1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Mike Olson. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)bt_utils.c 5.4 (Berkeley) 09/04/91"; 13 #endif /* LIBC_SCCS and not lint */ 14 15 #include <sys/param.h> 16 #include <db.h> 17 #include <stdio.h> 18 #include <stdlib.h> 19 #include <string.h> 20 #include "btree.h" 21 22 /* 23 * __BT_RET -- Build return key/data pair as a result of search or scan. 24 * 25 * Parameters: 26 * t: tree 27 * d: LEAF to be returned to the user. 28 * key: user's key structure 29 * data: user's data structure 30 * 31 * Returns: 32 * RET_SUCCESS, RET_ERROR. 33 */ 34 int 35 __bt_ret(t, e, key, data) 36 BTREE *t; 37 EPG *e; 38 DBT *key, *data; 39 { 40 register BLEAF *bl; 41 42 bl = GETBLEAF(e->page, e->index); 43 44 if (bl->flags & P_BIGKEY) { 45 if (__ovfl_get(t, bl->bytes, 46 &key->size, &t->bt_kbuf, &t->bt_kbufsz)) 47 return (RET_ERROR); 48 } else { 49 if (bl->ksize > t->bt_kbufsz) { 50 if ((t->bt_kbuf = 51 realloc(t->bt_kbuf, bl->ksize)) == NULL) 52 return (RET_ERROR); 53 t->bt_kbufsz = bl->ksize; 54 } 55 bcopy(bl->bytes, t->bt_kbuf, t->bt_kbufsz); 56 key->size = bl->ksize; 57 } 58 key->data = t->bt_kbuf; 59 60 if (bl->flags & P_BIGDATA) { 61 if (__ovfl_get(t, bl->bytes + bl->ksize, 62 &data->size, &t->bt_dbuf, &t->bt_dbufsz)) 63 return (RET_ERROR); 64 } else { 65 if (bl->dsize > t->bt_dbufsz) { 66 if ((t->bt_dbuf = 67 realloc(t->bt_dbuf, bl->dsize)) == NULL) 68 return (RET_ERROR); 69 t->bt_dbufsz = bl->dsize; 70 } 71 bcopy(bl->bytes + bl->ksize, t->bt_dbuf, t->bt_dbufsz); 72 data->size = bl->dsize; 73 } 74 data->data = t->bt_dbuf; 75 76 return (RET_SUCCESS); 77 } 78 79 /* 80 * __BT_CMP -- Compare a key to a given record. 81 * 82 * Parameters: 83 * t: tree 84 * k1: DBT pointer of first arg to comparison 85 * e: pointer to EPG for comparison 86 * 87 * Returns: 88 * < 0 if k1 is < record 89 * = 0 if k1 is = record 90 * > 0 if k1 is > record 91 */ 92 int 93 __bt_cmp(t, k1, e) 94 BTREE *t; 95 const DBT *k1; 96 EPG *e; 97 { 98 BINTERNAL *bi; 99 BLEAF *bl; 100 DBT k2; 101 PAGE *h; 102 void *bigkey; 103 104 /* 105 * The left-most key on internal pages, at any level of the tree, is 106 * guaranteed by the following code to be less than any user key. 107 * This saves us from having to update the leftmost key on an internal 108 * page when the user inserts a new key in the tree smaller than 109 * anything we've yet seen. 110 */ 111 h = e->page; 112 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF)) 113 return (1); 114 115 bigkey = NULL; 116 if (h->flags & P_BLEAF) { 117 bl = GETBLEAF(h, e->index); 118 if (bl->flags & P_BIGKEY) 119 bigkey = bl->bytes; 120 else { 121 k2.data = bl->bytes; 122 k2.size = bl->ksize; 123 } 124 } else { 125 bi = GETBINTERNAL(h, e->index); 126 if (bi->flags & P_BIGKEY) 127 bigkey = bi->bytes; 128 else { 129 k2.data = bi->bytes; 130 k2.size = bi->ksize; 131 } 132 } 133 134 if (bigkey) { 135 if (__ovfl_get(t, bigkey, 136 &k2.size, &t->bt_dbuf, &t->bt_dbufsz)) 137 return (RET_ERROR); 138 k2.data = t->bt_dbuf; 139 } 140 return((*t->bt_cmp)(k1, &k2)); 141 } 142 143 /* 144 * __BT_DEFCMP -- Default comparison routine. 145 * 146 * Parameters: 147 * a: DBT #1 148 * b: DBT #2 149 * 150 * Returns: 151 * < 0 if a is < b 152 * = 0 if a is = b 153 * > 0 if a is > b 154 */ 155 int 156 __bt_defcmp(a, b) 157 const DBT *a, *b; 158 { 159 register u_char *p1, *p2; 160 register int diff, len; 161 162 len = MIN(a->size, b->size); 163 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2) 164 if (diff = *p1 - *p2) 165 return(diff); 166 return(a->size - b->size); 167 } 168 169 /* 170 * __BT_DEFPFX -- Default prefix routine. 171 * 172 * Parameters: 173 * a: DBT #1 174 * b: DBT #2 175 * 176 * Returns: 177 * Number of bytes needed to distinguish b from a. 178 */ 179 int 180 __bt_defpfx(a, b) 181 const DBT *a, *b; 182 { 183 register u_char *p1, *p2; 184 register int len; 185 int cnt; 186 187 cnt = 1; 188 len = MIN(a->size, b->size); 189 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt) 190 if (*p1 != *p2) 191 return(cnt); 192 if (a->size == b->size) 193 return (a->size); 194 return(a->size + 1); 195 } 196