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rec_search.c revision 1.11 
      1 /*	$NetBSD: rec_search.c,v 1.11 2003/08/07 16:42:44 agc 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)rec_search.c	8.4 (Berkeley) 7/14/94";
     36 #else
     37 __RCSID("$NetBSD: rec_search.c,v 1.11 2003/08/07 16:42:44 agc Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/types.h>
     43 
     44 #include <errno.h>
     45 #include <stdio.h>
     46 
     47 #include <db.h>
     48 #include "recno.h"
     49 
     50 /*
     51  * __REC_SEARCH -- Search a btree for a key.
     52  *
     53  * Parameters:
     54  *	t:	tree to search
     55  *	recno:	key to find
     56  *	op: 	search operation
     57  *
     58  * Returns:
     59  *	EPG for matching record, if any, or the EPG for the location of the
     60  *	key, if it were inserted into the tree.
     61  *
     62  * Returns:
     63  *	The EPG for matching record, if any, or the EPG for the location
     64  *	of the key, if it were inserted into the tree, is entered into
     65  *	the bt_cur field of the tree.  A pointer to the field is returned.
     66  */
     67 EPG *
     68 __rec_search(t, recno, op)
     69 	BTREE *t;
     70 	recno_t recno;
     71 	enum SRCHOP op;
     72 {
     73 	register indx_t idx;
     74 	register PAGE *h;
     75 	EPGNO *parent;
     76 	RINTERNAL *r;
     77 	pgno_t pg;
     78 	indx_t top;
     79 	recno_t total;
     80 	int sverrno;
     81 
     82 	BT_CLR(t);
     83 	for (pg = P_ROOT, total = 0;;) {
     84 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
     85 			goto err;
     86 		if (h->flags & P_RLEAF) {
     87 			t->bt_cur.page = h;
     88 			t->bt_cur.index = recno - total;
     89 			return (&t->bt_cur);
     90 		}
     91 		for (idx = 0, top = NEXTINDEX(h);;) {
     92 			r = GETRINTERNAL(h, idx);
     93 			if (++idx == top || total + r->nrecs > recno)
     94 				break;
     95 			total += r->nrecs;
     96 		}
     97 
     98 		BT_PUSH(t, pg, idx - 1);
     99 
    100 		pg = r->pgno;
    101 		switch (op) {
    102 		case SDELETE:
    103 			--GETRINTERNAL(h, (idx - 1))->nrecs;
    104 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    105 			break;
    106 		case SINSERT:
    107 			++GETRINTERNAL(h, (idx - 1))->nrecs;
    108 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    109 			break;
    110 		case SEARCH:
    111 			mpool_put(t->bt_mp, h, 0);
    112 			break;
    113 		}
    114 
    115 	}
    116 	/* Try and recover the tree. */
    117 err:	sverrno = errno;
    118 	if (op != SEARCH)
    119 		while  ((parent = BT_POP(t)) != NULL) {
    120 			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
    121 				break;
    122 			if (op == SINSERT)
    123 				--GETRINTERNAL(h, parent->index)->nrecs;
    124 			else
    125 				++GETRINTERNAL(h, parent->index)->nrecs;
    126                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    127                 }
    128 	errno = sverrno;
    129 	return (NULL);
    130 }
    131