/* 
   Copyright (C) 1995 Free Software Foundation, Inc.
   Written by Michael I. Bushnell.

   This file is part of the GNU Hurd.

   The GNU Hurd 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, or (at
   your option) any later version.

   The GNU Hurd 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., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include "fshelp.h"
#include <hurd/fsys.h>

error_t
fshelp_set_active (struct transbox *box,
		   mach_port_t active,
		   int excl, int goaway, int flags)
{
  error_t error;
  
 start_over:
  if (excl && box->active != MACH_PORT_NULL)
    return EBUSY;
  
  if (goaway && box->active != MACH_PORT_NULL)
    {
      fsys_t control;

      error = fshelp_fetch_control (box, &control);
      if (error)
	return error;
      
      mutex_unlock (box->lock);
      error = fsys_goaway (control, flags);
      mutex_lock (box->lock);
      if (error)
	{
	  mach_port_deallocate (mach_task_self (), control);
	  return error;
	}
            
      /* If it changed while we were unlocked, better start over. */
      if (box->active != control)
	{
	  mach_port_deallocate (mach_task_self (), control);
	  goto start_over;
	}
      mach_port_deallocate (mach_task_self (), control);
    }
  
  if (box->active != MACH_PORT_NULL)
    mach_port_deallocate (mach_task_self (), box->active);

  box->active = active;
  return 0;
}