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pmap_prot2.c
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1 /*
2  * Copyright (c) 2009, Sun Microsystems, Inc.
3  * All rights reserved.
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8  * this list of conditions and the following disclaimer.
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13  * contributors may be used to endorse or promote products derived
14  * from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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27  */
28 
29 /*
30  * pmap_prot2.c
31  * Protocol for the local binder service, or pmap.
32  *
33  * Copyright (C) 1984, Sun Microsystems, Inc.
34  */
35 
36 #include <wintirpc.h>
37 #include <assert.h>
38 
39 #include <rpc/types.h>
40 #include <rpc/xdr.h>
41 #include <rpc/pmap_prot.h>
42 
43 
44 /*
45  * What is going on with linked lists? (!)
46  * First recall the link list declaration from pmap_prot.h:
47  *
48  * struct pmaplist {
49  * struct pmap pml_map;
50  * struct pmaplist *pml_map;
51  * };
52  *
53  * Compare that declaration with a corresponding xdr declaration that
54  * is (a) pointer-less, and (b) recursive:
55  *
56  * typedef union switch (bool_t) {
57  *
58  * case TRUE: struct {
59  * struct pmap;
60  * pmaplist_t foo;
61  * };
62  *
63  * case FALSE: struct {};
64  * } pmaplist_t;
65  *
66  * Notice that the xdr declaration has no nxt pointer while
67  * the C declaration has no bool_t variable. The bool_t can be
68  * interpreted as ``more data follows me''; if FALSE then nothing
69  * follows this bool_t; if TRUE then the bool_t is followed by
70  * an actual struct pmap, and then (recursively) by the
71  * xdr union, pamplist_t.
72  *
73  * This could be implemented via the xdr_union primitive, though this
74  * would cause a one recursive call per element in the list. Rather than do
75  * that we can ``unwind'' the recursion
76  * into a while loop and do the union arms in-place.
77  *
78  * The head of the list is what the C programmer wishes to past around
79  * the net, yet is the data that the pointer points to which is interesting;
80  * this sounds like a job for xdr_reference!
81  */
82 bool_t
83 xdr_pmaplist(xdrs, rp)
84  XDR *xdrs;
85  struct pmaplist **rp;
86 {
87  /*
88  * more_elements is pre-computed in case the direction is
89  * XDR_ENCODE or XDR_FREE. more_elements is overwritten by
90  * xdr_bool when the direction is XDR_DECODE.
91  */
92  bool_t more_elements;
93  int freeing;
94  struct pmaplist **next = NULL; /* pacify gcc */
95 
96  assert(xdrs != NULL);
97  assert(rp != NULL);
98 
99  freeing = (xdrs->x_op == XDR_FREE);
100 
101  for (;;) {
102  more_elements = (bool_t)(*rp != NULL);
103  if (! xdr_bool(xdrs, &more_elements))
104  return (FALSE);
105  if (! more_elements)
106  return (TRUE); /* we are done */
107  /*
108  * the unfortunate side effect of non-recursion is that in
109  * the case of freeing we must remember the next object
110  * before we free the current object ...
111  */
112  if (freeing)
113  next = &((*rp)->pml_next);
114  if (! xdr_reference(xdrs, (caddr_t *)rp,
115  (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap))
116  return (FALSE);
117  rp = (freeing) ? next : &((*rp)->pml_next);
118  }
119 }
120 
121 
122 /*
123  * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in
124  * functionality to xdr_pmaplist().
125  */
126 bool_t
128  XDR *xdrs;
129  struct pmaplist *rp;
130 {
131  return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp);
132 }
bool_t xdr_pmap(XDR *xdrs, struct pmap *regs)
Definition: pmap_prot.c:45
#define TRUE
Definition: types.h:120
bool_t xdr_reference(XDR *xdrs, caddr_t *pp, u_int size, xdrproc_t proc)
Definition: xdr_reference.c:62
int32_t bool_t
Definition: types.h:101
#define assert(x)
Definition: debug.h:53
char * caddr_t
Definition: rosdhcp.h:36
Definition: xdr.h:103
bool_t(* xdrproc_t)(XDR *,...)
Definition: xdr.h:144
bool_t xdr_pmaplist(XDR *xdrs, struct pmaplist **rp)
Definition: pmap_prot2.c:83
smooth NULL
Definition: ftsmooth.c:416
enum xdr_op x_op
Definition: xdr.h:104
bool_t xdr_pmaplist_ptr(XDR *xdrs, struct pmaplist *rp)
Definition: pmap_prot2.c:127
static unsigned __int64 next
Definition: rand_nt.c:6
UINT32 u_int
Definition: types.h:82
bool_t xdr_bool(XDR *xdrs, bool_t *bp)
Definition: xdr.c:428
Definition: xdr.h:87