fd_mask
fd_mask mask, *maskp;
fdmasks = howmany(s + 1, NFDBITS) * sizeof(fd_mask);
fd_mask fds_bits[2];
tmp = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
return (fd_set *)malloc(howmany(getdtablesize(), NFDBITS) * sizeof (fd_mask));
memset(s, '\0', howmany(getdtablesize(), NFDBITS) * sizeof (fd_mask));
sizeof(fd_mask));
sizeof(fd_mask));
fdsn = howmany(sock+1, NFDBITS) * sizeof(fd_mask);
fdsn = howmany(sock + 1, NFDBITS) * sizeof(fd_mask);