verify_trust_dir

# File lib/rubygems/security.rb, line 655
  def self.verify_trust_dir(path, perms)
    # if the directory exists, then make sure it is in fact a directory.  if
    # it doesn't exist, then create it with the appropriate permissions
    if File.exist?(path)
      # verify that the trust directory is actually a directory
      unless File.directory?(path)
        err = "trust directory #{path} isn't a directory"
        raise Gem::Security::Exception, err
      end
    else
      # trust directory doesn't exist, so create it with permissions
      FileUtils.mkdir_p(path)
      FileUtils.chmod(perms, path)
    end
  end