1 /* $NetBSD: bt_utils.c,v 1.16 2013/12/14 18:04:56 christos 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 #if HAVE_NBTOOL_CONFIG_H
36 #include "nbtool_config.h"
37 #endif
38
39 #include <sys/cdefs.h>
40 __RCSID("$NetBSD: bt_utils.c,v 1.16 2013/12/14 18:04:56 christos Exp $");
41
42 #include <sys/param.h>
43
44 #include <assert.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48
49 #include <db.h>
50 #include "btree.h"
51
52 /*
53 * __bt_ret --
54 * Build return key/data pair.
55 *
56 * Parameters:
57 * t: tree
58 * e: key/data pair to be returned
59 * key: user's key structure (NULL if not to be filled in)
60 * rkey: memory area to hold key
61 * data: user's data structure (NULL if not to be filled in)
62 * rdata: memory area to hold data
63 * copy: always copy the key/data item
64 *
65 * Returns:
66 * RET_SUCCESS, RET_ERROR.
67 */
68 int
__bt_ret(BTREE * t,EPG * e,DBT * key,DBT * rkey,DBT * data,DBT * rdata,int copy)69 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
70 {
71 BLEAF *bl;
72 void *p;
73
74 bl = GETBLEAF(e->page, e->index);
75
76 /*
77 * We must copy big keys/data to make them contiguous. Otherwise,
78 * leave the page pinned and don't copy unless the user specified
79 * concurrent access.
80 */
81 if (key == NULL)
82 goto dataonly;
83
84 if (bl->flags & P_BIGKEY) {
85 if (__ovfl_get(t, bl->bytes,
86 &key->size, &rkey->data, &rkey->size))
87 return (RET_ERROR);
88 key->data = rkey->data;
89 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
90 if (bl->ksize > rkey->size) {
91 p = realloc(rkey->data, bl->ksize);
92 if (p == NULL)
93 return (RET_ERROR);
94 rkey->data = p;
95 rkey->size = bl->ksize;
96 }
97 memmove(rkey->data, bl->bytes, bl->ksize);
98 key->size = bl->ksize;
99 key->data = rkey->data;
100 } else {
101 key->size = bl->ksize;
102 key->data = bl->bytes;
103 }
104
105 dataonly:
106 if (data == NULL)
107 return (RET_SUCCESS);
108
109 if (bl->flags & P_BIGDATA) {
110 if (__ovfl_get(t, bl->bytes + bl->ksize,
111 &data->size, &rdata->data, &rdata->size))
112 return (RET_ERROR);
113 data->data = rdata->data;
114 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
115 /* Use +1 in case the first record retrieved is 0 length. */
116 if (bl->dsize + 1 > rdata->size) {
117 p = realloc(rdata->data, bl->dsize + 1);
118 if (p == NULL)
119 return (RET_ERROR);
120 rdata->data = p;
121 rdata->size = bl->dsize + 1;
122 }
123 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
124 data->size = bl->dsize;
125 data->data = rdata->data;
126 } else {
127 data->size = bl->dsize;
128 data->data = bl->bytes + bl->ksize;
129 }
130
131 return (RET_SUCCESS);
132 }
133
134 /*
135 * __BT_CMP -- Compare a key to a given record.
136 *
137 * Parameters:
138 * t: tree
139 * k1: DBT pointer of first arg to comparison
140 * e: pointer to EPG for comparison
141 *
142 * Returns:
143 * < 0 if k1 is < record
144 * = 0 if k1 is = record
145 * > 0 if k1 is > record
146 */
147 int
__bt_cmp(BTREE * t,const DBT * k1,EPG * e)148 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
149 {
150 BINTERNAL *bi;
151 BLEAF *bl;
152 DBT k2;
153 PAGE *h;
154 void *bigkey;
155
156 /*
157 * The left-most key on internal pages, at any level of the tree, is
158 * guaranteed by the following code to be less than any user key.
159 * This saves us from having to update the leftmost key on an internal
160 * page when the user inserts a new key in the tree smaller than
161 * anything we've yet seen.
162 */
163 h = e->page;
164 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
165 return (1);
166
167 bigkey = NULL;
168 if (h->flags & P_BLEAF) {
169 bl = GETBLEAF(h, e->index);
170 if (bl->flags & P_BIGKEY)
171 bigkey = bl->bytes;
172 else {
173 k2.data = bl->bytes;
174 k2.size = bl->ksize;
175 }
176 } else {
177 bi = GETBINTERNAL(h, e->index);
178 if (bi->flags & P_BIGKEY)
179 bigkey = bi->bytes;
180 else {
181 k2.data = bi->bytes;
182 k2.size = bi->ksize;
183 }
184 }
185
186 if (bigkey) {
187 if (__ovfl_get(t, bigkey,
188 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
189 return (RET_ERROR);
190 k2.data = t->bt_rdata.data;
191 }
192 return ((*t->bt_cmp)(k1, &k2));
193 }
194
195 /*
196 * __BT_DEFCMP -- Default comparison routine.
197 *
198 * Parameters:
199 * a: DBT #1
200 * b: DBT #2
201 *
202 * Returns:
203 * < 0 if a is < b
204 * = 0 if a is = b
205 * > 0 if a is > b
206 */
207 int
__bt_defcmp(const DBT * a,const DBT * b)208 __bt_defcmp(const DBT *a, const DBT *b)
209 {
210 size_t len;
211 uint8_t *p1, *p2;
212
213 /*
214 * XXX
215 * If a size_t doesn't fit in an int, this routine can lose.
216 * What we need is a integral type which is guaranteed to be
217 * larger than a size_t, and there is no such thing.
218 */
219 len = MIN(a->size, b->size);
220 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
221 if (*p1 != *p2)
222 return ((int)*p1 - (int)*p2);
223 return ((int)a->size - (int)b->size);
224 }
225
226 /*
227 * __BT_DEFPFX -- Default prefix routine.
228 *
229 * Parameters:
230 * a: DBT #1
231 * b: DBT #2
232 *
233 * Returns:
234 * Number of bytes needed to distinguish b from a.
235 */
236 size_t
__bt_defpfx(const DBT * a,const DBT * b)237 __bt_defpfx(const DBT *a, const DBT *b)
238 {
239 uint8_t *p1, *p2;
240 size_t cnt, len;
241
242 cnt = 1;
243 len = MIN(a->size, b->size);
244 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
245 if (*p1 != *p2)
246 return (cnt);
247
248 /* a->size must be <= b->size, or they wouldn't be in this order. */
249 return (a->size < b->size ? a->size + 1 : a->size);
250 }
251