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rec_search.c revision 1.4 
      1 /*-
      2  * Copyright (c) 1990, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 /* from: static char sccsid[] = "@(#)rec_search.c	8.2 (Berkeley) 9/14/93"; */
     36 static char *rcsid = "$Id: rec_search.c,v 1.4 1993/09/17 01:06:58 cgd Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/types.h>
     40 
     41 #include <errno.h>
     42 #include <stdio.h>
     43 
     44 #include <db.h>
     45 #include "recno.h"
     46 
     47 /*
     48  * __REC_SEARCH -- Search a btree for a key.
     49  *
     50  * Parameters:
     51  *	t:	tree to search
     52  *	recno:	key to find
     53  *	op: 	search operation
     54  *
     55  * Returns:
     56  *	EPG for matching record, if any, or the EPG for the location of the
     57  *	key, if it were inserted into the tree.
     58  *
     59  * Returns:
     60  *	The EPG for matching record, if any, or the EPG for the location
     61  *	of the key, if it were inserted into the tree, is entered into
     62  *	the bt_cur field of the tree.  A pointer to the field is returned.
     63  */
     64 EPG *
     65 __rec_search(t, recno, op)
     66 	BTREE *t;
     67 	recno_t recno;
     68 	enum SRCHOP op;
     69 {
     70 	register indx_t index;
     71 	register PAGE *h;
     72 	EPGNO *parent;
     73 	RINTERNAL *r;
     74 	pgno_t pg;
     75 	indx_t top;
     76 	recno_t total;
     77 	int serrno;
     78 
     79 	BT_CLR(t);
     80 	for (pg = P_ROOT, total = 0;;) {
     81 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
     82 			goto err;
     83 		if (h->flags & P_RLEAF) {
     84 			t->bt_cur.page = h;
     85 			t->bt_cur.index = recno - total;
     86 			return (&t->bt_cur);
     87 		}
     88 		for (index = 0, top = NEXTINDEX(h);;) {
     89 			r = GETRINTERNAL(h, index);
     90 			if (++index == top || total + r->nrecs > recno)
     91 				break;
     92 			total += r->nrecs;
     93 		}
     94 
     95 		if (__bt_push(t, pg, index - 1) == RET_ERROR)
     96 			return (NULL);
     97 
     98 		pg = r->pgno;
     99 		switch (op) {
    100 		case SDELETE:
    101 			--GETRINTERNAL(h, (index - 1))->nrecs;
    102 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    103 			break;
    104 		case SINSERT:
    105 			++GETRINTERNAL(h, (index - 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:	serrno = 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 = serrno;
    127 	return (NULL);
    128 }
    129