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Bug 1240984 - Remove dummy ArrayBufferContents backstop, r=Waldo
MozReview-Commit-ID: h4oF04rDZn --HG-- extra : rebase_source : f1186c2c37c222e747b951207b0ed02a31a2639d
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@ -23,10 +23,7 @@ var buffer = new ArrayBuffer(BUF_MIN);
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var {get, set} = asmLink(m, this, null, buffer);
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set(4, 42);
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assertEq(get(4), 42);
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assertThrowsInstanceOf(() => detachArrayBuffer(buffer, "change-data"),
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InternalError);
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assertThrowsInstanceOf(() => detachArrayBuffer(buffer, "same-data"),
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InternalError);
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assertThrowsInstanceOf(() => detachArrayBuffer(buffer), Error);
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var m = asmCompile('stdlib', 'foreign', 'buffer',
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`"use asm";
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@ -42,8 +39,13 @@ var m = asmCompile('stdlib', 'foreign', 'buffer',
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var buffer = new ArrayBuffer(BUF_MIN);
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function ffi1()
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{
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assertThrowsInstanceOf(() => detachArrayBuffer(buffer, "change-data"),
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InternalError);
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assertThrowsInstanceOf(() => detachArrayBuffer(buffer), Error);
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}
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var inner = asmLink(m, this, {ffi: ffi1}, buffer);
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function ffi2()
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{
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assertThrowsInstanceOf(() => serialize([], [buffer]), Error);
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}
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var inner2 = asmLink(m, this, {ffi: ffi2}, buffer);
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@ -2107,12 +2107,7 @@ enum DetachDataDisposition {
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* Detach an ArrayBuffer, causing all associated views to no longer refer to
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* the ArrayBuffer's original attached memory.
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*
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* The |changeData| argument is a hint to inform internal behavior with respect
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* to the ArrayBuffer's internal pointer to associated data. |ChangeData|
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* attempts to set the internal pointer to fresh memory of the same size as the
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* original memory; |KeepData| attempts to preserve the original pointer, even
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* while the ArrayBuffer appears observably detached. There is no guarantee
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* this parameter is respected -- it's only a hint.
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* The |changeData| argument is obsolete and ignored.
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*/
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extern JS_FRIEND_API(bool)
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JS_DetachArrayBuffer(JSContext* cx, JS::HandleObject obj,
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@ -260,14 +260,12 @@ NoteViewBufferWasDetached(ArrayBufferViewObject* view,
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MarkObjectStateChange(cx, view);
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}
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/* static */ bool
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/* static */ void
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ArrayBufferObject::detach(JSContext* cx, Handle<ArrayBufferObject*> buffer,
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BufferContents newContents)
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{
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if (buffer->isWasm()) {
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JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_OUT_OF_MEMORY);
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return false;
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}
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MOZ_ASSERT(!buffer->isWasm(), "WASM/asm.js ArrayBuffers cannot be detached");
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MOZ_ASSERT(buffer->hasDetachableContents(), "detaching the non-detachable");
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// When detaching buffers where we don't know all views, the new data must
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// match the old data. All missing views are typed objects, which do not
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@ -314,7 +312,6 @@ ArrayBufferObject::detach(JSContext* cx, Handle<ArrayBufferObject*> buffer,
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buffer->setByteLength(0);
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buffer->setIsDetached();
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return true;
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}
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void
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@ -729,35 +726,39 @@ ArrayBufferObject::createDataViewForThis(JSContext* cx, unsigned argc, Value* vp
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/* static */ ArrayBufferObject::BufferContents
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ArrayBufferObject::stealContents(JSContext* cx, Handle<ArrayBufferObject*> buffer,
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bool hasStealableContents)
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bool forceCopy)
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{
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MOZ_ASSERT_IF(hasStealableContents, buffer->hasStealableContents());
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if (buffer->isDetached()) {
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JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED);
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return BufferContents::createPlain(nullptr);
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}
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if (!buffer->hasDetachableContents()) {
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JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
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return BufferContents::createPlain(nullptr);
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}
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BufferContents oldContents(buffer->dataPointer(), buffer->bufferKind());
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BufferContents newContents = AllocateArrayBufferContents(cx, buffer->byteLength());
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if (!newContents)
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return BufferContents::createPlain(nullptr);
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if (hasStealableContents) {
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// Return the old contents and give the detached buffer a pointer to
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// freshly allocated memory that we will never write to and should
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// never get committed.
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buffer->setOwnsData(DoesntOwnData);
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if (!ArrayBufferObject::detach(cx, buffer, newContents)) {
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js_free(newContents.data());
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return BufferContents::createPlain(nullptr);
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}
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if (!forceCopy && buffer->ownsData()) {
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// Return the old contents and reset the detached buffer's data
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// pointer. This pointer should never be accessed.
