1 /*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * 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 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)rec_search.c 5.8 (Berkeley) 2/14/93";
36 #endif /* LIBC_SCCS and not lint */
37
38 #include <sys/types.h>
39
40 #include <errno.h>
41 #include <stdio.h>
42
43 #include <db.h>
44 #include "recno.h"
45
46 /*
47 * __REC_SEARCH -- Search a btree for a key.
48 *
49 * Parameters:
50 * t: tree to search
51 * recno: key to find
52 * op: search operation
53 *
54 * Returns:
55 * EPG for matching record, if any, or the EPG for the location of the
56 * key, if it were inserted into the tree.
57 *
58 * Warnings:
59 * The EPG returned is in static memory, and will be overwritten by the
60 * next search of any kind in any tree.
61 */
62 EPG *
__rec_search(t,recno,op)63 __rec_search(t, recno, op)
64 BTREE *t;
65 recno_t recno;
66 enum SRCHOP op;
67 {
68 static EPG e;
69 register indx_t index;
70 register PAGE *h;
71 EPGNO *parent;
72 RINTERNAL *r;
73 pgno_t pg;
74 indx_t top;
75 recno_t total;
76 int serrno;
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 e.page = h;
84 e.index = recno - total;
85 return (&e);
86 }
87 for (index = 0, top = NEXTINDEX(h);;) {
88 r = GETRINTERNAL(h, index);
89 if (++index == top || total + r->nrecs > recno)
90 break;
91 total += r->nrecs;
92 }
93
94 if (__bt_push(t, pg, index - 1) == RET_ERROR)
95 return (NULL);
96
97 pg = r->pgno;
98 switch (op) {
99 case SDELETE:
100 --GETRINTERNAL(h, (index - 1))->nrecs;
101 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
102 break;
103 case SINSERT:
104 ++GETRINTERNAL(h, (index - 1))->nrecs;
105 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
106 break;
107 case SEARCH:
108 mpool_put(t->bt_mp, h, 0);
109 break;
110 }
111
112 }
113 /* Try and recover the tree. */
114 err: serrno = errno;
115 if (op != SEARCH)
116 while ((parent = BT_POP(t)) != NULL) {
117 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
118 break;
119 if (op == SINSERT)
120 --GETRINTERNAL(h, parent->index)->nrecs;
121 else
122 ++GETRINTERNAL(h, parent->index)->nrecs;
123 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
124 }
125 errno = serrno;
126 return (NULL);
127 }
128