lib/libc/db/recno/rec_search.c

   1 /*      $NetBSD: rec_search.c,v 1.14 2008/09/11 12:58:00 joerg Exp $    */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #if HAVE_NBTOOL_CONFIG_H
  33 #include "nbtool_config.h"
  34 #endif
  35
  36 #include <sys/cdefs.h>
  37 __RCSID("$NetBSD: rec_search.c,v 1.14 2008/09/11 12:58:00 joerg Exp $");
  38
  39 #include "namespace.h"
  40 #include <sys/types.h>
  41
  42 #include <assert.h>
  43 #include <errno.h>
  44 #include <stdio.h>
  45
  46 #include <db.h>
  47 #include "recno.h"
  48
  49 /*
  50  * __REC_SEARCH -- Search a btree for a key.
  51  *
  52  * Parameters:
  53  *      t:      tree to search
  54  *      recno:  key to find
  55  *      op:     search operation
  56  *
  57  * Returns:
  58  *      EPG for matching record, if any, or the EPG for the location of the
  59  *      key, if it were inserted into the tree.
  60  *
  61  * Returns:
  62  *      The EPG for matching record, if any, or the EPG for the location
  63  *      of the key, if it were inserted into the tree, is entered into
  64  *      the bt_cur field of the tree.  A pointer to the field is returned.
  65  */
  66 EPG *
  67 __rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
  68 {
  69         indx_t idx;
  70         PAGE *h;
  71         EPGNO *parent;
  72         RINTERNAL *r;
  73         pgno_t pg;
  74         indx_t top;
  75         recno_t total;
  76         int sverrno;
  77
  78         BT_CLR(t);
  79         for (pg = P_ROOT, total = 0;;) {
  80                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
  81                         goto err;
  82                 if (h->flags & P_RLEAF) {
  83                         t->bt_cur.page = h;
  84                         t->bt_cur.index = recno - total;
  85                         return (&t->bt_cur);
  86                 }
  87                 for (idx = 0, top = NEXTINDEX(h);;) {
  88                         r = GETRINTERNAL(h, idx);
  89                         if (++idx == top || total + r->nrecs > recno)
  90                                 break;
  91                         total += r->nrecs;
  92                 }
  93
  94                 BT_PUSH(t, pg, idx - 1);
  95
  96                 pg = r->pgno;
  97                 switch (op) {
  98                 case SDELETE:
  99                         --GETRINTERNAL(h, (idx - 1))->nrecs;
 100                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 101                         break;
 102                 case SINSERT:
 103                         ++GETRINTERNAL(h, (idx - 1))->nrecs;
 104                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 105                         break;
 106                 case SEARCH:
 107                         mpool_put(t->bt_mp, h, 0);
 108                         break;
 109                 }
 110
 111         }
 112         /* Try and recover the tree. */
 113 err:    sverrno = errno;
 114         if (op != SEARCH)
 115                 while  ((parent = BT_POP(t)) != NULL) {
 116                         if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
 117                                 break;
 118                         if (op == SINSERT)
 119                                 --GETRINTERNAL(h, parent->index)->nrecs;
 120                         else
 121                                 ++GETRINTERNAL(h, parent->index)->nrecs;
 122                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 123                 }
 124         errno = sverrno;
 125         return (NULL);
 126 }