rec_seq.c revision 14287 
1/*-
2 * Copyright (c) 1991, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static char sccsid[] = "@(#)rec_seq.c	8.3 (Berkeley) 7/14/94";
36#endif /* not lint */
37
38#include <sys/types.h>
39
40#include <errno.h>
41#include <limits.h>
42#include <stdio.h>
43#include <string.h>
44
45#include <db.h>
46#include "recno.h"
47
48/*
49 * __REC_SEQ -- Recno sequential scan interface.
50 *
51 * Parameters:
52 *	dbp:	pointer to access method
53 *	key:	key for positioning and return value
54 *	data:	data return value
55 *	flags:	R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
56 *
57 * Returns:
58 *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
59 */
60int
61__rec_seq(dbp, key, data, flags)
62	const DB *dbp;
63	DBT *key, *data;
64	u_int flags;
65{
66	BTREE *t;
67	EPG *e;
68	recno_t nrec;
69	int status;
70
71	t = dbp->internal;
72
73	/* Toss any page pinned across calls. */
74	if (t->bt_pinned != NULL) {
75		mpool_put(t->bt_mp, t->bt_pinned, 0);
76		t->bt_pinned = NULL;
77	}
78
79	switch(flags) {
80	case R_CURSOR:
81		if ((nrec = *(recno_t *)key->data) == 0)
82			goto einval;
83		break;
84	case R_NEXT:
85		if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
86			nrec = t->bt_cursor.rcursor + 1;
87			break;
88		}
89		/* FALLTHROUGH */
90	case R_FIRST:
91		nrec = 1;
92		break;
93	case R_PREV:
94		if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
95			if ((nrec = t->bt_cursor.rcursor - 1) == 0)
96				return (RET_SPECIAL);
97			break;
98		}
99		/* FALLTHROUGH */
100	case R_LAST:
101		if (!F_ISSET(t, R_EOF | R_INMEM) &&
102		    t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
103			return (RET_ERROR);
104		nrec = t->bt_nrecs;
105		break;
106	default:
107einval:		errno = EINVAL;
108		return (RET_ERROR);
109	}
110
111	if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
112		if (!F_ISSET(t, R_EOF | R_INMEM) &&
113		    (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
114			return (status);
115		if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
116			return (RET_SPECIAL);
117	}
118
119	if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
120		return (RET_ERROR);
121
122	F_SET(&t->bt_cursor, CURS_INIT);
123	t->bt_cursor.rcursor = nrec;
124
125	status = __rec_ret(t, e, nrec, key, data);
126	if (F_ISSET(t, B_DB_LOCK))
127		mpool_put(t->bt_mp, e->page, 0);
128	else
129		t->bt_pinned = e->page;
130	return (status);
131}
132