/* @(#)pmap_prot2.c	2.1 88/07/29 4.0 RPCSRC *//* * Sun RPC is a product of Sun Microsystems, Inc. and is provided for * unrestricted use provided that this legend is included on all tape * media and as a part of the software program in whole or part.  Users * may copy or modify Sun RPC without charge, but are not authorized * to license or distribute it to anyone else except as part of a product or * program developed by the user. * * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. * * Sun RPC is provided with no support and without any obligation on the * part of Sun Microsystems, Inc. to assist in its use, correction, * modification or enhancement. * * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC * OR ANY PART THEREOF. * * In no event will Sun Microsystems, Inc. be liable for any lost revenue * or profits or other special, indirect and consequential damages, even if * Sun has been advised of the possibility of such damages. * * Sun Microsystems, Inc. * 2550 Garcia Avenue * Mountain View, California  94043 */#if 0static char sccsid[] = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";#endif/* * pmap_prot2.c * Protocol for the local binder service, or pmap. * * Copyright (C) 1984, Sun Microsystems, Inc. */#include <rpc/types.h>#include <rpc/xdr.h>#include <rpc/pmap_prot.h>/* * What is going on with linked lists? (!) * First recall the link list declaration from pmap_prot.h: * * struct pmaplist { *      struct pmap pml_map; *      struct pmaplist *pml_map; * }; * * Compare that declaration with a corresponding xdr declaration that * is (a) pointer-less, and (b) recursive: * * typedef union switch (bool_t) { * *      case TRUE: struct { *              struct pmap; *              pmaplist_t foo; *      }; * *      case FALSE: struct {}; * } pmaplist_t; * * Notice that the xdr declaration has no nxt pointer while * the C declaration has no bool_t variable.  The bool_t can be * interpreted as ``more data follows me''; if FALSE then nothing * follows this bool_t; if TRUE then the bool_t is followed by * an actual struct pmap, and then (recursively) by the * xdr union, pamplist_t. * * This could be implemented via the xdr_union primitive, though this * would cause a one recursive call per element in the list.  Rather than do * that we can ``unwind'' the recursion * into a while loop and do the union arms in-place. * * The head of the list is what the C programmer wishes to past around * the net, yet is the data that the pointer points to which is interesting; * this sounds like a job for xdr_reference! */bool_txdr_pmaplist (xdrs, rp)     XDR *xdrs;     struct pmaplist **rp;{  /*   * more_elements is pre-computed in case the direction is   * XDR_ENCODE or XDR_FREE.  more_elements is overwritten by   * xdr_bool when the direction is XDR_DECODE.   */  bool_t more_elements;  int freeing = (xdrs->x_op == XDR_FREE);  struct pmaplist **next = NULL;  while (TRUE)    {      more_elements = (bool_t) (*rp != NULL);      if (!xdr_bool (xdrs, &more_elements))	return FALSE;      if (!more_elements)	return TRUE;		/* we are done */      /*       * the unfortunate side effect of non-recursion is that in       * the case of freeing we must remember the next object       * before we free the current object ...       */      if (freeing)	next = &((*rp)->pml_next);      if (!xdr_reference (xdrs, (caddr_t *) rp,			  (u_int) sizeof (struct pmaplist),			  (xdrproc_t) xdr_pmap))	  return FALSE;      rp = freeing ? next : &((*rp)->pml_next);    }}