lib/libc/rpc/pmap_prot2.c

   1 /*      $NetBSD: pmap_prot2.c,v 1.17 2013/03/11 20:19:29 tron Exp $     */
   2
   3 /*
   4  * Copyright (c) 2010, Oracle America, Inc.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are
   8  * met:
   9  *
  10  *     * Redistributions of source code must retain the above copyright
  11  *       notice, this list of conditions and the following disclaimer.
  12  *     * Redistributions in binary form must reproduce the above
  13  *       copyright notice, this list of conditions and the following
  14  *       disclaimer in the documentation and/or other materials
  15  *       provided with the distribution.
  16  *     * Neither the name of the "Oracle America, Inc." nor the names of its
  17  *       contributors may be used to endorse or promote products derived
  18  *       from this software without specific prior written permission.
  19  *
  20  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  23  *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  24  *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  25  *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  27  *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  29  *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  30  *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <sys/cdefs.h>
  35 #if defined(LIBC_SCCS) && !defined(lint)
  36 #if 0
  37 static char *sccsid = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
  38 static char *sccsid = "@(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC";
  39 #else
  40 __RCSID("$NetBSD: pmap_prot2.c,v 1.17 2013/03/11 20:19:29 tron Exp $");
  41 #endif
  42 #endif
  43
  44 /*
  45  * pmap_prot2.c
  46  * Protocol for the local binder service, or pmap.
  47  *
  48  * Copyright (C) 1984, Sun Microsystems, Inc.
  49  */
  50
  51 #include "namespace.h"
  52
  53 #include <assert.h>
  54
  55 #include <rpc/types.h>
  56 #include <rpc/xdr.h>
  57 #include <rpc/pmap_prot.h>
  58
  59 #ifdef __weak_alias
  60 __weak_alias(xdr_pmaplist,_xdr_pmaplist)
  61 #endif
  62
  63 /*
  64  * What is going on with linked lists? (!)
  65  * First recall the link list declaration from pmap_prot.h:
  66  *
  67  * struct pmaplist {
  68  *      struct pmap pml_map;
  69  *      struct pmaplist *pml_map;
  70  * };
  71  *
  72  * Compare that declaration with a corresponding xdr declaration that
  73  * is (a) pointer-less, and (b) recursive:
  74  *
  75  * typedef union switch (bool_t) {
  76  *
  77  *      case TRUE: struct {
  78  *              struct pmap;
  79  *              pmaplist_t foo;
  80  *      };
  81  *
  82  *      case FALSE: struct {};
  83  * } pmaplist_t;
  84  *
  85  * Notice that the xdr declaration has no nxt pointer while
  86  * the C declaration has no bool_t variable.  The bool_t can be
  87  * interpreted as ``more data follows me''; if FALSE then nothing
  88  * follows this bool_t; if TRUE then the bool_t is followed by
  89  * an actual struct pmap, and then (recursively) by the
  90  * xdr union, pamplist_t.
  91  *
  92  * This could be implemented via the xdr_union primitive, though this
  93  * would cause a one recursive call per element in the list.  Rather than do
  94  * that we can ``unwind'' the recursion
  95  * into a while loop and do the union arms in-place.
  96  *
  97  * The head of the list is what the C programmer wishes to past around
  98  * the net, yet is the data that the pointer points to which is interesting;
  99  * this sounds like a job for xdr_reference!
 100  */
 101 bool_t
 102 xdr_pmaplist(XDR *xdrs, struct pmaplist **rp)
 103 {
 104         /*
 105          * more_elements is pre-computed in case the direction is
 106          * XDR_ENCODE or XDR_FREE.  more_elements is overwritten by
 107          * xdr_bool when the direction is XDR_DECODE.
 108          */
 109         bool_t more_elements;
 110         int freeing;
 111         struct pmaplist **next  = NULL; /* pacify gcc */
 112
 113         _DIAGASSERT(xdrs != NULL);
 114         _DIAGASSERT(rp != NULL);
 115
 116         freeing = (xdrs->x_op == XDR_FREE);
 117
 118         for (;;) {
 119                 more_elements = (bool_t)(*rp != NULL);
 120                 if (! xdr_bool(xdrs, &more_elements))
 121                         return (FALSE);
 122                 if (! more_elements)
 123                         return (TRUE);  /* we are done */
 124                 /*
 125                  * the unfortunate side effect of non-recursion is that in
 126                  * the case of freeing we must remember the next object
 127                  * before we free the current object ...
 128                  */
 129                 if (freeing)
 130                         next = &((*rp)->pml_next);
 131                 if (! xdr_reference(xdrs, (caddr_t *)rp,
 132                     (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap))
 133                         return (FALSE);
 134                 rp = (freeing) ? next : &((*rp)->pml_next);
 135         }
 136 }
 137
 138
 139 /*
 140  * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in
 141  * functionality to xdr_pmaplist().
 142  */
 143 bool_t
 144 xdr_pmaplist_ptr(XDR *xdrs, struct pmaplist *rp)
 145 {
 146
 147         _DIAGASSERT(xdrs != NULL);
 148         _DIAGASSERT(rp != NULL);
 149
 150         return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp);
 151 }