Report a Close error in readAuthCookieFile.

// Read and validate the contents of an auth cookie file. Returns the 32-byte

// cookie. See section 4.2.1.2 of 217-ext-orport-auth.txt.

func readAuthCookieFile(filename string) ([]byte, error) {

func readAuthCookieFile(filename string) (cookie []byte, err error) {

	f, err := os.Open(filename)

	if err != nil {

		return nil, err

	}

	defer f.Close()

	defer func() {

		closeErr := f.Close()

		if err == nil {

			err = closeErr

		}

	}()

	return readAuthCookie(f)

}