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114 lines
4.0 KiB
C
114 lines
4.0 KiB
C
/*
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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) 2010, Oracle America, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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* * Neither the name of the "Oracle America, Inc." nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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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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XDR *xdrs;
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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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int freeing = (xdrs->x_op == XDR_FREE);
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struct pmaplist *next = NULL;
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while (TRUE)
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{
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more_elements = (bool_t) (*rp != NULL);
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if (!INTUSE(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 (!INTUSE(xdr_reference) (xdrs, (caddr_t *) rp,
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(u_int) sizeof (struct pmaplist),
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(xdrproc_t) INTUSE(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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INTDEF(xdr_pmaplist)
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