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Bug 1352681 - Make SAB rawBuffer refcounting for structured clone mor…

…e sophisticated. r=sfink

--HG--
extra : rebase_source : f5c97970013daab78075e2fe68c9704cda7064cd
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lars-t-hansen committed Apr 3, 2017
1 parent d4b0fe7 commit c86b9cb593c1b311791977d0e5d7f01f2411a92b
Showing with 118 additions and 16 deletions.
  1. +26 −1 js/public/StructuredClone.h
  2. +92 −15 js/src/vm/StructuredClone.cpp
@@ -17,6 +17,7 @@
#include "js/RootingAPI.h"
#include "js/TypeDecls.h"
#include "js/Value.h"
#include "js/Vector.h"
struct JSRuntime;
struct JSStructuredCloneReader;
@@ -188,6 +189,28 @@ enum OwnTransferablePolicy {
NoTransferables
};
namespace js
{
class SharedArrayRawBuffer;
class SharedArrayRawBufferRefs
{
public:
SharedArrayRawBufferRefs() = default;
SharedArrayRawBufferRefs(SharedArrayRawBufferRefs&& other) = default;
SharedArrayRawBufferRefs& operator=(SharedArrayRawBufferRefs&& other);
~SharedArrayRawBufferRefs();
MOZ_MUST_USE bool acquire(JSContext* cx, SharedArrayRawBuffer* rawbuf);
MOZ_MUST_USE bool acquireAll(JSContext* cx, const SharedArrayRawBufferRefs& that);
void takeOwnership(SharedArrayRawBufferRefs&&);
void releaseAll();
private:
js::Vector<js::SharedArrayRawBuffer*, 0, js::SystemAllocPolicy> refs_;
};
}
class MOZ_NON_MEMMOVABLE JS_PUBLIC_API(JSStructuredCloneData) :
public mozilla::BufferList<js::SystemAllocPolicy>
{
@@ -201,6 +224,7 @@ class MOZ_NON_MEMMOVABLE JS_PUBLIC_API(JSStructuredCloneData) :
const JSStructuredCloneCallbacks* callbacks_;
void* closure_;
OwnTransferablePolicy ownTransferables_;
js::SharedArrayRawBufferRefs refsHeld_;
void setOptionalCallbacks(const JSStructuredCloneCallbacks* callbacks,
void* closure,
@@ -279,7 +303,8 @@ class JS_PUBLIC_API(JSAutoStructuredCloneBuffer) {
void clear(const JSStructuredCloneCallbacks* optionalCallbacks=nullptr, void* closure=nullptr);
/** Copy some memory. It will be automatically freed by the destructor. */
bool copy(const JSStructuredCloneData& data, uint32_t version=JS_STRUCTURED_CLONE_VERSION,
bool copy(JSContext* cx, const JSStructuredCloneData& data,
uint32_t version=JS_STRUCTURED_CLONE_VERSION,
const JSStructuredCloneCallbacks* callbacks=nullptr, void* closure=nullptr);
/**
@@ -229,6 +229,69 @@ struct BufferIterator {
typename BufferList::IterImpl mIter;
};
SharedArrayRawBufferRefs&
SharedArrayRawBufferRefs::operator=(SharedArrayRawBufferRefs&& other)
{
takeOwnership(Move(other));
return *this;
}
SharedArrayRawBufferRefs::~SharedArrayRawBufferRefs()
{
releaseAll();
}
bool
SharedArrayRawBufferRefs::acquire(JSContext* cx, SharedArrayRawBuffer* rawbuf)
{
if (!refs_.append(rawbuf)) {
ReportOutOfMemory(cx);
return false;
}
if (!rawbuf->addReference()) {
refs_.popBack();
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_SC_SAB_REFCNT_OFLO);
return false;
}
return true;
}
bool
SharedArrayRawBufferRefs::acquireAll(JSContext* cx, const SharedArrayRawBufferRefs& that)
{
if (!refs_.reserve(refs_.length() + that.refs_.length())) {
ReportOutOfMemory(cx);
return false;
}
for (auto ref : that.refs_) {
if (!ref->addReference()) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_SC_SAB_REFCNT_OFLO);
return false;
}
MOZ_ALWAYS_TRUE(refs_.append(ref));
}
return true;
}
void
SharedArrayRawBufferRefs::takeOwnership(SharedArrayRawBufferRefs&& other)
{
MOZ_ASSERT(refs_.empty());
refs_ = Move(other.refs_);
}
void
SharedArrayRawBufferRefs::releaseAll()
{
for (auto ref : refs_)
ref->dropReference();
refs_.clear();
}
struct SCOutput {
public:
using Iter = BufferIterator<uint64_t, TempAllocPolicy>;
@@ -408,6 +471,9 @@ struct JSStructuredCloneWriter {
bool extractBuffer(JSStructuredCloneData* data) {
