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
39
40/*
41 * What is going on with linked lists? (!)
42 * First recall the link list declaration from pmap_prot.h:
43 *
44 * struct pmaplist {
45 * struct pmap pml_map;
46 * struct pmaplist *pml_map;
47 * };
48 *
49 * Compare that declaration with a corresponding xdr declaration that
50 * is (a) pointer-less, and (b) recursive:
51 *
52 * typedef union switch (bool_t) {
53 *
54 * case TRUE: struct {
55 * struct pmap;
56 * pmaplist_t foo;
57 * };
58 *
59 * case FALSE: struct {};
60 * } pmaplist_t;
61 *
62 * Notice that the xdr declaration has no nxt pointer while
63 * the C declaration has no bool_t variable. The bool_t can be
64 * interpreted as ``more data follows me''; if FALSE then nothing
65 * follows this bool_t; if TRUE then the bool_t is followed by
66 * an actual struct pmap, and then (recursively) by the
67 * xdr union, pamplist_t.
68 *
69 * This could be implemented via the xdr_union primitive, though this
70 * would cause a one recursive call per element in the list. Rather than do
71 * that we can ``unwind'' the recursion
72 * into a while loop and do the union arms in-place.
73 *
74 * The head of the list is what the C programmer wishes to past around
75 * the net, yet is the data that the pointer points to which is interesting;
76 * this sounds like a job for xdr_reference!
77 */
78bool_t
79xdr_pmaplist (XDR *xdrs, struct pmaplist **rp)
80{
81 /*
82 * more_elements is pre-computed in case the direction is
83 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by
84 * xdr_bool when the direction is XDR_DECODE.
85 */
86 bool_t more_elements;
87 int freeing = (xdrs->x_op == XDR_FREE);
88 struct pmaplist *next = NULL;
89
90 while (TRUE)
91 {
92 more_elements = (bool_t) (*rp != NULL);
93 if (!xdr_bool (xdrs, &more_elements))
94 return FALSE;
95 if (!more_elements)
96 return TRUE; /* we are done */
97 /*
98 * the unfortunate side effect of non-recursion is that in
99 * the case of freeing we must remember the next object
100 * before we free the current object ...
101 */
102 if (freeing)
103 next = (*rp)->pml_next;
104 if (!xdr_reference (xdrs, (caddr_t *) rp,
105 (u_int) sizeof (struct pmaplist),
106 (xdrproc_t) xdr_pmap))
107 return FALSE;
108 rp = freeing ? &next : &((*rp)->pml_next);
109 }
110}
111libc_hidden_nolink_sunrpc (xdr_pmaplist, GLIBC_2_0)
112