1 files changed, 47 insertions, 0 deletions
diff --git a/lib/readlinkat.c b/lib/readlinkat.c
new file mode 100644
index 00000000000..504e6ebbc49
--- /dev/null
+++ b/lib/readlinkat.c
@@ -0,0 +1,47 @@
+/* Read a symlink relative to an open directory.
+   Copyright (C) 2009-2013 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 <http://www.gnu.org/licenses/>.  */
+
+/* written by Eric Blake */
+
+#include <config.h>
+
+#include <unistd.h>
+
+/* Gnulib provides a readlink stub for mingw; use it for distinction
+   between EINVAL and ENOENT, rather than always failing with ENOSYS.  */
+
+/* POSIX 2008 says that unlike readlink, readlinkat returns 0 for
+   success instead of the buffer length.  But this would render
+   readlinkat worthless since readlink does not guarantee a
+   NUL-terminated buffer.  Assume this was a bug in POSIX.  */
+
+/* Read the contents of symlink FILE into buffer BUF of size LEN, in the
+   directory open on descriptor FD.  If possible, do it without changing
+   the working directory.  Otherwise, resort to using save_cwd/fchdir,
+   then readlink/restore_cwd.  If either the save_cwd or the restore_cwd
+   fails, then give a diagnostic and exit nonzero.  */
+
+#define AT_FUNC_NAME readlinkat
+#define AT_FUNC_F1 readlink
+#define AT_FUNC_POST_FILE_PARAM_DECLS , char *buf, size_t len
+#define AT_FUNC_POST_FILE_ARGS        , buf, len
+#define AT_FUNC_RESULT ssize_t
+#include "at-func.c"
+#undef AT_FUNC_NAME
+#undef AT_FUNC_F1
+#undef AT_FUNC_POST_FILE_PARAM_DECLS
+#undef AT_FUNC_POST_FILE_ARGS
+#undef AT_FUNC_RESULT