/*

 * pmap_prot2.c

 * Protocol for the local binder service, or pmap.

 *

 * Copyright (c) 2010, Oracle America, Inc.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are

 * met:

 *

 *     * Redistributions of source code must retain the above copyright

 *       notice, this list of conditions and the following disclaimer.

 *     * Redistributions in binary form must reproduce the above

 *       copyright notice, this list of conditions and the following

 *       disclaimer in the documentation and/or other materials

 *       provided with the distribution.

 *     * Neither the name of the "Oracle America, Inc." nor the names of its

 *       contributors may be used to endorse or promote products derived

 *       from this software without specific prior written permission.

 *

 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

 *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

 *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

 *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE

 *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <rpc/types.h>

#include <rpc/xdr.h>

#include <rpc/pmap_prot.h>

#include <shlib-compat.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_t

xdr_pmaplist (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);

    }

}

libc_hidden_nolink_sunrpc (xdr_pmaplist, GLIBC_2_0)