/* libdiskfs implementation of fs.defs: file_chmod
   Copyright (C) 1992, 1993, 1994, 1995 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"

/* Implement file_chmod as described in <hurd/fs.defs>. */
error_t
diskfs_S_file_chmod (struct protid *cred,
	      mode_t mode)
{
  struct userid *id;
  
  mode &= ~(S_IFMT | S_ISPARE);
  
  CHANGE_NODE_FIELD (cred,
		   ({
		     if (!(err = diskfs_isowner (np, cred)))
		       {
			 /* Run through each ID in the chain
			    to see if it is allowed to do the operations
			    requested.  Turn off bits as we find
			    that they are prohibited. */
			 assert (cred->id);
			 for (id = cred->id; id; id = id->next)
			   {
			     if (!_diskfs_idhasuid (0, id))
			       {
				 if (!S_ISDIR (np->dn_stat.st_mode))
				   mode &= ~S_ISVTX;
				 if (!diskfs_idhasgid (np->dn_stat.st_gid, id))
				   mode &= ~S_ISGID;
				 if (!diskfs_idhasuid (np->dn_stat.st_uid, id))
				   mode &= ~S_ISUID;
			       }
			   }
			 mode |= (np->dn_stat.st_mode & (S_IFMT | S_ISPARE));
			 np->dn_stat.st_mode = mode;
			 np->dn_set_ctime = 1;
		       }
		   }));
}