lib/libc/db/btree/bt_utils.c

   1 /*      $NetBSD: bt_utils.c,v 1.13 2008/09/10 17:52:35 joerg Exp $      */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Mike Olson.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #if HAVE_NBTOOL_CONFIG_H
  36 #include "nbtool_config.h"
  37 #endif
  38
  39 #include <sys/cdefs.h>
  40 __RCSID("$NetBSD: bt_utils.c,v 1.13 2008/09/10 17:52:35 joerg Exp $");
  41
  42 #include <sys/param.h>
  43
  44 #include <assert.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include <db.h>
  50 #include "btree.h"
  51
  52 /*
  53  * __bt_ret --
  54  *      Build return key/data pair.
  55  *
  56  * Parameters:
  57  *      t:      tree
  58  *      e:      key/data pair to be returned
  59  *      key:    user's key structure (NULL if not to be filled in)
  60  *      rkey:   memory area to hold key
  61  *      data:   user's data structure (NULL if not to be filled in)
  62  *      rdata:  memory area to hold data
  63  *       copy:  always copy the key/data item
  64  *
  65  * Returns:
  66  *      RET_SUCCESS, RET_ERROR.
  67  */
  68 int
  69 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
  70 {
  71         BLEAF *bl;
  72         void *p;
  73
  74         bl = GETBLEAF(e->page, e->index);
  75
  76         /*
  77          * We must copy big keys/data to make them contigous.  Otherwise,
  78          * leave the page pinned and don't copy unless the user specified
  79          * concurrent access.
  80          */
  81         if (key == NULL)
  82                 goto dataonly;
  83
  84         if (bl->flags & P_BIGKEY) {
  85                 if (__ovfl_get(t, bl->bytes,
  86                     &key->size, &rkey->data, &rkey->size))
  87                         return (RET_ERROR);
  88                 key->data = rkey->data;
  89         } else if (copy || F_ISSET(t, B_DB_LOCK)) {
  90                 if (bl->ksize > rkey->size) {
  91                         p = (void *)(rkey->data == NULL ?
  92                             malloc(bl->ksize) : realloc(rkey->data, bl->ksize));
  93                         if (p == NULL)
  94                                 return (RET_ERROR);
  95                         rkey->data = p;
  96                         rkey->size = bl->ksize;
  97                 }
  98                 memmove(rkey->data, bl->bytes, bl->ksize);
  99                 key->size = bl->ksize;
 100                 key->data = rkey->data;
 101         } else {
 102                 key->size = bl->ksize;
 103                 key->data = bl->bytes;
 104         }
 105
 106 dataonly:
 107         if (data == NULL)
 108                 return (RET_SUCCESS);
 109
 110         if (bl->flags & P_BIGDATA) {
 111                 if (__ovfl_get(t, bl->bytes + bl->ksize,
 112                     &data->size, &rdata->data, &rdata->size))
 113                         return (RET_ERROR);
 114                 data->data = rdata->data;
 115         } else if (copy || F_ISSET(t, B_DB_LOCK)) {
 116                 /* Use +1 in case the first record retrieved is 0 length. */
 117                 if (bl->dsize + 1 > rdata->size) {
 118                         p = (void *)(rdata->data == NULL ?
 119                             malloc(bl->dsize + 1) :
 120                             realloc(rdata->data, bl->dsize + 1));
 121                         if (p == NULL)
 122                                 return (RET_ERROR);
 123                         rdata->data = p;
 124                         rdata->size = bl->dsize + 1;
 125                 }
 126                 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
 127                 data->size = bl->dsize;
 128                 data->data = rdata->data;
 129         } else {
 130                 data->size = bl->dsize;
 131                 data->data = bl->bytes + bl->ksize;
 132         }
 133
 134         return (RET_SUCCESS);
 135 }
 136
 137 /*
 138  * __BT_CMP -- Compare a key to a given record.
 139  *
 140  * Parameters:
 141  *      t:      tree
 142  *      k1:     DBT pointer of first arg to comparison
 143  *      e:      pointer to EPG for comparison
 144  *
 145  * Returns:
 146  *      < 0 if k1 is < record
 147  *      = 0 if k1 is = record
 148  *      > 0 if k1 is > record
 149  */
 150 int
 151 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
 152 {
 153         BINTERNAL *bi;
 154         BLEAF *bl;
 155         DBT k2;
 156         PAGE *h;
 157         void *bigkey;
 158
 159         /*
 160          * The left-most key on internal pages, at any level of the tree, is
 161          * guaranteed by the following code to be less than any user key.
 162          * This saves us from having to update the leftmost key on an internal
 163          * page when the user inserts a new key in the tree smaller than
 164          * anything we've yet seen.
 165          */
 166         h = e->page;
 167         if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
 168                 return (1);
 169
 170         bigkey = NULL;
 171         if (h->flags & P_BLEAF) {
 172                 bl = GETBLEAF(h, e->index);
 173                 if (bl->flags & P_BIGKEY)
 174                         bigkey = bl->bytes;
 175                 else {
 176                         k2.data = bl->bytes;
 177                         k2.size = bl->ksize;
 178                 }
 179         } else {
 180                 bi = GETBINTERNAL(h, e->index);
 181                 if (bi->flags & P_BIGKEY)
 182                         bigkey = bi->bytes;
 183                 else {
 184                         k2.data = bi->bytes;
 185                         k2.size = bi->ksize;
 186                 }
 187         }
 188
 189         if (bigkey) {
 190                 if (__ovfl_get(t, bigkey,
 191                     &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
 192                         return (RET_ERROR);
 193                 k2.data = t->bt_rdata.data;
 194         }
 195         return ((*t->bt_cmp)(k1, &k2));
 196 }
 197
 198 /*
 199  * __BT_DEFCMP -- Default comparison routine.
 200  *
 201  * Parameters:
 202  *      a:      DBT #1
 203  *      b:      DBT #2
 204  *
 205  * Returns:
 206  *      < 0 if a is < b
 207  *      = 0 if a is = b
 208  *      > 0 if a is > b
 209  */
 210 int
 211 __bt_defcmp(const DBT *a, const DBT *b)
 212 {
 213         size_t len;
 214         uint8_t *p1, *p2;
 215
 216         /*
 217          * XXX
 218          * If a size_t doesn't fit in an int, this routine can lose.
 219          * What we need is a integral type which is guaranteed to be
 220          * larger than a size_t, and there is no such thing.
 221          */
 222         len = MIN(a->size, b->size);
 223         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
 224                 if (*p1 != *p2)
 225                         return ((int)*p1 - (int)*p2);
 226         return ((int)a->size - (int)b->size);
 227 }
 228
 229 /*
 230  * __BT_DEFPFX -- Default prefix routine.
 231  *
 232  * Parameters:
 233  *      a:      DBT #1
 234  *      b:      DBT #2
 235  *
 236  * Returns:
 237  *      Number of bytes needed to distinguish b from a.
 238  */
 239 size_t
 240 __bt_defpfx(const DBT *a, const DBT *b)
 241 {
 242         uint8_t *p1, *p2;
 243         size_t cnt, len;
 244
 245         cnt = 1;
 246         len = MIN(a->size, b->size);
 247         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
 248                 if (*p1 != *p2)
 249                         return (cnt);
 250
 251         /* a->size must be <= b->size, or they wouldn't be in this order. */
 252         return (a->size < b->size ? a->size + 1 : a->size);
 253 }