/* Test of select() substitute, reading from stdin.

   Copyright (C) 2008-2020 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2008.  */

#include <config.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/select.h>

#include <sys/time.h>

#include <unistd.h>

#include "macros.h"

int

main (void)

{

  printf ("Applying select() from standard input. Press Ctrl-C to abort.\n");

  for (;;)

    {

      struct timeval before;

      struct timeval after;

      unsigned long spent_usec;

      fd_set readfds;

      struct timeval timeout;

      int ret;

      gettimeofday (&before, NULL);

      FD_ZERO (&readfds);

      FD_SET (0, &readfds);

      timeout.tv_sec = 0;

      timeout.tv_usec = 500000;

      ret = select (1, &readfds, NULL, NULL, &timeout);

      gettimeofday (&after, NULL);

      spent_usec = (after.tv_sec - before.tv_sec) * 1000000

                   + after.tv_usec - before.tv_usec;

      if (ret < 0)

        {

          perror ("select failed");

          exit (1);

        }

      if ((ret == 0) != ! FD_ISSET (0, &readfds))

        {

          fprintf (stderr, "incorrect return value\n");

          exit (1);

        }

      if (ret == 0)

        {

          if (spent_usec < 250000)

            {

              fprintf (stderr, "returned too early\n");

              exit (1);

            }

          /* Timeout */

          printf (".");

          ASSERT (fflush (stdout) == 0);

        }

      else

        {

          char c;

          printf ("Input available! Trying to read 1 byte...\n");

          ASSERT (read (0, &c, 1) == 1);

        }

    }

}