1 /* $NetBSD: pmap_prot2.c,v 1.16 2012/03/20 17:14:50 matt Exp $ */ 2 3 /* 4 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for 5 * unrestricted use provided that this legend is included on all tape 6 * media and as a part of the software program in whole or part. Users 7 * may copy or modify Sun RPC without charge, but are not authorized 8 * to license or distribute it to anyone else except as part of a product or 9 * program developed by the user. 10 * 11 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE 12 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 13 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 14 * 15 * Sun RPC is provided with no support and without any obligation on the 16 * part of Sun Microsystems, Inc. to assist in its use, correction, 17 * modification or enhancement. 18 * 19 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 20 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC 21 * OR ANY PART THEREOF. 22 * 23 * In no event will Sun Microsystems, Inc. be liable for any lost revenue 24 * or profits or other special, indirect and consequential damages, even if 25 * Sun has been advised of the possibility of such damages. 26 * 27 * Sun Microsystems, Inc. 28 * 2550 Garcia Avenue 29 * Mountain View, California 94043 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char *sccsid = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro"; 36 static char *sccsid = "@(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC"; 37 #else 38 __RCSID("$NetBSD: pmap_prot2.c,v 1.16 2012/03/20 17:14:50 matt Exp $"); 39 #endif 40 #endif 41 42 /* 43 * pmap_prot2.c 44 * Protocol for the local binder service, or pmap. 45 * 46 * Copyright (C) 1984, Sun Microsystems, Inc. 47 */ 48 49 #include "namespace.h" 50 51 #include <assert.h> 52 53 #include <rpc/types.h> 54 #include <rpc/xdr.h> 55 #include <rpc/pmap_prot.h> 56 57 #ifdef __weak_alias 58 __weak_alias(xdr_pmaplist,_xdr_pmaplist) 59 #endif 60 61 /* 62 * What is going on with linked lists? (!) 63 * First recall the link list declaration from pmap_prot.h: 64 * 65 * struct pmaplist { 66 * struct pmap pml_map; 67 * struct pmaplist *pml_map; 68 * }; 69 * 70 * Compare that declaration with a corresponding xdr declaration that 71 * is (a) pointer-less, and (b) recursive: 72 * 73 * typedef union switch (bool_t) { 74 * 75 * case TRUE: struct { 76 * struct pmap; 77 * pmaplist_t foo; 78 * }; 79 * 80 * case FALSE: struct {}; 81 * } pmaplist_t; 82 * 83 * Notice that the xdr declaration has no nxt pointer while 84 * the C declaration has no bool_t variable. The bool_t can be 85 * interpreted as ``more data follows me''; if FALSE then nothing 86 * follows this bool_t; if TRUE then the bool_t is followed by 87 * an actual struct pmap, and then (recursively) by the 88 * xdr union, pamplist_t. 89 * 90 * This could be implemented via the xdr_union primitive, though this 91 * would cause a one recursive call per element in the list. Rather than do 92 * that we can ``unwind'' the recursion 93 * into a while loop and do the union arms in-place. 94 * 95 * The head of the list is what the C programmer wishes to past around 96 * the net, yet is the data that the pointer points to which is interesting; 97 * this sounds like a job for xdr_reference! 98 */ 99 bool_t 100 xdr_pmaplist(XDR *xdrs, struct pmaplist **rp) 101 { 102 /* 103 * more_elements is pre-computed in case the direction is 104 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by 105 * xdr_bool when the direction is XDR_DECODE. 106 */ 107 bool_t more_elements; 108 int freeing; 109 struct pmaplist **next = NULL; /* pacify gcc */ 110 111 _DIAGASSERT(xdrs != NULL); 112 _DIAGASSERT(rp != NULL); 113 114 freeing = (xdrs->x_op == XDR_FREE); 115 116 for (;;) { 117 more_elements = (bool_t)(*rp != NULL); 118 if (! xdr_bool(xdrs, &more_elements)) 119 return (FALSE); 120 if (! more_elements) 121 return (TRUE); /* we are done */ 122 /* 123 * the unfortunate side effect of non-recursion is that in 124 * the case of freeing we must remember the next object 125 * before we free the current object ... 126 */ 127 if (freeing) 128 next = &((*rp)->pml_next); 129 if (! xdr_reference(xdrs, (caddr_t *)rp, 130 (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap)) 131 return (FALSE); 132 rp = (freeing) ? next : &((*rp)->pml_next); 133 } 134 } 135 136 137 /* 138 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in 139 * functionality to xdr_pmaplist(). 140 */ 141 bool_t 142 xdr_pmaplist_ptr(XDR *xdrs, struct pmaplist *rp) 143 { 144 145 _DIAGASSERT(xdrs != NULL); 146 _DIAGASSERT(rp != NULL); 147 148 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp); 149 } 150