1 /* $NetBSD: pmap_prot2.c,v 1.14 2000/07/06 03:10:34 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2009, Sun Microsystems, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 * - Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 * - Neither the name of Sun Microsystems, Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #if defined(LIBC_SCCS) && !defined(lint)
32 static char *sccsid2 = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
33 static char *sccsid = "@(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC";
34 #endif
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37
38 /*
39 * pmap_prot2.c
40 * Protocol for the local binder service, or pmap.
41 *
42 * Copyright (C) 1984, Sun Microsystems, Inc.
43 */
44
45 #include "namespace.h"
46 #include <assert.h>
47
48 #include <rpc/types.h>
49 #include <rpc/xdr.h>
50 #include <rpc/pmap_prot.h>
51 #include "un-namespace.h"
52
53
54 /*
55 * What is going on with linked lists? (!)
56 * First recall the link list declaration from pmap_prot.h:
57 *
58 * struct pmaplist {
59 * struct pmap pml_map;
60 * struct pmaplist *pml_map;
61 * };
62 *
63 * Compare that declaration with a corresponding xdr declaration that
64 * is (a) pointer-less, and (b) recursive:
65 *
66 * typedef union switch (bool_t) {
67 *
68 * case TRUE: struct {
69 * struct pmap;
70 * pmaplist_t foo;
71 * };
72 *
73 * case FALSE: struct {};
74 * } pmaplist_t;
75 *
76 * Notice that the xdr declaration has no nxt pointer while
77 * the C declaration has no bool_t variable. The bool_t can be
78 * interpreted as ``more data follows me''; if FALSE then nothing
79 * follows this bool_t; if TRUE then the bool_t is followed by
80 * an actual struct pmap, and then (recursively) by the
81 * xdr union, pamplist_t.
82 *
83 * This could be implemented via the xdr_union primitive, though this
84 * would cause a one recursive call per element in the list. Rather than do
85 * that we can ``unwind'' the recursion
86 * into a while loop and do the union arms in-place.
87 *
88 * The head of the list is what the C programmer wishes to past around
89 * the net, yet is the data that the pointer points to which is interesting;
90 * this sounds like a job for xdr_reference!
91 */
92 bool_t
xdr_pmaplist(xdrs,rp)93 xdr_pmaplist(xdrs, rp)
94 XDR *xdrs;
95 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 */
136 bool_t
xdr_pmaplist_ptr(xdrs,rp)137 xdr_pmaplist_ptr(xdrs, rp)
138 XDR *xdrs;
139 struct pmaplist *rp;
140 {
141 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp);
142 }
143