOWN_ARENA); // Overwrite |source|'s data pointer *without* releasing the data. source->setDataPointer(BufferContents::createNoData()); // Detach |source| now that doing so won't release |contents|. RemoveCellMemory(source, newByteLength, MemoryUse::ArrayBufferContents); ArrayBufferObject::detach(cx, source); // Set |newBuffer|'s contents to |source|'s original contents. newBuffer->initialize(newByteLength, contents); AddCellMemory(newBuffer, newByteLength, MemoryUse::ArrayBufferContents); return newBuffer; } /* static */ ArrayBufferObject* ArrayBufferObject::copyAndDetachRealloc( JSContext* cx, size_t newByteLength, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(!source->isLengthPinned()); MOZ_ASSERT(source->bufferKind() == MALLOCED_ARRAYBUFFER_CONTENTS_ARENA); MOZ_ASSERT(newByteLength > FixedLengthArrayBufferObject::MaxInlineBytes, "prefer copying small buffers"); MOZ_ASSERT(newByteLength <= ArrayBufferObject::ByteLengthLimit, "caller must validate the byte count it passes"); size_t oldByteLength = source->associatedBytes(); MOZ_ASSERT(oldByteLength != newByteLength, "steal instead of realloc same size buffers"); MOZ_ASSERT(source->byteLength() <= oldByteLength, "source length is less-or-equal to |oldByteLength|"); Rooted newBuffer(cx, ArrayBufferObject::createEmpty(cx)); if (!newBuffer) { return nullptr; } // Extract the contents from |source|. BufferContents contents = source->contents(); MOZ_ASSERT(contents); MOZ_ASSERT(contents.kind() == MALLOCED_ARRAYBUFFER_CONTENTS_ARENA); // Reallocate the data pointer. auto newData = ReallocateArrayBufferContents(cx, contents.data(), oldByteLength, newByteLength); if (!newData) { // If reallocation failed, the old pointer is still valid, so just return. return nullptr; } auto newContents = BufferContents::createMallocedArrayBufferContentsArena(newData.release()); // Overwrite |source|'s data pointer *without* releasing the data. source->setDataPointer(BufferContents::createNoData()); // Detach |source| now that doing so won't release |contents|. RemoveCellMemory(source, oldByteLength, MemoryUse::ArrayBufferContents); ArrayBufferObject::detach(cx, source); // Set |newBuffer|'s contents to |newContents|. newBuffer->initialize(newByteLength, newContents); AddCellMemory(newBuffer, newByteLength, MemoryUse::ArrayBufferContents); // Zero initialize the newly allocated memory, if necessary. if (newByteLength > oldByteLength) { size_t count = newByteLength - oldByteLength; std::uninitialized_fill_n(newContents.data() + oldByteLength, count, 0); } return newBuffer; } /* static */ ResizableArrayBufferObject* ResizableArrayBufferObject::copyAndDetach( JSContext* cx, size_t newByteLength, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(!source->isLengthPinned()); MOZ_ASSERT(newByteLength <= source->maxByteLength()); if (source->maxByteLength() > ResizableArrayBufferObject::MaxInlineBytes && source->isMalloced()) { return copyAndDetachSteal(cx, newByteLength, source); } auto* newBuffer = ResizableArrayBufferObject::copy(cx, newByteLength, source); if (!newBuffer) { return nullptr; } ArrayBufferObject::detach(cx, source); return newBuffer; } /* static */ ResizableArrayBufferObject* ResizableArrayBufferObject::copyAndDetachSteal( JSContext* cx, size_t newByteLength, JS::Handle source) { MOZ_ASSERT(!source->isDetached()); MOZ_ASSERT(!source->isLengthPinned()); MOZ_ASSERT(newByteLength <= source->maxByteLength()); MOZ_ASSERT(source->isMalloced()); size_t sourceByteLength = source->byteLength(); size_t maxByteLength = source->maxByteLength(); MOZ_ASSERT(maxByteLength > ResizableArrayBufferObject::MaxInlineBytes, "prefer copying small buffers"); auto* newBuffer = ResizableArrayBufferObject::createEmpty(cx); if (!newBuffer) { return nullptr; } // Extract the contents from |source|. BufferContents contents = source->contents(); MOZ_ASSERT(contents); MOZ_ASSERT(contents.kind() == MALLOCED_ARRAYBUFFER_CONTENTS_ARENA || contents.kind() == MALLOCED_UNKNOWN_ARENA); // Overwrite |source|'s data pointer *without* releasing the data. source->setDataPointer(BufferContents::createNoData()); // Detach |source| now that doing so won't release |contents|. RemoveCellMemory(source, maxByteLength, MemoryUse::ArrayBufferContents); ArrayBufferObject::detach(cx, source); // Set |newBuffer|'s contents to |source|'s original contents. newBuffer->initialize(newByteLength, maxByteLength, contents); AddCellMemory(newBuffer, maxByteLength, MemoryUse::ArrayBufferContents); // Clear the bytes between `data[newByteLength..sourceByteLength]`. if (newByteLength < sourceByteLength) { size_t nbytes = sourceByteLength - newByteLength; memset(newBuffer->dataPointer() + newByteLength, 0, nbytes); } return newBuffer; } ArrayBufferObject* ArrayBufferObject::createZeroed( JSContext* cx, size_t nbytes, HandleObject proto /* = nullptr */) { // 24.1.1.1, step 3 (Inlined 6.2.6.1 CreateByteDataBlock, step 2). if (!CheckArrayBufferTooLarge(cx, nbytes)) { return nullptr; } AutoSetNewObjectMetadata metadata(cx); auto [buffer, toFill] = createBufferAndData(cx, nbytes, metadata, proto); (void)toFill; return buffer; } ResizableArrayBufferObject* ResizableArrayBufferObject::createZeroed( JSContext* cx, size_t byteLength, size_t maxByteLength, HandleObject proto /* = nullptr */) { // 24.1.1.1, step 3 (Inlined 6.2.6.1 CreateByteDataBlock, step 2). if (!CheckArrayBufferTooLarge(cx, byteLength) || !CheckArrayBufferTooLarge(cx, maxByteLength)) { return nullptr; } if (byteLength > maxByteLength) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_LARGER_THAN_MAXIMUM); return nullptr; } AutoSetNewObjectMetadata metadata(cx); auto [buffer, toFill] = createBufferAndData( cx, byteLength, maxByteLength, metadata, proto); (void)toFill; return buffer; } ArrayBufferObject* ArrayBufferObject::createEmpty(JSContext* cx) { AutoSetNewObjectMetadata metadata(cx); ArrayBufferObject* obj = NewArrayBufferObject(cx); if (!obj) { return nullptr; } obj->initialize(0, BufferContents::createNoData()); return obj; } ResizableArrayBufferObject* ResizableArrayBufferObject::createEmpty( JSContext* cx) { AutoSetNewObjectMetadata metadata(cx); auto* obj = NewResizableArrayBufferObject(cx); if (!obj) { return nullptr; } obj->initialize(0, 0, BufferContents::createNoData()); return obj; } ArrayBufferObject* ArrayBufferObject::createFromNewRawBuffer( JSContext* cx, WasmArrayRawBuffer* rawBuffer, size_t initialSize) { AutoSetNewObjectMetadata metadata(cx); ArrayBufferObject* buffer = NewArrayBufferObject(cx); if (!buffer) { WasmArrayRawBuffer::Release(rawBuffer->dataPointer()); return nullptr; } MOZ_ASSERT(initialSize == rawBuffer->byteLength()); auto contents = BufferContents::createWasm(rawBuffer->dataPointer()); buffer->initialize(initialSize, contents); AddCellMemory(buffer, initialSize, MemoryUse::ArrayBufferContents); return buffer; } /* static */ uint8_t* ArrayBufferObject::stealMallocedContents( JSContext* cx, Handle buffer) { CheckStealPreconditions(buffer, cx); switch (buffer->bufferKind()) { case MALLOCED_ARRAYBUFFER_CONTENTS_ARENA: case MALLOCED_UNKNOWN_ARENA: { uint8_t* stolenData = buffer->dataPointer(); MOZ_ASSERT(stolenData); // Resizable buffers are initially allocated with their maximum // byte-length. When stealing the buffer contents shrink the allocated // memory to the actually used byte-length. if (buffer->isResizable()) { auto* resizableBuffer = &buffer->as(); size_t byteLength = resizableBuffer->byteLength(); size_t maxByteLength = resizableBuffer->maxByteLength(); MOZ_ASSERT(byteLength <= maxByteLength); if (byteLength < maxByteLength) { auto newData = ReallocateArrayBufferContents( cx, stolenData, maxByteLength, byteLength); if (!newData) { // If reallocation failed, the old pointer is still valid. The // ArrayBuffer isn't detached and still owns the malloc'ed memory. return nullptr; } // The following code must be infallible, because the data