socket

Tejesh · 05-26-2009, 10:01 AM

Hi,

I am using the socket's select() function in Linux but i am facing a
problem i.e. in the timeout condition (if server is not present to
connect) then select() function has to return zero (as per man
description) but select() will not return zero (it will not wait to
get timeout and always return non zero value not as a error). But if i
test same thing in Windows then select() will return zero in timeout
condition...

can anyone tell me is there any problem with select() function in
Linux ??

jdiggitydogg · 06-04-2009, 10:28 PM

there is no problem with the select implementation in Linux. it sounds like you have looked at the man page, but have you experimented with the sample code in the man page?

Why not try this and see if your select is still not returning zero on timeout?

Code:

       #include <stdio.h>
       #include <sys/time.h>
       #include <sys/types.h>
       #include <unistd.h>

       int
       main(void) {
           fd_set rfds;
           struct timeval tv;
           int retval;

           /* Watch stdin (fd 0) to see when it has input. */
           FD_ZERO(&rfds);
           FD_SET(0, &rfds);

           /* Wait up to five seconds. */
           tv.tv_sec = 5;
           tv.tv_usec = 0;

           retval = select(1, &rfds, NULL, NULL, &tv);
           /* Don’t rely on the value of tv now! */

           if (retval == -1)
               perror("select()");
           else if (retval)
               printf("Data is available now.\n");
               /* FD_ISSET(0, &rfds) will be true. */
           else
               printf("No data within five seconds.\n");

           return 0;
       }

Tejesh · 06-10-2009, 04:38 AM

Thanks for reply..

Yes I checked with the test application and it seems tobe there is no problem with select() call.. I need to dig more in my code to find the exact problem... but do you have any idea what could be the problem ?