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auto newContents = BufferContents::createPlain(nullptr);
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buffer->setOwnsData(DoesntOwnData); // Do not free the stolen data.
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ArrayBufferObject::detach(cx, buffer, newContents);
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buffer->setOwnsData(DoesntOwnData); // Do not free the nullptr.
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return oldContents;
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}
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// Create a new chunk of memory to return since we cannot steal the
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// existing contents away from the buffer.
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memcpy(newContents.data(), oldContents.data(), buffer->byteLength());
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if (!ArrayBufferObject::detach(cx, buffer, oldContents)) {
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js_free(newContents.data());
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// Create a new chunk of memory to return since we cannot remove the
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// existing contents pointer from the buffer.
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BufferContents contentsCopy = AllocateArrayBufferContents(cx, buffer->byteLength());
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if (!contentsCopy)
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return BufferContents::createPlain(nullptr);
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}
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return newContents;
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if (buffer->byteLength() > 0)
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memcpy(contentsCopy.data(), oldContents.data(), buffer->byteLength());
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ArrayBufferObject::detach(cx, buffer, oldContents);
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return contentsCopy;
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}
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/* static */ void
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@ -1032,10 +1033,11 @@ ArrayBufferViewObject::trace(JSTracer* trc, JSObject* objArg)
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if (IsArrayBuffer(&bufSlot.toObject())) {
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ArrayBufferObject& buf = AsArrayBuffer(MaybeForwarded(&bufSlot.toObject()));
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uint32_t offset = uint32_t(obj->getFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT).toInt32());
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MOZ_ASSERT(buf.dataPointer() != nullptr);
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MOZ_ASSERT(offset <= INT32_MAX);
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if (buf.forInlineTypedObject()) {
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MOZ_ASSERT(buf.dataPointer() != nullptr);
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// The data is inline with an InlineTypedObject associated with the
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// buffer. Get a new address for the typed object if it moved.
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JSObject* view = buf.firstView();
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@ -1055,6 +1057,8 @@ ArrayBufferViewObject::trace(JSTracer* trc, JSObject* objArg)
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trc->runtime()->gc.nursery.maybeSetForwardingPointer(trc, srcData, dstData,
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/* direct = */ false);
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} else {
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MOZ_ASSERT_IF(buf.dataPointer() == nullptr, offset == 0);
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// The data may or may not be inline with the buffer. The buffer
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// can only move during a compacting GC, in which case its
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// objectMoved hook has already updated the buffer's data pointer.
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@ -1081,7 +1085,6 @@ JSObject::is<js::ArrayBufferObjectMaybeShared>() const
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void
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ArrayBufferViewObject::notifyBufferDetached(void* newData)
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{
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MOZ_ASSERT(newData != nullptr);
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if (is<DataViewObject>()) {
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as<DataViewObject>().notifyBufferDetached(newData);
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} else if (is<TypedArrayObject>()) {
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@ -1190,20 +1193,21 @@ JS_DetachArrayBuffer(JSContext* cx, HandleObject obj,
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Rooted<ArrayBufferObject*> buffer(cx, &obj->as<ArrayBufferObject>());
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if (changeData == ChangeData && buffer->hasStealableContents()) {
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ArrayBufferObject::BufferContents newContents =
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AllocateArrayBufferContents(cx, buffer->byteLength());
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if (!newContents)
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return false;
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if (!ArrayBufferObject::detach(cx, buffer, newContents)) {
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js_free(newContents.data());
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return false;
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}
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} else {
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if (!ArrayBufferObject::detach(cx, buffer, buffer->contents()))
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return false;
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if (buffer->isDetached())
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return true;
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if (buffer->isWasm()) {
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JS_ReportError(cx, "Cannot detach WASM ArrayBuffer");
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return false;
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}
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if (!buffer->hasDetachableContents()) {
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JS_ReportError(cx, "Cannot detach ArrayBuffer");
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return false;
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}
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ArrayBufferObject::detach(cx, buffer, buffer->contents());
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return true;
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}
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@ -1286,18 +1290,14 @@ JS_StealArrayBufferContents(JSContext* cx, HandleObject objArg)
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}
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Rooted<ArrayBufferObject*> buffer(cx, &obj->as<ArrayBufferObject>());
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if (buffer->isDetached()) {
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JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED);
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return nullptr;
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}
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// The caller assumes that a plain malloc'd buffer is returned.
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// hasStealableContents is true for mapped buffers, so we must additionally
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// require that the buffer is plain. In the future, we could consider
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// returning something that handles releasing the memory.
