Nonblocking IO (ITI8510)

We have two tasks today. Both with practicing nonblocking IO.

1. Canonical mode

Goal: To write a program which echoes characters on screen while typed until button 'q' is pressed. Then prints a newline.

Hints:

• Try to put the terminal into noncanonical mode and remove terminal echo See 'man termios' or [ Google for that.
• Note that you should restore the terminal mode before quitting since otherwise the terminal might get messed up (no echo).
• Working with bits:

flags &= ~NEWFLAG   // Clears the bit NEWFLAG on flags
flags |= NEWFLAG    // Set the bit NEWFLAG on flags
flags ^= NEWFLAG    // Toggle NEWLAG

2. Nonblocking reading from a FIFO

Goal: To write a program which prints a '.' character every half-a second unless some input is provided on a fifo file.

Hints:

• Use open() with O_NONBLOCK flag,
• FIFO can be made with a 'mkfifo fifoname' command and written to using 'cat > fifoname'.
• You have to open fifo before reading (open two terminal windows).
• It helps to set output to non-buffered mode (the default is line-buffered).