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/* Test of POSIX compatible fflush() function.
Copyright (C) 2008-2022 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
<https://pubs.opengroup.org/onlinepubs/9699919799/functions/fflush.html>:
"...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;
}
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