/* @(#)pmap_prot2.c	2.1 88/07/29 4.0 RPCSRC */

/*

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

 *

 * All rights reserved.

 *

 * 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.

 */

#if !defined(lint) && defined(SCCSIDS)

static 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.

 */

#include <gssrpc/types.h>

#include <gssrpc/xdr.h>

#include <gssrpc/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_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), xdr_pmap))

			return (FALSE);

		rp = (freeing) ? next : &((*rp)->pml_next);

	}

}