db/recno/FreeBSD/rec_search.c

   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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)rec_search.c        8.4 (Berkeley) 7/14/94";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/db/recno/rec_search.c,v 1.8 2009/03/04 00:58:04 delphij Exp $");
  35
  36 #include <sys/types.h>
  37
  38 #include <errno.h>
  39 #include <stdio.h>
  40
  41 #include <db.h>
  42 #include "recno.h"
  43
  44 /*
  45  * __REC_SEARCH -- Search a btree for a key.
  46  *
  47  * Parameters:
  48  *      t:      tree to search
  49  *      recno:  key to find
  50  *      op:     search operation
  51  *
  52  * Returns:
  53  *      EPG for matching record, if any, or the EPG for the location of the
  54  *      key, if it were inserted into the tree.
  55  *
  56  * Returns:
  57  *      The EPG for matching record, if any, or the EPG for the location
  58  *      of the key, if it were inserted into the tree, is entered into
  59  *      the bt_cur field of the tree.  A pointer to the field is returned.
  60  */
  61 EPG *
  62 __rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
  63 {
  64         indx_t idx;
  65         PAGE *h;
  66         EPGNO *parent;
  67         RINTERNAL *r;
  68         pgno_t pg;
  69         indx_t top;
  70         recno_t total;
  71         int sverrno;
  72
  73         BT_CLR(t);
  74         for (pg = P_ROOT, total = 0;;) {
  75                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
  76                         goto err;
  77                 if (h->flags & P_RLEAF) {
  78                         t->bt_cur.page = h;
  79                         t->bt_cur.index = recno - total;
  80                         return (&t->bt_cur);
  81                 }
  82                 for (idx = 0, top = NEXTINDEX(h);;) {
  83                         r = GETRINTERNAL(h, idx);
  84                         if (++idx == top || total + r->nrecs > recno)
  85                                 break;
  86                         total += r->nrecs;
  87                 }
  88
  89                 BT_PUSH(t, pg, idx - 1);
  90
  91                 pg = r->pgno;
  92                 switch (op) {
  93                 case SDELETE:
  94                         --GETRINTERNAL(h, (idx - 1))->nrecs;
  95                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
  96                         break;
  97                 case SINSERT:
  98                         ++GETRINTERNAL(h, (idx - 1))->nrecs;
  99                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 100                         break;
 101                 case SEARCH:
 102                         mpool_put(t->bt_mp, h, 0);
 103                         break;
 104                 }
 105
 106         }
 107         /* Try and recover the tree. */
 108 err:    sverrno = errno;
 109         if (op != SEARCH)
 110                 while  ((parent = BT_POP(t)) != NULL) {
 111                         if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
 112                                 break;
 113                         if (op == SINSERT)
 114                                 --GETRINTERNAL(h, parent->index)->nrecs;
 115                         else
 116                                 ++GETRINTERNAL(h, parent->index)->nrecs;
 117                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 118                 }
 119         errno = sverrno;
 120         return (NULL);
 121 }