1 /* $OpenBSD: bt_utils.c,v 1.9 2005/08/05 13:03:00 espie 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 #include <sys/param.h> 36 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 41 #include <db.h> 42 #include "btree.h" 43 44 /* 45 * __bt_ret -- 46 * Build return key/data pair. 47 * 48 * Parameters: 49 * t: tree 50 * e: key/data pair to be returned 51 * key: user's key structure (NULL if not to be filled in) 52 * rkey: memory area to hold key 53 * data: user's data structure (NULL if not to be filled in) 54 * rdata: memory area to hold data 55 * copy: always copy the key/data item 56 * 57 * Returns: 58 * RET_SUCCESS, RET_ERROR. 59 */ 60 int 61 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy) 62 { 63 BLEAF *bl; 64 void *p; 65 66 bl = GETBLEAF(e->page, e->index); 67 68 /* 69 * We must copy big keys/data to make them contigous. Otherwise, 70 * leave the page pinned and don't copy unless the user specified 71 * concurrent access. 72 */ 73 if (key == NULL) 74 goto dataonly; 75 76 if (bl->flags & P_BIGKEY) { 77 if (__ovfl_get(t, bl->bytes, 78 &key->size, &rkey->data, &rkey->size)) 79 return (RET_ERROR); 80 key->data = rkey->data; 81 } else if (copy || F_ISSET(t, B_DB_LOCK)) { 82 if (bl->ksize > rkey->size) { 83 p = (void *)(rkey->data == NULL ? 84 malloc(bl->ksize) : realloc(rkey->data, bl->ksize)); 85 if (p == NULL) 86 return (RET_ERROR); 87 rkey->data = p; 88 rkey->size = bl->ksize; 89 } 90 memmove(rkey->data, bl->bytes, bl->ksize); 91 key->size = bl->ksize; 92 key->data = rkey->data; 93 } else { 94 key->size = bl->ksize; 95 key->data = bl->bytes; 96 } 97 98 dataonly: 99 if (data == NULL) 100 return (RET_SUCCESS); 101 102 if (bl->flags & P_BIGDATA) { 103 if (__ovfl_get(t, bl->bytes + bl->ksize, 104 &data->size, &rdata->data, &rdata->size)) 105 return (RET_ERROR); 106 data->data = rdata->data; 107 } else if (copy || F_ISSET(t, B_DB_LOCK)) { 108 /* Use +1 in case the first record retrieved is 0 length. */ 109 if (bl->dsize + 1 > rdata->size) { 110 p = (void *)(rdata->data == NULL ? 111 malloc(bl->dsize + 1) : 112 realloc(rdata->data, bl->dsize + 1)); 113 if (p == NULL) 114 return (RET_ERROR); 115 rdata->data = p; 116 rdata->size = bl->dsize + 1; 117 } 118 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize); 119 data->size = bl->dsize; 120 data->data = rdata->data; 121 } else { 122 data->size = bl->dsize; 123 data->data = bl->bytes + bl->ksize; 124 } 125 126 return (RET_SUCCESS); 127 } 128 129 /* 130 * __BT_CMP -- Compare a key to a given record. 131 * 132 * Parameters: 133 * t: tree 134 * k1: DBT pointer of first arg to comparison 135 * e: pointer to EPG for comparison 136 * 137 * Returns: 138 * < 0 if k1 is < record 139 * = 0 if k1 is = record 140 * > 0 if k1 is > record 141 */ 142 int 143 __bt_cmp(BTREE *t, const DBT *k1, EPG *e) 144 { 145 BINTERNAL *bi; 146 BLEAF *bl; 147 DBT k2; 148 PAGE *h; 149 void *bigkey; 150 151 /* 152 * The left-most key on internal pages, at any level of the tree, is 153 * guaranteed by the following code to be less than any user key. 154 * This saves us from having to update the leftmost key on an internal 155 * page when the user inserts a new key in the tree smaller than 156 * anything we've yet seen. 157 */ 158 h = e->page; 159 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF)) 160 return (1); 161 162 bigkey = NULL; 163 if (h->flags & P_BLEAF) { 164 bl = GETBLEAF(h, e->index); 165 if (bl->flags & P_BIGKEY) 166 bigkey = bl->bytes; 167 else { 168 k2.data = bl->bytes; 169 k2.size = bl->ksize; 170 } 171 } else { 172 bi = GETBINTERNAL(h, e->index); 173 if (bi->flags & P_BIGKEY) 174 bigkey = bi->bytes; 175 else { 176 k2.data = bi->bytes; 177 k2.size = bi->ksize; 178 } 179 } 180 181 if (bigkey) { 182 if (__ovfl_get(t, bigkey, 183 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size)) 184 return (RET_ERROR); 185 k2.data = t->bt_rdata.data; 186 } 187 return ((*t->bt_cmp)(k1, &k2)); 188 } 189 190 /* 191 * __BT_DEFCMP -- Default comparison routine. 192 * 193 * Parameters: 194 * a: DBT #1 195 * b: DBT #2 196 * 197 * Returns: 198 * < 0 if a is < b 199 * = 0 if a is = b 200 * > 0 if a is > b 201 */ 202 int 203 __bt_defcmp(const DBT *a, const DBT *b) 204 { 205 size_t len; 206 u_char *p1, *p2; 207 208 /* 209 * XXX 210 * If a size_t doesn't fit in an int, this routine can lose. 211 * What we need is a integral type which is guaranteed to be 212 * larger than a size_t, and there is no such thing. 213 */ 214 len = MIN(a->size, b->size); 215 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2) 216 if (*p1 != *p2) 217 return ((int)*p1 - (int)*p2); 218 return ((int)a->size - (int)b->size); 219 } 220 221 /* 222 * __BT_DEFPFX -- Default prefix routine. 223 * 224 * Parameters: 225 * a: DBT #1 226 * b: DBT #2 227 * 228 * Returns: 229 * Number of bytes needed to distinguish b from a. 230 */ 231 size_t 232 __bt_defpfx(a, b) 233 const DBT *a, *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 } 247