"Resource temporarily unavailable" while reading from "dev/ttyS0"

#include <string.h># include <unistd.h># include <fcntl.h># include <errno.h># include <termios.h>
int main(void)
{
        char buf;
        int fd1;
        volatile int count;
        fd1 = open("/dev/urandom", O_RDWR | O_NOCTTY | O_NDELAY); //urandom for test.
        if (fd1 == -1)
        {
                perror("open_port: Unable to open /dev/ttyS0 - ");
                       exit(1);
        }
         fcntl(fd1, F_SETFL, FNDELAY);
            for(count = 0; count < 65556; count ++); // delay //it will be delay if count is volatile. And it's a bad way to set delay. 
        if(count = read(fd1, buf, 10) < 0)
           {
               perror("reading failed ");
               exit(2);
           }
        printf("%s", buf);
        close(fd1);
return 0;
}
~