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rec_search.c revision 1.9 
      1 /*	$NetBSD: rec_search.c,v 1.9 1997/07/21 14:06:46 jtc 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. 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 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)rec_search.c	8.4 (Berkeley) 7/14/94";
     40 #else
     41 __RCSID("$NetBSD: rec_search.c,v 1.9 1997/07/21 14:06:46 jtc Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include <sys/types.h>
     47 
     48 #include <errno.h>
     49 #include <stdio.h>
     50 
     51 #include <db.h>
     52 #include "recno.h"
     53 
     54 /*
     55  * __REC_SEARCH -- Search a btree for a key.
     56  *
     57  * Parameters:
     58  *	t:	tree to search
     59  *	recno:	key to find
     60  *	op: 	search operation
     61  *
     62  * Returns:
     63  *	EPG for matching record, if any, or the EPG for the location of the
     64  *	key, if it were inserted into the tree.
     65  *
     66  * Returns:
     67  *	The EPG for matching record, if any, or the EPG for the location
     68  *	of the key, if it were inserted into the tree, is entered into
     69  *	the bt_cur field of the tree.  A pointer to the field is returned.
     70  */
     71 EPG *
     72 __rec_search(t, recno, op)
     73 	BTREE *t;
     74 	recno_t recno;
     75 	enum SRCHOP op;
     76 {
     77 	register indx_t index;
     78 	register PAGE *h;
     79 	EPGNO *parent;
     80 	RINTERNAL *r;
     81 	pgno_t pg;
     82 	indx_t top;
     83 	recno_t total;
     84 	int sverrno;
     85 
     86 	BT_CLR(t);
     87 	for (pg = P_ROOT, total = 0;;) {
     88 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
     89 			goto err;
     90 		if (h->flags & P_RLEAF) {
     91 			t->bt_cur.page = h;
     92 			t->bt_cur.index = recno - total;
     93 			return (&t->bt_cur);
     94 		}
     95 		for (index = 0, top = NEXTINDEX(h);;) {
     96 			r = GETRINTERNAL(h, index);
     97 			if (++index == top || total + r->nrecs > recno)
     98 				break;
     99 			total += r->nrecs;
    100 		}
    101 
    102 		BT_PUSH(t, pg, index - 1);
    103 
    104 		pg = r->pgno;
    105 		switch (op) {
    106 		case SDELETE:
    107 			--GETRINTERNAL(h, (index - 1))->nrecs;
    108 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    109 			break;
    110 		case SINSERT:
    111 			++GETRINTERNAL(h, (index - 1))->nrecs;
    112 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    113 			break;
    114 		case SEARCH:
    115 			mpool_put(t->bt_mp, h, 0);
    116 			break;
    117 		}
    118 
    119 	}
    120 	/* Try and recover the tree. */
    121 err:	sverrno = errno;
    122 	if (op != SEARCH)
    123 		while  ((parent = BT_POP(t)) != NULL) {
    124 			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
    125 				break;
    126 			if (op == SINSERT)
    127 				--GETRINTERNAL(h, parent->index)->nrecs;
    128 			else
    129 				++GETRINTERNAL(h, parent->index)->nrecs;
    130                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    131                 }
    132 	errno = sverrno;
    133 	return (NULL);
    134 }
    135