1/*
2 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
7 * Reserved.  This file contains Original Code and/or Modifications of
8 * Original Code as defined in and that are subject to the Apple Public
9 * Source License Version 1.1 (the "License").  You may not use this file
10 * except in compliance with the License.  Please obtain a copy of the
11 * License at http://www.apple.com/publicsource and read it before using
12 * this file.
13 *
14 * The Original Code and all software distributed under the License are
15 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
16 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
17 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
19 * License for the specific language governing rights and limitations
20 * under the License.
21 *
22 * @APPLE_LICENSE_HEADER_END@
23 */
24/*
25 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
26 * unrestricted use provided that this legend is included on all tape
27 * media and as a part of the software program in whole or part.  Users
28 * may copy or modify Sun RPC without charge, but are not authorized
29 * to license or distribute it to anyone else except as part of a product or
30 * program developed by the user.
31 *
32 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
33 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
34 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
35 *
36 * Sun RPC is provided with no support and without any obligation on the
37 * part of Sun Microsystems, Inc. to assist in its use, correction,
38 * modification or enhancement.
39 *
40 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
41 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
42 * OR ANY PART THEREOF.
43 *
44 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
45 * or profits or other special, indirect and consequential damages, even if
46 * Sun has been advised of the possibility of such damages.
47 *
48 * Sun Microsystems, Inc.
49 * 2550 Garcia Avenue
50 * Mountain View, California  94043
51 */
52
53#if defined(LIBC_SCCS) && !defined(lint)
54/*static char *sccsid = "from: @(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";*/
55/*static char *sccsid = "from: @(#)pmap_prot2.c	2.1 88/07/29 4.0 RPCSRC";*/
56static char *rcsid = "$Id: pmap_prot2.c,v 1.3 2002/02/19 20:36:24 epeyton Exp $";
57#endif
58
59/*
60 * pmap_prot2.c
61 * Protocol for the local binder service, or pmap.
62 *
63 * Copyright (C) 1984, Sun Microsystems, Inc.
64 */
65
66#include <rpc/types.h>
67#include <rpc/xdr.h>
68#include <rpc/pmap_prot.h>
69
70
71/*
72 * What is going on with linked lists? (!)
73 * First recall the link list declaration from pmap_prot.h:
74 *
75 * struct pmaplist {
76 *	struct pmap pml_map;
77 *	struct pmaplist *pml_map;
78 * };
79 *
80 * Compare that declaration with a corresponding xdr declaration that
81 * is (a) pointer-less, and (b) recursive:
82 *
83 * typedef union switch (bool_t) {
84 *
85 *	case TRUE: struct {
86 *		struct pmap;
87 * 		pmaplist_t foo;
88 *	};
89 *
90 *	case FALSE: struct {};
91 * } pmaplist_t;
92 *
93 * Notice that the xdr declaration has no nxt pointer while
94 * the C declaration has no bool_t variable.  The bool_t can be
95 * interpreted as ``more data follows me''; if FALSE then nothing
96 * follows this bool_t; if TRUE then the bool_t is followed by
97 * an actual struct pmap, and then (recursively) by the
98 * xdr union, pamplist_t.
99 *
100 * This could be implemented via the xdr_union primitive, though this
101 * would cause a one recursive call per element in the list.  Rather than do
102 * that we can ``unwind'' the recursion
103 * into a while loop and do the union arms in-place.
104 *
105 * The head of the list is what the C programmer wishes to past around
106 * the net, yet is the data that the pointer points to which is interesting;
107 * this sounds like a job for xdr_reference!
108 */
109bool_t
110xdr_pmaplist(xdrs, rp)
111	register XDR *xdrs;
112	register struct pmaplist **rp;
113{
114	/*
115	 * more_elements is pre-computed in case the direction is
116	 * XDR_ENCODE or XDR_FREE.  more_elements is overwritten by
117	 * xdr_bool when the direction is XDR_DECODE.
118	 */
119	bool_t more_elements;
120	register int freeing = (xdrs->x_op == XDR_FREE);
121	register struct pmaplist **next = NULL;
122
123	while (TRUE) {
124		more_elements = (bool_t)(*rp != NULL);
125		if (! xdr_bool(xdrs, &more_elements))
126			return (FALSE);
127		if (! more_elements)
128			return (TRUE);  /* we are done */
129		/*
130		 * the unfortunate side effect of non-recursion is that in
131		 * the case of freeing we must remember the next object
132		 * before we free the current object ...
133		 */
134		if (freeing)
135			next = &((*rp)->pml_next);
136		if (! xdr_reference(xdrs, (caddr_t *)rp, (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap))
137			return (FALSE);
138		rp = (freeing) ? next : &((*rp)->pml_next);
139	}
140}
141