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  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)bt_utils.c  8.8 (Berkeley) 7/20/94";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/db/btree/bt_utils.c,v 1.3 2003/01/01 18:48:42 schweikh Exp $");
  42
  43 #include <sys/param.h>
  44
  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(t, e, key, rkey, data, rdata, copy)
  70         BTREE *t;
  71         EPG *e;
  72         DBT *key, *rkey, *data, *rdata;
  73         int copy;
  74 {
  75         BLEAF *bl;
  76         void *p;
  77
  78         bl = GETBLEAF(e->page, e->index);
  79
  80         /*
  81          * We must copy big keys/data to make them contigous.  Otherwise,
  82          * leave the page pinned and don't copy unless the user specified
  83          * concurrent access.
  84          */
  85         if (key == NULL)
  86                 goto dataonly;
  87
  88         if (bl->flags & P_BIGKEY) {
  89                 if (__ovfl_get(t, bl->bytes,
  90                     &key->size, &rkey->data, &rkey->size))
  91                         return (RET_ERROR);
  92                 key->data = rkey->data;
  93         } else if (copy || F_ISSET(t, B_DB_LOCK)) {
  94                 if (bl->ksize > rkey->size) {
  95                         p = (void *)(rkey->data == NULL ?
  96                             malloc(bl->ksize) : realloc(rkey->data, bl->ksize));
  97                         if (p == NULL)
  98                                 return (RET_ERROR);
  99                         rkey->data = p;
 100                         rkey->size = bl->ksize;
 101                 }
 102                 memmove(rkey->data, bl->bytes, bl->ksize);
 103                 key->size = bl->ksize;
 104                 key->data = rkey->data;
 105         } else {
 106                 key->size = bl->ksize;
 107                 key->data = bl->bytes;
 108         }
 109
 110 dataonly:
 111         if (data == NULL)
 112                 return (RET_SUCCESS);
 113
 114         if (bl->flags & P_BIGDATA) {
 115                 if (__ovfl_get(t, bl->bytes + bl->ksize,
 116                     &data->size, &rdata->data, &rdata->size))
 117                         return (RET_ERROR);
 118                 data->data = rdata->data;
 119         } else if (copy || F_ISSET(t, B_DB_LOCK)) {
 120                 /* Use +1 in case the first record retrieved is 0 length. */
 121                 if (bl->dsize + 1 > rdata->size) {
 122                         p = (void *)(rdata->data == NULL ?
 123                             malloc(bl->dsize + 1) :
 124                             realloc(rdata->data, bl->dsize + 1));
 125                         if (p == NULL)
 126                                 return (RET_ERROR);
 127                         rdata->data = p;
 128                         rdata->size = bl->dsize + 1;
 129                 }
 130                 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
 131                 data->size = bl->dsize;
 132                 data->data = rdata->data;
 133         } else {
 134                 data->size = bl->dsize;
 135                 data->data = bl->bytes + bl->ksize;
 136         }
 137
 138         return (RET_SUCCESS);
 139 }
 140
 141 /*
 142  * __BT_CMP -- Compare a key to a given record.
 143  *
 144  * Parameters:
 145  *      t:      tree
 146  *      k1:     DBT pointer of first arg to comparison
 147  *      e:      pointer to EPG for comparison
 148  *
 149  * Returns:
 150  *      < 0 if k1 is < record
 151  *      = 0 if k1 is = record
 152  *      > 0 if k1 is > record
 153  */
 154 int
 155 __bt_cmp(t, k1, e)
 156         BTREE *t;
 157         const DBT *k1;
 158         EPG *e;
 159 {
 160         BINTERNAL *bi;
 161         BLEAF *bl;
 162         DBT k2;
 163         PAGE *h;
 164         void *bigkey;
 165
 166         /*
 167          * The left-most key on internal pages, at any level of the tree, is
 168          * guaranteed by the following code to be less than any user key.
 169          * This saves us from having to update the leftmost key on an internal
 170          * page when the user inserts a new key in the tree smaller than
 171          * anything we've yet seen.
 172          */
 173         h = e->page;
 174         if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
 175                 return (1);
 176
 177         bigkey = NULL;
 178         if (h->flags & P_BLEAF) {
 179                 bl = GETBLEAF(h, e->index);
 180                 if (bl->flags & P_BIGKEY)
 181                         bigkey = bl->bytes;
 182                 else {
 183                         k2.data = bl->bytes;
 184                         k2.size = bl->ksize;
 185                 }
 186         } else {
 187                 bi = GETBINTERNAL(h, e->index);
 188                 if (bi->flags & P_BIGKEY)
 189                         bigkey = bi->bytes;
 190                 else {
 191                         k2.data = bi->bytes;
 192                         k2.size = bi->ksize;
 193                 }
 194         }
 195
 196         if (bigkey) {
 197                 if (__ovfl_get(t, bigkey,
 198                     &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
 199                         return (RET_ERROR);
 200                 k2.data = t->bt_rdata.data;
 201         }
 202         return ((*t->bt_cmp)(k1, &k2));
 203 }
 204
 205 /*
 206  * __BT_DEFCMP -- Default comparison routine.
 207  *
 208  * Parameters:
 209  *      a:      DBT #1
 210  *      b:      DBT #2
 211  *
 212  * Returns:
 213  *      < 0 if a is < b
 214  *      = 0 if a is = b
 215  *      > 0 if a is > b
 216  */
 217 int
 218 __bt_defcmp(a, b)
 219         const DBT *a, *b;
 220 {
 221         size_t len;
 222         u_char *p1, *p2;
 223
 224         /*
 225          * XXX
 226          * If a size_t doesn't fit in an int, this routine can lose.
 227          * What we need is an integral type which is guaranteed to be
 228          * larger than a size_t, and there is no such thing.
 229          */
 230         len = MIN(a->size, b->size);
 231         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
 232                 if (*p1 != *p2)
 233                         return ((int)*p1 - (int)*p2);
 234         return ((int)a->size - (int)b->size);
 235 }
 236
 237 /*
 238  * __BT_DEFPFX -- Default prefix routine.
 239  *
 240  * Parameters:
 241  *      a:      DBT #1
 242  *      b:      DBT #2
 243  *
 244  * Returns:
 245  *      Number of bytes needed to distinguish b from a.
 246  */
 247 size_t
 248 __bt_defpfx(a, b)
 249         const DBT *a, *b;
 250 {
 251         u_char *p1, *p2;
 252         size_t cnt, len;
 253
 254         cnt = 1;
 255         len = MIN(a->size, b->size);
 256         for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
 257                 if (*p1 != *p2)
 258                         return (cnt);
 259
 260         /* a->size must be <= b->size, or they wouldn't be in this order. */
 261         return (a->size < b->size ? a->size + 1 : a->size);
 262 }