240 lines
6 KiB
C
240 lines
6 KiB
C
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/* $NetBSD: bt_overflow.c,v 1.16 2008/09/11 12:58:00 joerg Exp $ */
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/*-
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* Copyright (c) 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Mike Olson.
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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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* 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 University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT 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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#if HAVE_NBTOOL_CONFIG_H
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#include "nbtool_config.h"
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#endif
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#include <sys/cdefs.h>
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#ifndef __minix
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__RCSID("$NetBSD: bt_overflow.c,v 1.16 2008/09/11 12:58:00 joerg Exp $");
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#endif
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#ifndef __minix
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#include "namespace.h"
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#endif
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#include <sys/param.h>
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <db.h>
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#include "btree.h"
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#define MAX(a, b) ((a) > (b) ? (a) : (b))
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#define MIN(a, b) ((a) < (b) ? (a) : (b))
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/*
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* Big key/data code.
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*
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* Big key and data entries are stored on linked lists of pages. The initial
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* reference is byte string stored with the key or data and is the page number
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* and size. The actual record is stored in a chain of pages linked by the
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* nextpg field of the PAGE header.
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*
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* The first page of the chain has a special property. If the record is used
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* by an internal page, it cannot be deleted and the P_PRESERVE bit will be set
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* in the header.
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*
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* XXX
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* A single DBT is written to each chain, so a lot of space on the last page
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* is wasted. This is a fairly major bug for some data sets.
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*/
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/*
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* __OVFL_GET -- Get an overflow key/data item.
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*
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* Parameters:
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* t: tree
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* p: pointer to { pgno_t, uint32_t }
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* buf: storage address
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* bufsz: storage size
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*
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* Returns:
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* RET_ERROR, RET_SUCCESS
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*/
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int
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__ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz)
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{
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PAGE *h;
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pgno_t pg;
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uint32_t sz, nb, plen;
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size_t temp;
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memmove(&pg, p, sizeof(pgno_t));
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memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(uint32_t));
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*ssz = sz;
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#ifdef DEBUG
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if (pg == P_INVALID || sz == 0)
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abort();
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#endif
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/* Make the buffer bigger as necessary. */
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if (*bufsz < sz) {
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*buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz));
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if (*buf == NULL)
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return (RET_ERROR);
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*bufsz = sz;
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}
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/*
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* Step through the linked list of pages, copying the data on each one
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* into the buffer. Never copy more than the data's length.
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*/
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temp = t->bt_psize - BTDATAOFF;
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_DBFIT(temp, uint32_t);
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plen = (uint32_t)temp;
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for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) {
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if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
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return (RET_ERROR);
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nb = MIN(sz, plen);
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memmove(p, (char *)(void *)h + BTDATAOFF, nb);
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mpool_put(t->bt_mp, h, 0);
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if ((sz -= nb) == 0)
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break;
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}
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return (RET_SUCCESS);
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}
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/*
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* __OVFL_PUT -- Store an overflow key/data item.
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*
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* Parameters:
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* t: tree
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* data: DBT to store
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* pgno: storage page number
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*
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* Returns:
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* RET_ERROR, RET_SUCCESS
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*/
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int
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__ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg)
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{
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PAGE *h, *last;
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void *p;
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pgno_t npg;
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uint32_t sz, nb, plen;
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size_t temp;
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/*
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* Allocate pages and copy the key/data record into them. Store the
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* number of the first page in the chain.
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*/
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temp = t->bt_psize - BTDATAOFF;
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_DBFIT(temp, uint32_t);
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plen = (uint32_t)temp;
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last = NULL;
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p = dbt->data;
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temp = dbt->size;
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_DBFIT(temp, uint32_t);
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sz = temp;
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for (;; p = (char *)p + plen, last = h) {
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if ((h = __bt_new(t, &npg)) == NULL)
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return (RET_ERROR);
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h->pgno = npg;
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h->nextpg = h->prevpg = P_INVALID;
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h->flags = P_OVERFLOW;
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h->lower = h->upper = 0;
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nb = MIN(sz, plen);
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(void)memmove((char *)(void *)h + BTDATAOFF, p, (size_t)nb);
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if (last) {
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last->nextpg = h->pgno;
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mpool_put(t->bt_mp, last, MPOOL_DIRTY);
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} else
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*pg = h->pgno;
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if ((sz -= nb) == 0) {
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mpool_put(t->bt_mp, h, MPOOL_DIRTY);
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break;
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}
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}
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return (RET_SUCCESS);
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}
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/*
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* __OVFL_DELETE -- Delete an overflow chain.
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*
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* Parameters:
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* t: tree
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* p: pointer to { pgno_t, uint32_t }
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*
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* Returns:
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* RET_ERROR, RET_SUCCESS
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*/
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int
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__ovfl_delete(BTREE *t, void *p)
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{
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PAGE *h;
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pgno_t pg;
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uint32_t sz, plen;
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size_t temp;
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(void)memmove(&pg, p, sizeof(pgno_t));
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(void)memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(uint32_t));
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#ifdef DEBUG
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if (pg == P_INVALID || sz == 0)
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abort();
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#endif
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if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
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return (RET_ERROR);
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/* Don't delete chains used by internal pages. */
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if (h->flags & P_PRESERVE) {
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mpool_put(t->bt_mp, h, 0);
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return (RET_SUCCESS);
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}
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/* Step through the chain, calling the free routine for each page. */
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temp = t->bt_psize - BTDATAOFF;
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_DBFIT(temp, uint32_t);
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plen = (uint32_t)temp;
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for (;; sz -= plen) {
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pg = h->nextpg;
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__bt_free(t, h);
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if (sz <= plen)
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break;
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if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
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return (RET_ERROR);
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}
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return (RET_SUCCESS);
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}
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