manual/examples/select.c

   1 /*@group*/
   2 #include <errno.h>
   3 #include <stdio.h>
   4 #include <unistd.h>
   5 #include <sys/types.h>
   6 #include <sys/time.h>
   7 /*@end group*/
   8
   9 /*@group*/
  10 int
  11 input_timeout (int filedes, unsigned int seconds)
  12 {
  13   fd_set set;
  14   struct timeval timeout;
  15 /*@end group*/
  16
  17   /* Initialize the file descriptor set. */
  18   FD_ZERO (&set);
  19   FD_SET (filedes, &set);
  20
  21   /* Initialize the timeout data structure. */
  22   timeout.tv_sec = seconds;
  23   timeout.tv_usec = 0;
  24
  25 /*@group*/
  26   /* @code{select} returns 0 if timeout, 1 if input available, -1 if error. */
  27   return TEMP_FAILURE_RETRY (select (FD_SETSIZE,
  28                                      &set, NULL, NULL,
  29                                      &timeout));
  30 }
  31 /*@end group*/
  32
  33 /*@group*/
  34 int
  35 main (void)
  36 {
  37   fprintf (stderr, "select returned %d.\n",
  38            input_timeout (STDIN_FILENO, 5));
  39   return 0;
  40 }
  41 /*@end group*/