1 /* $NetBSD: pmap_prot2.c,v 1.14 2000/07/06 03:10:34 christos 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 static char *sccsid = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro"; 35 static char *sccsid = "@(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC"; 36 static char *rcsid = "$FreeBSD$"; 37 #endif 38 39 /* 40 * pmap_prot2.c 41 * Protocol for the local binder service, or pmap. 42 * 43 * Copyright (C) 1984, Sun Microsystems, Inc. 44 */ 45 46 #include "namespace.h" 47 #include <assert.h> 48 49 #include <rpc/types.h> 50 #include <rpc/xdr.h> 51 #include <rpc/pmap_prot.h> 52 #include "un-namespace.h" 53 54 55 /* 56 * What is going on with linked lists? (!) 57 * First recall the link list declaration from pmap_prot.h: 58 * 59 * struct pmaplist { 60 * struct pmap pml_map; 61 * struct pmaplist *pml_map; 62 * }; 63 * 64 * Compare that declaration with a corresponding xdr declaration that 65 * is (a) pointer-less, and (b) recursive: 66 * 67 * typedef union switch (bool_t) { 68 * 69 * case TRUE: struct { 70 * struct pmap; 71 * pmaplist_t foo; 72 * }; 73 * 74 * case FALSE: struct {}; 75 * } pmaplist_t; 76 * 77 * Notice that the xdr declaration has no nxt pointer while 78 * the C declaration has no bool_t variable. The bool_t can be 79 * interpreted as ``more data follows me''; if FALSE then nothing 80 * follows this bool_t; if TRUE then the bool_t is followed by 81 * an actual struct pmap, and then (recursively) by the 82 * xdr union, pamplist_t. 83 * 84 * This could be implemented via the xdr_union primitive, though this 85 * would cause a one recursive call per element in the list. Rather than do 86 * that we can ``unwind'' the recursion 87 * into a while loop and do the union arms in-place. 88 * 89 * The head of the list is what the C programmer wishes to past around 90 * the net, yet is the data that the pointer points to which is interesting; 91 * this sounds like a job for xdr_reference! 92 */ 93 bool_t 94 xdr_pmaplist(xdrs, rp) 95 XDR *xdrs; 96 struct pmaplist **rp; 97 { 98 /* 99 * more_elements is pre-computed in case the direction is 100 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by 101 * xdr_bool when the direction is XDR_DECODE. 102 */ 103 bool_t more_elements; 104 int freeing; 105 struct pmaplist **next = NULL; /* pacify gcc */ 106 107 assert(xdrs != NULL); 108 assert(rp != NULL); 109 110 freeing = (xdrs->x_op == XDR_FREE); 111 112 for (;;) { 113 more_elements = (bool_t)(*rp != NULL); 114 if (! xdr_bool(xdrs, &more_elements)) 115 return (FALSE); 116 if (! more_elements) 117 return (TRUE); /* we are done */ 118 /* 119 * the unfortunate side effect of non-recursion is that in 120 * the case of freeing we must remember the next object 121 * before we free the current object ... 122 */ 123 if (freeing) 124 next = &((*rp)->pml_next); 125 if (! xdr_reference(xdrs, (caddr_t *)rp, 126 (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap)) 127 return (FALSE); 128 rp = (freeing) ? next : &((*rp)->pml_next); 129 } 130 } 131 132 133 /* 134 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in 135 * functionality to xdr_pmaplist(). 136 */ 137 bool_t 138 xdr_pmaplist_ptr(xdrs, rp) 139 XDR *xdrs; 140 struct pmaplist *rp; 141 { 142 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp); 143 } 144