1 #pragma ident	"%Z%%M%	%I%	%E% SMI"
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. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #if defined(LIBC_SCCS) && !defined(lint)
37 static char sccsid[] = "@(#)rec_search.c	8.4 (Berkeley) 7/14/94";
38 #endif /* LIBC_SCCS and not lint */
39 
40 #include <sys/types.h>
41 
42 #include <errno.h>
43 #include <stdio.h>
44 
45 #include "db-int.h"
46 #include "recno.h"
47 
48 /*
49  * __REC_SEARCH -- Search a btree for a key.
50  *
51  * Parameters:
52  *	t:	tree to search
53  *	recno:	key to find
54  *	op: 	search operation
55  *
56  * Returns:
57  *	EPG for matching record, if any, or the EPG for the location of the
58  *	key, if it were inserted into the tree.
59  *
60  * Returns:
61  *	The EPG for matching record, if any, or the EPG for the location
62  *	of the key, if it were inserted into the tree, is entered into
63  *	the bt_cur field of the tree.  A pointer to the field is returned.
64  */
65 EPG *
__rec_search(t,recno,op)66 __rec_search(t, recno, op)
67 	BTREE *t;
68 	recno_t recno;
69 	enum SRCHOP op;
70 {
71 	register indx_t idx;
72 	register PAGE *h;
73 	EPGNO *parent;
74 	RINTERNAL *r;
75 	db_pgno_t pg;
76 	indx_t top;
77 	recno_t total;
78 	int sverrno;
79 
80 	BT_CLR(t);
81 	for (pg = P_ROOT, total = 0;;) {
82 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
83 			goto err;
84 		if (h->flags & P_RLEAF) {
85 			t->bt_cur.page = h;
86 			t->bt_cur.index = recno - total;
87 			return (&t->bt_cur);
88 		}
89 		for (idx = 0, top = NEXTINDEX(h);;) {
90 			r = GETRINTERNAL(h, idx);
91 			if (++idx == top || total + r->nrecs > recno)
92 				break;
93 			total += r->nrecs;
94 		}
95 
96 		BT_PUSH(t, pg, idx - 1);
97 
98 		pg = r->pgno;
99 		switch (op) {
100 		case SDELETE:
101 			--GETRINTERNAL(h, (idx - 1))->nrecs;
102 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
103 			break;
104 		case SINSERT:
105 			++GETRINTERNAL(h, (idx - 1))->nrecs;
106 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
107 			break;
108 		case SEARCH:
109 			mpool_put(t->bt_mp, h, 0);
110 			break;
111 		}
112 
113 	}
114 	/* Try and recover the tree. */
115 err:	sverrno = errno;
116 	if (op != SEARCH)
117 		while  ((parent = BT_POP(t)) != NULL) {
118 			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
119 				break;
120 			if (op == SINSERT)
121 				--GETRINTERNAL(h, parent->index)->nrecs;
122 			else
123 				++GETRINTERNAL(h, parent->index)->nrecs;
124                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
125                 }
126 	errno = sverrno;
127 	return (NULL);
128 }
129