xref: /freebsd/lib/libc/db/recno/rec_seq.c (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1991, 1993, 1994
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 #ifndef lint
34 /* XXX use __SCCSID */
35 static char sccsid[] __unused = "@(#)rec_seq.c	8.3 (Berkeley) 7/14/94";
36 #endif /* not lint */
37 #include <sys/types.h>
38 
39 #include <errno.h>
40 #include <limits.h>
41 #include <stdio.h>
42 #include <string.h>
43 
44 #include <db.h>
45 #include "recno.h"
46 
47 /*
48  * __REC_SEQ -- Recno sequential scan interface.
49  *
50  * Parameters:
51  *	dbp:	pointer to access method
52  *	key:	key for positioning and return value
53  *	data:	data return value
54  *	flags:	R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
55  *
56  * Returns:
57  *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
58  */
59 int
60 __rec_seq(const DB *dbp, DBT *key, DBT *data, u_int flags)
61 {
62 	BTREE *t;
63 	EPG *e;
64 	recno_t nrec;
65 	int status;
66 
67 	t = dbp->internal;
68 
69 	/* Toss any page pinned across calls. */
70 	if (t->bt_pinned != NULL) {
71 		mpool_put(t->bt_mp, t->bt_pinned, 0);
72 		t->bt_pinned = NULL;
73 	}
74 
75 	switch(flags) {
76 	case R_CURSOR:
77 		if ((nrec = *(recno_t *)key->data) == 0)
78 			goto einval;
79 		break;
80 	case R_NEXT:
81 		if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
82 			nrec = t->bt_cursor.rcursor + 1;
83 			break;
84 		}
85 		/* FALLTHROUGH */
86 	case R_FIRST:
87 		nrec = 1;
88 		break;
89 	case R_PREV:
90 		if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
91 			if ((nrec = t->bt_cursor.rcursor - 1) == 0)
92 				return (RET_SPECIAL);
93 			break;
94 		}
95 		/* FALLTHROUGH */
96 	case R_LAST:
97 		if (!F_ISSET(t, R_EOF | R_INMEM) &&
98 		    t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
99 			return (RET_ERROR);
100 		nrec = t->bt_nrecs;
101 		break;
102 	default:
103 einval:		errno = EINVAL;
104 		return (RET_ERROR);
105 	}
106 
107 	if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
108 		if (!F_ISSET(t, R_EOF | R_INMEM) &&
109 		    (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
110 			return (status);
111 		if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
112 			return (RET_SPECIAL);
113 	}
114 
115 	if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
116 		return (RET_ERROR);
117 
118 	F_SET(&t->bt_cursor, CURS_INIT);
119 	t->bt_cursor.rcursor = nrec;
120 
121 	status = __rec_ret(t, e, nrec, key, data);
122 	if (F_ISSET(t, B_DB_LOCK))
123 		mpool_put(t->bt_mp, e->page, 0);
124 	else
125 		t->bt_pinned = e->page;
126 	return (status);
127 }
128