db/btree/FreeBSD/bt_utils.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Mike Olson.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)bt_utils.c  8.8 (Berkeley) 7/20/94";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/db/btree/bt_utils.c,v 1.7 2009/03/05 00:57:01 delphij Exp $");
  38
  39 #include <sys/param.h>
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44
  45 #include <db.h>
  46 #include "btree.h"
  47
  48 /*
  49  * __bt_ret --
  50  *      Build return key/data pair.
  51  *
  52  * Parameters:
  53  *      t:      tree
  54  *      e:      key/data pair to be returned
  55  *      key:    user's key structure (NULL if not to be filled in)
  56  *      rkey:   memory area to hold key
  57  *      data:   user's data structure (NULL if not to be filled in)
  58  *      rdata:  memory area to hold data
  59  *       copy:  always copy the key/data item
  60  *
  61  * Returns:
  62  *      RET_SUCCESS, RET_ERROR.
  63  */
  64 int
  65 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
  66 {
  67         BLEAF *bl;
  68         void *p;
  69
  70         bl = GETBLEAF(e->page, e->index);
  71
  72         /*
  73          * We must copy big keys/data to make them contigous.  Otherwise,
  74          * leave the page pinned and don't copy unless the user specified
  75          * concurrent access.
  76          */
  77         if (key == NULL)
  78                 goto dataonly;
  79
  80         if (bl->flags & P_BIGKEY) {
  81                 if (__ovfl_get(t, bl->bytes,
  82                     &key->size, &rkey->data, &rkey->size))
  83                         return (RET_ERROR);
  84                 key->data = rkey->data;
  85         } else if (copy || F_ISSET(t, B_DB_LOCK)) {
  86                 if (bl->ksize > rkey->size) {
  87                         p = realloc(rkey->data, bl->ksize);
  88                         if (p == NULL)
  89                                 return (RET_ERROR);
  90                         rkey->data = p;
  91                         rkey->size = bl->ksize;
  92                 }
  93                 memmove(rkey->data, bl->bytes, bl->ksize);
  94                 key->size = bl->ksize;
  95                 key->data = rkey->data;
  96         } else {
  97                 key->size = bl->ksize;
  98                 key->data = bl->bytes;
  99         }
 100
 101 dataonly:
 102         if (data == NULL)
 103                 return (RET_SUCCESS);
 104
 105         if (bl->flags & P_BIGDATA) {
 106                 if (__ovfl_get(t, bl->bytes + bl->ksize,
 107                     &data->size, &rdata->data, &rdata->size))
 108                         return (RET_ERROR);
 109                 data->data = rdata->data;
 110         } else if (copy || F_ISSET(t, B_DB_LOCK)) {
 111                 /* Use +1 in case the first record retrieved is 0 length. */
 112                 if (bl->dsize + 1 > rdata->size) {
 113                         p = realloc(rdata->data, bl->dsize + 1);
 114                         if (p == NULL)
 115                                 return (RET_ERROR);
 116                         rdata->data = p;
 117                         rdata->size = bl->dsize + 1;
 118                 }
 119                 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
 120                 data->size = bl->dsize;
 121                 data->data = rdata->data;
 122         } else {
 123                 data->size = bl->dsize;
 124                 data->data = bl->bytes + bl->ksize;
 125         }
 126
 127         return (RET_SUCCESS);
 128 }
 129
 130 /*
 131  * __BT_CMP -- Compare a key to a given record.
 132  *
 133  * Parameters:
 134  *      t:      tree
 135  *      k1:     DBT pointer of first arg to comparison
 136  *      e:      pointer to EPG for comparison
 137  *
 138  * Returns:
 139  *      < 0 if k1 is < record
 140  *      = 0 if k1 is = record
 141  *      > 0 if k1 is > record
 142  */
 143 int
 144 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
 145 {
 146         BINTERNAL *bi;
 147         BLEAF *bl;
 148         DBT k2;
 149         PAGE *h;
 150         void *bigkey;
 151
 152         /*
 153          * The left-most key on internal pages, at any level of the tree, is
 154          * guaranteed by the following code to be less than any user key.
 155          * This saves us from having to update the leftmost key on an internal
 156          * page when the user inserts a new key in the tree smaller than
 157          * anything we've yet seen.
 158          */
 159         h = e->page;
 160         if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
 161                 return (1);
 162
 163         bigkey = NULL;
 164         if (h->flags & P_BLEAF) {
 165                 bl = GETBLEAF(h, e->index);
 166                 if (bl->flags & P_BIGKEY)
 167                         bigkey = bl->bytes;
 168                 else {
 169                         k2.data = bl->bytes;
 170                         k2.size = bl->ksize;
 171                 }
 172         } else {
 173                 bi = GETBINTERNAL(h, e->index);
 174                 if (bi->flags & P_BIGKEY)
 175                         bigkey = bi->bytes;
 176                 else {
 177                         k2.data = bi->bytes;
 178                         k2.size = bi->ksize;
 179                 }
 180         }
 181
 182         if (bigkey) {
 183                 if (__ovfl_get(t, bigkey,
 184                     &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
 185                         return (RET_ERROR);
 186                 k2.data = t->bt_rdata.data;
 187         }
 188         return ((*t->bt_cmp)(k1, &k2));
 189 }
 190
 191 /*
 192  * __BT_DEFCMP -- Default comparison routine.
 193  *
 194  * Parameters:
 195  *      a:      DBT #1
 196  *      b:      DBT #2
 197  *
 198  * Returns:
 199  *      < 0 if a is < b
 200  *      = 0 if a is = b
 201  *      > 0 if a is > b
 202  */
 203 int
 204 __bt_defcmp(const DBT *a, const DBT *b)
 205 {
 206         size_t len;
 207         u_char *p1, *p2;
 208
 209         /*
 210          * XXX
 211          * If a size_t doesn't fit in an int, this routine can lose.
 212          * What we need is an integral type which is guaranteed to be
 213          * larger than a size_t, and there is no such thing.
 214          */
 215         len = MIN(a->size, b->size);
 216         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
 217                 if (*p1 != *p2)
 218                         return ((int)*p1 - (int)*p2);
 219         return ((int)a->size - (int)b->size);
 220 }
 221
 222 /*
 223  * __BT_DEFPFX -- Default prefix routine.
 224  *
 225  * Parameters:
 226  *      a:      DBT #1
 227  *      b:      DBT #2
 228  *
 229  * Returns:
 230  *      Number of bytes needed to distinguish b from a.
 231  */
 232 size_t
 233 __bt_defpfx(const DBT *a, const DBT *b)
 234 {
 235         u_char *p1, *p2;
 236         size_t cnt, len;
 237
 238         cnt = 1;
 239         len = MIN(a->size, b->size);
 240         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
 241                 if (*p1 != *p2)
 242                         return (cnt);
 243
 244         /* a->size must be <= b->size, or they wouldn't be in this order. */
 245         return (a->size < b->size ? a->size + 1 : a->size);
 246 }