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rec_search.c revision 1.1 
      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 static char sccsid[] = "@(#)rec_search.c	8.1 (Berkeley) 6/4/93";
     36 #endif /* LIBC_SCCS and not lint */
     37 
     38 #include <sys/types.h>
     39 
     40 #include <errno.h>
     41 #include <stdio.h>
     42 
     43 #include <db.h>
     44 #include "recno.h"
     45 
     46 /*
     47  * __REC_SEARCH -- Search a btree for a key.
     48  *
     49  * Parameters:
     50  *	t:	tree to search
     51  *	recno:	key to find
     52  *	op: 	search operation
     53  *
     54  * Returns:
     55  *	EPG for matching record, if any, or the EPG for the location of the
     56  *	key, if it were inserted into the tree.
     57  *
     58  * Warnings:
     59  *	The EPG returned is in static memory, and will be overwritten by the
     60  *	next search of any kind in any tree.
     61  */
     62 EPG *
     63 __rec_search(t, recno, op)
     64 	BTREE *t;
     65 	recno_t recno;
     66 	enum SRCHOP op;
     67 {
     68 	static EPG e;
     69 	register indx_t index;
     70 	register PAGE *h;
     71 	EPGNO *parent;
     72 	RINTERNAL *r;
     73 	pgno_t pg;
     74 	indx_t top;
     75 	recno_t total;
     76 	int serrno;
     77 
     78 	BT_CLR(t);
     79 	for (pg = P_ROOT, total = 0;;) {
     80 		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
     81 			goto err;
     82 		if (h->flags & P_RLEAF) {
     83 			e.page = h;
     84 			e.index = recno - total;
     85 			return (&e);
     86 		}
     87 		for (index = 0, top = NEXTINDEX(h);;) {
     88 			r = GETRINTERNAL(h, index);
     89 			if (++index == top || total + r->nrecs > recno)
     90 				break;
     91 			total += r->nrecs;
     92 		}
     93 
     94 		if (__bt_push(t, pg, index - 1) == RET_ERROR)
     95 			return (NULL);
     96 
     97 		pg = r->pgno;
     98 		switch (op) {
     99 		case SDELETE:
    100 			--GETRINTERNAL(h, (index - 1))->nrecs;
    101 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    102 			break;
    103 		case SINSERT:
    104 			++GETRINTERNAL(h, (index - 1))->nrecs;
    105 			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    106 			break;
    107 		case SEARCH:
    108 			mpool_put(t->bt_mp, h, 0);
    109 			break;
    110 		}
    111 
    112 	}
    113 	/* Try and recover the tree. */
    114 err:	serrno = errno;
    115 	if (op != SEARCH)
    116 		while  ((parent = BT_POP(t)) != NULL) {
    117 			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
    118 				break;
    119 			if (op == SINSERT)
    120 				--GETRINTERNAL(h, parent->index)->nrecs;
    121 			else
    122 				++GETRINTERNAL(h, parent->index)->nrecs;
    123                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    124                 }
    125 	errno = serrno;
    126 	return (NULL);
    127 }
    128