--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libiberty/filedescriptor.c	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,47 @@
+/* File descriptor related functions.
+
+   Copyright (C) 2019-2020 Free Software Foundation, Inc.
+
+   This file is part of the libiberty library.
+
+   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 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, write to the Free Software
+   Foundation, Inc., 51 Franklin Street - Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
+
+#include "config.h"
+#include "ansidecl.h"
+#include "libiberty.h"
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#if defined (_WIN32)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h> /* for GetFullPathName */
+#endif
+/* Return true when FD file descriptor exists.  */
+
+int
+is_valid_fd (int fd)
+{
+#if defined(_WIN32)
+  HANDLE h = (HANDLE) _get_osfhandle (fd);
+  return h != (HANDLE) -1;
+#elif defined(F_GETFD)
+  return fcntl (fd, F_GETFD) >= 0;
+#else
+  return dup2 (fd, fd) < 0;
+#endif
+}