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bool hasStealableContents = buffer->hasStealableContents() && buffer->hasMallocedContents();
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// The caller assumes that a plain malloc'd buffer is returned. ownsData is
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// true for (owned) mapped buffers, so we must additionally require that
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// the buffer is plain. In the future, we could consider returning
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// something that handles releasing the memory.
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bool forceCopy = !buffer->ownsData() || !buffer->hasMallocedContents();
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return ArrayBufferObject::stealContents(cx, buffer, hasStealableContents).data();
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return ArrayBufferObject::stealContents(cx, buffer, forceCopy).data();
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}
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JS_PUBLIC_API(JSObject*)
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@ -213,9 +213,6 @@ class ArrayBufferObject : public ArrayBufferObjectMaybeShared
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static bool fun_slice(JSContext* cx, unsigned argc, Value* vp);
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static bool fun_isView(JSContext* cx, unsigned argc, Value* vp);
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#ifdef NIGHTLY_BUILD
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static bool fun_transfer(JSContext* cx, unsigned argc, Value* vp);
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#endif
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static bool fun_species(JSContext* cx, unsigned argc, Value* vp);
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@ -246,21 +243,19 @@ class ArrayBufferObject : public ArrayBufferObjectMaybeShared
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static void trace(JSTracer* trc, JSObject* obj);
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static void objectMoved(JSObject* obj, const JSObject* old);
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// Detach the ArrayBuffer and return its contents (if possible), or
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// possibly a copy of its contents (if forceCopy is passed or the buffer
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// does not own the data).
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static BufferContents stealContents(JSContext* cx,
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Handle<ArrayBufferObject*> buffer,
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bool hasStealableContents);
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bool forceCopy);
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bool hasStealableContents() const {
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// Inline elements strictly adhere to the corresponding buffer.
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if (!ownsData())
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// Some types of buffer are simply not willing to be detached, eg Wasm
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// buffers.
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bool hasDetachableContents() const {
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if (isDetached())
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return false;
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// Detached contents aren't transferrable because we want a detached
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// buffer's contents to be backed by zeroed memory equal in length to
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// the original buffer contents. Transferring these contents would
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// allocate new ones based on the current byteLength, which is 0 for a
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// detached buffer -- not the original byteLength.
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return !isDetached();
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return isPlain() || isMapped();
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}
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// Return whether the buffer is allocated by js_malloc and should be freed
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@ -286,8 +281,8 @@ class ArrayBufferObject : public ArrayBufferObjectMaybeShared
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// Detach this buffer from its original memory. (This necessarily makes
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// views of this buffer unusable for modifying that original memory.)
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static MOZ_MUST_USE bool
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detach(JSContext* cx, Handle<ArrayBufferObject*> buffer, BufferContents newContents);
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static void detach(JSContext* cx, Handle<ArrayBufferObject*> buffer,
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BufferContents newContents);
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private:
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void changeViewContents(JSContext* cx, ArrayBufferViewObject* view,
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@ -325,6 +320,8 @@ class ArrayBufferObject : public ArrayBufferObjectMaybeShared
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bool isMapped() const { return bufferKind() == MAPPED; }
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bool isDetached() const { return flags() & DETACHED; }
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bool ownsData() const { return flags() & OWNS_DATA; }
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static ArrayBufferObject* createForWasm(JSContext* cx, uint32_t numBytes, bool signalsForOOB);
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static bool prepareForAsmJS(JSContext* cx, Handle<ArrayBufferObject*> buffer, bool signalsForOOB);
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@ -355,7 +352,6 @@ class ArrayBufferObject : public ArrayBufferObjectMaybeShared
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uint32_t flags() const;
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void setFlags(uint32_t flags);
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bool ownsData() const { return flags() & OWNS_DATA; }
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void setOwnsData(OwnsState owns) {
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setFlags(owns ? (flags() | OWNS_DATA) : (flags() & ~OWNS_DATA));
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}
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@ -1339,13 +1339,10 @@ JSStructuredCloneWriter::transferOwnership()
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// Structured cloning currently only has optimizations for mapped
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// and malloc'd buffers, not asm.js-ified buffers.
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bool hasStealableContents = arrayBuffer->hasStealableContents() &&
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(arrayBuffer->isMapped() || arrayBuffer->hasMallocedContents());
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ArrayBufferObject::BufferContents bufContents =
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ArrayBufferObject::stealContents(context(), arrayBuffer, hasStealableContents);
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ArrayBufferObject::stealContents(context(), arrayBuffer, false);
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if (!bufContents)
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return false; // Destructor will clean up the already-transferred data.
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return false; // already transferred data or non-transferable buffer type
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content = bufContents.data();
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tag = SCTAG_TRANSFER_MAP_ARRAY_BUFFER;
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