pointer of // |buffer| is possibly no longer valid after the above realloc. stolenData = newData.release(); } } RemoveCellMemory(buffer, buffer->associatedBytes(), MemoryUse::ArrayBufferContents); // Overwrite the old data pointer *without* releasing the contents // being stolen. buffer->setDataPointer(BufferContents::createNoData()); // Detach |buffer| now that doing so won't free |stolenData|. ArrayBufferObject::detach(cx, buffer); return stolenData; } case INLINE_DATA: case NO_DATA: case USER_OWNED: case MAPPED: case EXTERNAL: { // We can't use these data types directly. Make a copy to return. ArrayBufferContents copiedData = NewCopiedBufferContents(cx, buffer); if (!copiedData) { return nullptr; } // Detach |buffer|. This immediately releases the currently owned // contents, freeing or unmapping data in the MAPPED and EXTERNAL cases. ArrayBufferObject::detach(cx, buffer); return copiedData.release(); } case WASM: MOZ_ASSERT_UNREACHABLE( "wasm buffers aren't stealable except by a " "memory.grow operation that shouldn't call this " "function"); return nullptr; } MOZ_ASSERT_UNREACHABLE("garbage kind computed"); return nullptr; } /* static */ ArrayBufferObject::BufferContents ArrayBufferObject::extractStructuredCloneContents( JSContext* cx, Handle buffer) { if (buffer->isLengthPinned()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_PINNED); return BufferContents::createFailed(); } CheckStealPreconditions(buffer, cx); // We don't yet support extracting the contents of resizable buffers. MOZ_ASSERT(!buffer->isResizable(), "extracting the contents of resizable buffers not supported"); BufferContents contents = buffer->contents(); switch (contents.kind()) { case INLINE_DATA: case NO_DATA: case USER_OWNED: { ArrayBufferContents copiedData = NewCopiedBufferContents(cx, buffer); if (!copiedData) { return BufferContents::createFailed(); } ArrayBufferObject::detach(cx, buffer); return BufferContents::createMallocedArrayBufferContentsArena( copiedData.release()); } case MALLOCED_ARRAYBUFFER_CONTENTS_ARENA: case MALLOCED_UNKNOWN_ARENA: case MAPPED: { MOZ_ASSERT(contents); RemoveCellMemory(buffer, buffer->associatedBytes(), MemoryUse::ArrayBufferContents); // Overwrite the old data pointer *without* releasing old data. buffer->setDataPointer(BufferContents::createNoData()); // Detach |buffer| now that doing so won't release |oldContents|. ArrayBufferObject::detach(cx, buffer); return contents; } case WASM: JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_TRANSFER); return BufferContents::createFailed(); case EXTERNAL: MOZ_ASSERT_UNREACHABLE( "external ArrayBuffer shouldn't have passed the " "structured-clone preflighting"); break; } MOZ_ASSERT_UNREACHABLE("garbage kind computed"); return BufferContents::createFailed(); } /* static */ bool ArrayBufferObject::ensureNonInline(JSContext* cx, Handle buffer) { if (buffer->isDetached() || buffer->isPreparedForAsmJS()) { return true; } if (buffer->isLengthPinned()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_PINNED); return false; } BufferContents inlineContents = buffer->contents(); if (inlineContents.kind() != INLINE_DATA) { return true; } size_t nbytes = buffer->maxByteLength(); ArrayBufferContents copy = NewCopiedBufferContents(cx, buffer); if (!copy) { return false; } BufferContents outOfLineContents = BufferContents::createMallocedArrayBufferContentsArena(copy.release()); buffer->setDataPointer(outOfLineContents); AddCellMemory(buffer, nbytes, MemoryUse::ArrayBufferContents); if (!buffer->firstView()) { return true; // No views! Easy! } buffer->firstView()->as().notifyBufferMoved( inlineContents.data(), outOfLineContents.data()); auto& innerViews = ObjectRealm::get(buffer).innerViews.get(); if (InnerViewTable::ViewVector* views = innerViews.maybeViewsUnbarriered(buffer)) { for (JSObject* view : *views) { view->as().notifyBufferMoved( inlineContents.data(), outOfLineContents.data()); } } return true; } /* static */ void ArrayBufferObject::addSizeOfExcludingThis( JSObject* obj, mozilla::MallocSizeOf mallocSizeOf, JS::ClassInfo* info, JS::RuntimeSizes* runtimeSizes) { auto& buffer = obj->as(); switch (buffer.bufferKind()) { case INLINE_DATA: // Inline data's size should be reported by this object's size-class // reporting. break; case MALLOCED_ARRAYBUFFER_CONTENTS_ARENA: case MALLOCED_UNKNOWN_ARENA: if (buffer.isPreparedForAsmJS()) { info->objectsMallocHeapElementsAsmJS += mallocSizeOf(buffer.dataPointer()); } else { info->objectsMallocHeapElementsNormal += mallocSizeOf(buffer.dataPointer()); } break; case NO_DATA: // No data is no memory. MOZ_ASSERT(buffer.dataPointer() == nullptr); break; case USER_OWNED: // User-owned data should be accounted for by the user. break; case EXTERNAL: // External data will be accounted for by the owner of the buffer, // not this view. break; case MAPPED: info->objectsNonHeapElementsNormal += buffer.byteLength(); break; case WASM: if (!buffer.isDetached()) { info->objectsNonHeapElementsWasm += buffer.byteLength(); if (runtimeSizes) { MOZ_ASSERT(buffer.wasmMappedSize() >= buffer.byteLength()); runtimeSizes->wasmGuardPages += buffer.wasmMappedSize() - buffer.byteLength(); } } break; } } /* static */ void ArrayBufferObject::finalize(JS::GCContext* gcx, JSObject* obj) { obj->as().releaseData(gcx); } /* static */ void ArrayBufferObject::copyData(ArrayBufferObject* toBuffer, size_t toIndex, ArrayBufferObject* fromBuffer, size_t fromIndex, size_t count) { MOZ_ASSERT(!toBuffer->isDetached()); MOZ_ASSERT(toBuffer->byteLength() >= count); MOZ_ASSERT(toBuffer->byteLength() >= toIndex + count); MOZ_ASSERT(!fromBuffer->isDetached()); MOZ_ASSERT(fromBuffer->byteLength() >= fromIndex); MOZ_ASSERT(fromBuffer->byteLength() >= fromIndex + count); memcpy(toBuffer->dataPointer() + toIndex, fromBuffer->dataPointer() + fromIndex, count); } template /* static */ size_t ArrayBufferObject::objectMoved(JSObject* obj, JSObject* old) { auto& dst = obj->as(); const auto& src = old->as(); MOZ_ASSERT( !obj->runtimeFromMainThread()->gc.nursery().isInside(src.dataPointer())); // Fix up possible inline data pointer. if (src.hasInlineData()) { dst.setFixedSlot(DATA_SLOT, PrivateValue(dst.inlineDataPointer())); } return 0; } JSObject* ArrayBufferObject::firstView() { return getFixedSlot(FIRST_VIEW_SLOT).isObject() ? &getFixedSlot(FIRST_VIEW_SLOT).toObject() : nullptr; } void ArrayBufferObject::setFirstView(ArrayBufferViewObject* view) { setFixedSlot(FIRST_VIEW_SLOT, ObjectOrNullValue(view)); } bool ArrayBufferObject::addView(JSContext* cx, ArrayBufferViewObject* view) { if (!firstView()) { setFirstView(view); return true; } return ObjectRealm::get(this).innerViews.get().addView(cx, this, view); } #if defined(DEBUG) || defined(JS_JITSPEW) template void BufferKindToString(ArrayBufferObject::BufferKind kind, KnownF known, UnknownF unknown) { switch (kind) { case ArrayBufferObject::BufferKind::INLINE_DATA: known("INLINE_DATA"); break; case ArrayBufferObject::BufferKind::MALLOCED_ARRAYBUFFER_CONTENTS_ARENA: known("MALLOCED_ARRAYBUFFER_CONTENTS_ARENA"); break; case ArrayBufferObject::BufferKind::NO_DATA: known("NO_DATA"); break; case ArrayBufferObject::BufferKind::USER_OWNED: known("USER_OWNED"); break; case ArrayBufferObject::BufferKind::WASM: known("WASM"); break; case ArrayBufferObject::BufferKind::MAPPED: known("MAPPED"); break; case ArrayBufferObject::BufferKind::EXTERNAL: known("EXTERNAL"); break; case ArrayBufferObject::BufferKind::MALLOCED_UNKNOWN_ARENA: known("MALLOCED_UNKNOWN_ARENA"); break; default: unknown(uint8_t(kind)); break; } } template void ForEachArrayBufferFlag(uint32_t flags, KnownF known, UnknownF unknown) { for (uint32_t i = ArrayBufferObject::ArrayBufferFlags::BUFFER_KIND_MASK + 1; i; i = i << 1) { if (!