db/recno/rec_search.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  */
  54
  55
  56 #include <sys/types.h>
  57
  58 #include <errno.h>
  59 #include <stdio.h>
  60
  61 #include <db.h>
  62 #include "recno.h"
  63
  64 /*
  65  * __REC_SEARCH -- Search a btree for a key.
  66  *
  67  * Parameters:
  68  *      t:      tree to search
  69  *      recno:  key to find
  70  *      op:     search operation
  71  *
  72  * Returns:
  73  *      EPG for matching record, if any, or the EPG for the location of the
  74  *      key, if it were inserted into the tree.
  75  *
  76  * Returns:
  77  *      The EPG for matching record, if any, or the EPG for the location
  78  *      of the key, if it were inserted into the tree, is entered into
  79  *      the bt_cur field of the tree.  A pointer to the field is returned.
  80  */
  81 EPG *
  82 __rec_search(t, recno, op)
  83         BTREE *t;
  84         recno_t recno;
  85         enum SRCHOP op;
  86 {
  87         register indx_t index;
  88         register PAGE *h;
  89         EPGNO *parent;
  90         RINTERNAL *r;
  91         pgno_t pg;
  92         indx_t top;
  93         recno_t total;
  94         int sverrno;
  95
  96         BT_CLR(t);
  97         for (pg = P_ROOT, total = 0;;) {
  98                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
  99                         goto err;
 100                 if (h->flags & P_RLEAF) {
 101                         t->bt_cur.page = h;
 102                         t->bt_cur.index = recno - total;
 103                         return (&t->bt_cur);
 104                 }
 105                 for (index = 0, top = NEXTINDEX(h);;) {
 106                         r = GETRINTERNAL(h, index);
 107                         if (++index == top || total + r->nrecs > recno)
 108                                 break;
 109                         total += r->nrecs;
 110                 }
 111
 112                 if (__bt_push(t, pg, index - 1) == RET_ERROR)
 113                         return (NULL);
 114
 115                 pg = r->pgno;
 116                 switch (op) {
 117                 case SDELETE:
 118                         --GETRINTERNAL(h, (index - 1))->nrecs;
 119                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 120                         break;
 121                 case SINSERT:
 122                         ++GETRINTERNAL(h, (index - 1))->nrecs;
 123                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 124                         break;
 125                 case SEARCH:
 126                         mpool_put(t->bt_mp, h, 0);
 127                         break;
 128                 }
 129
 130         }
 131         /* Try and recover the tree. */
 132 err:    sverrno = errno;
 133         if (op != SEARCH)
 134                 while  ((parent = BT_POP(t)) != NULL) {
 135                         if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
 136                                 break;
 137                         if (op == SINSERT)
 138                                 --GETRINTERNAL(h, parent->index)->nrecs;
 139                         else
 140                                 ++GETRINTERNAL(h, parent->index)->nrecs;
 141                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 142                 }
 143         errno = sverrno;
 144         return (NULL);
 145 }