303 lines
11 KiB
C
303 lines
11 KiB
C
/* handle.c
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Functions for maintaining handles on objects. */
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/*
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* Copyright (c) 1999-2000 Internet Software Consortium.
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* All rights reserved.
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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
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* are met:
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*
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* 1. 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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of The Internet Software Consortium nor the names
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* of its 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 INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This software has been written for the Internet Software Consortium
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* by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
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* To learn more about the Internet Software Consortium, see
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* ``http://www.isc.org/''. To learn more about Vixie Enterprises,
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* see ``http://www.vix.com''. To learn more about Nominum, Inc., see
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* ``http://www.nominum.com''.
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*/
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#include <omapip/omapip_p.h>
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/* The handle table is a hierarchical tree designed for quick mapping
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of handle identifiers to objects. Objects contain their own handle
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identifiers if they have them, so the reverse mapping is also
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quick. The hierarchy is made up of table objects, each of which
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has 120 entries, a flag indicating whether the table is a leaf
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table or an indirect table, the handle of the first object covered
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by the table and the first object after that that's *not* covered
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by the table, a count of how many objects of either type are
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currently stored in the table, and an array of 120 entries pointing
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either to objects or tables.
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When we go to add an object to the table, we look to see if the
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next object handle to be assigned is covered by the outermost
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table. If it is, we find the place within that table where the
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next handle should go, and if necessary create additional nodes in
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the tree to contain the new handle. The pointer to the object is
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then stored in the correct position.
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Theoretically, we could have some code here to free up handle
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tables as they go out of use, but by and large handle tables won't
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go out of use, so this is being skipped for now. It shouldn't be
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too hard to implement in the future if there's a different
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application. */
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omapi_handle_table_t *omapi_handle_table;
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omapi_handle_t omapi_next_handle = 1; /* Next handle to be assigned. */
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static isc_result_t omapi_handle_lookup_in (omapi_object_t **,
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omapi_handle_t,
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omapi_handle_table_t *);
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static isc_result_t omapi_object_handle_in_table (omapi_handle_t,
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omapi_handle_table_t *,
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omapi_object_t *);
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static isc_result_t omapi_handle_table_enclose (omapi_handle_table_t **);
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isc_result_t omapi_object_handle (omapi_handle_t *h, omapi_object_t *o)
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{
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isc_result_t status;
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if (o -> handle) {
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*h = o -> handle;
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return ISC_R_SUCCESS;
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}
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if (!omapi_handle_table) {
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omapi_handle_table = dmalloc (sizeof *omapi_handle_table, MDL);
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if (!omapi_handle_table)
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return ISC_R_NOMEMORY;
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memset (omapi_handle_table, 0, sizeof *omapi_handle_table);
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omapi_handle_table -> first = 0;
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omapi_handle_table -> limit = OMAPI_HANDLE_TABLE_SIZE;
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omapi_handle_table -> leafp = 1;
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}
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/* If this handle doesn't fit in the outer table, we need to
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make a new outer table. This is a while loop in case for
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some reason we decide to do disjoint handle allocation,
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where the next level of indirection still isn't big enough
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to enclose the next handle ID. */
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while (omapi_next_handle >= omapi_handle_table -> limit) {
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omapi_handle_table_t *new;
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new = dmalloc (sizeof *new, MDL);
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if (!new)
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return ISC_R_NOMEMORY;
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memset (new, 0, sizeof *new);
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new -> first = 0;
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new -> limit = (omapi_handle_table -> limit *
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OMAPI_HANDLE_TABLE_SIZE);
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new -> leafp = 0;
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new -> children [0].table = omapi_handle_table;
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omapi_handle_table = new;
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}
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/* Try to cram this handle into the existing table. */
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status = omapi_object_handle_in_table (omapi_next_handle,
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omapi_handle_table, o);
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/* If it worked, return the next handle and increment it. */
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if (status == ISC_R_SUCCESS) {
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*h = omapi_next_handle;
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omapi_next_handle++;
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return ISC_R_SUCCESS;
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}
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if (status != ISC_R_NOSPACE)
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return status;
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status = omapi_handle_table_enclose (&omapi_handle_table);
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if (status != ISC_R_SUCCESS)
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return status;
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status = omapi_object_handle_in_table (omapi_next_handle,
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omapi_handle_table, o);
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if (status != ISC_R_SUCCESS)
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return status;
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*h = omapi_next_handle;
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omapi_next_handle++;
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return ISC_R_SUCCESS;
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}
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static isc_result_t omapi_object_handle_in_table (omapi_handle_t h,
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omapi_handle_table_t *table,
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omapi_object_t *o)
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{
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omapi_handle_table_t *inner;
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omapi_handle_t scale, index;
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isc_result_t status;
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if (table -> first > h || table -> limit <= h)
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return ISC_R_NOSPACE;
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/* If this is a leaf table, just stash the object in the
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appropriate place. */
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if (table -> leafp) {
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status = (omapi_object_reference
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(&table -> children [h - table -> first].object,