(flags & i)) { continue; } switch (ArrayBufferObject::ArrayBufferFlags(flags & i)) { case ArrayBufferObject::ArrayBufferFlags::DETACHED: known("DETACHED"); break; case ArrayBufferObject::ArrayBufferFlags::FOR_ASMJS: known("FOR_ASMJS"); break; default: unknown(i); break; } } } void ArrayBufferObject::dumpOwnFields(js::JSONPrinter& json) const { json.formatProperty("byteLength", "%zu", size_t(getFixedSlot(BYTE_LENGTH_SLOT).toPrivate())); BufferKindToString( bufferKind(), [&](const char* name) { json.property("bufferKind", name); }, [&](uint8_t value) { json.formatProperty("bufferKind", "Unknown(%02x)", value); }); json.beginInlineListProperty("flags"); ForEachArrayBufferFlag( flags(), [&](const char* name) { json.value("%s", name); }, [&](uint32_t value) { json.value("Unknown(%08x)", value); }); json.endInlineList(); void* data = dataPointer(); if (data) { json.formatProperty("data", "0x%p", data); } else { json.nullProperty("data"); } } void ArrayBufferObject::dumpOwnStringContent(js::GenericPrinter& out) const { out.printf("byteLength=%zu, ", size_t(getFixedSlot(BYTE_LENGTH_SLOT).toPrivate())); BufferKindToString( bufferKind(), [&](const char* name) { out.printf("bufferKind=%s, ", name); }, [&](uint8_t value) { out.printf("bufferKind=Unknown(%02x), ", value); }); out.printf("flags=["); bool first = true; ForEachArrayBufferFlag( flags(), [&](const char* name) { if (!first) { out.put(","); } first = false; out.put(name); }, [&](uint32_t value) { if (!first) { out.put(","); } first = false; out.printf("Unknown(%08x)", value); }); out.put("], "); void* data = dataPointer(); if (data) { out.printf("data=0x%p", data); } else { out.put("data=null"); } } #endif /* * InnerViewTable */ inline bool InnerViewTable::Views::empty() { return views.empty(); } inline bool InnerViewTable::Views::hasNurseryViews() { return firstNurseryView < views.length(); } bool InnerViewTable::Views::addView(ArrayBufferViewObject* view) { // Add the view to the list, ensuring that all nursery views are at end. if (!views.append(view)) { return false; } if (!gc::IsInsideNursery(view)) { // Move tenured views before |firstNurseryView|. if (firstNurseryView != views.length() - 1) { std::swap(views[firstNurseryView], views.back()); } firstNurseryView++; } check(); return true; } bool InnerViewTable::Views::sweepAfterMinorGC(JSTracer* trc) { return traceWeak(trc, firstNurseryView); } bool InnerViewTable::Views::traceWeak(JSTracer* trc, size_t startIndex) { // Use |trc| to trace the view vector from |startIndex| to the end, removing // dead views and updating |firstNurseryView|. size_t index = startIndex; bool sawNurseryView = false; views.mutableEraseIf( [&](auto& view) { if (!JS::GCPolicy::traceWeak(trc, &view)) { return true; } if (!sawNurseryView && gc::IsInsideNursery(view)) { sawNurseryView = true; firstNurseryView = index; } index++; return false; }, startIndex); if (!sawNurseryView) { firstNurseryView = views.length(); } check(); return !views.empty(); } inline void InnerViewTable::Views::check() { #ifdef DEBUG MOZ_ASSERT(firstNurseryView <= views.length()); if (views.length() < 100) { for (size_t i = 0; i < views.length(); i++) { MOZ_ASSERT(gc::IsInsideNursery(views[i]) == (i >= firstNurseryView)); } } #endif } bool InnerViewTable::addView(JSContext* cx, ArrayBufferObject* buffer, ArrayBufferViewObject* view) { // ArrayBufferObject entries are only added when there are multiple views. MOZ_ASSERT(buffer->firstView()); MOZ_ASSERT(!gc::IsInsideNursery(buffer)); // Ensure the buffer is present in the map, getting the list of views. auto ptr = map.lookupForAdd(buffer); if (!ptr && !map.add(ptr, buffer, Views(cx->zone()))) { ReportOutOfMemory(cx); return false; } Views& views = ptr->value(); bool isNurseryView = gc::IsInsideNursery(view); bool hadNurseryViews = views.hasNurseryViews(); if (!views.addView(view)) { ReportOutOfMemory(cx); return false; } // If we added the first nursery view, add the buffer to the list of buffers // which have nursery views. if (isNurseryView && !hadNurseryViews && nurseryKeysValid) { #ifdef DEBUG if (nurseryKeys.length() < 