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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
#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
// 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
// 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
// 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);
(void)err;
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 )
*
*/
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
*
*/
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 = buffer->maxByteLength();
MOZ_ASSERT_IF(buffer->isDetached(), maxByteLength == 0);
// Step 7.
args.rval().setNumber(maxByteLength);
return true;
}
/**
* 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
*
*/
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
*
*/
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
*
*/
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
*
*/
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 ] )
*
*/
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 ] )
*
*/
bool ArrayBufferObject::transfer(JSContext* cx, unsigned argc, Value* vp) {
CallArgs args = CallArgsFromVp(argc, vp);
return CallNonGenericMethod<IsArrayBuffer, transferImpl>(cx, args);
}
/**
* ArrayBuffer.prototype.transferToFixedLength ( [ newLength ] )
*
*/
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 ] )
*
*/
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 )
*
*/
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 )
*
*/
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.
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);
// Update all views of the buffer to account for the buffer having been
// resized.
auto& innerViews = ObjectRealm::get(this).innerViews.get();
if (InnerViewTable::ViewVector* views =
innerViews.maybeViewsUnbarriered(this)) {
for (auto& view : *views) {
view->notifyBufferResized();
}
}
if (auto* view = firstView()) {
view->as<ArrayBufferViewObject>().notifyBufferResized();
}
}
/* clang-format off */
/*
* [SMDOC] WASM Linear Memory structure
*
* Wasm Raw Buf Linear Memory Structure
*
* The linear heap in Wasm is an mmaped array buffer. Several constants manage
* its lifetime:
*
* - byteLength - the wasm-visible current length of the buffer in
* bytes. Accesses in the range [0, byteLength] succeed. May only increase.
*
* - boundsCheckLimit - the size against which we perform bounds checks. The
* value of this depends on the bounds checking strategy chosen for the array
* buffer and the specific bounds checking semantics. For asm.js code and
* for wasm code running with explicit bounds checking, it is the always the
* same as the byteLength. For wasm code using the huge-memory trick, it is
* always wasm::GuardSize smaller than mappedSize.
*
* See also "Linear memory addresses and bounds checking" in
* wasm/WasmMemory.cpp.
*
* See also WasmMemoryObject::boundsCheckLimit().
*
* - sourceMaxSize - the optional declared limit on how far byteLength can grow
* in pages. This is the unmodified maximum size from the source module or
* JS-API invocation. This may not be representable in byte lengths, nor
* feasible for a module to actually grow to due to implementation limits.
* It is used for correct linking checks and js-types reflection.
*
* - clampedMaxSize - the maximum size on how far the byteLength can grow in
* pages. This value respects implementation limits and is always
* representable as a byte length. Every memory has a clampedMaxSize, even if
* no maximum was specified in source. When a memory has no sourceMaxSize,
* the clampedMaxSize will be the maximum amount of memory that can be grown
* to while still respecting implementation limits.
*
* - mappedSize - the actual mmapped size. Access in the range [0, mappedSize]
* will either succeed, or be handled by the wasm signal handlers. If
* sourceMaxSize is present at initialization, then we attempt to map the
* whole clampedMaxSize. Otherwise we only map the region needed for the
* initial size.
*
* The below diagram shows the layout of the wasm heap. The wasm-visible portion
* of the heap starts at 0. There is one extra page prior to the start of the
* wasm heap which contains the WasmArrayRawBuffer struct at its end (i.e. right
* before the start of the WASM heap).
*
* WasmArrayRawBuffer
* \ ArrayBufferObject::dataPointer()
* \ /
* \ |
* ______|_|______________________________________________________
* |______|_|______________|___________________|___________________|
* 0 byteLength clampedMaxSize mappedSize
*
* \_______________________/
* COMMITED
* \_____________________________________/
* SLOP
* \______________________________________________________________/
* MAPPED
*
* Invariants on byteLength, clampedMaxSize, and mappedSize:
* - byteLength only increases
* - 0 <= byteLength <= clampedMaxSize <= mappedSize
* - if sourceMaxSize is not specified, mappedSize may grow.
* It is otherwise constant.
* - initialLength <= clampedMaxSize <= sourceMaxSize (if present)
* - clampedMaxSize <= wasm::MaxMemoryPages()
*
* Invariants on boundsCheckLimit:
* - for wasm code with the huge-memory trick,
* clampedMaxSize <= boundsCheckLimit <= mappedSize
* - for asm.js code or wasm with explicit bounds checking,
* byteLength == boundsCheckLimit <= clampedMaxSize
* - on ARM, boundsCheckLimit must be a valid ARM immediate.
* - if sourceMaxSize is not specified, boundsCheckLimit may grow as
* mappedSize grows. They are otherwise constant.
* NOTE: For asm.js on 32-bit platforms and on all platforms when running with
* explicit bounds checking, we guarantee that
*
* byteLength == maxSize == boundsCheckLimit == mappedSize
*
* That is, signal handlers will not be invoked.
*
* The region between byteLength and mappedSize is the SLOP - an area where we use
* signal handlers to catch things that slip by bounds checks. Logically it has
* two parts:
*
* - from byteLength to boundsCheckLimit - this part of the SLOP serves to catch
* accesses to memory we have reserved but not yet grown into. This allows us
* to grow memory up to max (when present) without having to patch/update the
* bounds checks.
