1 /* 2 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for 3 * unrestricted use provided that this legend is included on all tape 4 * media and as a part of the software program in whole or part. Users 5 * may copy or modify Sun RPC without charge, but are not authorized 6 * to license or distribute it to anyone else except as part of a product or 7 * program developed by the user. 8 * 9 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE 10 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 11 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 12 * 13 * Sun RPC is provided with no support and without any obligation on the 14 * part of Sun Microsystems, Inc. to assist in its use, correction, 15 * modification or enhancement. 16 * 17 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 18 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC 19 * OR ANY PART THEREOF. 20 * 21 * In no event will Sun Microsystems, Inc. be liable for any lost revenue 22 * or profits or other special, indirect and consequential damages, even if 23 * Sun has been advised of the possibility of such damages. 24 * 25 * Sun Microsystems, Inc. 26 * 2550 Garcia Avenue 27 * Mountain View, California 94043 28 * 29 * @(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro 30 * @(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC 31 * $NetBSD: pmap_prot2.c,v 1.14 2000/07/06 03:10:34 christos Exp $ 32 * $FreeBSD: src/lib/libc/rpc/pmap_prot2.c,v 1.10 2004/10/16 06:11:35 obrien Exp $ 33 * $DragonFly: src/lib/libc/rpc/pmap_prot2.c,v 1.4 2005/11/13 12:27:04 swildner Exp $ 34 */ 35 36 /* 37 * pmap_prot2.c 38 * Protocol for the local binder service, or pmap. 39 * 40 * Copyright (C) 1984, Sun Microsystems, Inc. 41 */ 42 43 #include "namespace.h" 44 #include <assert.h> 45 46 #include <rpc/types.h> 47 #include <rpc/xdr.h> 48 #include <rpc/pmap_prot.h> 49 #include "un-namespace.h" 50 51 52 /* 53 * What is going on with linked lists? (!) 54 * First recall the link list declaration from pmap_prot.h: 55 * 56 * struct pmaplist { 57 * struct pmap pml_map; 58 * struct pmaplist *pml_map; 59 * }; 60 * 61 * Compare that declaration with a corresponding xdr declaration that 62 * is (a) pointer-less, and (b) recursive: 63 * 64 * typedef union switch (bool_t) { 65 * 66 * case TRUE: struct { 67 * struct pmap; 68 * pmaplist_t foo; 69 * }; 70 * 71 * case FALSE: struct {}; 72 * } pmaplist_t; 73 * 74 * Notice that the xdr declaration has no nxt pointer while 75 * the C declaration has no bool_t variable. The bool_t can be 76 * interpreted as ``more data follows me''; if FALSE then nothing 77 * follows this bool_t; if TRUE then the bool_t is followed by 78 * an actual struct pmap, and then (recursively) by the 79 * xdr union, pamplist_t. 80 * 81 * This could be implemented via the xdr_union primitive, though this 82 * would cause a one recursive call per element in the list. Rather than do 83 * that we can ``unwind'' the recursion 84 * into a while loop and do the union arms in-place. 85 * 86 * The head of the list is what the C programmer wishes to past around 87 * the net, yet is the data that the pointer points to which is interesting; 88 * this sounds like a job for xdr_reference! 89 */ 90 bool_t 91 xdr_pmaplist(XDR *xdrs, struct pmaplist **rp) 92 { 93 /* 94 * more_elements is pre-computed in case the direction is 95 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by 96 * xdr_bool when the direction is XDR_DECODE. 97 */ 98 bool_t more_elements; 99 int freeing; 100 struct pmaplist **next = NULL; /* pacify gcc */ 101 102 assert(xdrs != NULL); 103 assert(rp != NULL); 104 105 freeing = (xdrs->x_op == XDR_FREE); 106 107 for (;;) { 108 more_elements = (bool_t)(*rp != NULL); 109 if (! xdr_bool(xdrs, &more_elements)) 110 return (FALSE); 111 if (! more_elements) 112 return (TRUE); /* we are done */ 113 /* 114 * the unfortunate side effect of non-recursion is that in 115 * the case of freeing we must remember the next object 116 * before we free the current object ... 117 */ 118 if (freeing) 119 next = &((*rp)->pml_next); 120 if (! xdr_reference(xdrs, (caddr_t *)rp, 121 (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap)) 122 return (FALSE); 123 rp = (freeing) ? next : &((*rp)->pml_next); 124 } 125 } 126 127 128 /* 129 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in 130 * functionality to xdr_pmaplist(). 131 */ 132 bool_t 133 xdr_pmaplist_ptr(XDR *xdrs, struct pmaplist *rp) 134 { 135 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp); 136 } 137