100) { for (auto* key : nurseryKeys) { MOZ_ASSERT(key != buffer); } } #endif if (!nurseryKeys.append(buffer)) { nurseryKeysValid = false; } } return true; } InnerViewTable::ViewVector* InnerViewTable::maybeViewsUnbarriered( ArrayBufferObject* buffer) { auto ptr = map.lookup(buffer); if (ptr) { return &ptr->value().views; } return nullptr; } void InnerViewTable::removeViews(ArrayBufferObject* buffer) { auto ptr = map.lookup(buffer); MOZ_ASSERT(ptr); map.remove(ptr); } bool InnerViewTable::traceWeak(JSTracer* trc) { return map.traceWeak(trc); } void InnerViewTable::sweepAfterMinorGC(JSTracer* trc) { MOZ_ASSERT(needsSweepAfterMinorGC()); if (nurseryKeysValid) { for (size_t i = 0; i < nurseryKeys.length(); i++) { ArrayBufferObject* buffer = nurseryKeys[i]; MOZ_ASSERT(!gc::IsInsideNursery(buffer)); auto ptr = map.lookup(buffer); if (ptr && !ptr->value().sweepAfterMinorGC(trc)) { map.remove(ptr); } } } else { for (ArrayBufferViewMap::Enum e(map); !e.empty(); e.popFront()) { MOZ_ASSERT(!gc::IsInsideNursery(e.front().key())); if (!e.front().value().sweepAfterMinorGC(trc)) { e.removeFront(); } } } nurseryKeys.clear(); nurseryKeysValid = true; } size_t InnerViewTable::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) { size_t vectorSize = 0; for (auto r = map.all(); !r.empty(); r.popFront()) { vectorSize += r.front().value().views.sizeOfExcludingThis(mallocSizeOf); } return vectorSize + map.shallowSizeOfExcludingThis(mallocSizeOf) + nurseryKeys.sizeOfExcludingThis(mallocSizeOf); } template <> bool JSObject::is() const { return is() || is(); } JS_PUBLIC_API size_t JS::GetArrayBufferByteLength(JSObject* obj) { ArrayBufferObject* aobj = obj->maybeUnwrapAs(); return aobj ? aobj->byteLength() : 0; } JS_PUBLIC_API uint8_t* JS::GetArrayBufferData(JSObject* obj, bool* isSharedMemory, const JS::AutoRequireNoGC&) { ArrayBufferObject* aobj = obj->maybeUnwrapIf(); if (!aobj) { return nullptr; } *isSharedMemory = false; return aobj->dataPointer(); } static ArrayBufferObject* UnwrapOrReportArrayBuffer( JSContext* cx, JS::Handle maybeArrayBuffer) { JSObject* obj = CheckedUnwrapStatic(maybeArrayBuffer); if (!obj) { ReportAccessDenied(cx); return nullptr; } if (!obj->is()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_REQUIRED); return nullptr; } return &obj->as(); } JS_PUBLIC_API bool JS::DetachArrayBuffer(JSContext* cx, HandleObject obj) { AssertHeapIsIdle(); CHECK_THREAD(cx); cx->check(obj); Rooted unwrappedBuffer( cx, UnwrapOrReportArrayBuffer(cx, obj)); if (!unwrappedBuffer) { return false; } if (unwrappedBuffer->hasDefinedDetachKey()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_TRANSFER); return false; } if (unwrappedBuffer->isLengthPinned()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_PINNED); return false; } AutoRealm ar(cx, unwrappedBuffer); ArrayBufferObject::detach(cx, unwrappedBuffer); return true; } JS_PUBLIC_API bool JS::HasDefinedArrayBufferDetachKey(JSContext* cx, HandleObject obj, bool* isDefined) { Rooted unwrappedBuffer( cx, UnwrapOrReportArrayBuffer(cx, obj)); if (!unwrappedBuffer) { return false; } *isDefined = unwrappedBuffer->hasDefinedDetachKey(); return true; } JS_PUBLIC_API bool JS::IsDetachedArrayBufferObject(JSObject* obj) { ArrayBufferObject* aobj = obj->maybeUnwrapIf(); if (!aobj) { return false; } return aobj->isDetached(); } JS_PUBLIC_API JSObject* JS::NewArrayBuffer(JSContext* cx, size_t nbytes) { AssertHeapIsIdle(); CHECK_THREAD(cx); return ArrayBufferObject::createZeroed(cx, nbytes); } JS_PUBLIC_API JSObject* JS::NewArrayBufferWithContents( JSContext* cx, size_t nbytes, mozilla::UniquePtr contents) { auto* result = NewArrayBufferWithContents( cx, nbytes, contents.get(), JS::NewArrayBufferOutOfMemory::CallerMustFreeMemory); if (result) { // If and only if an ArrayBuffer is successfully created, ownership of // |contents| is transferred to the new ArrayBuffer. (void)contents.release(); } return result; } JS_PUBLIC_API