sec_read
while ((c = sec_read (fileno (din), buf, bufsize)) > 0) {
if(sec_read(fileno(F), &c, 1) <= 0)
int sec_read (int, void *, int);
while ((cnt = sec_read(fileno(instr), buf, bufsize)) > 0) {
while ((cnt = sec_read(fileno(instr),
if(sec_read(fileno(F), &c, 1) <= 0)