133 lines
4.0 KiB
C
133 lines
4.0 KiB
C
/* $NetBSD: rec_search.c,v 1.7 1996/05/03 21:38:52 cgd Exp $ */
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. 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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* 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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. 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 defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)rec_search.c 8.4 (Berkeley) 7/14/94";
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#else
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static char rcsid[] = "$NetBSD: rec_search.c,v 1.7 1996/05/03 21:38:52 cgd Exp $";
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#endif
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#endif /* LIBC_SCCS and not lint */
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#include <sys/types.h>
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#include <errno.h>
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#include <stdio.h>
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#include <db.h>
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#include "recno.h"
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/*
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* __REC_SEARCH -- Search a btree for a key.
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*
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* Parameters:
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* t: tree to search
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* recno: key to find
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* op: search operation
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*
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* Returns:
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* EPG for matching record, if any, or the EPG for the location of the
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* key, if it were inserted into the tree.
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*
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* Returns:
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* The EPG for matching record, if any, or the EPG for the location
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* of the key, if it were inserted into the tree, is entered into
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* the bt_cur field of the tree. A pointer to the field is returned.
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*/
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EPG *
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__rec_search(t, recno, op)
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BTREE *t;
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recno_t recno;
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enum SRCHOP op;
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{
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register indx_t index;
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register PAGE *h;
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EPGNO *parent;
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RINTERNAL *r;
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pgno_t pg;
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indx_t top;
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recno_t total;
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int sverrno;
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BT_CLR(t);
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for (pg = P_ROOT, total = 0;;) {
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if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
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goto err;
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if (h->flags & P_RLEAF) {
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t->bt_cur.page = h;
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t->bt_cur.index = recno - total;
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return (&t->bt_cur);
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}
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for (index = 0, top = NEXTINDEX(h);;) {
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r = GETRINTERNAL(h, index);
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if (++index == top || total + r->nrecs > recno)
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break;
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total += r->nrecs;
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}
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BT_PUSH(t, pg, index - 1);
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pg = r->pgno;
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switch (op) {
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case SDELETE:
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--GETRINTERNAL(h, (index - 1))->nrecs;
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mpool_put(t->bt_mp, h, MPOOL_DIRTY);
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break;
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case SINSERT:
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++GETRINTERNAL(h, (index - 1))->nrecs;
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mpool_put(t->bt_mp, h, MPOOL_DIRTY);
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break;
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case SEARCH:
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mpool_put(t->bt_mp, h, 0);
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break;
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}
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}
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/* Try and recover the tree. */
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err: sverrno = errno;
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if (op != SEARCH)
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while ((parent = BT_POP(t)) != NULL) {
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if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
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break;
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if (op == SINSERT)
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--GETRINTERNAL(h, parent->index)->nrecs;
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else
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++GETRINTERNAL(h, parent->index)->nrecs;
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mpool_put(t->bt_mp, h, MPOOL_DIRTY);
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}
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errno = sverrno;
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return (NULL);
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}
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