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Bug 1503006 - Part 3: Trivial slot accessor methods for class ReadableStreamReader. r=tcampbell

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This commit changes ReadableStreamReaderGenericRelease to use
UnwrapInternalSlot when accessing reader.[[closedPromise]]. Before this commit,
the code assumed that there would be a promise in the slot, not a wrapper.
I think that was actually correct, because it's impossible for the stream to
still be readable and the reader to have a [[closedPromise]] that's a wrapper.
Still, it's a bit precarious (and I'm still not 100% sure about that), so I just
changed it to unwrap.

Depends on D10374

Differential Revision: https://phabricator.services.mozilla.com/D10428

--HG--
extra : moz-landing-system : lando
This commit is contained in:
Jason Orendorff 2018-10-31 23:27:31 +00:00
parent 06f8c8024c
commit a31ca6742c
3 changed files with 109 additions and 104 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

153
js/src/builtin/Stream.cpp
View File

@ -18,34 +18,6 @@
using namespace js;
/**
* Memory layout of Stream Reader instances.
*
* See https://streams.spec.whatwg.org/#default-reader-internal-slots and
* https://streams.spec.whatwg.org/#byob-reader-internal-slots for details.
*
* Note that [[readRequests]] and [[readIntoRequests]] are treated the same in
* our implementation.
*
* Of the stored values, Stream and ClosedPromise might be cross-compartment
* wrapper wrappers.
*
* For Stream, this can happen if the Reader was created by applying a
* different compartment's ReadableStream.prototype.getReader method.
*
* For ClosedPromise, it can be caused by applying a different compartment's
* ReadableStream*Reader.prototype.releaseLock method.
*
* Requests is guaranteed to be in the same compartment as the Reader, but can
* contain wrapped request objects from other globals.
*/
enum ReaderSlots {
ReaderSlot_Stream,
ReaderSlot_Requests,
ReaderSlot_ClosedPromise,
ReaderSlotCount,
};
enum ReaderType {
ReaderType_Default,
ReaderType_BYOB
@ -202,18 +174,6 @@ RemoveControllerFlags(ReadableStreamController* controller, uint32_t flags)
Int32Value(ControllerFlags(controller) & ~flags));
}
inline static bool
ReaderHasStream(const ReadableStreamReader* reader)
{
return !reader->getFixedSlot(ReaderSlot_Stream).isUndefined();
}
bool
js::ReadableStreamReaderIsClosed(const JSObject* reader)
{
return !ReaderHasStream(&reader->as<ReadableStreamReader>());
}
static inline ReadableStream*
StreamFromController(const ReadableStreamController* controller)
{
@ -274,8 +234,8 @@ UnwrapStreamFromReader(JSContext *cx,
Handle<ReadableStreamReader*> reader,
MutableHandle<ReadableStream*> unwrappedResult)
{
MOZ_ASSERT(ReaderHasStream(reader));
return UnwrapInternalSlot(cx, reader, ReaderSlot_Stream, unwrappedResult);
MOZ_ASSERT(reader->hasStream());
return UnwrapInternalSlot(cx, reader, ReadableStreamReader::Slot_Stream, unwrappedResult);
}
/**
@ -1399,7 +1359,7 @@ ReadableStreamTee(JSContext* cx, Handle<ReadableStream*> stream, bool cloneForBr
// Our implementation stores the controllers on the TeeState instead.
// Step 21: Upon rejection of reader.[[closedPromise]] with reason r,
RootedObject closedPromise(cx, &reader->getFixedSlot(ReaderSlot_ClosedPromise).toObject());
RootedObject closedPromise(cx, reader->closedPromise());
RootedObject onRejected(cx, NewHandler(cx, TeeReaderClosedHandler, teeState));
if (!onRejected) {
@ -1452,7 +1412,7 @@ ReadableStreamAddReadOrReadIntoRequest(JSContext* cx, Handle<ReadableStream*> st
// Step 5: Append read{Into}Request as the last element of
// stream.[[reader]].[[read{Into}Requests]].
// Since [[promise]] is the Record's only field, we store it directly.
if (!AppendToListAtSlot(cx, reader, ReaderSlot_Requests, promise)) {
if (!AppendToListAtSlot(cx, reader, ReadableStreamReader::Slot_Requests, promise)) {
return nullptr;
}
@ -1565,39 +1525,36 @@ ReadableStreamCloseInternal(JSContext* cx, Handle<ReadableStream*> stream)
if (reader->is<ReadableStreamDefaultReader>()) {
// Step a: Repeat for each readRequest that is an element of
// reader.[[readRequests]],
RootedValue val(cx, reader->getFixedSlot(ReaderSlot_Requests));
if (!val.isUndefined()) {
RootedNativeObject readRequests(cx, &val.toObject().as<NativeObject>());
uint32_t len = readRequests->getDenseInitializedLength();
RootedObject readRequest(cx);
RootedObject resultObj(cx);
RootedValue resultVal(cx);
for (uint32_t i = 0; i < len; i++) {
