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rec_search.c revision 1.13 
      1 /*	$NetBSD: rec_search.c,v 1.13 2008/09/10 17:52:36 joerg 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 __RCSID("$NetBSD: rec_search.c,v 1.13 2008/09/10 17:52:36 joerg Exp $");
     34 
     35 #include "namespace.h"
     36 #include <sys/types.h>
     37 
     38 #include <assert.h>
     39 #include <errno.h>
     40 #include <stdio.h>
     41 
     42 #include <db.h>
     43 #include "recno.h"
     44 
     45 /*
     46  * __REC_SEARCH -- Search a btree for a key.
     47  *
     48  * Parameters:
     49  *	t:	tree to search
     50  *	recno:	key to find
     51  *	op: 	search operation
     52  *
     53  * Returns:
     54  *	EPG for matching record, if any, or the EPG for the location of the
     55  *	key, if it were inserted into the tree.
     56  *
     57  * Returns:
     58  *	The EPG for matching record, if any, or the EPG for the location
     59  *	of the key, if it were inserted into the tree, is entered into
     60  *	the bt_cur field of the tree.  A pointer to the field is returned.
     61  */
     62 EPG *
     63 __rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
     64 {
     65 	indx_t idx;
     66 	PAGE *h;
     67 	EPGNO *parent;
     68 	RINTERNAL *r;
     69 	pgno_t pg;
     70 	indx_t top;
     71 	recno_t total;
     72 	int sverrno;
     73 
     74 	BT_CLR(t);
     75 	for (pg = P_ROOT, total = 0;;) {
     76 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
     77 			goto err;
     78 		if (h->flags & P_RLEAF) {
     79 			t->bt_cur.page = h;
     80 			t->bt_cur.index = recno - total;
     81 			return (&t->bt_cur);
     82 		}
     83 		for (idx = 0, top = NEXTINDEX(h);;) {
     84 			r = GETRINTERNAL(h, idx);
     85 			if (++idx == top || total + r->nrecs > recno)
     86 				break;
     87 			total += r->nrecs;
     88 		}
     89 
     90 		BT_PUSH(t, pg, idx - 1);
     91 
     92 		pg = r->pgno;
     93 		switch (op) {
     94 		case SDELETE:
     95 			--GETRINTERNAL(h, (idx - 1))->nrecs;
     96 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
     97 			break;
     98 		case SINSERT:
     99 			++GETRINTERNAL(h, (idx - 1))->nrecs;
    100 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    101 			break;
    102 		case SEARCH:
    103 			mpool_put(t->bt_mp, h, 0);
    104 			break;
    105 		}
    106 
    107 	}
    108 	/* Try and recover the tree. */
    109 err:	sverrno = errno;
    110 	if (op != SEARCH)
    111 		while  ((parent = BT_POP(t)) != NULL) {
    112 			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
    113 				break;
    114 			if (op == SINSERT)
    115 				--GETRINTERNAL(h, parent->index)->nrecs;
    116 			else
    117 				++GETRINTERNAL(h, parent->index)->nrecs;
    118                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    119                 }
    120 	errno = sverrno;
    121 	return (NULL);
    122 }
    123