/* Test of select() substitute, reading or writing from a given file descriptor.

   Copyright (C) 2008-2017 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 <http://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>

int

main (int argc, char *argv[])

{

  if (argc == 4)

    {

      char mode = argv[1][0];

      if (mode == 'r' || mode == 'w')

        {

          int fd = atoi (argv[2]);

          if (fd >= 0)

            {

              const char *result_file_name = argv[3];

              FILE *result_file = fopen (result_file_name, "wb");

              if (result_file != NULL)

                {

                  fd_set fds;

                  struct timeval timeout;

                  int ret;

                  FD_ZERO (&fds);

                  FD_SET (fd, &fds);

                  timeout.tv_sec = 0;

                  timeout.tv_usec = 10000;

                  ret = (mode == 'r'

                         ? select (fd + 1, &fds, NULL, NULL, &timeout)

                         : select (fd + 1, NULL, &fds, NULL, &timeout));

                  if (ret < 0)

                    {

                      perror ("select failed");

                      exit (1);

                    }

                  if ((ret == 0) != ! FD_ISSET (fd, &fds))

                    {

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

                      exit (1);

                    }

                  fprintf (result_file, "%d\n", ret);

                  exit (0);

                }

            }

        }

    }

  fprintf (stderr, "Usage: test-select-fd mode fd result-file-name\n");

  exit (1);

}