// Step i: Resolve readRequest.[[promise]] with
// ! CreateIterResultObject(undefined, true).
readRequest = &readRequests->getDenseElement(i).toObject();
if (needsWrapping && !cx->compartment()->wrap(cx, &readRequest)) {
return false;
}
resultObj = CreateIterResultObject(cx, UndefinedHandleValue, true);
if (!resultObj) {
return false;
}
resultVal = ObjectValue(*resultObj);
if (!ResolvePromise(cx, readRequest, resultVal)) {
return false;
}
RootedNativeObject readRequests(cx, reader->requests());
uint32_t len = readRequests->getDenseInitializedLength();
RootedObject readRequest(cx);
RootedObject resultObj(cx);
RootedValue resultVal(cx);
for (uint32_t i = 0; i < len; i++) {
// Step i: Resolve readRequest.[[promise]] with
// ! CreateIterResultObject(undefined, true).
readRequest = &readRequests->getDenseElement(i).toObject();
if (needsWrapping && !cx->compartment()->wrap(cx, &readRequest)) {
return false;
}
// Step b: Set reader.[[readRequests]] to an empty List.
reader->setFixedSlot(ReaderSlot_Requests, UndefinedValue());
resultObj = CreateIterResultObject(cx, UndefinedHandleValue, true);
if (!resultObj) {
return false;
}
resultVal = ObjectValue(*resultObj);
if (!ResolvePromise(cx, readRequest, resultVal)) {
return false;
}
}
// Step b: Set reader.[[readRequests]] to an empty List.
reader->clearRequests();
}
// Step 6: Resolve reader.[[closedPromise]] with undefined.
// Step 7: Return (implicit).
RootedObject closedPromise(cx, &reader->getFixedSlot(ReaderSlot_ClosedPromise).toObject());
RootedObject closedPromise(cx, reader->closedPromise());
if (needsWrapping && !cx->compartment()->wrap(cx, &closedPromise)) {
return false;
}
@ -1652,9 +1609,9 @@ ReadableStreamErrorInternal(JSContext* cx, Handle<ReadableStream*> stream, Handl
// Steps 7,8: (Identical in our implementation.)
// Step a: Repeat for each readRequest that is an element of
// reader.[[readRequests]],
RootedValue val(cx, reader->getFixedSlot(ReaderSlot_Requests));
RootedNativeObject readRequests(cx, &val.toObject().as<NativeObject>());
RootedNativeObject readRequests(cx, reader->requests());
RootedObject readRequest(cx);
RootedValue val(cx);
uint32_t len = readRequests->getDenseInitializedLength();
for (uint32_t i = 0; i < len; i++) {
// Step i: Reject readRequest.[[promise]] with e.
@ -1674,12 +1631,12 @@ ReadableStreamErrorInternal(JSContext* cx, Handle<ReadableStream*> stream, Handl
}
// Step b: Set reader.[[readRequests]] to a new empty List.
if (!SetNewList(cx, reader, ReaderSlot_Requests)) {
if (!SetNewList(cx, reader, ReadableStreamReader::Slot_Requests)) {
return false;
}
// Step 9: Reject reader.[[closedPromise]] with e.
RootedObject closedPromise(cx, &reader->getFixedSlot(ReaderSlot_ClosedPromise).toObject());
RootedObject closedPromise(cx, reader->closedPromise());
// The closedPromise might have been created in another compartment.
// RejectPromise can deal with wrapped Promise objects, but has to be
@ -1738,8 +1695,7 @@ ReadableStreamFulfillReadOrReadIntoRequest(JSContext* cx, Handle<ReadableStream*
// Step 3: Remove readIntoRequest from reader.[[readIntoRequests]], shifting
// all other elements downward (so that the second becomes the first,
// and so on).
RootedValue val(cx, reader->getFixedSlot(ReaderSlot_Requests));
RootedNativeObject readIntoRequests(cx, &val.toObject().as<NativeObject>());
RootedNativeObject readIntoRequests(cx, reader->requests());
RootedObject readIntoRequest(cx, ShiftFromList<JSObject>(cx, readIntoRequests));
MOZ_ASSERT(readIntoRequest);
if (!cx->compartment()->wrap(cx, &readIntoRequest)) {
@ -1756,7 +1712,7 @@ ReadableStreamFulfillReadOrReadIntoRequest(JSContext* cx, Handle<ReadableStream*
if (!iterResult) {
return false;
}
val = ObjectValue(*iterResult);
RootedValue val(cx, ObjectValue(*iterResult));
return ResolvePromise(cx, readIntoRequest, val);
}
@ -1780,8 +1736,7 @@ ReadableStreamGetNumReadRequests(ReadableStream* stream)
return 0;
}
Value readRequests = reader->getFixedSlot(ReaderSlot_Requests);
return readRequests.toObject().as<NativeObject>().getDenseInitializedLength();
return reader->requests()->getDenseInitializedLength();
}
enum class ReaderMode
@ -1870,7 +1825,7 @@ CreateReadableStreamDefaultReader(JSContext* cx, Handle<ReadableStream*> stream)
}
// Step 4: Set this.[[readRequests]] to a new empty List.
if (!SetNewList(cx, reader, ReaderSlot_Requests)) {
if (!SetNewList(cx, reader, ReadableStreamReader::Slot_Requests)) {
return nullptr;
}
