1 /*-
2 * Copyright (c) 1990, 1993, 1994
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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)bt_utils.c 8.8 (Berkeley) 7/20/94
33 * $FreeBSD: head/lib/libc/db/btree/bt_utils.c 189387 2009-03-05 00:57:01Z delphij $
34 */
35
36 #include <sys/param.h>
37
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41
42 #include <db.h>
43 #include "btree.h"
44
45 /*
46 * __bt_ret --
47 * Build return key/data pair.
48 *
49 * Parameters:
50 * t: tree
51 * e: key/data pair to be returned
52 * key: user's key structure (NULL if not to be filled in)
53 * rkey: memory area to hold key
54 * data: user's data structure (NULL if not to be filled in)
55 * rdata: memory area to hold data
56 * copy: always copy the key/data item
57 *
58 * Returns:
59 * RET_SUCCESS, RET_ERROR.
60 */
61 int
__bt_ret(BTREE * t,EPG * e,DBT * key,DBT * rkey,DBT * data,DBT * rdata,int copy)62 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
63 {
64 BLEAF *bl;
65 void *p;
66
67 bl = GETBLEAF(e->page, e->index);
68
69 /*
70 * We must copy big keys/data to make them contigous. Otherwise,
71 * leave the page pinned and don't copy unless the user specified
72 * concurrent access.
73 */
74 if (key == NULL)
75 goto dataonly;
76
77 if (bl->flags & P_BIGKEY) {
78 if (__ovfl_get(t, bl->bytes,
79 &key->size, &rkey->data, &rkey->size))
80 return (RET_ERROR);
81 key->data = rkey->data;
82 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
83 if (bl->ksize > rkey->size) {
84 p = realloc(rkey->data, bl->ksize);
85 if (p == NULL)
86 return (RET_ERROR);
87 rkey->data = p;
88 rkey->size = bl->ksize;
89 }
90 memmove(rkey->data, bl->bytes, bl->ksize);
91 key->size = bl->ksize;
92 key->data = rkey->data;
93 } else {
94 key->size = bl->ksize;
95 key->data = bl->bytes;
96 }
97
98 dataonly:
99 if (data == NULL)
100 return (RET_SUCCESS);
101
102 if (bl->flags & P_BIGDATA) {
103 if (__ovfl_get(t, bl->bytes + bl->ksize,
104 &data->size, &rdata->data, &rdata->size))
105 return (RET_ERROR);
106 data->data = rdata->data;
107 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
108 /* Use +1 in case the first record retrieved is 0 length. */
109 if (bl->dsize + 1 > rdata->size) {
110 p = realloc(rdata->data, bl->dsize + 1);
111 if (p == NULL)
112 return (RET_ERROR);
113 rdata->data = p;
114 rdata->size = bl->dsize + 1;
115 }
116 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
117 data->size = bl->dsize;
118 data->data = rdata->data;
119 } else {
120 data->size = bl->dsize;
121 data->data = bl->bytes + bl->ksize;
122 }
123
124 return (RET_SUCCESS);
125 }
126
127 /*
128 * __BT_CMP -- Compare a key to a given record.
129 *
130 * Parameters:
131 * t: tree
132 * k1: DBT pointer of first arg to comparison
133 * e: pointer to EPG for comparison
134 *
135 * Returns:
136 * < 0 if k1 is < record
137 * = 0 if k1 is = record
138 * > 0 if k1 is > record
139 */
140 int
__bt_cmp(BTREE * t,const DBT * k1,EPG * e)141 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
142 {
143 BINTERNAL *bi;
144 BLEAF *bl;
145 DBT k2;
146 PAGE *h;
147 void *bigkey;
148
149 /*
150 * The left-most key on internal pages, at any level of the tree, is
151 * guaranteed by the following code to be less than any user key.
152 * This saves us from having to update the leftmost key on an internal
153 * page when the user inserts a new key in the tree smaller than
154 * anything we've yet seen.
155 */
156 h = e->page;
157 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
158 return (1);
159
160 bigkey = NULL;
161 if (h->flags & P_BLEAF) {
162 bl = GETBLEAF(h, e->index);
163 if (bl->flags & P_BIGKEY)
164 bigkey = bl->bytes;
165 else {
166 k2.data = bl->bytes;
167 k2.size = bl->ksize;
168 }
169 } else {
170 bi = GETBINTERNAL(h, e->index);
171 if (bi->flags & P_BIGKEY)
172 bigkey = bi->bytes;
173 else {
174 k2.data = bi->bytes;
175 k2.size = bi->ksize;
176 }
177 }
178
179 if (bigkey) {
180 if (__ovfl_get(t, bigkey,
181 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
182 return (RET_ERROR);
183 k2.data = t->bt_rdata.data;
184 }
185 return ((*t->bt_cmp)(k1, &k2));
186 }
187
188 /*
189 * __BT_DEFCMP -- Default comparison routine.
190 *
191 * Parameters:
192 * a: DBT #1
193 * b: DBT #2
194 *
195 * Returns:
196 * < 0 if a is < b
197 * = 0 if a is = b
198 * > 0 if a is > b
199 */
200 int
__bt_defcmp(const DBT * a,const DBT * b)201 __bt_defcmp(const DBT *a, const DBT *b)
202 {
203 size_t len;
204 unsigned char *p1, *p2;
205
206 /*
207 * XXX
208 * If a size_t doesn't fit in an int, this routine can lose.
209 * What we need is an integral type which is guaranteed to be
210 * larger than a size_t, and there is no such thing.
211 */
212 len = MIN(a->size, b->size);
213 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
214 if (*p1 != *p2)
215 return ((int)*p1 - (int)*p2);
216 return ((int)a->size - (int)b->size);
217 }
218
219 /*
220 * __BT_DEFPFX -- Default prefix routine.
221 *
222 * Parameters:
223 * a: DBT #1
224 * b: DBT #2
225 *
226 * Returns:
227 * Number of bytes needed to distinguish b from a.
228 */
229 size_t
__bt_defpfx(const DBT * a,const DBT * b)230 __bt_defpfx(const DBT *a, const DBT *b)
231 {
232 unsigned char *p1, *p2;
233 size_t cnt, len;
234
235 cnt = 1;
236 len = MIN(a->size, b->size);
237 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
238 if (*p1 != *p2)
239 return (cnt);
240
241 /* a->size must be <= b->size, or they wouldn't be in this order. */
242 return (a->size < b->size ? a->size + 1 : a->size);
243 }
244