1 /* @(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC */
2 /*
3 * Copyright (c) 2010, Oracle America, Inc.
4 *
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 *
10 * * Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * * Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * * Neither the name of the "Oracle America, Inc." nor the names of
19 * its contributors may be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
23 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
25 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
26 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
27 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
28 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
29 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
30 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
31 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
32 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 */
34 #if !defined(lint) && defined(SCCSIDS)
35 static char sccsid[] = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
36 #endif
37
38 /*
39 * pmap_prot2.c
40 * Protocol for the local binder service, or pmap.
41 */
42
43 #include <gssrpc/types.h>
44 #include <gssrpc/xdr.h>
45 #include <gssrpc/pmap_prot.h>
46
47
48 /*
49 * What is going on with linked lists? (!)
50 * First recall the link list declaration from pmap_prot.h:
51 *
52 * struct pmaplist {
53 * struct pmap pml_map;
54 * struct pmaplist *pml_map;
55 * };
56 *
57 * Compare that declaration with a corresponding xdr declaration that
58 * is (a) pointer-less, and (b) recursive:
59 *
60 * typedef union switch (bool_t) {
61 *
62 * case TRUE: struct {
63 * struct pmap;
64 * pmaplist_t foo;
65 * };
66 *
67 * case FALSE: struct {};
68 * } pmaplist_t;
69 *
70 * Notice that the xdr declaration has no nxt pointer while
71 * the C declaration has no bool_t variable. The bool_t can be
72 * interpreted as ``more data follows me''; if FALSE then nothing
73 * follows this bool_t; if TRUE then the bool_t is followed by
74 * an actual struct pmap, and then (recursively) by the
75 * xdr union, pamplist_t.
76 *
77 * This could be implemented via the xdr_union primitive, though this
78 * would cause a one recursive call per element in the list. Rather than do
79 * that we can ``unwind'' the recursion
80 * into a while loop and do the union arms in-place.
81 *
82 * The head of the list is what the C programmer wishes to past around
83 * the net, yet is the data that the pointer points to which is interesting;
84 * this sounds like a job for xdr_reference!
85 */
86 bool_t
xdr_pmaplist(XDR * xdrs,struct pmaplist ** rp)87 xdr_pmaplist(XDR *xdrs, struct pmaplist **rp)
88 {
89 /*
90 * more_elements is pre-computed in case the direction is
91 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by
92 * xdr_bool when the direction is XDR_DECODE.
93 */
94 bool_t more_elements;
95 int freeing = (xdrs->x_op == XDR_FREE);
96 struct pmaplist **next = NULL;
97
98 while (TRUE) {
99 more_elements = (bool_t)(*rp != NULL);
100 if (! xdr_bool(xdrs, &more_elements))
101 return (FALSE);
102 if (! more_elements)
103 return (TRUE); /* we are done */
104 /*
105 * the unfortunate side effect of non-recursion is that in
106 * the case of freeing we must remember the next object
107 * before we free the current object ...
108 */
109 if (freeing)
110 next = &((*rp)->pml_next);
111 if (! xdr_reference(xdrs, (caddr_t *)rp,
112 (u_int)sizeof(struct pmaplist), xdr_pmap))
113 return (FALSE);
114 rp = (freeing) ? next : &((*rp)->pml_next);
115 }
116 }
117