*
* - from boundsCheckLimit to mappedSize - this part of the SLOP allows us to
* bounds check against base pointers and fold some constant offsets inside
* loads. This enables better Bounds Check Elimination. See "Linear memory
* addresses and bounds checking" in wasm/WasmMemory.cpp.
*
*/
/* clang-format on */
[[nodiscard]] bool WasmArrayRawBuffer::growToPagesInPlace(Pages newPages) {
size_t newSize = newPages.byteLength();
size_t oldSize = byteLength();
MOZ_ASSERT(newSize >= oldSize);
MOZ_ASSERT(newPages <= clampedMaxPages());
MOZ_ASSERT(newSize <= mappedSize());
size_t delta = newSize - oldSize;
MOZ_ASSERT(delta % wasm::PageSize == 0);
uint8_t* dataEnd = dataPointer() + oldSize;
MOZ_ASSERT(uintptr_t(dataEnd) % gc::SystemPageSize() == 0);
if (delta && !CommitBufferMemory(dataEnd, delta)) {
return false;
}
length_ = newSize;
return true;
}
bool WasmArrayRawBuffer::extendMappedSize(Pages maxPages) {
size_t newMappedSize = wasm::ComputeMappedSize(maxPages);
MOZ_ASSERT(mappedSize_ <= newMappedSize);
if (mappedSize_ == newMappedSize) {
return true;
}
if (!ExtendBufferMapping(dataPointer(), mappedSize_, newMappedSize)) {
return false;
}
mappedSize_ = newMappedSize;
return true;
}
void WasmArrayRawBuffer::tryGrowMaxPagesInPlace(Pages deltaMaxPages) {
Pages newMaxPages = clampedMaxPages_;
DebugOnly<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()) {
return maxByteLength();
}
if (isMapped()) {
return RoundUp(byteLength(), js::gc::SystemPageSize());
}
MOZ_CRASH("Unexpected buffer kind");
}
void ArrayBufferObject::setByteLength(size_t length) {
MOZ_ASSERT(length <= ArrayBufferObject::ByteLengthLimit);
setFixedSlot(BYTE_LENGTH_SLOT, PrivateValue(length));
}
size_t ArrayBufferObject::wasmMappedSize() const {
if (isWasm()) {
return contents().wasmBuffer()->mappedSize();
}
return byteLength();
}
IndexType ArrayBufferObject::wasmIndexType() const {
if (isWasm()) {
return contents().wasmBuffer()->indexType();
}
MOZ_ASSERT(isPreparedForAsmJS());
return wasm::IndexType::I32;
}
Pages ArrayBufferObject::wasmPages() const {
if (isWasm()) {
return contents().wasmBuffer()->pages();
}
MOZ_ASSERT(isPreparedForAsmJS());
return Pages::fromByteLengthExact(byteLength());
}
Pages ArrayBufferObject::wasmClampedMaxPages() const {
if (isWasm()) {
return contents().wasmBuffer()->clampedMaxPages();
}
MOZ_ASSERT(isPreparedForAsmJS());
return Pages::fromByteLengthExact(byteLength());
}
Maybe<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->maxByteLength();
ArrayBufferContents copy = NewCopiedBufferContents(cx, buffer);
if (!copy) {
return false;
}
BufferContents outOfLineContents =
BufferContents::createMallocedArrayBufferContentsArena(copy.release());
buffer->setDataPointer(outOfLineContents);
AddCellMemory(buffer, nbytes, MemoryUse::ArrayBufferContents);
if (!buffer->firstView()) {
return true; // No views! Easy!
}
buffer->firstView()->as<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>();
#ifdef DEBUG
// Check the data pointer is not inside the nursery, but take account of the
// fact that inline data pointers for zero length buffers can point to the end
// of a chunk which can abut the start of the nursery.
if (src.byteLength() != 0 || (uintptr_t(src.dataPointer()) & gc::ChunkMask)) {
Nursery& nursery = obj->runtimeFromMainThread()->gc.nursery();
MOZ_ASSERT(!nursery.isInside(src.dataPointer()));
}
#endif
// 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 (const 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) {
nurseryKeys.traceWeak(trc);
map.traceWeak(trc);
return true;
}
void InnerViewTable::sweepAfterMinorGC(JSTracer* trc) {
MOZ_ASSERT(needsSweepAfterMinorGC());
NurseryKeysVector keys;
bool valid = true;
std::swap(nurseryKeys, keys);
std::swap(nurseryKeysValid, valid);
// Use nursery keys vector if possible.
if (valid) {
for (ArrayBufferObject* buffer : keys) {
MOZ_ASSERT(!gc::IsInsideNursery(buffer));
auto ptr = map.lookup(buffer);
if (ptr && !sweepViewsAfterMinorGC(trc, buffer, ptr->value())) {
map.remove(ptr);
}
}
return;
}
// Otherwise look at every map entry.
for (ArrayBufferViewMap::Enum e(map); !e.empty(); e.popFront()) {
MOZ_ASSERT(!gc::IsInsideNursery(e.front().key()));
if (!sweepViewsAfterMinorGC(trc, e.front().key(), e.front().value())) {
e.removeFront();
}
}
}
bool InnerViewTable::sweepViewsAfterMinorGC(JSTracer* trc,
ArrayBufferObject* buffer,
Views& views) {
if (!views.sweepAfterMinorGC(trc)) {
return false; // No more views.
}
if (views.hasNurseryViews() && !nurseryKeys.append(buffer)) {
nurseryKeysValid = false;
}
return 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;
}
// 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;
}