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 41 #include <sys/param.h> 42 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 47 #include <db.h> 48 #include "btree.h" 49 50 /* 51 * __bt_ret -- 52 * Build return key/data pair. 53 * 54 * Parameters: 55 * t: tree 56 * e: key/data pair to be returned 57 * key: user's key structure (NULL if not to be filled in) 58 * rkey: memory area to hold key 59 * data: user's data structure (NULL if not to be filled in) 60 * rdata: memory area to hold data 61 * copy: always copy the key/data item 62 * 63 * Returns: 64 * RET_SUCCESS, RET_ERROR. 65 */ 66 int 67 __bt_ret(t, e, key, rkey, data, rdata, copy) 68 BTREE *t; 69 EPG *e; 70 DBT *key, *rkey, *data, *rdata; 71 int copy; 72 { 73 BLEAF *bl; 74 void *p; 75 76 bl = GETBLEAF(e->page, e->index); 77 78 /* 79 * We must copy big keys/data to make them contigous. Otherwise, 80 * leave the page pinned and don't copy unless the user specified 81 * concurrent access. 82 */ 83 if (key == NULL) 84 goto dataonly; 85 86 if (bl->flags & P_BIGKEY) { 87 if (__ovfl_get(t, bl->bytes, 88 &key->size, &rkey->data, &rkey->size)) 89 return (RET_ERROR); 90 key->data = rkey->data; 91 } else if (copy || F_ISSET(t, B_DB_LOCK)) { 92 if (bl->ksize > rkey->size) { 93 p = (void *)(rkey->data == NULL ? 94 malloc(bl->ksize) : realloc(rkey->data, bl->ksize)); 95 if (p == NULL) 96 return (RET_ERROR); 97 rkey->data = p; 98 rkey->size = bl->ksize; 99 } 100 memmove(rkey->data, bl->bytes, bl->ksize); 101 key->size = bl->ksize; 102 key->data = rkey->data; 103 } else { 104 key->size = bl->ksize; 105 key->data = bl->bytes; 106 } 107 108 dataonly: 109 if (data == NULL) 110 return (RET_SUCCESS); 111 112 if (bl->flags & P_BIGDATA) { 113 if (__ovfl_get(t, bl->bytes + bl->ksize, 114 &data->size, &rdata->data, &rdata->size)) 115 return (RET_ERROR); 116 data->data = rdata->data; 117 } else if (copy || F_ISSET(t, B_DB_LOCK)) { 118 /* Use +1 in case the first record retrieved is 0 length. */ 119 if (bl->dsize + 1 > rdata->size) { 120 p = (void *)(rdata->data == NULL ? 121 malloc(bl->dsize + 1) : 122 realloc(rdata->data, bl->dsize + 1)); 123 if (p == NULL) 124 return (RET_ERROR); 125 rdata->data = p; 126 rdata->size = bl->dsize + 1; 127 } 128 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize); 129 data->size = bl->dsize; 130 data->data = rdata->data; 131 } else { 132 data->size = bl->dsize; 133 data->data = bl->bytes + bl->ksize; 134 } 135 136 return (RET_SUCCESS); 137 } 138 139 /* 140 * __BT_CMP -- Compare a key to a given record. 141 * 142 * Parameters: 143 * t: tree 144 * k1: DBT pointer of first arg to comparison 145 * e: pointer to EPG for comparison 146 * 147 * Returns: 148 * < 0 if k1 is < record 149 * = 0 if k1 is = record 150 * > 0 if k1 is > record 151 */ 152 int 153 __bt_cmp(t, k1, e) 154 BTREE *t; 155 const DBT *k1; 156 EPG *e; 157 { 158 BINTERNAL *bi; 159 BLEAF *bl; 160 DBT k2; 161 PAGE *h; 162 void *bigkey; 163 164 /* 165 * The left-most key on internal pages, at any level of the tree, is 166 * guaranteed by the following code to be less than any user key. 167 * This saves us from having to update the leftmost key on an internal 168 * page when the user inserts a new key in the tree smaller than 169 * anything we've yet seen. 170 */ 171 h = e->page; 172 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF)) 173 return (1); 174 175 bigkey = NULL; 176 if (h->flags & P_BLEAF) { 177 bl = GETBLEAF(h, e->index); 178 if (bl->flags & P_BIGKEY) 179 bigkey = bl->bytes; 180 else { 181 k2.data = bl->bytes; 182 k2.size = bl->ksize; 183 } 184 } else { 185 bi = GETBINTERNAL(h, e->index); 186 if (bi->flags & P_BIGKEY) 187 bigkey = bi->bytes; 188 else { 189 k2.data = bi->bytes; 190 k2.size = bi->ksize; 191 } 192 } 193 194 if (bigkey) { 195 if (__ovfl_get(t, bigkey, 196 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size)) 197 return (RET_ERROR); 198 k2.data = t->bt_rdata.data; 199 } 200 return ((*t->bt_cmp)(k1, &k2)); 201 } 202 203 /* 204 * __BT_DEFCMP -- Default comparison routine. 205 * 206 * Parameters: 207 * a: DBT #1 208 * b: DBT #2 209 * 210 * Returns: 211 * < 0 if a is < b 212 * = 0 if a is = b 213 * > 0 if a is > b 214 */ 215 int 216 __bt_defcmp(a, b) 217 const DBT *a, *b; 218 { 219 register size_t len; 220 register u_char *p1, *p2; 221 222 /* 223 * XXX 224 * If a size_t doesn't fit in an int, this routine can lose. 225 * What we need is a integral type which is guaranteed to be 226 * larger than a size_t, and there is no such thing. 227 */ 228 len = MIN(a->size, b->size); 229 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2) 230 if (*p1 != *p2) 231 return ((int)*p1 - (int)*p2); 232 return ((int)a->size - (int)b->size); 233 } 234 235 /* 236 * __BT_DEFPFX -- Default prefix routine. 237 * 238 * Parameters: 239 * a: DBT #1 240 * b: DBT #2 241 * 242 * Returns: 243 * Number of bytes needed to distinguish b from a. 244 */ 245 size_t 246 __bt_defpfx(a, b) 247 const DBT *a, *b; 248 { 249 register u_char *p1, *p2; 250 register size_t cnt, len; 251 252 cnt = 1; 253 len = MIN(a->size, b->size); 254 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt) 255 if (*p1 != *p2) 256 return (cnt); 257 258 /* a->size must be <= b->size, or they wouldn't be in this order. */ 259 return (a->size < b->size ? a->size + 1 : a->size); 260 } 261