Initial revision

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@14877 138bc75d-0d04-0410-961f-82ee72b054a4

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diff --git a/libiberty/fdmatch.c b/libiberty/fdmatch.c
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+/* 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., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+
+/*
+
+NAME
+
+	fdmatch -- see if two file descriptors refer to same file
+
+SYNOPSIS
+
+	int fdmatch (int fd1, int fd2)
+
+DESCRIPTION
+
+	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 (stdout for example) or from the SVR4 /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&minor
+	device numbers and inode numbers.
+
+BUGS
+
+	(FIXME: does this work for networks?)
+	It works for NFS, which assigns a device number to each mount.
+
+*/
+
+#include "ansidecl.h"
+#include "libiberty.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+
+int fdmatch (fd1, fd2)
+	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);
+    }
+}