1/* 2 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved. 3 * 4 * @APPLE_LICENSE_HEADER_START@ 5 * 6 * Portions Copyright (c) 1999 Apple Computer, Inc. All Rights 7 * Reserved. This file contains Original Code and/or Modifications of 8 * Original Code as defined in and that are subject to the Apple Public 9 * Source License Version 1.1 (the "License"). You may not use this file 10 * except in compliance with the License. Please obtain a copy of the 11 * License at http://www.apple.com/publicsource and read it before using 12 * this file. 13 * 14 * The Original Code and all software distributed under the License are 15 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER 16 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 17 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. Please see the 19 * License for the specific language governing rights and limitations 20 * under the License. 21 * 22 * @APPLE_LICENSE_HEADER_END@ 23 */ 24/* 25 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for 26 * unrestricted use provided that this legend is included on all tape 27 * media and as a part of the software program in whole or part. Users 28 * may copy or modify Sun RPC without charge, but are not authorized 29 * to license or distribute it to anyone else except as part of a product or 30 * program developed by the user. 31 * 32 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE 33 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 34 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 35 * 36 * Sun RPC is provided with no support and without any obligation on the 37 * part of Sun Microsystems, Inc. to assist in its use, correction, 38 * modification or enhancement. 39 * 40 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 41 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC 42 * OR ANY PART THEREOF. 43 * 44 * In no event will Sun Microsystems, Inc. be liable for any lost revenue 45 * or profits or other special, indirect and consequential damages, even if 46 * Sun has been advised of the possibility of such damages. 47 * 48 * Sun Microsystems, Inc. 49 * 2550 Garcia Avenue 50 * Mountain View, California 94043 51 */ 52 53#if defined(LIBC_SCCS) && !defined(lint) 54/*static char *sccsid = "from: @(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";*/ 55/*static char *sccsid = "from: @(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC";*/ 56static char *rcsid = "$Id: pmap_prot2.c,v 1.3 2002/02/19 20:36:24 epeyton Exp $"; 57#endif 58 59/* 60 * pmap_prot2.c 61 * Protocol for the local binder service, or pmap. 62 * 63 * Copyright (C) 1984, Sun Microsystems, Inc. 64 */ 65 66#include <rpc/types.h> 67#include <rpc/xdr.h> 68#include <rpc/pmap_prot.h> 69 70 71/* 72 * What is going on with linked lists? (!) 73 * First recall the link list declaration from pmap_prot.h: 74 * 75 * struct pmaplist { 76 * struct pmap pml_map; 77 * struct pmaplist *pml_map; 78 * }; 79 * 80 * Compare that declaration with a corresponding xdr declaration that 81 * is (a) pointer-less, and (b) recursive: 82 * 83 * typedef union switch (bool_t) { 84 * 85 * case TRUE: struct { 86 * struct pmap; 87 * pmaplist_t foo; 88 * }; 89 * 90 * case FALSE: struct {}; 91 * } pmaplist_t; 92 * 93 * Notice that the xdr declaration has no nxt pointer while 94 * the C declaration has no bool_t variable. The bool_t can be 95 * interpreted as ``more data follows me''; if FALSE then nothing 96 * follows this bool_t; if TRUE then the bool_t is followed by 97 * an actual struct pmap, and then (recursively) by the 98 * xdr union, pamplist_t. 99 * 100 * This could be implemented via the xdr_union primitive, though this 101 * would cause a one recursive call per element in the list. Rather than do 102 * that we can ``unwind'' the recursion 103 * into a while loop and do the union arms in-place. 104 * 105 * The head of the list is what the C programmer wishes to past around 106 * the net, yet is the data that the pointer points to which is interesting; 107 * this sounds like a job for xdr_reference! 108 */ 109bool_t 110xdr_pmaplist(xdrs, rp) 111 register XDR *xdrs; 112 register struct pmaplist **rp; 113{ 114 /* 115 * more_elements is pre-computed in case the direction is 116 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by 117 * xdr_bool when the direction is XDR_DECODE. 118 */ 119 bool_t more_elements; 120 register int freeing = (xdrs->x_op == XDR_FREE); 121 register struct pmaplist **next = NULL; 122 123 while (TRUE) { 124 more_elements = (bool_t)(*rp != NULL); 125 if (! xdr_bool(xdrs, &more_elements)) 126 return (FALSE); 127 if (! more_elements) 128 return (TRUE); /* we are done */ 129 /* 130 * the unfortunate side effect of non-recursion is that in 131 * the case of freeing we must remember the next object 132 * before we free the current object ... 133 */ 134 if (freeing) 135 next = &((*rp)->pml_next); 136 if (! xdr_reference(xdrs, (caddr_t *)rp, (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap)) 137 return (FALSE); 138 rp = (freeing) ? next : &((*rp)->pml_next); 139 } 140} 141