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rec_search.c revision 1.8 
      1 /*	$NetBSD: rec_search.c,v 1.8 1997/07/13 18:52:14 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. 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 1.8 1997/07/13 18:52:14 christos Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include <sys/types.h>
     46 
     47 #include <errno.h>
     48 #include <stdio.h>
     49 
     50 #include <db.h>
     51 #include "recno.h"
     52 
     53 /*
     54  * __REC_SEARCH -- Search a btree for a key.
     55  *
     56  * Parameters:
     57  *	t:	tree to search
     58  *	recno:	key to find
     59  *	op: 	search operation
     60  *
     61  * Returns:
     62  *	EPG for matching record, if any, or the EPG for the location of the
     63  *	key, if it were inserted into the tree.
     64  *
     65  * Returns:
     66  *	The EPG for matching record, if any, or the EPG for the location
     67  *	of the key, if it were inserted into the tree, is entered into
     68  *	the bt_cur field of the tree.  A pointer to the field is returned.
     69  */
     70 EPG *
     71 __rec_search(t, recno, op)
     72 	BTREE *t;
     73 	recno_t recno;
     74 	enum SRCHOP op;
     75 {
     76 	register indx_t index;
     77 	register PAGE *h;
     78 	EPGNO *parent;
     79 	RINTERNAL *r;
     80 	pgno_t pg;
     81 	indx_t top;
     82 	recno_t total;
     83 	int sverrno;
     84 
     85 	BT_CLR(t);
     86 	for (pg = P_ROOT, total = 0;;) {
     87 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
     88 			goto err;
     89 		if (h->flags & P_RLEAF) {
     90 			t->bt_cur.page = h;
     91 			t->bt_cur.index = recno - total;
     92 			return (&t->bt_cur);
     93 		}
     94 		for (index = 0, top = NEXTINDEX(h);;) {
     95 			r = GETRINTERNAL(h, index);
     96 			if (++index == top || total + r->nrecs > recno)
     97 				break;
     98 			total += r->nrecs;
     99 		}
    100 
    101 		BT_PUSH(t, pg, index - 1);
    102 
    103 		pg = r->pgno;
    104 		switch (op) {
    105 		case SDELETE:
    106 			--GETRINTERNAL(h, (index - 1))->nrecs;
    107 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    108 			break;
    109 		case SINSERT:
    110 			++GETRINTERNAL(h, (index - 1))->nrecs;
    111 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    112 			break;
    113 		case SEARCH:
    114 			mpool_put(t->bt_mp, h, 0);
    115 			break;
    116 		}
    117 
    118 	}
    119 	/* Try and recover the tree. */
    120 err:	sverrno = errno;
    121 	if (op != SEARCH)
    122 		while  ((parent = BT_POP(t)) != NULL) {
    123 			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
    124 				break;
    125 			if (op == SINSERT)
    126 				--GETRINTERNAL(h, parent->index)->nrecs;
    127 			else
    128 				++GETRINTERNAL(h, parent->index)->nrecs;
    129                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    130                 }
    131 	errno = sverrno;
    132 	return (NULL);
    133 }
    134