JSObject* JS::NewArrayBufferWithContents( JSContext* cx, size_t nbytes, void* data, NewArrayBufferOutOfMemory) { AssertHeapIsIdle(); CHECK_THREAD(cx); MOZ_ASSERT_IF(!data, nbytes == 0); if (!data) { // Don't pass nulled contents to |createForContents|. return ArrayBufferObject::createZeroed(cx, 0); } using BufferContents = ArrayBufferObject::BufferContents; BufferContents contents = BufferContents::createMallocedUnknownArena(data); return ArrayBufferObject::createForContents(cx, nbytes, contents); } JS_PUBLIC_API JSObject* JS::CopyArrayBuffer(JSContext* cx, Handle arrayBuffer) { AssertHeapIsIdle(); CHECK_THREAD(cx); MOZ_ASSERT(arrayBuffer != nullptr); Rooted unwrappedSource( cx, UnwrapOrReportArrayBuffer(cx, arrayBuffer)); if (!unwrappedSource) { return nullptr; } if (unwrappedSource->isDetached()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED); return nullptr; } return ArrayBufferObject::copy(cx, unwrappedSource->byteLength(), unwrappedSource); } JS_PUBLIC_API JSObject* JS::NewExternalArrayBuffer( JSContext* cx, size_t nbytes, mozilla::UniquePtr contents) { AssertHeapIsIdle(); CHECK_THREAD(cx); MOZ_ASSERT(contents); using BufferContents = ArrayBufferObject::BufferContents; BufferContents bufferContents = BufferContents::createExternal( contents.get(), contents.get_deleter().freeFunc(), contents.get_deleter().userData()); auto* result = ArrayBufferObject::createForContents(cx, nbytes, bufferContents); if (result) { // If and only if an ArrayBuffer is successfully created, ownership of // |contents| is transferred to the new ArrayBuffer. (void)contents.release(); } return result; } JS_PUBLIC_API JSObject* JS::NewArrayBufferWithUserOwnedContents(JSContext* cx, size_t nbytes, void* data) { AssertHeapIsIdle(); CHECK_THREAD(cx); MOZ_ASSERT(data); using BufferContents = ArrayBufferObject::BufferContents; BufferContents contents = BufferContents::createUserOwned(data); return ArrayBufferObject::createForContents(cx, nbytes, contents); } JS_PUBLIC_API bool JS::IsArrayBufferObject(JSObject* obj) { return obj->canUnwrapAs(); } JS_PUBLIC_API bool JS::ArrayBufferHasData(JSObject* obj) { return !obj->unwrapAs().isDetached(); } JS_PUBLIC_API JSObject* JS::UnwrapArrayBuffer(JSObject* obj) { return obj->maybeUnwrapIf(); } JS_PUBLIC_API JSObject* JS::UnwrapSharedArrayBuffer(JSObject* obj) { return obj->maybeUnwrapIf(); } JS_PUBLIC_API void* JS::StealArrayBufferContents(JSContext* cx, HandleObject obj) { AssertHeapIsIdle(); CHECK_THREAD(cx); cx->check(obj); Rooted unwrappedBuffer( cx, UnwrapOrReportArrayBuffer(cx, obj)); if (!unwrappedBuffer) { return nullptr; } if (unwrappedBuffer->isDetached()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED); return nullptr; } if (unwrappedBuffer->isLengthPinned()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_LENGTH_PINNED); return nullptr; } if (unwrappedBuffer->hasDefinedDetachKey()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_TRANSFER); return nullptr; } AutoRealm ar(cx, unwrappedBuffer); return ArrayBufferObject::stealMallocedContents(cx, unwrappedBuffer); } JS_PUBLIC_API JSObject* JS::NewMappedArrayBufferWithContents(JSContext* cx, size_t nbytes, void* data) { AssertHeapIsIdle(); CHECK_THREAD(cx); MOZ_ASSERT(data); using BufferContents = ArrayBufferObject::BufferContents; BufferContents contents = BufferContents::createMapped(data); return ArrayBufferObject::createForContents(cx, nbytes, contents); } JS_PUBLIC_API void* JS::CreateMappedArrayBufferContents(int fd, size_t offset, size_t length) { return ArrayBufferObject::createMappedContents(fd, offset, length).data(); } JS_PUBLIC_API void JS::ReleaseMappedArrayBufferContents(void* contents, size_t length) { gc::DeallocateMappedContent(contents, length); } JS_PUBLIC_API bool JS::IsMappedArrayBufferObject(JSObject* obj) { ArrayBufferObject* aobj = obj->maybeUnwrapIf(); if (!aobj) { return false; } return aobj->isMapped(); } JS_PUBLIC_API