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