Bug 1264642 - Part 4. Use BufferList to replace raw buffers in Struct…

…uredClone. r=baku r=billm r=jorendorff

In JS StructuredClone BufferList<SystemAllocPolicy> is typedef'd to
JSStructuredCloneData and use everywhere in gecko that stores structured
clone data.

This patch changed some raw pointers to UniquePtr<JSStructuredCloneData>
and some to stack allocated JSStructuredCloneData for better life time
management. Some parameters or methods are deleted because of changing
to the new data structure.

MessagePortMessage now has the exactly same structure with
ClonedMessageData. Maybe in the future they can be consolidated.

MozReview-Commit-ID: 1IY9p5eKLgv

dom/base/StructuredCloneHolder.cpp

@@ -133,7 +133,9 @@ StructuredCloneCallbacksError(JSContext* aCx,
   NS_WARNING("Failed to clone data.");
 }
 
-const JSStructuredCloneCallbacks gCallbacks = {
+} // anonymous namespace
+
+const JSStructuredCloneCallbacks StructuredCloneHolder::sCallbacks = {
   StructuredCloneCallbacksRead,
   StructuredCloneCallbacksWrite,
   StructuredCloneCallbacksError,
@@ -142,8 +144,6 @@ const JSStructuredCloneCallbacks gCallbacks = {
   StructuredCloneCallbacksFreeTransfer
 };
 
-} // anonymous namespace
-
 // StructuredCloneHolderBase class
 
 StructuredCloneHolderBase::StructuredCloneHolderBase(StructuredCloneScope aScope)
@@ -185,9 +185,9 @@ StructuredCloneHolderBase::Write(JSContext* aCx,
   MOZ_ASSERT(!mBuffer, "Double Write is not allowed");
   MOZ_ASSERT(!mClearCalled, "This method cannot be called after Clear.");
 
-  mBuffer = new JSAutoStructuredCloneBuffer(mStructuredCloneScope, &gCallbacks, this);
+  mBuffer = MakeUnique<JSAutoStructuredCloneBuffer>(mStructuredCloneScope, &StructuredCloneHolder::sCallbacks, this);
 
-  if (!mBuffer->write(aCx, aValue, aTransfer, &gCallbacks, this)) {
+  if (!mBuffer->write(aCx, aValue, aTransfer, &StructuredCloneHolder::sCallbacks, this)) {
     mBuffer = nullptr;
     return false;
   }
@@ -202,7 +202,7 @@ StructuredCloneHolderBase::Read(JSContext* aCx,
   MOZ_ASSERT(mBuffer, "Read() without Write() is not allowed.");
   MOZ_ASSERT(!mClearCalled, "This method cannot be called after Clear.");
 
-  bool ok = mBuffer->read(aCx, aValue, &gCallbacks, this);
+  bool ok = mBuffer->read(aCx, aValue, &StructuredCloneHolder::sCallbacks, this);
   return ok;
 }
 
@@ -311,20 +311,18 @@ StructuredCloneHolder::Read(nsISupports* aParent,
 void
 StructuredCloneHolder::ReadFromBuffer(nsISupports* aParent,
                                       JSContext* aCx,
-                                      uint64_t* aBuffer,
-                                      size_t aBufferLength,
+                                      JSStructuredCloneData& aBuffer,
                                       JS::MutableHandle<JS::Value> aValue,
                                       ErrorResult& aRv)
 {
-  ReadFromBuffer(aParent, aCx, aBuffer, aBufferLength,
+  ReadFromBuffer(aParent, aCx, aBuffer,
                  JS_STRUCTURED_CLONE_VERSION, aValue, aRv);
 }
 
 void
 StructuredCloneHolder::ReadFromBuffer(nsISupports* aParent,
                                       JSContext* aCx,
-                                      uint64_t* aBuffer,
-                                      size_t aBufferLength,
+                                      JSStructuredCloneData& aBuffer,
                                       uint32_t aAlgorithmVersion,
                                       JS::MutableHandle<JS::Value> aValue,
                                       ErrorResult& aRv)
@@ -333,53 +331,18 @@ StructuredCloneHolder::ReadFromBuffer(nsISupports* aParent,
                 mCreationThread == NS_GetCurrentThread());
 
   MOZ_ASSERT(!mBuffer, "ReadFromBuffer() must be called without a Write().");
-  MOZ_ASSERT(aBuffer);
 
   mozilla::AutoRestore<nsISupports*> guard(mParent);
   mParent = aParent;
 
