1 files changed, 97 insertions, 0 deletions
diff --git a/lib/save-cwd.c b/lib/save-cwd.c
new file mode 100644
index 0000000..c2608d5
--- /dev/null
+++ b/lib/save-cwd.c
@@ -0,0 +1,97 @@
+/* save-cwd.c -- Save and restore current working directory.
+
+   Copyright (C) 1995, 1997-1998, 2003-2006, 2009-2020 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.  */
+
+#include <config.h>
+
+#include "save-cwd.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "chdir-long.h"
+#include "unistd--.h"
+
+#if GNULIB_FCNTL_SAFER
+# include "fcntl--.h"
+#else
+# define GNULIB_FCNTL_SAFER 0
+#endif
+
+/* Record the location of the current working directory in CWD so that
+   the program may change to other directories and later use restore_cwd
+   to return to the recorded location.  This function may allocate
+   space using malloc (via getcwd) or leave a file descriptor open;
+   use free_cwd to perform the necessary free or close.  Upon failure,
+   no memory is allocated, any locally opened file descriptors are
+   closed;  return non-zero -- in that case, free_cwd need not be
+   called, but doing so is ok.  Otherwise, return zero.
+
+   The _raison d'etre_ for this interface is that the working directory
+   is sometimes inaccessible, and getcwd is not robust or as efficient.
+   So, we prefer to use the open/fchdir approach, but fall back on
+   getcwd if necessary.  This module works for most cases with just
+   the getcwd-lgpl module, but to be truly robust, use the getcwd module.
+
+   Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin,
+   SCO Xenix.  Also, SunOS 4 and Irix 5.3 provide the function, yet it
+   doesn't work for partitions on which auditing is enabled.  If
+   you're still using an obsolete system with these problems, please
+   send email to the maintainer of this code.  */
+
+int
+save_cwd (struct saved_cwd *cwd)
+{
+  cwd->name = NULL;
+
+  cwd->desc = open (".", O_SEARCH | O_CLOEXEC);
+  if (!GNULIB_FCNTL_SAFER)
+    cwd->desc = fd_safer_flag (cwd->desc, O_CLOEXEC);
+  if (cwd->desc < 0)
+    {
+      cwd->name = getcwd (NULL, 0);
+      return cwd->name ? 0 : -1;
+    }
+
+  return 0;
+}
+
+/* Change to recorded location, CWD, in directory hierarchy.
+   Upon failure, return -1 (errno is set by chdir or fchdir).
+   Upon success, return zero.  */
+
+int
+restore_cwd (const struct saved_cwd *cwd)
+{
+  if (0 <= cwd->desc)
+    return fchdir (cwd->desc);
+  else
+    return chdir_long (cwd->name);
+}
+
+void
+free_cwd (struct saved_cwd *cwd)
+{
+  if (cwd->desc >= 0)
+    close (cwd->desc);
+  free (cwd->name);
+}