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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /js/src/vm/ArrayBufferObject.cpp
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/src/vm/ArrayBufferObject.cpp')
-rw-r--r--js/src/vm/ArrayBufferObject.cpp3305
1 files changed, 3305 insertions, 0 deletions
diff --git a/js/src/vm/ArrayBufferObject.cpp b/js/src/vm/ArrayBufferObject.cpp
new file mode 100644
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+++ b/js/src/vm/ArrayBufferObject.cpp
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+/* -*- 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 <algorithm> // std::max, std::min
+#include <memory> // std::uninitialized_copy_n
+#include <string.h>
+#if !defined(XP_WIN) && !defined(__wasi__)
+# include <sys/mman.h>
+#endif
+#include <tuple> // std::tuple
+#include <type_traits>
+#ifdef MOZ_VALGRIND
+# include <valgrind/memcheck.h>
+#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<uint64_t, mozilla::ReleaseAcquire> wasmReservedBytes(0);
+// The number of bytes of wasm memory reserved since the last GC trigger.
+static Atomic<uint64_t, mozilla::ReleaseAcquire> 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<ArrayBufferObject::class_constructor, 1,
+ gc::AllocKind::FUNCTION>,
+ 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<ArrayBufferObject>();
+}
+
+#ifdef NIGHTLY_BUILD
+static bool IsResizableArrayBuffer(HandleValue v) {
+ return v.isObject() && v.toObject().is<ResizableArrayBufferObject>();
+}
+#endif
+
+MOZ_ALWAYS_INLINE bool ArrayBufferObject::byteLengthGetterImpl(
+ JSContext* cx, const CallArgs& args) {
+ MOZ_ASSERT(IsArrayBuffer(args.thisv()));
+ auto* buffer = &args.thisv().toObject().as<ArrayBufferObject>();
+ args.rval().setNumber(buffer->byteLength());
+ return true;
+}
+
+bool ArrayBufferObject::byteLengthGetter(JSContext* cx, unsigned argc,
+ Value* vp) {
+ CallArgs args = CallArgsFromVp(argc, vp);
+ return CallNonGenericMethod<IsArrayBuffer, byteLengthGetterImpl>(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<ArrayBufferObject*> arrayBuffer,
+ Handle<Value> 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<size_t> maxByteLength;
+ if (preserveResizability == PreserveResizability::Yes &&
+ arrayBuffer->isResizable()) {
+ auto* resizableBuffer = &arrayBuffer->as<ResizableArrayBufferObject>();
+ 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<ResizableArrayBufferObject*> resizableBuffer(
+ cx, &arrayBuffer->as<ResizableArrayBufferObject>());
+ 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<ArrayBufferObject>();
+
+ // Steps 4-6.
+ size_t maxByteLength;
+ if (buffer->isResizable()) {
+ maxByteLength = buffer->as<ResizableArrayBufferObject>().maxByteLength();
+ } else {
+ maxByteLength = buffer->byteLength();
+ }
+ 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<IsArrayBuffer, maxByteLengthGetterImpl>(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<ArrayBufferObject>();
+ 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<IsArrayBuffer, resizableGetterImpl>(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<ArrayBufferObject>();
+ 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<IsArrayBuffer, detachedGetterImpl>(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<ArrayBufferObject*> buffer(
+ cx, &args.thisv().toObject().as<ArrayBufferObject>());
+ 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<IsArrayBuffer, transferImpl>(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<ArrayBufferObject*> buffer(
+ cx, &args.thisv().toObject().as<ArrayBufferObject>());
+ 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<IsArrayBuffer, transferToFixedLengthImpl>(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<ResizableArrayBufferObject*> obj(
+ cx, &args.thisv().toObject().as<ResizableArrayBufferObject>());
+
+ // 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<IsResizableArrayBuffer, resizeImpl>(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<uint64_t> maxByteLength;
+#ifdef NIGHTLY_BUILD
+ if (JS::Prefs::experimental_arraybuffer_resizable()) {
+ // Inline call to GetArrayBufferMaxByteLengthOption.
