/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.1 (the "License").  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 * 
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 * 
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 * 
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 * 
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 * 
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */

#if defined(LIBC_SCCS) && !defined(lint)
/*static char *sccsid = "from: @(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";*/
/*static char *sccsid = "from: @(#)pmap_prot2.c	2.1 88/07/29 4.0 RPCSRC";*/
static char *rcsid = "$Id: pmap_prot2.c,v 1.2 1999/10/14 21:56:53 wsanchez Exp $";
#endif

/*
 * pmap_prot2.c
 * Protocol for the local binder service, or pmap.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 */

#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/pmap_prot.h>


/* 
 * What is going on with linked lists? (!)
 * First recall the link list declaration from pmap_prot.h:
 *
 * struct pmaplist {
 *	struct pmap pml_map;
 *	struct pmaplist *pml_map;
 * };
 *
 * Compare that declaration with a corresponding xdr declaration that 
 * is (a) pointer-less, and (b) recursive:
 *
 * typedef union switch (bool_t) {
 * 
 *	case TRUE: struct {
 *		struct pmap;
 * 		pmaplist_t foo;
 *	};
 *
 *	case FALSE: struct {};
 * } pmaplist_t;
 *
 * Notice that the xdr declaration has no nxt pointer while
 * the C declaration has no bool_t variable.  The bool_t can be
 * interpreted as ``more data follows me''; if FALSE then nothing
 * follows this bool_t; if TRUE then the bool_t is followed by
 * an actual struct pmap, and then (recursively) by the 
 * xdr union, pamplist_t.  
 *
 * This could be implemented via the xdr_union primitive, though this
 * would cause a one recursive call per element in the list.  Rather than do
 * that we can ``unwind'' the recursion
 * into a while loop and do the union arms in-place.
 *
 * The head of the list is what the C programmer wishes to past around
 * the net, yet is the data that the pointer points to which is interesting;
 * this sounds like a job for xdr_reference!
 */
bool_t
xdr_pmaplist(xdrs, rp)
	register XDR *xdrs;
	register struct pmaplist **rp;
{
	/*
	 * more_elements is pre-computed in case the direction is
	 * XDR_ENCODE or XDR_FREE.  more_elements is overwritten by
	 * xdr_bool when the direction is XDR_DECODE.
	 */
	bool_t more_elements;
	register int freeing = (xdrs->x_op == XDR_FREE);
	register struct pmaplist **next;

	while (TRUE) {
		more_elements = (bool_t)(*rp != NULL);
		if (! xdr_bool(xdrs, &more_elements))
			return (FALSE);
		if (! more_elements)
			return (TRUE);  /* we are done */
		/*
		 * the unfortunate side effect of non-recursion is that in
		 * the case of freeing we must remember the next object
		 * before we free the current object ...
		 */
		if (freeing)
			next = &((*rp)->pml_next); 
		if (! xdr_reference(xdrs, (caddr_t *)rp,
		    (u_int)sizeof(struct pmaplist), xdr_pmap))
			return (FALSE);
		rp = (freeing) ? next : &((*rp)->pml_next);
	}
}