-  if (!JS_ReadStructuredClone(aCx, aBuffer, aBufferLength, aAlgorithmVersion,
-                              mStructuredCloneScope, aValue, &gCallbacks,
+  if (!JS_ReadStructuredClone(aCx, aBuffer, aAlgorithmVersion,
+                              mStructuredCloneScope, aValue, &sCallbacks,
                               this)) {
     JS_ClearPendingException(aCx);
     aRv.Throw(NS_ERROR_DOM_DATA_CLONE_ERR);
   }
 }
 
-void
-StructuredCloneHolder::MoveBufferDataToArray(FallibleTArray<uint8_t>& aArray,
-                                             ErrorResult& aRv)
-{
-  MOZ_ASSERT_IF(mStructuredCloneScope == StructuredCloneScope::SameProcessSameThread,
-                mCreationThread == NS_GetCurrentThread());
-
-  MOZ_ASSERT(mBuffer, "MoveBuffer() cannot be called without a Write().");
-
-  if (NS_WARN_IF(!aArray.SetLength(BufferSize(), mozilla::fallible))) {
-    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
-    return;
-  }
-
-  uint64_t* buffer;
-  size_t size;
-  mBuffer->steal(&buffer, &size);
-  mBuffer = nullptr;
-
-  memcpy(aArray.Elements(), buffer, size);
-  js_free(buffer);
-}
-
-void
-StructuredCloneHolder::FreeBuffer(uint64_t* aBuffer,
-                                  size_t aBufferLength)
-{
-  MOZ_ASSERT(!mBuffer, "FreeBuffer() must be called without a Write().");
-  MOZ_ASSERT(aBuffer);
-  MOZ_ASSERT(aBufferLength);
-
-  JS_ClearStructuredClone(aBuffer, aBufferLength, &gCallbacks, this, false);
-}
-
 /* static */ JSObject*
 StructuredCloneHolder::ReadFullySerializableObjects(JSContext* aCx,
                                                     JSStructuredCloneReader* aReader,

dom/base/StructuredCloneHolder.h

@@ -8,7 +8,7 @@
 
 #include "js/StructuredClone.h"
 #include "mozilla/Move.h"
-#include "nsAutoPtr.h"
+#include "mozilla/UniquePtr.h"
 #include "nsISupports.h"
 #include "nsTArray.h"
 
@@ -102,20 +102,14 @@ class StructuredCloneHolderBase
     return !!mBuffer;
   }
 
-  uint64_t* BufferData() const
+  JSStructuredCloneData& BufferData() const
   {
     MOZ_ASSERT(mBuffer, "Write() has never been called.");
     return mBuffer->data();
   }
 
-  size_t BufferSize() const
-  {
-    MOZ_ASSERT(mBuffer, "Write() has never been called.");
-    return mBuffer->nbytes();
-  }
-
 protected:
-  nsAutoPtr<JSAutoStructuredCloneBuffer> mBuffer;
+  UniquePtr<JSAutoStructuredCloneBuffer> mBuffer;
 
   StructuredCloneScope mStructuredCloneScope;
 
@@ -172,12 +166,6 @@ class StructuredCloneHolder : public StructuredCloneHolderBase
             JS::MutableHandle<JS::Value> aValue,
             ErrorResult &aRv);
 
-  // Sometimes, when IPC is involved, you must send a buffer after a Write().
-  // This method 'steals' the internal data from this class.
-  // You should free this buffer with StructuredCloneHolder::FreeBuffer().
-  void MoveBufferDataToArray(FallibleTArray<uint8_t>& aArray,
-                             ErrorResult& aRv);
-
   // Call this method to know if this object is keeping some DOM object alive.
   bool HasClonedDOMObjects() const
   {
@@ -266,29 +254,25 @@ class StructuredCloneHolder : public StructuredCloneHolderBase
                                              JSStructuredCloneWriter* aWriter,
                                              JS::Handle<JSObject*> aObj);
 
