--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libiberty/fdmatch.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,68 @@
+/* Compare two open file descriptors to see if they refer to the same file.
+   Copyright (C) 1991 Free Software Foundation, Inc.
+
+This file is part of the libiberty library.
+Libiberty is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+Libiberty 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with libiberty; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
+Boston, MA 02110-1301, USA.  */
+
+
+/*
+
+@deftypefn Extension int fdmatch (int @var{fd1}, int @var{fd2})
+
+Check to see if two open file descriptors refer to the same file.
+This is useful, for example, when we have an open file descriptor for
+an unnamed file, and the name of a file that we believe to correspond
+to that fd.  This can happen when we are exec'd with an already open
+file (@code{stdout} for example) or from the SVR4 @file{/proc} calls
+that return open file descriptors for mapped address spaces.  All we
+have to do is open the file by name and check the two file descriptors
+for a match, which is done by comparing major and minor device numbers
+and inode numbers.
+
+@end deftypefn
+
+BUGS
+
+	(FIXME: does this work for networks?)
+	It works for NFS, which assigns a device number to each mount.
+
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+#include "ansidecl.h"
+#include "libiberty.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+
+int fdmatch (int fd1, int fd2)
+{
+  struct stat sbuf1;
+  struct stat sbuf2;
+
+  if ((fstat (fd1, &sbuf1) == 0) &&
+      (fstat (fd2, &sbuf2) == 0) &&
+      (sbuf1.st_dev == sbuf2.st_dev) &&
+      (sbuf1.st_ino == sbuf2.st_ino))
+    {
+      return (1);
+    }
+  else
+    {
+      return (0);
+    }
+}