1 /* 2 * Copyright (c) 2009, Sun Microsystems, Inc. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * - Redistributions of source code must retain the above copyright notice, 8 * this list of conditions and the following disclaimer. 9 * - Redistributions in binary form must reproduce the above copyright notice, 10 * this list of conditions and the following disclaimer in the documentation 11 * and/or other materials provided with the distribution. 12 * - Neither the name of Sun Microsystems, Inc. nor the names of its 13 * contributors may be used to endorse or promote products derived 14 * from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * pmap_prot2.c 31 * Protocol for the local binder service, or pmap. 32 * 33 * Copyright (C) 1984, Sun Microsystems, Inc. 34 */ 35 36 #include <wintirpc.h> 37 #include <assert.h> 38 39 #include <rpc/types.h> 40 #include <rpc/xdr.h> 41 #include <rpc/pmap_prot.h> 42 43 44 /* 45 * What is going on with linked lists? (!) 46 * First recall the link list declaration from pmap_prot.h: 47 * 48 * struct pmaplist { 49 * struct pmap pml_map; 50 * struct pmaplist *pml_map; 51 * }; 52 * 53 * Compare that declaration with a corresponding xdr declaration that 54 * is (a) pointer-less, and (b) recursive: 55 * 56 * typedef union switch (bool_t) { 57 * 58 * case TRUE: struct { 59 * struct pmap; 60 * pmaplist_t foo; 61 * }; 62 * 63 * case FALSE: struct {}; 64 * } pmaplist_t; 65 * 66 * Notice that the xdr declaration has no nxt pointer while 67 * the C declaration has no bool_t variable. The bool_t can be 68 * interpreted as ``more data follows me''; if FALSE then nothing 69 * follows this bool_t; if TRUE then the bool_t is followed by 70 * an actual struct pmap, and then (recursively) by the 71 * xdr union, pamplist_t. 72 * 73 * This could be implemented via the xdr_union primitive, though this 74 * would cause a one recursive call per element in the list. Rather than do 75 * that we can ``unwind'' the recursion 76 * into a while loop and do the union arms in-place. 77 * 78 * The head of the list is what the C programmer wishes to past around 79 * the net, yet is the data that the pointer points to which is interesting; 80 * this sounds like a job for xdr_reference! 81 */ 82 bool_t 83 xdr_pmaplist(xdrs, rp) 84 XDR *xdrs; 85 struct pmaplist **rp; 86 { 87 /* 88 * more_elements is pre-computed in case the direction is 89 * XDR_ENCODE or XDR_FREE. more_elements is overwritten by 90 * xdr_bool when the direction is XDR_DECODE. 91 */ 92 bool_t more_elements; 93 int freeing; 94 struct pmaplist **next = NULL; /* pacify gcc */ 95 96 assert(xdrs != NULL); 97 assert(rp != NULL); 98 99 freeing = (xdrs->x_op == XDR_FREE); 100 101 for (;;) { 102 more_elements = (bool_t)(*rp != NULL); 103 if (! xdr_bool(xdrs, &more_elements)) 104 return (FALSE); 105 if (! more_elements) 106 return (TRUE); /* we are done */ 107 /* 108 * the unfortunate side effect of non-recursion is that in 109 * the case of freeing we must remember the next object 110 * before we free the current object ... 111 */ 112 if (freeing) 113 next = &((*rp)->pml_next); 114 if (! xdr_reference(xdrs, (caddr_t *)rp, 115 (u_int)sizeof(struct pmaplist), (xdrproc_t)xdr_pmap)) 116 return (FALSE); 117 rp = (freeing) ? next : &((*rp)->pml_next); 118 } 119 } 120 121 122 /* 123 * xdr_pmaplist_ptr() is specified to take a PMAPLIST *, but is identical in 124 * functionality to xdr_pmaplist(). 125 */ 126 bool_t 127 xdr_pmaplist_ptr(xdrs, rp) 128 XDR *xdrs; 129 struct pmaplist *rp; 130 { 131 return xdr_pmaplist(xdrs, (struct pmaplist **)(void *)rp); 132 } 133