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Hash : 87555a59
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Date : 2025-05-28T10:40:21

open, openat: handle O_DIRECTORY on special files

On deficient platforms where we must check for directories
ourselves when opening files, check before opening as well as after.
This prevents a hang when trying to open a special file like a
fifo in a context where a directory is required.  Although there
is still a race so we could still hang in a perverse situation,
it’s the best we can do and it is better than hanging in the
more-common case.
* lib/open.c (lstatif): New static function.
(open) [REPLACE_FCHDIR]: Also inspect O_CREAT.
* lib/open.c (open), lib/openat.c (rpl_openat):
When checking for directories, also do this before opening.
Also, respect O_NOFOLLOW when checking for directories.
* lib/openat.c: Remove a few more unnecessary differences from open.c.
* modules/open (Depends-on): Depend on lstat.
* modules/openat (Depends-on): Add fstatat.
* modules/open-tests, modules/openat-tests:
(configure.ac) Check for alarm decl.
* tests/test-open.c, tests/test-openat.c:
Include sys/stat.h, for mkfifo.
[HAVE_DECL_ALARM]: Include signal.h, for alarm.
* tests/test-open.h (test_open): Fail if test takes too long
because we tried to open a fifo.  Test opening /dev/null,
/dev/tty and a fifo, with a trailing "/" and with O_DIRECTORY.

tests/test-open.c

/* Test of opening a file descriptor.
   Copyright (C) 2007-2025 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>, 2007.  */

#include <config.h>

#include <fcntl.h>

#include "signature.h"
SIGNATURE_CHECK (open, int, (char const *, int, ...));

#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>

#if HAVE_DECL_ALARM
# include <signal.h>
#endif

#include "macros.h"

#define BASE "test-open.t"

#include "test-open.h"

int
main (void)
{
  int result = test_open (open, true);
  return (result ? result : test_exit_status);
}

kc3-lang/gnulib/tests/test-open.c

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tests/test-open.c