JSObject* JS::GetObjectAsArrayBuffer(JSObject* obj, size_t* length, uint8_t** data) { ArrayBufferObject* aobj = obj->maybeUnwrapIf(); if (!aobj) { return nullptr; } *length = aobj->byteLength(); *data = aobj->dataPointer(); return aobj; } JS_PUBLIC_API void JS::GetArrayBufferLengthAndData(JSObject* obj, size_t* length, bool* isSharedMemory, uint8_t** data) { auto& aobj = obj->as(); *length = aobj.byteLength(); *data = aobj.dataPointer(); *isSharedMemory = false; } const JSClass* const JS::ArrayBuffer::FixedLengthUnsharedClass = &FixedLengthArrayBufferObject::class_; const JSClass* const JS::ArrayBuffer::ResizableUnsharedClass = &ResizableArrayBufferObject::class_; const JSClass* const JS::ArrayBuffer::FixedLengthSharedClass = &FixedLengthSharedArrayBufferObject::class_; const JSClass* const JS::ArrayBuffer::GrowableSharedClass = &GrowableSharedArrayBufferObject::class_; /* static */ JS::ArrayBuffer JS::ArrayBuffer::create(JSContext* cx, size_t nbytes) { AssertHeapIsIdle(); CHECK_THREAD(cx); return JS::ArrayBuffer(ArrayBufferObject::createZeroed(cx, nbytes)); } mozilla::Span JS::ArrayBuffer::getData( bool* isSharedMemory, const JS::AutoRequireNoGC& nogc) { auto* buffer = obj->maybeUnwrapAs(); if (!buffer) { return nullptr; } size_t length = buffer->byteLength(); if (buffer->is()) { *isSharedMemory = true; return {buffer->dataPointerEither().unwrap(), length}; } *isSharedMemory = false; return {buffer->as().dataPointer(), length}; }; JS::ArrayBuffer JS::ArrayBuffer::unwrap(JSObject* maybeWrapped) { if (!maybeWrapped) { return JS::ArrayBuffer(nullptr); } auto* ab = maybeWrapped->maybeUnwrapIf(); return fromObject(ab); } bool JS::ArrayBufferCopyData(JSContext* cx, Handle toBlock, size_t toIndex, Handle fromBlock, size_t fromIndex, size_t count) { Rooted unwrappedToBlock( cx, toBlock->maybeUnwrapIf()); if (!unwrappedToBlock) { ReportAccessDenied(cx); return false; } Rooted unwrappedFromBlock( cx, fromBlock->maybeUnwrapIf()); if (!unwrappedFromBlock) { ReportAccessDenied(cx); return false; } // Verify that lengths still make sense and throw otherwise. if (toIndex + count < toIndex || // size_t overflow fromIndex + count < fromIndex || // size_t overflow toIndex + count > unwrappedToBlock->byteLength() || fromIndex + count > unwrappedFromBlock->byteLength()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARRAYBUFFER_COPY_RANGE); return false; } // If both are array buffers, can use ArrayBufferCopyData if (unwrappedToBlock->is() && unwrappedFromBlock->is()) { Rooted toArray( cx, &unwrappedToBlock->as()); Rooted fromArray( cx, &unwrappedFromBlock->as()); ArrayBufferObject::copyData(toArray, toIndex, fromArray, fromIndex, count); return true; } Rooted toArray( cx, &unwrappedToBlock->as()); Rooted fromArray( cx, &unwrappedFromBlock->as()); SharedArrayBufferObject::copyData(toArray, toIndex, fromArray, fromIndex, count); return true; } // https://tc39.es/ecma262/#sec-clonearraybuffer // We only support the case where cloneConstructor is %ArrayBuffer%. Note, // this means that cloning a SharedArrayBuffer will produce an ArrayBuffer JSObject* JS::ArrayBufferClone(JSContext* cx, Handle srcBuffer, size_t srcByteOffset, size_t srcLength) { MOZ_ASSERT(srcBuffer->is()); // 2. (reordered) If IsDetachedBuffer(srcBuffer) is true, throw a TypeError // exception. if (IsDetachedArrayBufferObject(srcBuffer)) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED); return nullptr; } // 1. Let targetBuffer be ? AllocateArrayBuffer(cloneConstructor, srcLength). JS::RootedObject targetBuffer(cx, JS::NewArrayBuffer(cx, srcLength)); if (!targetBuffer) { return nullptr; } // 3. Let srcBlock be srcBuffer.[[ArrayBufferData]]. // 4. Let targetBlock be targetBuffer.[[ArrayBufferData]]. // 5. Perform CopyDataBlockBytes(targetBlock, 0, srcBlock, srcByteOffset, // srcLength). if (!ArrayBufferCopyData(cx, targetBuffer, 0, srcBuffer, srcByteOffset, srcLength)) { return nullptr; } // 6. Return targetBuffer. return targetBuffer; }