Bug 1173320 - patch 6/8 - Make FileList clonable to workers if it doesn't contain Directories, r=smaug

dom/base/FileList.cpp

@@ -111,5 +111,17 @@ FileList::ToSequence(Sequence<OwningFileOrDirectory>& aSequence,
   }
 }
 
+bool
+FileList::ClonableToDifferentThreadOrProcess() const
+{
+  for (uint32_t i = 0; i < mFilesOrDirectories.Length(); ++i) {
+    if (mFilesOrDirectories[i].IsDirectory()) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 } // namespace dom
 } // namespace mozilla

dom/base/FileList.h

@@ -97,6 +97,8 @@ public:
   void ToSequence(Sequence<OwningFileOrDirectory>& aSequence,
                   ErrorResult& aRv) const;
 
+  bool ClonableToDifferentThreadOrProcess() const;
+
 private:
   ~FileList() {}
 

dom/base/StructuredCloneHolder.cpp

@@ -1008,7 +1008,6 @@ StructuredCloneHolder::CustomReadHandler(JSContext* aCx,
   }
 
   if (aTag == SCTAG_DOM_FILELIST) {
-    MOZ_ASSERT(mSupportedContext == SameProcessSameThread);
     return ReadFileList(aCx, aReader, aIndex, this);
   }
 
@@ -1049,9 +1048,11 @@ StructuredCloneHolder::CustomWriteHandler(JSContext* aCx,
   }
 
   // See if this is a FileList object.
-  if (mSupportedContext == SameProcessSameThread) {
+  {
     FileList* fileList = nullptr;
-    if (NS_SUCCEEDED(UNWRAP_OBJECT(FileList, aObj, fileList))) {
+    if (NS_SUCCEEDED(UNWRAP_OBJECT(FileList, aObj, fileList)) &&
+        (mSupportedContext == SameProcessSameThread ||
+         fileList->ClonableToDifferentThreadOrProcess())) {
       return WriteFileList(aWriter, fileList, this);
     }
   }

dom/base/test/test_postMessages.html

@@ -84,7 +84,7 @@ function create_fileList() {
     var domFile = fileList.files[0];
     is(domFile.name, "prefs.js", "fileName should be prefs.js");
 
-    clonableObjects.push({ crossThreads: false, data: fileList.files });
+    clonableObjects.push({ crossThreads: true, data: fileList.files });
     script.destroy();
     next();
   }