db/btree/bt_utils.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Mike Olson.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61
  62 #include <sys/param.h>
  63
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <string.h>
  67
  68 #include <db.h>
  69 #include "btree.h"
  70
  71 /*
  72  * __BT_RET -- Build return key/data pair as a result of search or scan.
  73  *
  74  * Parameters:
  75  *      t:      tree
  76  *      d:      LEAF to be returned to the user.
  77  *      key:    user's key structure (NULL if not to be filled in)
  78  *      data:   user's data structure
  79  *
  80  * Returns:
  81  *      RET_SUCCESS, RET_ERROR.
  82  */
  83 int
  84 __bt_ret(t, e, key, data)
  85         BTREE *t;
  86         EPG *e;
  87         DBT *key, *data;
  88 {
  89         register BLEAF *bl;
  90         register void *p;
  91
  92         bl = GETBLEAF(e->page, e->index);
  93
  94         /*
  95          * We always copy big keys/data to make them contigous.  Otherwise,
  96          * we leave the page pinned and don't copy unless the user specified
  97          * concurrent access.
  98          */
  99         if (bl->flags & P_BIGDATA) {
 100                 if (__ovfl_get(t, bl->bytes + bl->ksize,
 101                     &data->size, &t->bt_dbuf, &t->bt_dbufsz))
 102                         return (RET_ERROR);
 103                 data->data = t->bt_dbuf;
 104         } else if (ISSET(t, B_DB_LOCK)) {
 105                 /* Use +1 in case the first record retrieved is 0 length. */
 106                 if (bl->dsize + 1 > t->bt_dbufsz) {
 107                         if ((p =
 108                             (void *)realloc(t->bt_dbuf, bl->dsize + 1)) == NULL)
 109                                 return (RET_ERROR);
 110                         t->bt_dbuf = p;
 111                         t->bt_dbufsz = bl->dsize + 1;
 112                 }
 113                 memmove(t->bt_dbuf, bl->bytes + bl->ksize, bl->dsize);
 114                 data->size = bl->dsize;
 115                 data->data = t->bt_dbuf;
 116         } else {
 117                 data->size = bl->dsize;
 118                 data->data = bl->bytes + bl->ksize;
 119         }
 120
 121         if (key == NULL)
 122                 return (RET_SUCCESS);
 123
 124         if (bl->flags & P_BIGKEY) {
 125                 if (__ovfl_get(t, bl->bytes,
 126                     &key->size, &t->bt_kbuf, &t->bt_kbufsz))
 127                         return (RET_ERROR);
 128                 key->data = t->bt_kbuf;
 129         } else if (ISSET(t, B_DB_LOCK)) {
 130                 if (bl->ksize > t->bt_kbufsz) {
 131                         if ((p =
 132                             (void *)realloc(t->bt_kbuf, bl->ksize)) == NULL)
 133                                 return (RET_ERROR);
 134                         t->bt_kbuf = p;
 135                         t->bt_kbufsz = bl->ksize;
 136                 }
 137                 memmove(t->bt_kbuf, bl->bytes, bl->ksize);
 138                 key->size = bl->ksize;
 139                 key->data = t->bt_kbuf;
 140         } else {
 141                 key->size = bl->ksize;
 142                 key->data = bl->bytes;
 143         }
 144         return (RET_SUCCESS);
 145 }
 146
 147 /*
 148  * __BT_CMP -- Compare a key to a given record.
 149  *
 150  * Parameters:
 151  *      t:      tree
 152  *      k1:     DBT pointer of first arg to comparison
 153  *      e:      pointer to EPG for comparison
 154  *
 155  * Returns:
 156  *      < 0 if k1 is < record
 157  *      = 0 if k1 is = record
 158  *      > 0 if k1 is > record
 159  */
 160 int
 161 __bt_cmp(t, k1, e)
 162         BTREE *t;
 163         const DBT *k1;
 164         EPG *e;
 165 {
 166         BINTERNAL *bi;
 167         BLEAF *bl;
 168         DBT k2;
 169         PAGE *h;
 170         void *bigkey;
 171
 172         /*
 173          * The left-most key on internal pages, at any level of the tree, is
 174          * guaranteed by the following code to be less than any user key.
 175          * This saves us from having to update the leftmost key on an internal
 176          * page when the user inserts a new key in the tree smaller than
 177          * anything we've yet seen.
 178          */
 179         h = e->page;
 180         if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
 181                 return (1);
 182
 183         bigkey = NULL;
 184         if (h->flags & P_BLEAF) {
 185                 bl = GETBLEAF(h, e->index);
 186                 if (bl->flags & P_BIGKEY)
 187                         bigkey = bl->bytes;
 188                 else {
 189                         k2.data = bl->bytes;
 190                         k2.size = bl->ksize;
 191                 }
 192         } else {
 193                 bi = GETBINTERNAL(h, e->index);
 194                 if (bi->flags & P_BIGKEY)
 195                         bigkey = bi->bytes;
 196                 else {
 197                         k2.data = bi->bytes;
 198                         k2.size = bi->ksize;
 199                 }
 200         }
 201
 202         if (bigkey) {
 203                 if (__ovfl_get(t, bigkey,
 204                     &k2.size, &t->bt_dbuf, &t->bt_dbufsz))
 205                         return (RET_ERROR);
 206                 k2.data = t->bt_dbuf;
 207         }
 208         return ((*t->bt_cmp)(k1, &k2));
 209 }
 210
 211 /*
 212  * __BT_DEFCMP -- Default comparison routine.
 213  *
 214  * Parameters:
 215  *      a:      DBT #1
 216  *      b:      DBT #2
 217  *
 218  * Returns:
 219  *      < 0 if a is < b
 220  *      = 0 if a is = b
 221  *      > 0 if a is > b
 222  */
 223 int
 224 __bt_defcmp(a, b)
 225         const DBT *a, *b;
 226 {
 227         register size_t len;
 228         register u_char *p1, *p2;
 229
 230         /*
 231          * XXX
 232          * If a size_t doesn't fit in an int, this routine can lose.
 233          * What we need is a integral type which is guaranteed to be
 234          * larger than a size_t, and there is no such thing.
 235          */
 236         len = MIN(a->size, b->size);
 237         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
 238                 if (*p1 != *p2)
 239                         return ((int)*p1 - (int)*p2);
 240         return ((int)a->size - (int)b->size);
 241 }
 242
 243 /*
 244  * __BT_DEFPFX -- Default prefix routine.
 245  *
 246  * Parameters:
 247  *      a:      DBT #1
 248  *      b:      DBT #2
 249  *
 250  * Returns:
 251  *      Number of bytes needed to distinguish b from a.
 252  */
 253 size_t
 254 __bt_defpfx(a, b)
 255         const DBT *a, *b;
 256 {
 257         register u_char *p1, *p2;
 258         register size_t cnt, len;
 259
 260         cnt = 1;
 261         len = MIN(a->size, b->size);
 262         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
 263                 if (*p1 != *p2)
 264                         return (cnt);
 265
 266         /* a->size must be <= b->size, or they wouldn't be in this order. */
 267         return (a->size < b->size ? a->size + 1 : a->size);
 268 }