Re: cygwin 1.5.23-2 : CREAD termios option don't work

["Florent Morin" <morinflorent at gmail dot com>]

Hello,

Like you say, CREAD isn't the real problem.

I use select() to read/write socket and read/write serial. But, after
writing the content of socket on serial port, I can't read serial port
(access denied).

This is an extract of my source code :

---------------- CODE ---------------------

   int serial_fd;
   int max_fd;

   unsigned char buffer[MAX_CANON];
   int size;
   int converted_size;

   unsigned char buffer2[MAX_CANON];
   int size2;

   fd_set read_set;
   fd_set write_set;

   nice(15);

   /* opening serial port read/write, non-block */
   serial_fd = open ( port_settings->device,
                      O_NONBLOCK | O_RDWR | O_NOCTTY);

   max_fd = socket_fd < serial_fd ? serial_fd : socket_fd;

   alarm(ALARM_TIMEOUT);

   while (1) {
       FD_ZERO(&read_set);
       FD_SET(socket_fd, &read_set);
       FD_SET(serial_fd, &read_set);

       FD_ZERO(&write_set);
       FD_SET(socket_fd, &write_set);
       FD_SET(serial_fd, &write_set);

       if ( select(max_fd + 1,
                   &read_set,
                   &write_set,
                   NULL,
                   NULL) < 0)
           perror("select");

       if (FD_ISSET(socket_fd, &read_set)
        && !FD_ISSET(serial_fd, &read_set)
        && FD_ISSET(serial_fd, &write_set)) {
           alarm(0);
           memset(&buffer, 0, MAX_CANON);
           size = read(socket_fd, buffer, MAX_CANON - 1);
           converted_size = convert_telnet(&buffer, size);
           while (write(serial_fd, buffer, converted_size) < 0) {
               if (errno == EAGAIN) {
                   error("write", 0);
                   sleep(1);
               } else
                   error("write", 1);
           }
           alarm(ALARM_TIMEOUT);
       }

       if (FD_ISSET(serial_fd, &read_set)
        && FD_ISSET(socket_fd, &write_set)) {
           alarm(0);
           memset(&buffer2, 0, MAX_CANON);
           printf("read serial");
           size2 = read(serial_fd, buffer2, MAX_CANON - 1);
           if (size2 > 0) {
               while (write(socket_fd, buffer2, size2) < 0) {
                   if (errno == EAGAIN) {
                       error("write", 0);
                       sleep(1);
                   } else
                       error("write", 1);
               }
           }
           alarm(ALARM_TIMEOUT);
       }

       sleep(1);

   }

   close(serial_fd);

---------------- /CODE ---------------------

I have tested it on Linux. It works fine. When I send data throw
telnet protocol, the data are received by the peripheral connected to
serial and vice-versa.

Perhaps I don't use the functions very well. So, if you can help me, thanks.

Florent Morin.


2007/1/12, Brian Ford <Brian.Ford@flightsafety.com>:
> On Fri, 12 Jan 2007, Corinna Vinschen wrote:
> > On Jan 11 16:53, Florent Morin wrote:
> > > For testing, I have tried with a working program : stty. It works fine
> > > with all options, but not with CREAD.
> > >
> > > $ stty cread < /dev/ttyS0
> > > stty: /dev/ttyS0: unable to perform all requested operations
> > >
> > > Can someone explain this ?
> >
> > Please consider to debug this yourself.  Cygwin has no volunteer which
> > is fluent with serial I/O right now.
>
> This is not a regression from 1.5.18, which I know worked fine with serial
> I/O.  I will try to test 1.5.23 when I get a chance, but I have no reason
> to suspect it is broken.
>
> CREAD appears to always be enabled but not indicated by tcgetattr or
> controllable via tcsetattr right now.  So, the test case above is not
> indicative of the original problem.
>
> To the OP, posting your code might be informative.
>
> --
> Brian Ford
> Lead Realtime Software Engineer
> VITAL - Visual Simulation Systems
> FlightSafety International
> the best safety device in any aircraft is a well-trained crew...
>
>
>
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