1 files changed, 94 insertions, 0 deletions
diff --git a/gnulib-tests/test-dirent-safer.c b/gnulib-tests/test-dirent-safer.c
new file mode 100644
index 0000000..80755f9
--- /dev/null
+++ b/gnulib-tests/test-dirent-safer.c
@@ -0,0 +1,94 @@
+/* Test that directory streams leave standard fds alone.
+   Copyright (C) 2009-2022 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/>.  */
+
+/* Written by Eric Blake <ebb9@byu.net>, 2009.  */
+
+#include <config.h>
+
+#include "dirent--.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+
+/* This test intentionally closes stderr.  So, we arrange to have fd 10
+   (outside the range of interesting fd's during the test) set up to
+   duplicate the original stderr.  */
+
+#define BACKUP_STDERR_FILENO 10
+#define ASSERT_STREAM myerr
+#include "macros.h"
+
+static FILE *myerr;
+
+int
+main (void)
+{
+  int i;
+  DIR *dp;
+  /* The dirent-safer module works without the use of fdopendir (which
+     would also pull in fchdir and openat); but if those modules were
+     also used, we ensure that they are safe.  In particular, the
+     gnulib version of fdopendir is unable to guarantee that
+     dirfd(fdopendir(fd))==fd, but we can at least guarantee that if
+     they are not equal, the fd returned by dirfd is safe.  */
+#if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
+  int dfd;
+#endif
+
+  /* We close fd 2 later, so save it in fd 10.  */
+  if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
+      || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
+    return 2;
+
+#if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
+  dfd = open (".", O_RDONLY);
+  ASSERT (STDERR_FILENO < dfd);
+#endif
+
+  /* Four iterations, with progressively more standard descriptors
+     closed.  */
+  for (i = -1; i <= STDERR_FILENO; i++)
+    {
+      if (0 <= i)
+        ASSERT (close (i) == 0);
+      dp = opendir (".");
+      ASSERT (dp);
+      ASSERT (dirfd (dp) == -1 || STDERR_FILENO < dirfd (dp));
+      ASSERT (closedir (dp) == 0);
+
+#if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
+      {
+        int fd = fcntl (dfd, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
+        ASSERT (STDERR_FILENO < fd);
+        dp = fdopendir (fd);
+        ASSERT (dp);
+        ASSERT (dirfd (dp) == -1 || STDERR_FILENO < dirfd (dp));
+        ASSERT (closedir (dp) == 0);
+        errno = 0;
+        ASSERT (close (fd) == -1);
+        ASSERT (errno == EBADF);
+      }
+#endif
+    }
+
+#if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
+  ASSERT (close (dfd) == 0);
+#endif
+
+  return 0;
+}