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o, MDL));
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if (status != ISC_R_SUCCESS)
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return status;
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o -> handle = h;
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return ISC_R_SUCCESS;
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}
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/* Scale is the number of handles represented by each child of this
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table. For a leaf table, scale would be 1. For a first level
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of indirection, 120. For a second, 120 * 120. Et cetera. */
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scale = (table -> limit - table -> first) / OMAPI_HANDLE_TABLE_SIZE;
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/* So the next most direct table from this one that contains the
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handle must be the subtable of this table whose index into this
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table's array of children is the handle divided by the scale. */
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index = (h - table -> first) / scale;
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inner = table -> children [index].table;
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/* If there is no more direct table than this one in the slot
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we came up with, make one. */
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if (!inner) {
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inner = dmalloc (sizeof *inner, MDL);
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if (!inner)
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return ISC_R_NOMEMORY;
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memset (inner, 0, sizeof *inner);
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inner -> first = index * scale + table -> first;
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inner -> limit = inner -> first + scale;
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if (scale == OMAPI_HANDLE_TABLE_SIZE)
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inner -> leafp = 1;
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table -> children [index].table = inner;
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}
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status = omapi_object_handle_in_table (h, inner, o);
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if (status == ISC_R_NOSPACE) {
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status = (omapi_handle_table_enclose
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(&table -> children [index].table));
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if (status != ISC_R_SUCCESS)
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return status;
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return omapi_object_handle_in_table
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(h, table -> children [index].table, o);
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}
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return status;
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}
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static isc_result_t omapi_handle_table_enclose (omapi_handle_table_t **table)
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{
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omapi_handle_table_t *inner = *table;
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omapi_handle_table_t *new;
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int index, base, scale;
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/* The scale of the table we're enclosing is going to be the
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difference between its "first" and "limit" members. So the
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scale of the table enclosing it is going to be that multiplied
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by the table size. */
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scale = (inner -> first - inner -> limit) * OMAPI_HANDLE_TABLE_SIZE;
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/* The range that the enclosing table covers is going to be
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the result of subtracting the remainder of dividing the
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enclosed table's first entry number by the enclosing
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table's scale. If handle IDs are being allocated
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sequentially, the enclosing table's "first" value will be
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the same as the enclosed table's "first" value. */
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base = inner -> first - inner -> first % scale;
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/* The index into the enclosing table at which the enclosed table
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will be stored is going to be the difference between the "first"
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value of the enclosing table and the enclosed table - zero, if
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we are allocating sequentially. */
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index = (base - inner -> first) / OMAPI_HANDLE_TABLE_SIZE;
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new = dmalloc (sizeof *new, MDL);
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if (!new)
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return ISC_R_NOMEMORY;
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memset (new, 0, sizeof *new);
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new -> first = base;
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new -> limit = base + scale;
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if (scale == OMAPI_HANDLE_TABLE_SIZE)
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new -> leafp = 0;
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new -> children [index].table = inner;
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*table = new;
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return ISC_R_SUCCESS;
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}
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isc_result_t omapi_handle_lookup (omapi_object_t **o, omapi_handle_t h)
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{
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return omapi_handle_lookup_in (o, h, omapi_handle_table);
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}
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static isc_result_t omapi_handle_lookup_in (omapi_object_t **o,
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omapi_handle_t h,
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omapi_handle_table_t *table)
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{
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omapi_handle_table_t *inner;
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omapi_handle_t scale, index;
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if (!table || table -> first > h || table -> limit <= h)
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return ISC_R_NOTFOUND;
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/* If this is a leaf table, just grab the object. */
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if (table -> leafp) {
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/* Not there? */
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if (!table -> children [h - table -> first].object)
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return ISC_R_NOTFOUND;
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return omapi_object_reference
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(o, table -> children [h - table -> first].object,
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MDL);
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}
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/* Scale is the number of handles represented by each child of this
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table. For a leaf table, scale would be 1. For a first level
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of indirection, 120. For a second, 120 * 120. Et cetera. */
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scale = (table -> limit - table -> first) / OMAPI_HANDLE_TABLE_SIZE;
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/* So the next most direct table from this one that contains the
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handle must be the subtable of this table whose index into this
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table's array of children is the handle divided by the scale. */
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index = (h - table -> first) / scale;
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inner = table -> children [index].table;
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return omapi_handle_lookup_in (o, h, table -> children [index].table);
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}
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/* For looking up objects based on handles that have been sent on the wire. */
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isc_result_t omapi_handle_td_lookup (omapi_object_t **obj,
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omapi_typed_data_t *handle)
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{
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omapi_handle_t h;
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if (handle -> type == omapi_datatype_int)
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h = handle -> u.integer;
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else if (handle -> type == omapi_datatype_data &&
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handle -> u.buffer.len == sizeof h) {
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memcpy (&h, handle -> u.buffer.value, sizeof h);
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h = ntohl (h);
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} else
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return ISC_R_INVALIDARG;
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return omapi_handle_lookup (obj, h);
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}
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