db/recno/rec_search.c

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