On Oct 23 16:27, J. L. Sloan wrote: > If I use termios(3) to set VTIME and VMIN to values greater than zero for > a serial port, I can no longer interrupt a read(2) against the descriptor > with SIGALRM. Replacing read(2) with nanosleep(2) yields EINTR as > expected. Not setting VTIME and VMIN, read(2) yields EINTR as desired. > Test program and cygcheck output attached. Could be this is intended > behavior. It seems more likely that this is a bug in the driver for my > USB-to-serial adapter. Cygwin 1.7.17 snapshot 2012-10-16.
VMIN shouldn't have any influence on that behaviour, in theory. If you use VTIME values > 0, the Cygwin code doesn't use it's own interruptible wait routine, but rather calls ReadFile directly and relies on OS timeout handling. So, yes, it's kind of expected right now. I think it should be possible to rewrite the VTIME behaviour so that it doesn't rely on the OS timeout but instead adds a timer to the interruptible wait. Adding the timer is pretty simple, but changing the setting of the SetCommTimeouts values might be tricky. See http://cygwin.com/cgi-bin/cvsweb.cgi/src/winsup/cygwin/fhandler_serial.cc?rev=1.89&content-type=text/x-cvsweb-markup&cvsroot=src especially the VMIN/VTIME comment deep down in fhandler_serial::tcsetattr(). Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