bool success = out.extractBuffer(data);
if (success) {
// Move the SharedArrayRawBuf references here, SCOutput::extractBuffer
// moves the serialized data.
data->refsHeld_.takeOwnership(Move(refsHeld));
data->setOptionalCallbacks(callbacks, closure,
OwnTransferablePolicy::OwnsTransferablesIfAny);
}
@@ -486,6 +552,9 @@ struct JSStructuredCloneWriter {
const JS::CloneDataPolicy cloneDataPolicy;
// SharedArrayRawBuffers whose reference counts we have incremented.
SharedArrayRawBufferRefs refsHeld;
friend bool JS_WriteString(JSStructuredCloneWriter* w, HandleString str);
friend bool JS_WriteTypedArray(JSStructuredCloneWriter* w, HandleValue v);
friend bool JS_ObjectNotWritten(JSStructuredCloneWriter* w, HandleObject obj);
@@ -1161,12 +1230,8 @@ JSStructuredCloneWriter::writeSharedArrayBuffer(HandleObject obj)
Rooted<SharedArrayBufferObject*> sharedArrayBuffer(context(), &CheckedUnwrap(obj)->as<SharedArrayBufferObject>());
SharedArrayRawBuffer* rawbuf = sharedArrayBuffer->rawBufferObject();
// Avoids a race condition where the parent thread frees the buffer
// before the child has accepted the transferable.
if (!rawbuf->addReference()) {
JS_ReportErrorNumberASCII(context(), GetErrorMessage, nullptr, JSMSG_SC_SAB_REFCNT_OFLO);
if (!refsHeld.acquire(context(), rawbuf))
return false;
}
intptr_t p = reinterpret_cast<intptr_t>(rawbuf);
return out.writePair(SCTAG_SHARED_ARRAY_BUFFER_OBJECT, static_cast<uint32_t>(sizeof(p))) &&
@@ -1894,18 +1959,24 @@ JSStructuredCloneReader::readSharedArrayBuffer(uint32_t nbytes, MutableHandleVal
// in any case. Just fail at the receiving end if we can't handle it.
if (!context()->compartment()->creationOptions().getSharedMemoryAndAtomicsEnabled()) {
// The sending side performed a reference increment before sending.
// Account for that here before leaving.
if (rawbuf)
rawbuf->dropReference();
JS_ReportErrorNumberASCII(context(), GetErrorMessage, nullptr, JSMSG_SC_SAB_DISABLED);
return false;
}
// The constructor absorbs the reference count increment performed by the sender.
// The new object will have a new reference to the rawbuf.
if (!rawbuf->addReference()) {
JS_ReportErrorNumberASCII(context(), GetErrorMessage, nullptr, JSMSG_SC_SAB_REFCNT_OFLO);
return false;
}
JSObject* obj = SharedArrayBufferObject::New(context(), rawbuf);
if (!obj) {
rawbuf->dropReference();
return false;
}
vp.setObject(*obj);
return true;
}
@@ -2591,13 +2662,14 @@ JSAutoStructuredCloneBuffer::clear(const JSStructuredCloneCallbacks* optionalCal
if (data_.ownTransferables_ == OwnTransferablePolicy::OwnsTransferablesIfAny)
DiscardTransferables(data_, callbacks, closure);
data_.ownTransferables_ = OwnTransferablePolicy::NoTransferables;
data_.refsHeld_.releaseAll();
data_.Clear();
version_ = 0;
}
bool
JSAutoStructuredCloneBuffer::copy(const JSStructuredCloneData& srcData, uint32_t version,
const JSStructuredCloneCallbacks* callbacks,
JSAutoStructuredCloneBuffer::copy(JSContext* cx, const JSStructuredCloneData& srcData,
uint32_t version, const JSStructuredCloneCallbacks* callbacks,
void* closure)
{
// transferable objects cannot be copied
@@ -2608,11 +2680,16 @@ JSAutoStructuredCloneBuffer::copy(const JSStructuredCloneData& srcData, uint32_t
auto iter = srcData.Iter();
while (!iter.Done()) {
data_.WriteBytes(iter.Data(), iter.RemainingInSegment());
iter.Advance(srcData, iter.RemainingInSegment());
if (!data_.WriteBytes(iter.Data(), iter.RemainingInSegment()))
return false;
iter.Advance(srcData, iter.RemainingInSegment());
}
version_ = version;
if (!data_.refsHeld_.acquireAll(cx, srcData.refsHeld_))
return false;
data_.setOptionalCallbacks(callbacks, closure, OwnTransferablePolicy::NoTransferables);
return true;
}

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