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Re: cygwin 1.5.23-2 : I can't use select() with serial device and socket
This code works fine on Linux and Cygwin (Windows XP SP2) :
------------------------------- CODE
----------------------------------------------------
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#define BUFFER_SIZE 256
#define DEVICE "/dev/ttyS0"
#define TO_WRITE "test communication"
int main (void)
{
char buffer_read[BUFFER_SIZE];
int data_read;
char buffer_write[BUFFER_SIZE] = TO_WRITE;
int data_write;
int serial_fd;
serial_fd = open(DEVICE, O_NONBLOCK | O_NOCTTY | O_RDWR);
if (serial_fd < 0) {
perror("open");
return EXIT_FAILURE;
} else
printf("Serial port opened.\n");
printf("Begin writing %s...\n", buffer_write);
data_write = write(serial_fd, buffer_write, strlen(buffer_write));
if (data_write < 0)
perror("write");
else
printf("%d caracters written.\n", data_write);
memset(&buffer_read, 0, BUFFER_SIZE);
printf("Begin reading...\n");
while ((data_read = read(serial_fd,
buffer_read,
BUFFER_SIZE - 1)) < 0) {
if (errno == EAGAIN)
memset(&buffer_read, 0, BUFFER_SIZE);
else {
perror("read");
return EXIT_FAILURE;
}
}
if (data_read < 0)
perror("read");
else
printf("Data readed (%d) : %s\n", data_read, buffer_read);
close(serial_fd);
return EXIT_SUCCESS;
}
---------------------------------------------------------- /CODE
--------------------------------------------
This code works fine on Linux but doesn't work on Cygwin :
-------------------------------------- CODE
-----------------------------------------------
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#define BUFFER_SIZE 256
#define DEVICE "/dev/ttyS0"
#define TO_WRITE "test communication"
int main (void)
{
char buffer_read[BUFFER_SIZE];
int data_read;
char buffer_write[BUFFER_SIZE] = TO_WRITE;
int data_write;
int serial_fd;
serial_fd = open(DEVICE, O_NONBLOCK | O_NOCTTY | O_RDWR);
if (serial_fd < 0) {
perror("open");
return EXIT_FAILURE;
} else
printf("Serial port opened.\n");
printf("Begin writing %s...\n", buffer_write);
data_write = write(serial_fd, buffer_write, strlen(buffer_write));
if (data_write < 0)
perror("write");
else
printf("%d caracters written.\n", data_write);
memset(&buffer_read, 0, BUFFER_SIZE);
printf("Begin reading...\n");
while ((data_read = read(serial_fd,
buffer_read,
BUFFER_SIZE - 1)) < 0) {
if (errno == EAGAIN)
memset(&buffer_read, 0, BUFFER_SIZE);
else {
perror("read");
return EXIT_FAILURE;
}
}
if (data_read < 0)
perror("read");
else
printf("Data readed (%d) : %s\n", data_read, buffer_read);
close(serial_fd);
return EXIT_SUCCESS;
}
------------------------------------------------ /CODE
----------------------------------------------------------
The second code write on socket, but it says that serial port isn't
ready to read.
Can someone explain it to me ?
Thanks.
Florent.
2007/1/18, Florent Morin <morinflorent@gmail.com>:
I use unix names. I will post an example code tomorrow.
2007/1/18, Brian Dessent <brian@dessent.net>:
> Florent Morin wrote:
>
> > I have a problem using cygwin. My program does this :
> > - It accept a socket connection,
> > - it listen on it,
> > - it open serial device read/write (O_RDWR),
> > - it create 2 fd_sets,
> > - listening loop :
> > - adding file descriptors to sets,
> > - call select(),
> > - if something is on serial port, I write it to socket,
> > - if something is on socket, i write it to serial
> >
> > It works fine on Linux.
> >
> > With windows, only read or write works fine.
> >
> > If I begin on reading on serial, I can't write after (access denied).
> > If I begin on writing on serial, I can't read after (access denied).
>
> There's probably not enough information here to help. It would be
> easier if you provided a simplified standalone testcase that we can
> compile and run. Are you opening the serial device using the standard
> unix name (/dev/ttyS0) and not the DOS name ("COM1")? The latter will
> succeed but probably not work with things like ioctl or select, because
> in order to emulate those APIs Cygwin has to know to treat the handle
> specifically as a serial device, which it only does if you open it using
> the unix form.
>
> Brian
>
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