+ if (args.get(1).isObject()) {
+ Rooted<JSObject*> options(cx, &args[1].toObject());
+
+ Rooted<Value> 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<uint8_t[], JS::FreePolicy>;
+
+static ArrayBufferContents AllocateUninitializedArrayBufferContents(
+ JSContext* cx, size_t nbytes) {
+ // First attempt a normal allocation.
+ uint8_t* p =
+ cx->maybe_pod_arena_malloc<uint8_t>(js::ArrayBufferContentsArena, nbytes);
+ if (MOZ_UNLIKELY(!p)) {
+ // Otherwise attempt a large allocation, calling the
+ // large-allocation-failure callback if necessary.
+ p = static_cast<uint8_t*>(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<uint8_t>(js::ArrayBufferContentsArena, nbytes);
+ if (MOZ_UNLIKELY(!p)) {
+ // Otherwise attempt a large allocation, calling the
+ // large-allocation-failure callback if necessary.
+ p = static_cast<uint8_t*>(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<uint8_t>(
+ 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<uint8_t*>(cx->runtime()->onOutOfMemoryCanGC(
+ js::AllocFunction::Realloc, js::ArrayBufferContentsArena, newSize,
+ old));
+ if (!p) {
+ ReportOutOfMemory(cx);
+ }
+ }
+
+ return ArrayBufferContents(p);
+}
+
+static ArrayBufferContents NewCopiedBufferContents(
+ JSContext* cx, Handle<ArrayBufferObject*> 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<ArrayBufferObject*> 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.
+ //
+ // Typed object buffers are not exposed and cannot be detached.
+
+ 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<ArrayBufferViewObject>().notifyBufferDetached();
+ }
+ innerViews.removeViews(buffer);
+ }
+ if (JSObject* view = buffer->firstView()) {
+ view->as<ArrayBufferViewObject>().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<ResizableArrayBufferObject>().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);
+}
+
+/* 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<bool> 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<Pages>& sourceMaxPages, const Maybe<size_t>& 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<uint8_t*>(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<WasmArrayRawBuffer>,
+ "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 <typename ObjT, typename RawbufT>
+static ArrayBufferObjectMaybeShared* CreateSpecificWasmBuffer(
+ JSContext* cx, const wasm::MemoryDesc& memory) {
+ bool useHugeMemory = wasm::IsHugeMemoryEnabled(memory.indexType());
+ Pages initialPages = memory.initialPages();
+ Maybe<Pages> sourceMaxPages = memory.maximumPages();
+ Pages clampedMaxPages = wasm::ClampedMaxPages(
+ memory.indexType(), initialPages, sourceMaxPages, useHugeMemory);
+
+ Maybe<size_t> 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<ArrayBufferObjectMaybeShared*> 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<SharedArrayBufferObject,
+ WasmSharedArrayRawBuffer>(cx, memory);
+ }
+ return CreateSpecificWasmBuffer<ArrayBufferObject, WasmArrayRawBuffer>(
+ 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<uint8_t*>(fixedData(JSCLASS_RESERVED_SLOTS(&class_)));
+}
+
+uint8_t* ResizableArrayBufferObject::inlineDataPointer() const {
+ return static_cast<uint8_t*>(fixedData(JSCLASS_RESERVED_SLOTS(&class_)));
+}
+
+uint8_t* ArrayBufferObject::dataPointer() const {
+ return static_cast<uint8_t*>(getFixedSlot(DATA_SLOT).toPrivate());
+}
+
+SharedMem<uint8_t*> ArrayBufferObject::dataPointerShared() const {
+ return SharedMem<uint8_t*>::unshared(getFixedSlot(DATA_SLOT).toPrivate());
+}
+
+ArrayBufferObject::FreeInfo* ArrayBufferObject::freeInfo() const {
+ MOZ_ASSERT(isExternal());
+ MOZ_ASSERT(!isResizable());
+ auto* data = as<FixedLengthArrayBufferObject>().inlineDataPointer();
