/* libdiskfs implementation of fs.defs: file_set_translator
   Copyright (C) 1992, 1993, 1994 Free Software Foundation

   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, 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., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include "priv.h"
#include "fs_S.h"
#include <hurd/paths.h>

/* Implement file_set_translator as described in <hurd/fs.defs>. */
kern_return_t
diskfs_S_file_set_translator (struct protid *cred,
			      int passive_flags,
			      int active_flags,
			      int killtrans_flags,
			      char *passive,
			      u_int passivelen,
			      fsys_t active)
{
  struct node *np;
  error_t error;

  if (!cred)
    return EOPNOTSUPP;
  
  if (!(passive_flags & FS_TRANS_SET) && !(active_flags & FS_TRANS_SET))
    return 0;

  if (passive[passivelen - 1])
    return EINVAL;

  np = cred->po->np;

  mutex_lock (&np->lock);

  if (error = diskfs_isowner (np, cred))
    {
      mutex_unlock (&np->lock);
      return error;
    }

  /* Handle exclusive bits */
  if (((active_flags & FS_TRANS_SET)
       && (active_flags & FS_TRANS_EXCL)
       && np->translator.control != MACH_PORT_NULL)
      || ((passive_flags & FS_TRANS_SET)
	  && (passive_flags & FS_TRANS_EXCL)
	  && diskfs_node_translated (np)))
    {
      mutex_unlock (&np->lock);
      return EBUSY;
    }
  
  /* Kill existing active translator */
  if (np->translator.control != MACH_PORT_NULL)
    diskfs_destroy_translator (np, killtrans_flags);

  /* Set passive translator */
  if (passive_flags & FS_TRANS_SET)
    {
      if (!(passive_flags & FS_TRANS_FORCE))
	{
	  /* Handle the short-circuited translators */
	  mode_t newmode = 0;
	
	  if (diskfs_shortcut_symlink && !strcmp (passive, _HURD_SYMLINK))
	    newmode = S_IFLNK;
	  if (diskfs_shortcut_chrdev && !(strcmp (passive, _HURD_CHRDEV)))
	    newmode = S_IFCHR;
	  else if (diskfs_shortcut_blkdev && !strcmp (passive, _HURD_BLKDEV))
	    newmode = S_IFBLK;
	  else if (diskfs_shortcut_fifo && !strcmp (passive, _HURD_FIFO))
	    newmode = S_IFIFO;
	  else if (diskfs_shortcut_ifsock && !strcmp (passive, _HURD_IFSOCK))
	    newmode = S_IFSOCK;
	
	  if (newmode)
	    {
	      if (S_ISDIR (np->dn_stat.st_mode))
		{
		  /* We can't allow this, because if the mode of the directory
		     changes, the links will be lost.  Perhaps it might be 
		     allowed for empty directories, but that's too much of a
		     pain.  */
		  mutex_unlock (&np->lock);
		  return EISDIR;
		}
	      if (newmode == S_IFBLK || newmode == S_IFCHR)
		{
		  /* Find the device number from the arguments
		     of the translator. */
		  int major, minor;
		  char *arg;
	      
		  arg = passive + strlen (passive) + 1;
		  assert (arg <= passive + passivelen);
		  if (arg == passive + passivelen)
		    {
		      mutex_unlock (&np->lock);
		      return EINVAL;
		    }
		  major = strtol (arg, 0, 0);

		  arg = arg + strlen (arg) + 1;
		  assert (arg < passive + passivelen);
		  if (arg == passive + passivelen)
		    {
		      mutex_unlock (&np->lock);
		      return EINVAL;
		    }
		  minor = strtol (arg, 0, 0);
	      
		  np->dn_stat.st_rdev = (((major & 0377) << 8)
					 | (minor & 0377));
		}

	      diskfs_truncate (np, 0);
	      if (newmode == S_IFLNK)
		{
		  char *arg = passive + strlen (passive) + 1;
		  assert (arg <= passive + passivelen);
		  if (arg == passive + passivelen)
		    {
		      mutex_unlock (&np->lock);
		      return EINVAL;
		    }

		  if (diskfs_create_symlink_hook)
		    error = (*diskfs_create_symlink_hook)(np, arg);
		  if (!diskfs_create_symlink_hook || error == EINVAL)
		    /* Store the argument in the file as the
		       target of the link */
		    error = diskfs_node_rdwr (np, arg, 0, strlen (arg),
					      1, cred, 0);
		  if (error)
		    {
		      mutex_unlock (&np->lock);
		      return error;
		    }
		}
	      np->dn_stat.st_mode = (np->dn_stat.st_mode & ~S_IFMT) | newmode;
	      diskfs_node_update (np, 1);
	      mutex_unlock (&np->lock);
	      return 0;
	    }
	}
      error = diskfs_set_translator (np, passive, passivelen, cred);
    }

  /* Set active translator */
  if (active_flags & FS_TRANS_SET)
    {
      if (existing != MACH_PORT_NULL)
	fshelp_set_control (&np->translator, existing);
      else
	/* Should have been cleared above. */
	assert (np->translator.control == MACH_PORT_NULL);
    }

  mutex_unlock (&np->lock);
  return error;
}