code: def Run(self, args):
      
      # Make sure we limit the size of our output
      if args.length > constants.CLIENT_MAX_BUFFER_SIZE:
        raise RuntimeError("Can not read buffers this large.")
  
      data = vfs.ReadVFS(args.pathspec, args.offset, args.length)
  
      digest = hashlib.sha256(data).digest()
  
      # Now report the hash of this blob to our flow as well as the offset and
      # length.
      self.SendReply(
          rdf_client.BufferReference(
              offset=args.offset, length=len(data), data=digest))
docs: Reads a buffer on the client and sends it to the server.