Implement Blob.close().

Source/core/fileapi/File.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 197 matching lines @@
 {
     if (hasValidSnapshotMetadata()) {
         snapshotSize = m_snapshotSize;
         snapshotModificationTime = m_snapshotModificationTime;
         return;
     }
 
     // Obtains a snapshot of the file by capturing its current size and modification time. This is used when we slice a file for the first time.
     // If we fail to retrieve the size or modification time, probably due to that the file has been deleted, 0 size is returned.
     FileMetadata metadata;
     if (!getFileMetadata(m_path, metadata)) {

[michaeln, 2014/02/18 18:59:54]

Is getFileMetadata() safe to call with an empty path, or maybe this is
unreachable for those that have been closed? The method is in the public section
which makes me wonder.

[sof, 2014/02/19 11:47:39]

It would be relying on whatever behavior that method provides for empty paths,
it's reachable. I've made this (and other) calls conditional on there being a
backing file; please check if that looks better/safer.

         snapshotSize = 0;
         snapshotModificationTime = invalidFileTime();
         return;
     }
 
     snapshotSize = metadata.length;
     snapshotModificationTime = metadata.modificationTime;
 }
 
+void File::close(ExecutionContext* executionContext)
+{
+    if (!hasBeenClosed()) {
+        // Reset the File to its closed representation, an empty
+        // Blob. The name isn't cleared, as it should still be
+        // available.
+        m_hasBackingFile = false;
+        m_path = String();
+        m_fileSystemURL = KURL();
+        invalidateSnapshotMetadata();
+        m_relativePath = String();
+        Blob::close(executionContext);
+    }
+}
+
 void File::appendTo(BlobData& blobData) const
 {
     if (!m_hasBackingFile) {
         Blob::appendTo(blobData);
         return;
     }
 
     // FIXME: This involves synchronous file operation. We need to figure out how to make it asynchronous.
     long long size;
     double modificationTime;
     captureSnapshot(size, modificationTime);
     if (!m_fileSystemURL.isEmpty()) {
         blobData.appendFileSystemURL(m_fileSystemURL, 0, size, modificationTime);
         return;
     }
     ASSERT(!m_path.isEmpty());
     blobData.appendFile(m_path, 0, size, modificationTime);
 }
 
 } // namespace WebCore