1 /* $OpenBSD: bt_utils.c,v 1.13 2022/12/27 17:10:06 jmc 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 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38
39 #include <db.h>
40 #include "btree.h"
41
42 #define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
43
44 /*
45 * __bt_ret --
46 * Build return key/data pair.
47 *
48 * Parameters:
49 * t: tree
50 * e: key/data pair to be returned
51 * key: user's key structure (NULL if not to be filled in)
52 * rkey: memory area to hold key
53 * data: user's data structure (NULL if not to be filled in)
54 * rdata: memory area to hold data
55 * copy: always copy the key/data item
56 *
57 * Returns:
58 * RET_SUCCESS, RET_ERROR.
59 */
60 int
__bt_ret(BTREE * t,EPG * e,DBT * key,DBT * rkey,DBT * data,DBT * rdata,int copy)61 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
62 {
63 BLEAF *bl;
64 void *p;
65
66 bl = GETBLEAF(e->page, e->index);
67
68 /*
69 * We must copy big keys/data to make them contiguous. Otherwise,
70 * leave the page pinned and don't copy unless the user specified
71 * concurrent access.
72 */
73 if (key == NULL)
74 goto dataonly;
75
76 if (bl->flags & P_BIGKEY) {
77 if (__ovfl_get(t, bl->bytes,
78 &key->size, &rkey->data, &rkey->size))
79 return (RET_ERROR);
80 key->data = rkey->data;
81 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
82 if (bl->ksize > rkey->size) {
83 p = realloc(rkey->data, bl->ksize);
84 if (p == NULL)
85 return (RET_ERROR);
86 rkey->data = p;
87 rkey->size = bl->ksize;
88 }
89 memmove(rkey->data, bl->bytes, bl->ksize);
90 key->size = bl->ksize;
91 key->data = rkey->data;
92 } else {
93 key->size = bl->ksize;
94 key->data = bl->bytes;
95 }
96
97 dataonly:
98 if (data == NULL)
99 return (RET_SUCCESS);
100
101 if (bl->flags & P_BIGDATA) {
102 if (__ovfl_get(t, bl->bytes + bl->ksize,
103 &data->size, &rdata->data, &rdata->size))
104 return (RET_ERROR);
105 data->data = rdata->data;
106 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
107 /* Use +1 in case the first record retrieved is 0 length. */
108 if (bl->dsize + 1 > rdata->size) {
109 p = realloc(rdata->data, bl->dsize + 1);
110 if (p == NULL)
111 return (RET_ERROR);
112 rdata->data = p;
113 rdata->size = bl->dsize + 1;
114 }
115 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
116 data->size = bl->dsize;
117 data->data = rdata->data;
118 } else {
119 data->size = bl->dsize;
120 data->data = bl->bytes + bl->ksize;
121 }
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
__bt_cmp(BTREE * t,const DBT * k1,EPG * e)140 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
141 {
142 BINTERNAL *bi;
143 BLEAF *bl;
144 DBT k2;
145 PAGE *h;
146 void *bigkey;
147
148 /*
149 * The left-most key on internal pages, at any level of the tree, is
150 * guaranteed by the following code to be less than any user key.
151 * This saves us from having to update the leftmost key on an internal
152 * page when the user inserts a new key in the tree smaller than
153 * anything we've yet seen.
154 */
155 h = e->page;
156 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
157 return (1);
158
159 bigkey = NULL;
160 if (h->flags & P_BLEAF) {
161 bl = GETBLEAF(h, e->index);
162 if (bl->flags & P_BIGKEY)
163 bigkey = bl->bytes;
164 else {
165 k2.data = bl->bytes;
166 k2.size = bl->ksize;
167 }
168 } else {
169 bi = GETBINTERNAL(h, e->index);
170 if (bi->flags & P_BIGKEY)
171 bigkey = bi->bytes;
172 else {
173 k2.data = bi->bytes;
174 k2.size = bi->ksize;
175 }
176 }
177
178 if (bigkey) {
179 if (__ovfl_get(t, bigkey,
180 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
181 return (RET_ERROR);
182 k2.data = t->bt_rdata.data;
183 }
184 return ((*t->bt_cmp)(k1, &k2));
185 }
186
187 /*
188 * __BT_DEFCMP -- Default comparison routine.
189 *
190 * Parameters:
191 * a: DBT #1
192 * b: DBT #2
193 *
194 * Returns:
195 * < 0 if a is < b
196 * = 0 if a is = b
197 * > 0 if a is > b
198 */
199 int
__bt_defcmp(const DBT * a,const DBT * b)200 __bt_defcmp(const DBT *a, const DBT *b)
201 {
202 size_t len;
203 u_char *p1, *p2;
204
205 /*
206 * XXX
207 * If a size_t doesn't fit in an int, this routine can lose.
208 * What we need is a integral type which is guaranteed to be
209 * larger than a size_t, and there is no such thing.
210 */
211 len = MINIMUM(a->size, b->size);
212 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
213 if (*p1 != *p2)
214 return ((int)*p1 - (int)*p2);
215 return ((int)a->size - (int)b->size);
216 }
217
218 /*
219 * __BT_DEFPFX -- Default prefix routine.
220 *
221 * Parameters:
222 * a: DBT #1
223 * b: DBT #2
224 *
225 * Returns:
226 * Number of bytes needed to distinguish b from a.
227 */
228 size_t
__bt_defpfx(const DBT * a,const DBT * b)229 __bt_defpfx(const DBT *a, const DBT *b)
230 {
231 u_char *p1, *p2;
232 size_t cnt, len;
233
234 cnt = 1;
235 len = MINIMUM(a->size, b->size);
236 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
237 if (*p1 != *p2)
238 return (cnt);
239
240 /* a->size must be <= b->size, or they wouldn't be in this order. */
241 return (a->size < b->size ? a->size + 1 : a->size);
242 }
243