1 /* $NetBSD: bt_utils.c,v 1.6 1995/02/27 13:21:04 cgd 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)bt_utils.c 8.5 (Berkeley) 6/20/94"; 42 #else 43 static char rcsid[] = "$NetBSD: bt_utils.c,v 1.6 1995/02/27 13:21:04 cgd Exp $"; 44 #endif 45 #endif /* LIBC_SCCS and not lint */ 46 47 #include <sys/param.h> 48 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 53 #include <db.h> 54 #include "btree.h" 55 56 /* 57 * __BT_RET -- Build return key/data pair as a result of search or scan. 58 * 59 * Parameters: 60 * t: tree 61 * d: LEAF to be returned to the user. 62 * key: user's key structure (NULL if not to be filled in) 63 * data: user's data structure 64 * 65 * Returns: 66 * RET_SUCCESS, RET_ERROR. 67 */ 68 int 69 __bt_ret(t, e, key, data) 70 BTREE *t; 71 EPG *e; 72 DBT *key, *data; 73 { 74 register BLEAF *bl; 75 register void *p; 76 77 bl = GETBLEAF(e->page, e->index); 78 79 /* 80 * We always copy big keys/data to make them contigous. Otherwise, 81 * we leave the page pinned and don't copy unless the user specified 82 * concurrent access. 83 */ 84 if (bl->flags & P_BIGDATA) { 85 if (__ovfl_get(t, bl->bytes + bl->ksize, 86 &data->size, &t->bt_dbuf, &t->bt_dbufsz)) 87 return (RET_ERROR); 88 data->data = t->bt_dbuf; 89 } else if (ISSET(t, B_DB_LOCK)) { 90 /* Use +1 in case the first record retrieved is 0 length. */ 91 if (bl->dsize + 1 > t->bt_dbufsz) { 92 p = (void *)(t->bt_dbuf == NULL ? 93 malloc(bl->dsize + 1) : 94 realloc(t->bt_dbuf, bl->dsize + 1)); 95 if (p == NULL) 96 return (RET_ERROR); 97 t->bt_dbuf = p; 98 t->bt_dbufsz = bl->dsize + 1; 99 } 100 memmove(t->bt_dbuf, bl->bytes + bl->ksize, bl->dsize); 101 data->size = bl->dsize; 102 data->data = t->bt_dbuf; 103 } else { 104 data->size = bl->dsize; 105 data->data = bl->bytes + bl->ksize; 106 } 107 108 if (key == NULL) 109 return (RET_SUCCESS); 110 111 if (bl->flags & P_BIGKEY) { 112 if (__ovfl_get(t, bl->bytes, 113 &key->size, &t->bt_kbuf, &t->bt_kbufsz)) 114 return (RET_ERROR); 115 key->data = t->bt_kbuf; 116 } else if (ISSET(t, B_DB_LOCK)) { 117 if (bl->ksize > t->bt_kbufsz) { 118 p = (void *)(t->bt_kbuf == NULL ? 119 malloc(bl->ksize) : realloc(t->bt_kbuf, bl->ksize)); 120 if (p == NULL) 121 return (RET_ERROR); 122 t->bt_kbuf = p; 123 t->bt_kbufsz = bl->ksize; 124 } 125 memmove(t->bt_kbuf, bl->bytes, bl->ksize); 126 key->size = bl->ksize; 127 key->data = t->bt_kbuf; 128 } else { 129 key->size = bl->ksize; 130 key->data = bl->bytes; 131 } 132 return (RET_SUCCESS); 133 } 134 135 /* 136 * __BT_CMP -- Compare a key to a given record. 137 * 138 * Parameters: 139 * t: tree 140 * k1: DBT pointer of first arg to comparison 141 * e: pointer to EPG for comparison 142 * 143 * Returns: 144 * < 0 if k1 is < record 145 * = 0 if k1 is = record 146 * > 0 if k1 is > record 147 */ 148 int 149 __bt_cmp(t, k1, e) 150 BTREE *t; 151 const DBT *k1; 152 EPG *e; 153 { 154 BINTERNAL *bi; 155 BLEAF *bl; 156 DBT k2; 157 PAGE *h; 158 void *bigkey; 159 160 /* 161 * The left-most key on internal pages, at any level of the tree, is 162 * guaranteed by the following code to be less than any user key. 163 * This saves us from having to update the leftmost key on an internal 164 * page when the user inserts a new key in the tree smaller than 165 * anything we've yet seen. 166 */ 167 h = e->page; 168 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF)) 169 return (1); 170 171 bigkey = NULL; 172 if (h->flags & P_BLEAF) { 173 bl = GETBLEAF(h, e->index); 174 if (bl->flags & P_BIGKEY) 175 bigkey = bl->bytes; 176 else { 177 k2.data = bl->bytes; 178 k2.size = bl->ksize; 179 } 180 } else { 181 bi = GETBINTERNAL(h, e->index); 182 if (bi->flags & P_BIGKEY) 183 bigkey = bi->bytes; 184 else { 185 k2.data = bi->bytes; 186 k2.size = bi->ksize; 187 } 188 } 189 190 if (bigkey) { 191 if (__ovfl_get(t, bigkey, 192 &k2.size, &t->bt_dbuf, &t->bt_dbufsz)) 193 return (RET_ERROR); 194 k2.data = t->bt_dbuf; 195 } 196 return ((*t->bt_cmp)(k1, &k2)); 197 } 198 199 /* 200 * __BT_DEFCMP -- Default comparison routine. 201 * 202 * Parameters: 203 * a: DBT #1 204 * b: DBT #2 205 * 206 * Returns: 207 * < 0 if a is < b 208 * = 0 if a is = b 209 * > 0 if a is > b 210 */ 211 int 212 __bt_defcmp(a, b) 213 const DBT *a, *b; 214 { 215 register size_t len; 216 register u_char *p1, *p2; 217 218 /* 219 * XXX 220 * If a size_t doesn't fit in an int, this routine can lose. 221 * What we need is a integral type which is guaranteed to be 222 * larger than a size_t, and there is no such thing. 223 */ 224 len = MIN(a->size, b->size); 225 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2) 226 if (*p1 != *p2) 227 return ((int)*p1 - (int)*p2); 228 return ((int)a->size - (int)b->size); 229 } 230 231 /* 232 * __BT_DEFPFX -- Default prefix routine. 233 * 234 * Parameters: 235 * a: DBT #1 236 * b: DBT #2 237 * 238 * Returns: 239 * Number of bytes needed to distinguish b from a. 240 */ 241 size_t 242 __bt_defpfx(a, b) 243 const DBT *a, *b; 244 { 245 register u_char *p1, *p2; 246 register size_t cnt, len; 247 248 cnt = 1; 249 len = MIN(a->size, b->size); 250 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt) 251 if (*p1 != *p2) 252 return (cnt); 253 254 /* a->size must be <= b->size, or they wouldn't be in this order. */ 255 return (a->size < b->size ? a->size + 1 : a->size); 256 } 257