rec_search.c revision 8870 
1/*-
2 * Copyright (c) 1990, 1993
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#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)rec_search.c	8.3 (Berkeley) 2/21/94";
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 * Returns:
59 *	The EPG for matching record, if any, or the EPG for the location
60 *	of the key, if it were inserted into the tree, is entered into
61 *	the bt_cur field of the tree.  A pointer to the field is returned.
62 */
63EPG *
64__rec_search(t, recno, op)
65	BTREE *t;
66	recno_t recno;
67	enum SRCHOP op;
68{
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 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 (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. */
114err:	sverrno = 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 = sverrno;
126	return (NULL);
127}
128