+ return reinterpret_cast<FreeInfo*>(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()) {
+ if (isResizable()) {
+ return as<ResizableArrayBufferObject>().maxByteLength();
+ }
+ return byteLength();
+ }
+ 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<Pages> ArrayBufferObject::wasmSourceMaxPages() const {
+ if (isWasm()) {
+ return contents().wasmBuffer()->sourceMaxPages();
+ }
+ MOZ_ASSERT(isPreparedForAsmJS());
+ return Some<Pages>(Pages::fromByteLengthExact(byteLength()));
+}
+
+size_t js::WasmArrayBufferMappedSize(const ArrayBufferObjectMaybeShared* buf) {
+ if (buf->is<ArrayBufferObject>()) {
+ return buf->as<ArrayBufferObject>().wasmMappedSize();
+ }
+ return buf->as<SharedArrayBufferObject>().wasmMappedSize();
+}
+
+IndexType js::WasmArrayBufferIndexType(
+ const ArrayBufferObjectMaybeShared* buf) {
+ if (buf->is<ArrayBufferObject>()) {
+ return buf->as<ArrayBufferObject>().wasmIndexType();
+ }
+ return buf->as<SharedArrayBufferObject>().wasmIndexType();
+}
+Pages js::WasmArrayBufferPages(const ArrayBufferObjectMaybeShared* buf) {
+ if (buf->is<ArrayBufferObject>()) {
+ return buf->as<ArrayBufferObject>().wasmPages();
+ }
+ return buf->as<SharedArrayBufferObject>().volatileWasmPages();
+}
+Pages js::WasmArrayBufferClampedMaxPages(
+ const ArrayBufferObjectMaybeShared* buf) {
+ if (buf->is<ArrayBufferObject>()) {
+ return buf->as<ArrayBufferObject>().wasmClampedMaxPages();
+ }
+ return buf->as<SharedArrayBufferObject>().wasmClampedMaxPages();
+}
+Maybe<Pages> js::WasmArrayBufferSourceMaxPages(
+ const ArrayBufferObjectMaybeShared* buf) {
+ if (buf->is<ArrayBufferObject>()) {
+ return buf->as<ArrayBufferObject>().wasmSourceMaxPages();
+ }
+ return Some(buf->as<SharedArrayBufferObject>().wasmSourceMaxPages());
+}
+
+static void CheckStealPreconditions(Handle<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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 <class ArrayBufferType>
+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<ArrayBufferType, FixedLengthArrayBufferObject> ||
+ std::is_same_v<ArrayBufferType, ResizableArrayBufferObject>);
+
+ 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<SharedShape*> 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<ArrayBufferType>(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<FixedLengthArrayBufferObject>(cx, nullptr,
+ allocKind);
+}
+static ResizableArrayBufferObject* NewResizableArrayBufferObject(
+ JSContext* cx) {
+ constexpr auto allocKind =
+ GetArrayBufferGCObjectKind(ResizableArrayBufferObject::RESERVED_SLOTS);
+ return NewArrayBufferObject<ResizableArrayBufferObject>(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<ArrayBufferObject*> buffer(
+ cx, NewArrayBufferObject<FixedLengthArrayBufferObject>(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 <class ArrayBufferType, ArrayBufferObject::FillContents FillType>
+/* static */ std::tuple<ArrayBufferType*, uint8_t*>
+ArrayBufferObject::createUninitializedBufferAndData(
+ JSContext* cx, size_t nbytes, AutoSetNewObjectMetadata&,
+ JS::Handle<JSObject*> proto) {
+ MOZ_ASSERT(nbytes <= ArrayBufferObject::ByteLengthLimit,
+ "caller must validate the byte count it passes");
+
+ static_assert(std::is_same_v<ArrayBufferType, FixedLengthArrayBufferObject> ||
+ std::is_same_v<ArrayBufferType, ResizableArrayBufferObject>);
+
+ // 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<ArrayBufferType>(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 <ArrayBufferObject::FillContents FillType>
+/* static */ std::tuple<ArrayBufferObject*, uint8_t*>
+ArrayBufferObject::createBufferAndData(
+ JSContext* cx, size_t nbytes, AutoSetNewObjectMetadata& metadata,
+ JS::Handle<JSObject*> proto /* = nullptr */) {
