1 /* $NetBSD: pmap_prot2.c,v 1.14 2000/07/06 03:10:34 christos Exp $ */
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32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char *sccsid2 = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
34 static char *sccsid = "@(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC";
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
41 * Protocol for the local binder service, or pmap.
43 * Copyright (C) 1984, Sun Microsystems, Inc.
46 #include "namespace.h"
49 #include <rpc/types.h>
51 #include <rpc/pmap_prot.h>
52 #include "un-namespace.h"
56 * What is going on with linked lists? (!)
57 * First recall the link list declaration from pmap_prot.h:
60 * struct pmap pml_map;
61 * struct pmaplist *pml_map;
64 * Compare that declaration with a corresponding xdr declaration that
65 * is (a) pointer-less, and (b) recursive:
67 * typedef union switch (bool_t) {
74 * case FALSE: struct {};
77 * Notice that the xdr declaration has no nxt pointer while
78 * the C declaration has no bool_t variable. The bool_t can be
79 * interpreted as ``more data follows me''; if FALSE then nothing
80 * follows this bool_t; if TRUE then the bool_t is followed by
81 * an actual struct pmap, and then (recursively) by the
82 * xdr union, pamplist_t.
84 * This could be implemented via the xdr_union primitive, though this
85 * would cause a one recursive call per element in the list. Rather than do
86 * that we can ``unwind'' the recursion
87 * into a while loop and do the union arms in-place.
89 * The head of the list is what the C programmer wishes to past around
90 * the net, yet is the data that the pointer points to which is interesting;
91 * this sounds like a job for xdr_reference!
94 xdr_pmaplist(xdrs, rp)
99 * more_elements is pre-computed in case the direction is
100 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by
101 * xdr_bool when the direction is XDR_DECODE.
103 bool_t more_elements;
105 struct pmaplist **next = NULL; /* pacify gcc */
107 assert(xdrs != NULL);
110 freeing = (xdrs->x_op == XDR_FREE);
113 more_elements = (bool_t)(*rp != NULL);
114 if (! xdr_bool(xdrs, &more_elements))
117 return (TRUE); /* we are done */
119 * the unfortunate side effect of non-recursion is that in
120 * the case of freeing we must remember the next object
121 * before we free the current object ...
124 next = &((*rp)->pml_next);
125 if (! xdr_reference(xdrs, (caddr_t *)rp,
126 (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap))
128 rp = (freeing) ? next : &((*rp)->pml_next);
134 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in
135 * functionality to xdr_pmaplist().
138 xdr_pmaplist_ptr(xdrs, rp)
142 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp);