1 files changed, 103 insertions, 0 deletions
diff --git a/lib/save-cwd.c b/lib/save-cwd.c
new file mode 100644
index 0000000..f07973a
--- /dev/null
+++ b/lib/save-cwd.c
@@ -0,0 +1,103 @@
+/* save-cwd.c -- Save and restore current working directory.
+
+   Copyright (C) 1995, 1997, 1998, 2003, 2004, 2005, 2006 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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Jim Meyering.  */
+
+#include <config.h>
+
+#include "save-cwd.h"
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "chdir-long.h"
+#include "fcntl--.h"
+#include "xgetcwd.h"
+
+/* On systems without the fchdir function (WOE), pretend that open
+   always returns -1 so that save_cwd resorts to using xgetcwd.
+   Since chdir_long requires fchdir, use chdir instead.  */
+#if !HAVE_FCHDIR
+# undef open
+# define open(File, Flags) (-1)
+# undef fchdir
+# define fchdir(Fd) (abort (), -1)
+# undef chdir_long
+# define chdir_long(Dir) chdir (Dir)
+#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 xgetcwd) 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.
+
+   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_RDONLY);
+  if (cwd->desc < 0)
+    {
+      cwd->name = xgetcwd ();
+      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);
+  if (cwd->name)
+    free (cwd->name);
+}