1/*	$NetBSD: pmap_prot2.c,v 1.14 2000/07/06 03:10:34 christos Exp $	*/
2
3/*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (c) 2009, Sun Microsystems, Inc.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions are met:
11 * - Redistributions of source code must retain the above copyright notice,
12 *   this list of conditions and the following disclaimer.
13 * - Redistributions in binary form must reproduce the above copyright notice,
14 *   this list of conditions and the following disclaimer in the documentation
15 *   and/or other materials provided with the distribution.
16 * - Neither the name of Sun Microsystems, Inc. nor the names of its
17 *   contributors may be used to endorse or promote products derived
18 *   from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char *sccsid2 = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
35static char *sccsid = "@(#)pmap_prot2.c	2.1 88/07/29 4.0 RPCSRC";
36#endif
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD$");
39
40/*
41 * pmap_prot2.c
42 * Protocol for the local binder service, or pmap.
43 *
44 * Copyright (C) 1984, Sun Microsystems, Inc.
45 */
46
47#include "namespace.h"
48#include <assert.h>
49
50#include <rpc/types.h>
51#include <rpc/xdr.h>
52#include <rpc/pmap_prot.h>
53#include "un-namespace.h"
54
55
56/*
57 * What is going on with linked lists? (!)
58 * First recall the link list declaration from pmap_prot.h:
59 *
60 * struct pmaplist {
61 *	struct pmap pml_map;
62 *	struct pmaplist *pml_map;
63 * };
64 *
65 * Compare that declaration with a corresponding xdr declaration that
66 * is (a) pointer-less, and (b) recursive:
67 *
68 * typedef union switch (bool_t) {
69 *
70 *	case TRUE: struct {
71 *		struct pmap;
72 * 		pmaplist_t foo;
73 *	};
74 *
75 *	case FALSE: struct {};
76 * } pmaplist_t;
77 *
78 * Notice that the xdr declaration has no nxt pointer while
79 * the C declaration has no bool_t variable.  The bool_t can be
80 * interpreted as ``more data follows me''; if FALSE then nothing
81 * follows this bool_t; if TRUE then the bool_t is followed by
82 * an actual struct pmap, and then (recursively) by the
83 * xdr union, pamplist_t.
84 *
85 * This could be implemented via the xdr_union primitive, though this
86 * would cause a one recursive call per element in the list.  Rather than do
87 * that we can ``unwind'' the recursion
88 * into a while loop and do the union arms in-place.
89 *
90 * The head of the list is what the C programmer wishes to past around
91 * the net, yet is the data that the pointer points to which is interesting;
92 * this sounds like a job for xdr_reference!
93 */
94bool_t
95xdr_pmaplist(XDR *xdrs, struct pmaplist **rp)
96{
97	/*
98	 * more_elements is pre-computed in case the direction is
99	 * XDR_ENCODE or XDR_FREE.  more_elements is overwritten by
100	 * xdr_bool when the direction is XDR_DECODE.
101	 */
102	bool_t more_elements;
103	int freeing;
104	struct pmaplist **next	= NULL; /* pacify gcc */
105
106	assert(xdrs != NULL);
107	assert(rp != NULL);
108
109	freeing = (xdrs->x_op == XDR_FREE);
110
111	for (;;) {
112		more_elements = (bool_t)(*rp != NULL);
113		if (! xdr_bool(xdrs, &more_elements))
114			return (FALSE);
115		if (! more_elements)
116			return (TRUE);  /* we are done */
117		/*
118		 * the unfortunate side effect of non-recursion is that in
119		 * the case of freeing we must remember the next object
120		 * before we free the current object ...
121		 */
122		if (freeing)
123			next = &((*rp)->pml_next);
124		if (! xdr_reference(xdrs, (caddr_t *)rp,
125		    (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap))
126			return (FALSE);
127		rp = (freeing) ? next : &((*rp)->pml_next);
128	}
129}
130
131
132/*
133 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in
134 * functionality to xdr_pmaplist().
135 */
136bool_t
137xdr_pmaplist_ptr(XDR *xdrs, struct pmaplist *rp)
138{
139	return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp);
140}
141