Test fclose on an unopened file.

Add new file libio/tst-fclosed-unopened.c that tests whether fclose on
an unopened file returns EOF.

Calling fclose on unopened files normally causes a use-after-free bug,
however the standard streams are an exception since they are not
deallocated by fclose.

fclose returning EOF for unopened files is not part of the external
contract but there are dependancies on this behaviour.  For example,
gnulib's close_stdout in lib/closeout.c.

Tested for x86_64.

Signed-off-by: Aaron Merey <amerey@redhat.com>
This commit is contained in:
Aaron Merey 2024-08-29 12:02:25 -04:00
parent 9c0d6f7a10
commit 3e4a01870e
2 changed files with 41 additions and 0 deletions

View File

@ -95,6 +95,7 @@ tests = \
tst-eof \
tst-ext \
tst-ext2 \
tst-fclose-unopened \
tst-fdopen-seek-failure \
tst-fgetc-after-eof \
tst-fgetwc \

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@ -0,0 +1,40 @@
/* Test using fclose on an unopened file.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <support/check.h>
/* Verify that fclose on an unopened file returns EOF. This is not part
of the fclose external contract but there are dependancies on this
behaviour. */
static int
do_test (void)
{
TEST_COMPARE (fclose (stdin), 0);
/* Attempt to close the unopened file and verify that EOF is returned.
Calling fclose on a file twice normally causes a use-after-free bug,
however the standard streams are an exception since they are not
deallocated by fclose. */
TEST_COMPARE (fclose (stdin), EOF);
return 0;
}
#include <support/test-driver.c>