site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com unsigned char buffer[15]; size_t len = 0; int fd = /* something to get your descriptor */ do { ssize_t ret = read( fd, &buffer[0] + len, sizeof(buffer) - len ); if( ret == -1 ) break; len += ret; } while( len < sizeof(buffer) ); Now you've read len bytes of data. -- Steve Checkoway _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... This email sent to site_archiver@lists.apple.com On Jul 10, 2006, at 10:34 AM, Sean McBride wrote: The read() man page says "The system guarantees to read the number of bytes requested if the descriptor references a normal file that has that many bytes left before the end-of-file, but in no other case." Indeed with my serial device, if I say to read 15 bytes it sometimes returns after reading 10 bytes. Is there anyway to have read() block until the requested length is ready? Is my only other choice some kind of loop that calls read() and usleep() over and over? If so, how do I choose a sleep duration? Read(2) will block if there is no data so there's no need to sleep. Using select(2) is one way to go about it but with only one file descriptor/socket, it seems pointless to me. smime.p7s