@ -1928,12 +1883,12 @@ ReadableStreamDefaultReader_closed(JSContext* cx, unsigned argc, Value* vp)
}
// Step 2: Return this.[[closedPromise]].
RootedValue closedPromise(cx, reader->getFixedSlot(ReaderSlot_ClosedPromise));
RootedObject closedPromise(cx, reader->closedPromise());
if (!cx->compartment()->wrap(cx, &closedPromise)) {
return false;
}
args.rval().set(closedPromise);
args.rval().setObject(*closedPromise);
return true;
}
@ -1961,7 +1916,7 @@ ReadableStreamDefaultReader_cancel(JSContext* cx, unsigned argc, Value* vp)
// Step 2: If this.[[ownerReadableStream]] is undefined, return a promise
// rejected with a TypeError exception.
if (!ReaderHasStream(reader)) {
if (!reader->hasStream()) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
JSMSG_READABLESTREAMREADER_NOT_OWNED, "cancel");
return ReturnPromiseRejectedWithPendingError(cx, args);
@ -1996,7 +1951,7 @@ ReadableStreamDefaultReader_read(JSContext* cx, unsigned argc, Value* vp)
// Step 2: If this.[[ownerReadableStream]] is undefined, return a promise
// rejected with a TypeError exception.
if (!ReaderHasStream(reader)) {
if (!reader->hasStream()) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
JSMSG_READABLESTREAMREADER_NOT_OWNED, "read");
return ReturnPromiseRejectedWithPendingError(cx, args);
@ -2037,20 +1992,20 @@ ReadableStreamDefaultReader_releaseLock(JSContext* cx, unsigned argc, Value* vp)
}
// Step 2: If this.[[ownerReadableStream]] is undefined, return.
if (!ReaderHasStream(reader)) {
if (!reader->hasStream()) {
args.rval().setUndefined();
return true;
}
// Step 3: If this.[[readRequests]] is not empty, throw a TypeError exception.
Value val = reader->getFixedSlot(ReaderSlot_Requests);
Value val = reader->getFixedSlot(ReadableStreamReader::Slot_Requests);
if (!val.isUndefined()) {
NativeObject* readRequests = &val.toObject().as<NativeObject>();
uint32_t len = readRequests->getDenseInitializedLength();
if (len != 0) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
JSMSG_READABLESTREAMREADER_NOT_EMPTY,
"releaseLock");
JSMSG_READABLESTREAMREADER_NOT_EMPTY,
"releaseLock");
return false;
}
}
@ -2075,7 +2030,7 @@ const Class ReadableStreamReader::class_ = {
"ReadableStreamReader"
};
CLASS_SPEC(ReadableStreamDefaultReader, 1, ReaderSlotCount, ClassSpec::DontDefineConstructor, 0,
CLASS_SPEC(ReadableStreamDefaultReader, 1, SlotCount, ClassSpec::DontDefineConstructor, 0,
JS_NULL_CLASS_OPS);
@ -2125,7 +2080,7 @@ ReadableStreamReaderGenericInitialize(JSContext* cx, Handle<ReadableStreamReader
if (!cx->compartment()->wrap(cx, &wrappedStream)) {
return false;
}
reader->setFixedSlot(ReaderSlot_Stream, ObjectValue(*wrappedStream));
reader->setStream(wrappedStream);
AutoRealm ar(cx, stream);
RootedObject wrappedReader(cx, reader);
if (!cx->compartment()->wrap(cx, &wrappedReader)) {
@ -2133,7 +2088,7 @@ ReadableStreamReaderGenericInitialize(JSContext* cx, Handle<ReadableStreamReader
}
stream->setReader(wrappedReader);
} else {
reader->setFixedSlot(ReaderSlot_Stream, ObjectValue(*stream));
reader->setStream(stream);
stream->setReader(reader);
}
@ -2166,7 +2121,7 @@ ReadableStreamReaderGenericInitialize(JSContext* cx, Handle<ReadableStreamReader
return false;
}
reader->setFixedSlot(ReaderSlot_ClosedPromise, ObjectValue(*promise));
reader->setClosedPromise(promise);
return true;
}
@ -2206,8 +2161,14 @@ ReadableStreamReaderGenericRelease(JSContext* cx, Handle<ReadableStreamReader*>
// Step 3: If reader.[[ownerReadableStream]].[[state]] is "readable", reject
// reader.[[closedPromise]] with a TypeError exception.
if (stream->readable()) {
Value val = reader->getFixedSlot(ReaderSlot_ClosedPromise);
Rooted<PromiseObject*> closedPromise(cx, &val.toObject().as<PromiseObject>());
Rooted<PromiseObject*> closedPromise(cx);
if (!UnwrapInternalSlot(cx,
reader,
ReadableStreamReader::Slot_ClosedPromise,
&closedPromise))
{
return false;
}
if (closedPromise->compartment() != cx->compartment()) {
ar.emplace(cx, closedPromise);
if (!cx->compartment()->wrap(cx, &exn)) {
@ -2230,14 +2191,14 @@ ReadableStreamReaderGenericRelease(JSContext* cx, Handle<ReadableStreamReader*>
return false;
}
}
reader->setFixedSlot(ReaderSlot_ClosedPromise, ObjectValue(*closedPromise));
reader->setClosedPromise(closedPromise);
}
// Step 5: Set reader.[[ownerReadableStream]].[[reader]] to undefined.
stream->clearReader();
// Step 6: Set reader.[[ownerReadableStream]] to undefined.
reader->setFixedSlot(ReaderSlot_Stream, UndefinedValue());
reader->clearStream();
return true;
}

