db/recno/rec_search.c

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #if defined(LIBC_SCCS) && !defined(lint)
  59 static char sccsid[] = "@(#)rec_search.c        8.4 (Berkeley) 7/14/94";
  60 #endif /* LIBC_SCCS and not lint */
  61 #include <sys/cdefs.h>
  62
  63 #include <sys/types.h>
  64
  65 #include <errno.h>
  66 #include <stdio.h>
  67
  68 #include <db.h>
  69 #include "recno.h"
  70
  71 /*
  72  * __REC_SEARCH -- Search a btree for a key.
  73  *
  74  * Parameters:
  75  *      t:      tree to search
  76  *      recno:  key to find
  77  *      op:     search operation
  78  *
  79  * Returns:
  80  *      EPG for matching record, if any, or the EPG for the location of the
  81  *      key, if it were inserted into the tree.
  82  *
  83  * Returns:
  84  *      The EPG for matching record, if any, or the EPG for the location
  85  *      of the key, if it were inserted into the tree, is entered into
  86  *      the bt_cur field of the tree.  A pointer to the field is returned.
  87  */
  88 EPG *
  89 __rec_search(t, recno, op)
  90         BTREE *t;
  91         recno_t recno;
  92         enum SRCHOP op;
  93 {
  94         indx_t index;
  95         PAGE *h;
  96         EPGNO *parent;
  97         RINTERNAL *r;
  98         pgno_t pg;
  99         indx_t top;
 100         recno_t total;
 101         int sverrno;
 102
 103         BT_CLR(t);
 104         for (pg = P_ROOT, total = 0;;) {
 105                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 106                         goto err;
 107                 if (h->flags & P_RLEAF) {
 108                         t->bt_cur.page = h;
 109                         t->bt_cur.index = recno - total;
 110                         return (&t->bt_cur);
 111                 }
 112                 for (index = 0, top = NEXTINDEX(h);;) {
 113                         r = GETRINTERNAL(h, index);
 114                         if (++index == top || total + r->nrecs > recno)
 115                                 break;
 116                         total += r->nrecs;
 117                 }
 118
 119                 BT_PUSH(t, pg, index - 1);
 120
 121                 pg = r->pgno;
 122                 switch (op) {
 123                 case SDELETE:
 124                         --GETRINTERNAL(h, (index - 1))->nrecs;
 125                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 126                         break;
 127                 case SINSERT:
 128                         ++GETRINTERNAL(h, (index - 1))->nrecs;
 129                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 130                         break;
 131                 case SEARCH:
 132                         mpool_put(t->bt_mp, h, 0);
 133                         break;
 134                 }
 135
 136         }
 137         /* Try and recover the tree. */
 138 err:    sverrno = errno;
 139         if (op != SEARCH)
 140                 while  ((parent = BT_POP(t)) != NULL) {
 141                         if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
 142                                 break;
 143                         if (op == SINSERT)
 144                                 --GETRINTERNAL(h, parent->index)->nrecs;
 145                         else
 146                                 ++GETRINTERNAL(h, parent->index)->nrecs;
 147                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 148                 }
 149         errno = sverrno;
 150         return (NULL);
 151 }