Upload a signed blob into the datastore.

  Args:
    content: File content to upload.
    aff4_path: aff4 path to upload to.
    client_context: The configuration contexts to use.
    limit: The maximum size of the chunk to use.
    token: A security token.

  Raises:
    IOError: On failure to write.

def UploadSignedConfigBlob(content,
                           aff4_path,
                           client_context=None,
                           limit=None,
                           token=None):
  """Upload a signed blob into the datastore.

  Args:
    content: File content to upload.
    aff4_path: aff4 path to upload to.
    client_context: The configuration contexts to use.
    limit: The maximum size of the chunk to use.
    token: A security token.

  Raises:
    IOError: On failure to write.
  """
  if limit is None:
    limit = config.CONFIG["Datastore.maximum_blob_size"]

  # Get the values of these parameters which apply to the client running on the
  # target platform.
  if client_context is None:
    # Default to the windows client.
    client_context = ["Platform:Windows", "Client Context"]

  config.CONFIG.Validate(
      parameters="PrivateKeys.executable_signing_private_key")

  signing_key = config.CONFIG.Get(
      "PrivateKeys.executable_signing_private_key", context=client_context)

  verification_key = config.CONFIG.Get(
      "Client.executable_signing_public_key", context=client_context)

  signed_binary_utils.WriteSignedBinary(
      rdfvalue.RDFURN(aff4_path),
      content,
      signing_key,
      public_key=verification_key,
      chunk_size=limit,
      token=token)

  logging.info("Uploaded to %s", aff4_path)