1/*
2 * pmap_prot2.c
3 * Protocol for the local binder service, or pmap.
4 *
5 * Copyright (c) 2010, Oracle America, Inc.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
9 * met:
10 *
11 * * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following
15 * disclaimer in the documentation and/or other materials
16 * provided with the distribution.
17 * * Neither the name of the "Oracle America, Inc." nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
26 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
28 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
30 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
31 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
32 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 */
34
35#include <rpc/types.h>
36#include <rpc/xdr.h>
37#include <rpc/pmap_prot.h>
38#include <shlib-compat.h>
39
40
41/*
42 * What is going on with linked lists? (!)
43 * First recall the link list declaration from pmap_prot.h:
44 *
45 * struct pmaplist {
46 * struct pmap pml_map;
47 * struct pmaplist *pml_map;
48 * };
49 *
50 * Compare that declaration with a corresponding xdr declaration that
51 * is (a) pointer-less, and (b) recursive:
52 *
53 * typedef union switch (bool_t) {
54 *
55 * case TRUE: struct {
56 * struct pmap;
57 * pmaplist_t foo;
58 * };
59 *
60 * case FALSE: struct {};
61 * } pmaplist_t;
62 *
63 * Notice that the xdr declaration has no nxt pointer while
64 * the C declaration has no bool_t variable. The bool_t can be
65 * interpreted as ``more data follows me''; if FALSE then nothing
66 * follows this bool_t; if TRUE then the bool_t is followed by
67 * an actual struct pmap, and then (recursively) by the
68 * xdr union, pamplist_t.
69 *
70 * This could be implemented via the xdr_union primitive, though this
71 * would cause a one recursive call per element in the list. Rather than do
72 * that we can ``unwind'' the recursion
73 * into a while loop and do the union arms in-place.
74 *
75 * The head of the list is what the C programmer wishes to past around
76 * the net, yet is the data that the pointer points to which is interesting;
77 * this sounds like a job for xdr_reference!
78 */
79bool_t
80xdr_pmaplist (XDR *xdrs, struct pmaplist **rp)
81{
82 /*
83 * more_elements is pre-computed in case the direction is
84 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by
85 * xdr_bool when the direction is XDR_DECODE.
86 */
87 bool_t more_elements;
88 int freeing = (xdrs->x_op == XDR_FREE);
89 struct pmaplist *next = NULL;
90
91 while (TRUE)
92 {
93 more_elements = (bool_t) (*rp != NULL);
94 if (!xdr_bool (xdrs, &more_elements))
95 return FALSE;
96 if (!more_elements)
97 return TRUE; /* we are done */
98 /*
99 * the unfortunate side effect of non-recursion is that in
100 * the case of freeing we must remember the next object
101 * before we free the current object ...
102 */
103 if (freeing)
104 next = (*rp)->pml_next;
105 if (!xdr_reference (xdrs, (caddr_t *) rp,
106 (u_int) sizeof (struct pmaplist),
107 (xdrproc_t) xdr_pmap))
108 return FALSE;
109 rp = freeing ? &next : &((*rp)->pml_next);
110 }
111}
112libc_hidden_nolink_sunrpc (xdr_pmaplist, GLIBC_2_0)
113