1 /* $NetBSD: rec_search.c,v 1.16 2016/09/24 21:31:25 christos Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993
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 #if HAVE_NBTOOL_CONFIG_H
33 #include "nbtool_config.h"
34 #endif
35
36 #include <sys/cdefs.h>
37 __RCSID("$NetBSD: rec_search.c,v 1.16 2016/09/24 21:31:25 christos Exp $");
38
39 #include "namespace.h"
40 #include <sys/types.h>
41
42 #include <assert.h>
43 #include <errno.h>
44 #include <stdio.h>
45
46 #include <db.h>
47 #include "recno.h"
48
49 /*
50 * __REC_SEARCH -- Search a btree for a key.
51 *
52 * Parameters:
53 * t: tree to search
54 * recno: key to find
55 * op: search operation
56 *
57 * Returns:
58 * EPG for matching record, if any, or the EPG for the location of the
59 * key, if it were inserted into the tree.
60 *
61 * Returns:
62 * The EPG for matching record, if any, or the EPG for the location
63 * of the key, if it were inserted into the tree, is entered into
64 * the bt_cur field of the tree. A pointer to the field is returned.
65 */
66 EPG *
__rec_search(BTREE * t,recno_t recno,enum SRCHOP op)67 __rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
68 {
69 indx_t idx;
70 PAGE *h;
71 EPGNO *parent;
72 RINTERNAL *r;
73 pgno_t pg;
74 indx_t top;
75 recno_t total;
76 int sverrno;
77
78 BT_CLR(t);
79 for (pg = P_ROOT, total = 0;;) {
80 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
81 goto err;
82 if (h->flags & P_RLEAF) {
83 t->bt_cur.page = h;
84 t->bt_cur.index = recno - total;
85 return (&t->bt_cur);
86 }
87 for (idx = 0, top = NEXTINDEX(h);;) {
88 r = GETRINTERNAL(h, idx);
89 if (++idx == top || total + r->nrecs > recno)
90 break;
91 total += r->nrecs;
92 }
93
94 BT_PUSH(t, pg, idx - 1);
95
96 pg = r->pgno;
97 switch (op) {
98 case SDELETE:
99 --GETRINTERNAL(h, (idx - 1))->nrecs;
100 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
101 break;
102 case SINSERT:
103 ++GETRINTERNAL(h, (idx - 1))->nrecs;
104 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
105 break;
106 case SEARCH:
107 mpool_put(t->bt_mp, h, 0);
108 break;
109 }
110
111 }
112 /* Try and recover the tree. */
113 err: sverrno = errno;
114 if (op != SEARCH)
115 while ((parent = BT_POP(t)) != NULL) {
116 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
117 break;
118 if (op == SINSERT)
119 --GETRINTERNAL(h, parent->index)->nrecs;
120 else
121 ++GETRINTERNAL(h, parent->index)->nrecs;
122 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
123 }
124 errno = sverrno;
125 return (NULL);
126 }
127