module Spruz::SecureWrite

def secure_write(filename, content = nil, mode = 'w')
  temp = File.new(filename + ".tmp.#$$.#{Time.now.to_f}", mode)
  if content.nil? and block_given?
    yield temp
  elsif !content.nil?
    temp.write content
  else
    raise ArgumentError, "either content or block argument required"
  end
  temp.fsync
  size = temp.stat.size
  temp.close
  File.rename temp.path, filename
  size
ensure
  temp and !temp.closed? and temp.close
  File.file?(temp.path) and File.unlink temp.path
end