PROC_FASTOPEN_KEY
proc_fd = open(PROC_FASTOPEN_KEY, O_RDWR);
error(1, errno, "Unable to open %s", PROC_FASTOPEN_KEY);
error(1, errno, "Unable to read %s", PROC_FASTOPEN_KEY);
error(1, 0, "Unable to parse %s", PROC_FASTOPEN_KEY);
error(1, errno, "Unable to write %s", PROC_FASTOPEN_KEY);