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 } 152