1 files changed, 54 insertions, 0 deletions
diff --git a/src/grep/lib/opendirat.c b/src/grep/lib/opendirat.c
new file mode 100644
index 0000000..116d6dd
--- /dev/null
+++ b/src/grep/lib/opendirat.c
@@ -0,0 +1,54 @@
+/* Open a directory relative to another directory.
+
+   Copyright 2006-2021 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 Jim Meyering and Paul Eggert.  */
+
+#include <config.h>
+
+#include <opendirat.h>
+
+#include <errno.h>
+#include <fcntl--.h>
+#include <unistd.h>
+
+/* Relative to DIR_FD, open the directory DIR, passing EXTRA_FLAGS to
+   the underlying openat call.  On success, store into *PNEW_FD the
+   underlying file descriptor of the newly opened directory and return
+   the directory stream.  On failure, return NULL and set errno.
+
+   On success, *PNEW_FD is at least 3, so this is a "safer" function.  */
+
+DIR *
+opendirat (int dir_fd, char const *dir, int extra_flags, int *pnew_fd)
+{
+  int open_flags = (O_RDONLY | O_CLOEXEC | O_DIRECTORY | O_NOCTTY
+                    | O_NONBLOCK | extra_flags);
+  int new_fd = openat (dir_fd, dir, open_flags);
+
+  if (new_fd < 0)
+    return NULL;
+  DIR *dirp = fdopendir (new_fd);
+  if (dirp)
+    *pnew_fd = new_fd;
+  else
+    {
+      int fdopendir_errno = errno;
+      close (new_fd);
+      errno = fdopendir_errno;
+    }
+  return dirp;
+}