1 /* $NetBSD: pmap_prot2.c,v 1.14 2000/07/06 03:10:34 christos Exp $ */
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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";
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
40 * Protocol for the local binder service, or pmap.
42 * Copyright (C) 1984, Sun Microsystems, Inc.
45 #include "namespace.h"
48 #include <rpc/types.h>
50 #include <rpc/pmap_prot.h>
51 #include "un-namespace.h"
55 * What is going on with linked lists? (!)
56 * First recall the link list declaration from pmap_prot.h:
59 * struct pmap pml_map;
60 * struct pmaplist *pml_map;
63 * Compare that declaration with a corresponding xdr declaration that
64 * is (a) pointer-less, and (b) recursive:
66 * typedef union switch (bool_t) {
73 * case FALSE: struct {};
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.
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.
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!
93 xdr_pmaplist(xdrs, rp)
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.
102 bool_t more_elements;
104 struct pmaplist **next = NULL; /* pacify gcc */
106 assert(xdrs != NULL);
109 freeing = (xdrs->x_op == XDR_FREE);
112 more_elements = (bool_t)(*rp != NULL);
113 if (! xdr_bool(xdrs, &more_elements))
116 return (TRUE); /* we are done */
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 ...
123 next = &((*rp)->pml_next);
124 if (! xdr_reference(xdrs, (caddr_t *)rp,
125 (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap))
127 rp = (freeing) ? next : &((*rp)->pml_next);
133 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in
134 * functionality to xdr_pmaplist().
137 xdr_pmaplist_ptr(xdrs, rp)
141 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp);