On 2020-03-12 09:05, Thomas Dickey wrote:
If not "correct", it's certainly inconsistent with all other systems.
I noticed it recently:
https://invisible-island.net/ncurses/tack/CHANGES.html#t20200220
https://github.com/cygwinports/tack/issues/1
It's either recently-broken, or just coincidence :-)
Beer fine for you Thomas for copying email-addresses in the reply :-)
Looking at Linux tty line discipline reveals the VMIN and VTIME are
ignored if O_NONBLOCK flag is set.
if (!input_available_p(tty, 0)) {
up_read(&tty->termios_rwsem);
tty_buffer_flush_work(tty->port);
down_read(&tty->termios_rwsem);
if (!input_available_p(tty, 0)) {
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
retval = -EIO;
break;
}
if (tty_hung_up_p(file))
break;
/*
* Abort readers for ttys which never actually
* get hung up. See __tty_hangup().
*/
if (test_bit(TTY_HUPPING, &tty->flags))
break;
if (!timeout)
break; *<= EXIT HERE if VTIME == 0*
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN; *<==== EXIT HERE*
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
up_read(&tty->termios_rwsem);
timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, *<===
BLOCKING HERE!*
timeout);
down_read(&tty->termios_rwsem);
continue;
}
}
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