56
js/src/builtin/Stream.h
View File

@ -13,14 +13,9 @@
namespace js {
class ReadableStreamReader;
class ReadableStreamController;
class ReadableStreamReader : public NativeObject
{
public:
static const Class class_;
};
class ReadableStream : public NativeObject
{
public:
@ -132,6 +127,55 @@ class ReadableStream : public NativeObject
static const Class protoClass_;
};
class ReadableStreamReader : public NativeObject
{
public:
/**
* Memory layout of Stream Reader instances.
*
* See https://streams.spec.whatwg.org/#default-reader-internal-slots and
* https://streams.spec.whatwg.org/#byob-reader-internal-slots for details.
*
* Note that [[readRequests]] and [[readIntoRequests]] are treated the same
* in our implementation.
*
* Of the stored values, Stream and ClosedPromise might be
* cross-compartment wrapper wrappers.
*
* For Stream, this can happen if the Reader was created by applying a
* different compartment's ReadableStream.prototype.getReader method.
*
* For ClosedPromise, it can be caused by applying a different
* compartment's ReadableStream*Reader.prototype.releaseLock method.
*
* Requests is guaranteed to be in the same compartment as the Reader, but
* can contain wrapped request objects from other globals.
*/
enum Slots {
Slot_Stream,
Slot_Requests,
Slot_ClosedPromise,
SlotCount,
};
bool hasStream() const { return !getFixedSlot(Slot_Stream).isUndefined(); }
void setStream(JSObject* stream) { setFixedSlot(Slot_Stream, ObjectValue(*stream)); }
void clearStream() { setFixedSlot(Slot_Stream, UndefinedValue()); }
bool isClosed() { return !hasStream(); }
NativeObject* requests() const {
return &getFixedSlot(Slot_Requests).toObject().as<NativeObject>();
}
void clearRequests() { setFixedSlot(Slot_Requests, UndefinedValue()); }
JSObject* closedPromise() const { return &getFixedSlot(Slot_ClosedPromise).toObject(); }
void setClosedPromise(JSObject* wrappedPromise) {
setFixedSlot(Slot_ClosedPromise, ObjectValue(*wrappedPromise));
}
static const Class class_;
};
class ReadableStreamDefaultReader : public ReadableStreamReader
{
public:

4
js/src/jsapi.cpp
View File

@ -4953,11 +4953,11 @@ JS::ReadableStreamError(JSContext* cx, HandleObject streamObj, HandleValue error
JS_PUBLIC_API(bool)
JS::ReadableStreamReaderIsClosed(JSContext* cx, HandleObject readerObj, bool* result)
{
RootedObject reader(cx, ToUnwrapped<NativeObject>(cx, readerObj));
Rooted<ReadableStreamReader*> reader(cx, ToUnwrapped<ReadableStreamReader>(cx, readerObj));
if (!reader)
return false;
*result = js::ReadableStreamReaderIsClosed(reader);
*result = reader->isClosed();
return true;
}