+ MOZ_ASSERT(nbytes <= ArrayBufferObject::ByteLengthLimit,
+ "caller must validate the byte count it passes");
+
+ auto [buffer, data] =
+ createUninitializedBufferAndData<FixedLengthArrayBufferObject, FillType>(
+ 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 <ArrayBufferObject::FillContents FillType>
+/* static */ std::tuple<ResizableArrayBufferObject*, uint8_t*>
+ResizableArrayBufferObject::createBufferAndData(
+ JSContext* cx, size_t byteLength, size_t maxByteLength,
+ AutoSetNewObjectMetadata& metadata, Handle<JSObject*> 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<ResizableArrayBufferObject, FillType>(
+ 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<ArrayBufferObject*> 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<FillContents::Zero>(
+ 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<FillContents::Uninitialized>(
+ 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<ResizableArrayBufferObject*> 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<FillContents::Zero>(
+ 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<FillContents::Uninitialized>(
+ 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ResizableArrayBufferObject*> 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<ResizableArrayBufferObject*> 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<FillContents::Zero>(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<FillContents::Zero>(
+ 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<ArrayBufferObject*> 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<ResizableArrayBufferObject>();
+ 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<ArrayBufferObject*> 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<ArrayBufferObject*> 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->byteLength();
+ 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<ArrayBufferViewObject>().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<ArrayBufferViewObject>().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<ArrayBufferObject>();
+ 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<ArrayBufferObject>().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 <class ArrayBufferType>
+/* static */
+size_t ArrayBufferObject::objectMoved(JSObject* obj, JSObject* old) {
+ auto& dst = obj->as<ArrayBufferType>();
+ const auto& src = old->as<ArrayBufferType>();
+
+ 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 <typename KnownF, typename UnknownF>
+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 <typename KnownF, typename UnknownF>
+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<ViewVector::ElementType>::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<js::ArrayBufferObjectMaybeShared>() const {
+ return is<ArrayBufferObject>() || is<SharedArrayBufferObject>();
+}
+
+JS_PUBLIC_API size_t JS::GetArrayBufferByteLength(JSObject* obj) {
+ ArrayBufferObject* aobj = obj->maybeUnwrapAs<ArrayBufferObject>();
+ return aobj ? aobj->byteLength() : 0;
+}
+
+JS_PUBLIC_API uint8_t* JS::GetArrayBufferData(JSObject* obj,
+ bool* isSharedMemory,
+ const JS::AutoRequireNoGC&) {
+ ArrayBufferObject* aobj = obj->maybeUnwrapIf<ArrayBufferObject>();
+ if (!aobj) {
+ return nullptr;
+ }
+ *isSharedMemory = false;
+ return aobj->dataPointer();
+}
+
+static ArrayBufferObject* UnwrapOrReportArrayBuffer(
+ JSContext* cx, JS::Handle<JSObject*> maybeArrayBuffer) {
+ JSObject* obj = CheckedUnwrapStatic(maybeArrayBuffer);
+ if (!obj) {
+ ReportAccessDenied(cx);
+ return nullptr;
+ }
+
+ if (!obj->is<ArrayBufferObject>()) {
+ JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+ JSMSG_ARRAYBUFFER_REQUIRED);
+ return nullptr;
+ }
+
