/* Test of POSIX compatible fflush() function.
   Copyright (C) 2008-2019 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/>.  */

#include <config.h>

#include <stdio.h>

#include "binary-io.h"
#include "macros.h"

int
main (int argc, char **argv)
{
  int c;

  /* Avoid the well-known bugs of fflush() on streams in O_TEXT mode
     on native Windows platforms.  */
  set_binary_mode (0, O_BINARY);

  if (argc > 1)
    switch (argv[1][0])
      {
      case '1':
        /* Check fflush after a backup ungetc() call.  This is case 1a in
           terms of
           <https://lists.gnu.org/r/bug-gnulib/2008-03/msg00131.html>,
           according to the Austin Group's resolution on 2009-01-08.  */

        c = fgetc (stdin);
        ASSERT (c == '#');

        c = fgetc (stdin);
        ASSERT (c == '!');

        /* Here the file-position indicator must be 2.  */

        c = ungetc ('!', stdin);
        ASSERT (c == '!');

        fflush (stdin);

        /* Here the file-position indicator must be 1.  */

        c = fgetc (stdin);
        ASSERT (c == '!');

        c = fgetc (stdin);
        ASSERT (c == '/');

        return 0;

      case '2':
        /* Check fflush after a non-backup ungetc() call.  This is case 2a in
           terms of
           <https://lists.gnu.org/r/bug-gnulib/2008-03/msg00131.html>,
           according to the Austin Group's resolution on 2009-01-08.  */
        /* Check that fflush after a non-backup ungetc() call discards the
           ungetc buffer.  This is mandated by POSIX
           <http://www.opengroup.org/susv3/functions/ungetc.html>:
             "The value of the file-position indicator for the stream after
              reading or discarding all pushed-back bytes shall be the same
              as it was before the bytes were pushed back."
           <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt>
             "[After fflush(),] the file offset of the underlying open file
              description shall be set to the file position of the stream, and
              any characters pushed back onto the stream by ungetc() or
              ungetwc() that have not subsequently been read from the stream
              shall be discarded."  */

        c = fgetc (stdin);
        ASSERT (c == '#');

        c = fgetc (stdin);
        ASSERT (c == '!');

        /* Here the file-position indicator must be 2.  */

        c = ungetc ('@', stdin);
        ASSERT (c == '@');

        fflush (stdin);

        /* Here the file-position indicator must be 1.  */

        c = fgetc (stdin);
        ASSERT (c == '!');

        c = fgetc (stdin);
        ASSERT (c == '/');

        return 0;
      }

  return 1;
}