Bug 1303095 - XMLHttpRequestString should be fallible, r=mccr8

dom/xhr/XMLHttpRequestMainThread.cpp

@@ -581,7 +581,10 @@ XMLHttpRequestMainThread::GetResponseText(nsAString& aResponseText,
     return;
   }
 
-  snapshot.GetAsString(aResponseText);
+  if (!snapshot.GetAsString(aResponseText)) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
 }
 
 void
@@ -645,7 +648,9 @@ XMLHttpRequestMainThread::CreateResponseParsedJSON(JSContext* aCx)
   }
 
   nsAutoString string;
-  mResponseText.GetAsString(string);
+  if (!mResponseText.GetAsString(string)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
 
   // The Unicode converter has already zapped the BOM if there was one
   JS::Rooted<JS::Value> value(aCx);

dom/xhr/XMLHttpRequestString.cpp

@@ -47,11 +47,11 @@ public:
     mData.Append(aString);
   }
 
-  void
+  MOZ_MUST_USE bool
   GetAsString(nsAString& aString)
   {
     MutexAutoLock lock(mMutex);
-    aString = mData;
+    return aString.Assign(mData, mozilla::fallible);
   }
 
   size_t
@@ -60,12 +60,12 @@ public:
     return mData.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
   }
 
-  void
+  MOZ_MUST_USE bool
   GetAsString(nsAString& aString, uint32_t aLength)
   {
     MutexAutoLock lock(mMutex);
     MOZ_ASSERT(aLength <= mData.Length());
-    aString.Assign(mData.BeginReading(), aLength);
+    return aString.Assign(mData.BeginReading(), aLength, mozilla::fallible);
   }
 
   void
@@ -120,7 +120,7 @@ XMLHttpRequestString::Append(const nsAString& aString)
   mBuffer->Append(aString);
 }
 
-void
+bool
 XMLHttpRequestString::GetAsString(nsAString& aString) const
 {
   return mBuffer->GetAsString(aString);
@@ -186,13 +186,12 @@ XMLHttpRequestStringSnapshot::Set(XMLHttpRequestStringBuffer* aBuffer,
   mVoid = false;
 }
 
-void
+bool
 XMLHttpRequestStringSnapshot::GetAsString(nsAString& aString) const
 {
   if (mBuffer) {
     MOZ_ASSERT(!mVoid);
-    mBuffer->GetAsString(aString, mLength);
-    return;
+    return mBuffer->GetAsString(aString, mLength);
   }
 
   aString.Truncate();
@@ -200,6 +199,8 @@ XMLHttpRequestStringSnapshot::GetAsString(nsAString& aString) const
   if (mVoid) {
     aString.SetIsVoid(true);
   }
+
+  return true;
 }
 
 // ---------------------------------------------------------------------------

dom/xhr/XMLHttpRequestString.h

@@ -41,7 +41,7 @@ public:
   // This method should be called only when the string is really needed because
   // it can cause the duplication of the strings in case the loading of the XHR
   // is not completed yet.
-  void GetAsString(nsAString& aString) const;
+  MOZ_MUST_USE bool GetAsString(nsAString& aString) const;
 
   size_t SizeOfThis(MallocSizeOf aMallocSizeOf) const;
 
@@ -118,7 +118,7 @@ public:
     return !mLength;
   }
 
-  void GetAsString(nsAString& aString) const;
+  MOZ_MUST_USE bool GetAsString(nsAString& aString) const;
 
 private:
   XMLHttpRequestStringSnapshot(const XMLHttpRequestStringSnapshot&) = delete;

dom/xhr/XMLHttpRequestWorker.cpp

@@ -2425,9 +2425,10 @@ XMLHttpRequestWorker::GetResponseText(nsAString& aResponseText, ErrorResult& aRv
     return;
   }
 
-  nsAutoString foo;
-  mStateData.mResponseText.GetAsString(foo);
-  aResponseText.Assign(foo.BeginReading(), foo.Length());
+  if (!mStateData.mResponseText.GetAsString(aResponseText)) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
 }
 
 void