1 /*- 2 * Copyright (c) 1990, 1993 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 8.4 (Berkeley) 2/21/94"; 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 -- Build return key/data pair as a result of search or scan. 52 * 53 * Parameters: 54 * t: tree 55 * d: LEAF to be returned to the user. 56 * key: user's key structure (NULL if not to be filled in) 57 * data: user's data structure 58 * 59 * Returns: 60 * RET_SUCCESS, RET_ERROR. 61 */ 62 int 63 __bt_ret(t, e, key, data) 64 BTREE *t; 65 EPG *e; 66 DBT *key, *data; 67 { 68 register BLEAF *bl; 69 register void *p; 70 71 bl = GETBLEAF(e->page, e->index); 72 73 /* 74 * We always copy big keys/data to make them contigous. Otherwise, 75 * we leave the page pinned and don't copy unless the user specified 76 * concurrent access. 77 */ 78 if (bl->flags & P_BIGDATA) { 79 if (__ovfl_get(t, bl->bytes + bl->ksize, 80 &data->size, &t->bt_dbuf, &t->bt_dbufsz)) 81 return (RET_ERROR); 82 data->data = t->bt_dbuf; 83 } else if (ISSET(t, B_DB_LOCK)) { 84 /* Use +1 in case the first record retrieved is 0 length. */ 85 if (bl->dsize + 1 > t->bt_dbufsz) { 86 if ((p = 87 (void *)realloc(t->bt_dbuf, bl->dsize + 1)) == NULL) 88 return (RET_ERROR); 89 t->bt_dbuf = p; 90 t->bt_dbufsz = bl->dsize + 1; 91 } 92 memmove(t->bt_dbuf, bl->bytes + bl->ksize, bl->dsize); 93 data->size = bl->dsize; 94 data->data = t->bt_dbuf; 95 } else { 96 data->size = bl->dsize; 97 data->data = bl->bytes + bl->ksize; 98 } 99 100 if (key == NULL) 101 return (RET_SUCCESS); 102 103 if (bl->flags & P_BIGKEY) { 104 if (__ovfl_get(t, bl->bytes, 105 &key->size, &t->bt_kbuf, &t->bt_kbufsz)) 106 return (RET_ERROR); 107 key->data = t->bt_kbuf; 108 } else if (ISSET(t, B_DB_LOCK)) { 109 if (bl->ksize > t->bt_kbufsz) { 110 if ((p = 111 (void *)realloc(t->bt_kbuf, bl->ksize)) == NULL) 112 return (RET_ERROR); 113 t->bt_kbuf = p; 114 t->bt_kbufsz = bl->ksize; 115 } 116 memmove(t->bt_kbuf, bl->bytes, bl->ksize); 117 key->size = bl->ksize; 118 key->data = t->bt_kbuf; 119 } else { 120 key->size = bl->ksize; 121 key->data = bl->bytes; 122 } 123 return (RET_SUCCESS); 124 } 125 126 /* 127 * __BT_CMP -- Compare a key to a given record. 128 * 129 * Parameters: 130 * t: tree 131 * k1: DBT pointer of first arg to comparison 132 * e: pointer to EPG for comparison 133 * 134 * Returns: 135 * < 0 if k1 is < record 136 * = 0 if k1 is = record 137 * > 0 if k1 is > record 138 */ 139 int 140 __bt_cmp(t, k1, e) 141 BTREE *t; 142 const DBT *k1; 143 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_dbuf, &t->bt_dbufsz)) 184 return (RET_ERROR); 185 k2.data = t->bt_dbuf; 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(a, b) 204 const DBT *a, *b; 205 { 206 register size_t len; 207 register 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 a 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(a, b) 234 const DBT *a, *b; 235 { 236 register u_char *p1, *p2; 237 register size_t cnt, len; 238 239 cnt = 1; 240 len = MIN(a->size, b->size); 241 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt) 242 if (*p1 != *p2) 243 return (cnt); 244 245 /* a->size must be <= b->size, or they wouldn't be in this order. */ 246 return (a->size < b->size ? a->size + 1 : a->size); 247 } 248