lib/libc/db/recno/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  * 3. 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  * @(#)rec_search.c     8.4 (Berkeley) 7/14/94
  30  * $DragonFly: src/lib/libc/db/recno/rec_search.c,v 1.5 2005/11/12 23:01:55 swildner Exp $
  31  */
  32
  33 #include <sys/types.h>
  34
  35 #include <errno.h>
  36 #include <stdio.h>
  37
  38 #include <db.h>
  39 #include "recno.h"
  40
  41 /*
  42  * __REC_SEARCH -- Search a btree for a key.
  43  *
  44  * Parameters:
  45  *      t:      tree to search
  46  *      recno:  key to find
  47  *      op:     search operation
  48  *
  49  * Returns:
  50  *      EPG for matching record, if any, or the EPG for the location of the
  51  *      key, if it were inserted into the tree.
  52  *
  53  * Returns:
  54  *      The EPG for matching record, if any, or the EPG for the location
  55  *      of the key, if it were inserted into the tree, is entered into
  56  *      the bt_cur field of the tree.  A pointer to the field is returned.
  57  */
  58 EPG *
  59 __rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
  60 {
  61         indx_t index;
  62         PAGE *h;
  63         EPGNO *parent;
  64         RINTERNAL *r;
  65         pgno_t pg;
  66         indx_t top;
  67         recno_t total;
  68         int sverrno;
  69
  70         BT_CLR(t);
  71         for (pg = P_ROOT, total = 0;;) {
  72                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
  73                         goto err;
  74                 if (h->flags & P_RLEAF) {
  75                         t->bt_cur.page = h;
  76                         t->bt_cur.index = recno - total;
  77                         return (&t->bt_cur);
  78                 }
  79                 for (index = 0, top = NEXTINDEX(h);;) {
  80                         r = GETRINTERNAL(h, index);
  81                         if (++index == top || total + r->nrecs > recno)
  82                                 break;
  83                         total += r->nrecs;
  84                 }
  85
  86                 BT_PUSH(t, pg, index - 1);
  87
  88                 pg = r->pgno;
  89                 switch (op) {
  90                 case SDELETE:
  91                         --GETRINTERNAL(h, (index - 1))->nrecs;
  92                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
  93                         break;
  94                 case SINSERT:
  95                         ++GETRINTERNAL(h, (index - 1))->nrecs;
  96                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
  97                         break;
  98                 case SEARCH:
  99                         mpool_put(t->bt_mp, h, 0);
 100                         break;
 101                 }
 102
 103         }
 104         /* Try and recover the tree. */
 105 err:    sverrno = errno;
 106         if (op != SEARCH)
 107                 while  ((parent = BT_POP(t)) != NULL) {
 108                         if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
 109                                 break;
 110                         if (op == SINSERT)
 111                                 --GETRINTERNAL(h, parent->index)->nrecs;
 112                         else
 113                                 ++GETRINTERNAL(h, parent->index)->nrecs;
 114                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 115                 }
 116         errno = sverrno;
 117         return (NULL);
 118 }