/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993, 1994
 *      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.
 * 3. 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.
 */

#include <sys/types.h>

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

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

/*
 * __REC_SEQ -- Recno sequential scan interface.
 *
 * Parameters:
 *      dbp:    pointer to access method
 *      key:    key for positioning and return value
 *      data:   data return value
 *      flags:  R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
 *
 * Returns:
 *      RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
 */
int
__rec_seq(const DB *dbp, DBT *key, DBT *data, u_int flags)
{
        BTREE *t;
        EPG *e;
        recno_t nrec;
        int status;

        t = dbp->internal;

        /* Toss any page pinned across calls. */
        if (t->bt_pinned != NULL) {
                mpool_put(t->bt_mp, t->bt_pinned, 0);
                t->bt_pinned = NULL;
        }

        switch(flags) {
        case R_CURSOR:
                if ((nrec = *(recno_t *)key->data) == 0)
                        goto einval;
                break;
        case R_NEXT:
                if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
                        nrec = t->bt_cursor.rcursor + 1;
                        break;
                }
                /* FALLTHROUGH */
        case R_FIRST:
                nrec = 1;
                break;
        case R_PREV:
                if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
                        if ((nrec = t->bt_cursor.rcursor - 1) == 0)
                                return (RET_SPECIAL);
                        break;
                }
                /* FALLTHROUGH */
        case R_LAST:
                if (!F_ISSET(t, R_EOF | R_INMEM) &&
                    t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
                        return (RET_ERROR);
                nrec = t->bt_nrecs;
                break;
        default:
einval:         errno = EINVAL;
                return (RET_ERROR);
        }

        if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
                if (!F_ISSET(t, R_EOF | R_INMEM) &&
                    (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
                        return (status);
                if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
                        return (RET_SPECIAL);
        }

        if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
                return (RET_ERROR);

        F_SET(&t->bt_cursor, CURS_INIT);
        t->bt_cursor.rcursor = nrec;

        status = __rec_ret(t, e, nrec, key, data);
        if (F_ISSET(t, B_DB_LOCK))
                mpool_put(t->bt_mp, e->page, 0);
        else
                t->bt_pinned = e->page;
        return (status);
}