source: rtems-libbsd/freebsd/lib/libc/db/recno/rec_search.c @ 2404264

/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)rec_search.c        8.4 (Berkeley) 7/14/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <rtems/bsd/sys/types.h>

#include <errno.h>
#include <stdio.h>

#include <db.h>
#include "recno.h"

/*
 * __REC_SEARCH -- Search a btree for a key.
 *
 * Parameters:
 *      t:      tree to search
 *      recno:  key to find
 *      op:     search operation
 *
 * Returns:
 *      EPG for matching record, if any, or the EPG for the location of the
 *      key, if it were inserted into the tree.
 *
 * Returns:
 *      The EPG for matching record, if any, or the EPG for the location
 *      of the key, if it were inserted into the tree, is entered into
 *      the bt_cur field of the tree.  A pointer to the field is returned.
 */
EPG *
__rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
{
        indx_t idx;
        PAGE *h;
        EPGNO *parent;
        RINTERNAL *r;
        pgno_t pg;
        indx_t top;
        recno_t total;
        int sverrno;

        BT_CLR(t);
        for (pg = P_ROOT, total = 0;;) {
                if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
                        goto err;
                if (h->flags & P_RLEAF) {
                        t->bt_cur.page = h;
                        t->bt_cur.index = recno - total;
                        return (&t->bt_cur);
                }
                for (idx = 0, top = NEXTINDEX(h);;) {
                        r = GETRINTERNAL(h, idx);
                        if (++idx == top || total + r->nrecs > recno)
                                break;
                        total += r->nrecs;
                }

                BT_PUSH(t, pg, idx - 1);

                pg = r->pgno;
                switch (op) {
                case SDELETE:
                        --GETRINTERNAL(h, (idx - 1))->nrecs;
                        mpool_put(t->bt_mp, h, MPOOL_DIRTY);
                        break;
                case SINSERT:
                        ++GETRINTERNAL(h, (idx - 1))->nrecs;
                        mpool_put(t->bt_mp, h, MPOOL_DIRTY);
                        break;
                case SEARCH:
                        mpool_put(t->bt_mp, h, 0);
                        break;
                }

        }
        /* Try and recover the tree. */
err:    sverrno = errno;
        if (op != SEARCH)
                while  ((parent = BT_POP(t)) != NULL) {
                        if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
                                break;
                        if (op == SINSERT)
                                --GETRINTERNAL(h, parent->index)->nrecs;
                        else
                                ++GETRINTERNAL(h, parent->index)->nrecs;
                        mpool_put(t->bt_mp, h, MPOOL_DIRTY);
                }
        errno = sverrno;
        return (NULL);
}