Hurd: implement renameat

Provide an implementation of renameat, mostly based on rename.

ChangeLog

@@ -1,3 +1,7 @@
+2012-07-31  Pino Toscano  <toscano.pino@tiscali.it>
+
+	* sysdeps/mach/hurd/renameat.c: New file, mostly copied from rename.c.
+
 2012-07-31  Roland McGrath  <roland@hack.frob.com>
 
 	* include/sys/socket.h (__libc_accept, __libc_accept4):

sysdeps/mach/hurd/renameat.c

@@ -0,0 +1,51 @@
+/* Rename a file using relative source and destination names.  Hurd version.
+   Copyright (C) 1991-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <hurd.h>
+#include <hurd/fd.h>
+
+/* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */
+int
+renameat (oldfd, old, newfd, new)
+     int oldfd;
+     const char *old;
+     int newfd;
+     const char *new;
+{
+  error_t err;
+  file_t olddir, newdir;
+  const char *oldname, *newname;
+
+  olddir = __directory_name_split_at (oldfd, old, (char **) &oldname);
+  if (olddir == MACH_PORT_NULL)
+    return -1;
+  newdir = __directory_name_split_at (newfd, new, (char **) &newname);
+  if (newdir == MACH_PORT_NULL)
+    {
+       __mach_port_deallocate (__mach_task_self (), olddir);
+      return -1;
+    }
+
+  err = __dir_rename (olddir, oldname, newdir, newname, 0);
+  __mach_port_deallocate (__mach_task_self (), olddir);
+  __mach_port_deallocate (__mach_task_self (), newdir);
+  if (err)
+    return __hurd_fail (err);
+  return 0;
+}