loop until ntp time is set

struct tm *currtime;
long tloc;

time(&tloc); // get time in seconds since epoch
currtime = localtime(&tloc); // convert seconds to date structure

while (currtime->tm_year < 100) // loop until ntp time is set (year

// >= 2000)
{
sleep(15);
time(&tloc);
currtime = localtime(&tloc);
}