+  static const JSStructuredCloneCallbacks sCallbacks;
+
 protected:
   // If you receive a buffer from IPC, you can use this method to retrieve a
   // JS::Value. It can happen that you want to pre-populate the array of Blobs
   // and/or the PortIdentifiers.
   void ReadFromBuffer(nsISupports* aParent,
                       JSContext* aCx,
-                      uint64_t* aBuffer,
-                      size_t aBufferLength,
+                      JSStructuredCloneData& aBuffer,
                       JS::MutableHandle<JS::Value> aValue,
                       ErrorResult &aRv);
 
   void ReadFromBuffer(nsISupports* aParent,
                       JSContext* aCx,
-                      uint64_t* aBuffer,
-                      size_t aBufferLength,
+                      JSStructuredCloneData& aBuffer,
                       uint32_t aAlgorithmVersion,
                       JS::MutableHandle<JS::Value> aValue,
                       ErrorResult &aRv);
 
-  // Use this method to free a buffer generated by MoveToBuffer().
-  void FreeBuffer(uint64_t* aBuffer,
-                  size_t aBufferLength);
-
   bool mSupportsCloning;
   bool mSupportsTransferring;
 

dom/base/nsFrameMessageManager.cpp

@@ -276,8 +276,13 @@ BuildClonedMessageData(typename BlobTraits<Flavor>::ConcreteContentManagerType*
                        ClonedMessageData& aClonedData)
 {
   SerializedStructuredCloneBuffer& buffer = aClonedData.data();
-  buffer.data = aData.Data();
-  buffer.dataLength = aData.DataLength();
+  auto iter = aData.Data().Iter();
+  size_t size = aData.Data().Size();
+  bool success;
+  buffer.data = aData.Data().Borrow<js::SystemAllocPolicy>(iter, size, &success);
+  if (NS_WARN_IF(!success)) {
+    return false;
+  }
   aClonedData.identfiers().AppendElements(aData.PortIdentifiers());
 
   const nsTArray<RefPtr<BlobImpl>>& blobImpls = aData.BlobImpls();
@@ -325,7 +330,7 @@ UnpackClonedMessageData(const ClonedMessageData& aClonedData,
   const InfallibleTArray<ProtocolType*>& blobs = DataBlobs<Flavor>::Blobs(aClonedData);
   const InfallibleTArray<MessagePortIdentifier>& identifiers = aClonedData.identfiers();
 
-  aData.UseExternalData(buffer.data, buffer.dataLength);
+  aData.UseExternalData(buffer.data);
 
   aData.PortIdentifiers().AppendElements(identifiers);
 

dom/base/nsStructuredCloneContainer.cpp

@@ -137,7 +137,11 @@ nsStructuredCloneContainer::GetDataAsBase64(nsAString &aOut)
     return NS_ERROR_FAILURE;
   }
 
-  nsAutoCString binaryData(reinterpret_cast<char*>(Data()), DataLength());
+  auto iter = Data().Iter();
+  size_t size = Data().Size();
+  nsAutoCString binaryData;
+  binaryData.SetLength(size);
+  Data().ReadBytes(iter, binaryData.BeginWriting(), size);
   nsAutoCString base64Data;
   nsresult rv = Base64Encode(binaryData, base64Data);
   if (NS_WARN_IF(NS_FAILED(rv))) {

dom/broadcastchannel/BroadcastChannel.cpp

@@ -152,9 +152,13 @@ class BCPostMessageRunnable final : public nsIRunnable,
 
     ClonedMessageData message;
 
+    bool success;
     SerializedStructuredCloneBuffer& buffer = message.data();
-    buffer.data = mData->BufferData();
-    buffer.dataLength = mData->BufferSize();
+    auto iter = mData->BufferData().Iter();
+    buffer.data = mData->BufferData().Borrow<js::SystemAllocPolicy>(iter, mData->BufferData().Size(), &success);
+    if (NS_WARN_IF(!success)) {
+      return NS_OK;
+    }
 
     PBackgroundChild* backgroundManager = mActor->Manager();
     MOZ_ASSERT(backgroundManager);

dom/broadcastchannel/BroadcastChannelChild.cpp

@@ -91,12 +91,11 @@ BroadcastChannelChild::RecvNotify(const ClonedMessageData& aData)
   cloneData.BlobImpls().AppendElements(blobs);
 
   const SerializedStructuredCloneBuffer& buffer = aData.data();
-  cloneData.UseExternalData(buffer.data, buffer.dataLength);
-
   JSContext* cx = jsapi.cx();
   JS::Rooted<JS::Value> value(cx, JS::NullValue());
-  if (buffer.dataLength) {
+  if (buffer.data.Size()) {
     ErrorResult rv;
+    cloneData.UseExternalData(buffer.data);
     cloneData.Read(cx, &value, rv);
     if (NS_WARN_IF(rv.Failed())) {
       rv.SuppressException();