+ return &obj->as<ArrayBufferObject>();
+}
+
+JS_PUBLIC_API bool JS::DetachArrayBuffer(JSContext* cx, HandleObject obj) {
+ AssertHeapIsIdle();
+ CHECK_THREAD(cx);
+ cx->check(obj);
+
+ Rooted<ArrayBufferObject*> 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<ArrayBufferObject*> 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<ArrayBufferObject>();
+ 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<void, JS::FreePolicy> 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<JSObject*> arrayBuffer) {
+ AssertHeapIsIdle();
+ CHECK_THREAD(cx);
+
+ MOZ_ASSERT(arrayBuffer != nullptr);
+
+ Rooted<ArrayBufferObject*> 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<void, JS::BufferContentsDeleter> 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<ArrayBufferObject>();
+}
+
+JS_PUBLIC_API bool JS::ArrayBufferHasData(JSObject* obj) {
+ return !obj->unwrapAs<ArrayBufferObject>().isDetached();
+}
+
+JS_PUBLIC_API JSObject* JS::UnwrapArrayBuffer(JSObject* obj) {
+ return obj->maybeUnwrapIf<ArrayBufferObject>();
+}
+
+JS_PUBLIC_API JSObject* JS::UnwrapSharedArrayBuffer(JSObject* obj) {
+ return obj->maybeUnwrapIf<SharedArrayBufferObject>();
+}
+
+JS_PUBLIC_API void* JS::StealArrayBufferContents(JSContext* cx,
+ HandleObject obj) {
+ AssertHeapIsIdle();
+ CHECK_THREAD(cx);
+ cx->check(obj);
+
+ Rooted<ArrayBufferObject*> 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<ArrayBufferObject>();
+ 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<ArrayBufferObject>();
+ 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<ArrayBufferObject>();
+ *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<uint8_t> JS::ArrayBuffer::getData(
+ bool* isSharedMemory, const JS::AutoRequireNoGC& nogc) {
+ auto* buffer = obj->maybeUnwrapAs<ArrayBufferObjectMaybeShared>();
+ if (!buffer) {
+ return nullptr;
+ }
+ size_t length = buffer->byteLength();
+ if (buffer->is<SharedArrayBufferObject>()) {
+ *isSharedMemory = true;
+ return {buffer->dataPointerEither().unwrap(), length};
+ }
+ *isSharedMemory = false;
+ return {buffer->as<ArrayBufferObject>().dataPointer(), length};
+};
+
+JS::ArrayBuffer JS::ArrayBuffer::unwrap(JSObject* maybeWrapped) {
+ if (!maybeWrapped) {
+ return JS::ArrayBuffer(nullptr);
+ }
+ auto* ab = maybeWrapped->maybeUnwrapIf<ArrayBufferObjectMaybeShared>();
+ return fromObject(ab);
+}
+
+bool JS::ArrayBufferCopyData(JSContext* cx, Handle<JSObject*> toBlock,
+ size_t toIndex, Handle<JSObject*> fromBlock,
+ size_t fromIndex, size_t count) {
+ Rooted<ArrayBufferObjectMaybeShared*> unwrappedToBlock(
+ cx, toBlock->maybeUnwrapIf<ArrayBufferObjectMaybeShared>());
+ if (!unwrappedToBlock) {
+ ReportAccessDenied(cx);
+ return false;
+ }
+
+ Rooted<ArrayBufferObjectMaybeShared*> unwrappedFromBlock(
+ cx, fromBlock->maybeUnwrapIf<ArrayBufferObjectMaybeShared>());
+ 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<ArrayBufferObject>() &&
+ unwrappedFromBlock->is<ArrayBufferObject>()) {
+ Rooted<ArrayBufferObject*> toArray(
+ cx, &unwrappedToBlock->as<ArrayBufferObject>());
+ Rooted<ArrayBufferObject*> fromArray(
+ cx, &unwrappedFromBlock->as<ArrayBufferObject>());
+ ArrayBufferObject::copyData(toArray, toIndex, fromArray, fromIndex, count);
+ return true;
+ }
+
+ Rooted<ArrayBufferObjectMaybeShared*> toArray(
+ cx, &unwrappedToBlock->as<ArrayBufferObjectMaybeShared>());
+ Rooted<ArrayBufferObjectMaybeShared*> fromArray(
+ cx, &unwrappedFromBlock->as<ArrayBufferObjectMaybeShared>());
+ 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<JSObject*> srcBuffer,
+ size_t srcByteOffset, size_t srcLength) {
+ MOZ_ASSERT(srcBuffer->is<ArrayBufferObjectMaybeShared>());
+
+ // 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;
+}