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. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #if defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid[] = "@(#)bt_utils.c 8.8 (Berkeley) 7/20/94";
39 #endif /* LIBC_SCCS and not lint */
40
41 #include <sys/param.h>
42
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46
47 #include "db-int.h"
48 #include "btree.h"
49
50 /*
51 * __bt_ret --
52 * Build return key/data pair.
53 *
54 * Parameters:
55 * t: tree
56 * e: key/data pair to be returned
57 * key: user's key structure (NULL if not to be filled in)
58 * rkey: memory area to hold key
59 * data: user's data structure (NULL if not to be filled in)
60 * rdata: memory area to hold data
61 * copy: always copy the key/data item
62 *
63 * Returns:
64 * RET_SUCCESS, RET_ERROR.
65 */
66 int
__bt_ret(t,e,key,rkey,data,rdata,copy)67 __bt_ret(t, e, key, rkey, data, rdata, copy)
68 BTREE *t;
69 EPG *e;
70 DBT *key, *rkey, *data, *rdata;
71 int copy;
72 {
73 BLEAF *bl;
74 void *p;
75
76 bl = GETBLEAF(e->page, e->index);
77
78 /*
79 * We must copy big keys/data to make them contigous. Otherwise,
80 * leave the page pinned and don't copy unless the user specified
81 * concurrent access.
82 */
83 if (key == NULL)
84 goto dataonly;
85
86 if (bl->flags & P_BIGKEY) {
87 if (__ovfl_get(t, bl->bytes,
88 &key->size, &rkey->data, &rkey->size))
89 return (RET_ERROR);
90 key->data = rkey->data;
91 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
92 if (bl->ksize > rkey->size) {
93 p = (void *)(rkey->data == NULL ?
94 malloc(bl->ksize) : realloc(rkey->data, bl->ksize));
95 if (p == NULL)
96 return (RET_ERROR);
97 rkey->data = p;
98 rkey->size = bl->ksize;
99 }
100 memmove(rkey->data, bl->bytes, bl->ksize);
101 key->size = bl->ksize;
102 key->data = rkey->data;
103 } else {
104 key->size = bl->ksize;
105 key->data = bl->bytes;
106 }
107
108 dataonly:
109 if (data == NULL)
110 return (RET_SUCCESS);
111
112 if (bl->flags & P_BIGDATA) {
113 if (__ovfl_get(t, bl->bytes + bl->ksize,
114 &data->size, &rdata->data, &rdata->size))
115 return (RET_ERROR);
116 data->data = rdata->data;
117 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
118 /* Use +1 in case the first record retrieved is 0 length. */
119 if (bl->dsize + 1 > rdata->size) {
120 p = (void *)(rdata->data == NULL ?
121 malloc(bl->dsize + 1) :
122 realloc(rdata->data, bl->dsize + 1));
123 if (p == NULL)
124 return (RET_ERROR);
125 rdata->data = p;
126 rdata->size = bl->dsize + 1;
127 }
128 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
129 data->size = bl->dsize;
130 data->data = rdata->data;
131 } else {
132 data->size = bl->dsize;
133 data->data = bl->bytes + bl->ksize;
134 }
135
136 return (RET_SUCCESS);
137 }
138
139 /*
140 * __BT_CMP -- Compare a key to a given record.
141 *
142 * Parameters:
143 * t: tree
144 * k1: DBT pointer of first arg to comparison
145 * e: pointer to EPG for comparison
146 *
147 * Returns:
148 * < 0 if k1 is < record
149 * = 0 if k1 is = record
150 * > 0 if k1 is > record
151 */
152 int
__bt_cmp(t,k1,e)153 __bt_cmp(t, k1, e)
154 BTREE *t;
155 const DBT *k1;
156 EPG *e;
157 {
158 BINTERNAL *bi;
159 BLEAF *bl;
160 DBT k2;
161 PAGE *h;
162 void *bigkey;
163
164 /*
165 * The left-most key on internal pages, at any level of the tree, is
166 * guaranteed by the following code to be less than any user key.
167 * This saves us from having to update the leftmost key on an internal
168 * page when the user inserts a new key in the tree smaller than
169 * anything we've yet seen.
170 */
171 h = e->page;
172 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
173 return (1);
174
175 bigkey = NULL;
176 if (h->flags & P_BLEAF) {
177 bl = GETBLEAF(h, e->index);
178 if (bl->flags & P_BIGKEY)
179 bigkey = bl->bytes;
180 else {
181 k2.data = bl->bytes;
182 k2.size = bl->ksize;
183 }
184 } else {
185 bi = GETBINTERNAL(h, e->index);
186 if (bi->flags & P_BIGKEY)
187 bigkey = bi->bytes;
188 else {
189 k2.data = bi->bytes;
190 k2.size = bi->ksize;
191 }
192 }
193
194 if (bigkey) {
195 if (__ovfl_get(t, bigkey,
196 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
197 return (RET_ERROR);
198 k2.data = t->bt_rdata.data;
199 }
200 return ((*t->bt_cmp)(k1, &k2));
201 }
202
203 /*
204 * __BT_DEFCMP -- Default comparison routine.
205 *
206 * Parameters:
207 * a: DBT #1
208 * b: DBT #2
209 *
210 * Returns:
211 * < 0 if a is < b
212 * = 0 if a is = b
213 * > 0 if a is > b
214 */
215 int
__bt_defcmp(a,b)216 __bt_defcmp(a, b)
217 const DBT *a, *b;
218 {
219 register size_t len;
220 register u_char *p1, *p2;
221
222 /*
223 * XXX
224 * If a size_t doesn't fit in an int, this routine can lose.
225 * What we need is a integral type which is guaranteed to be
226 * larger than a size_t, and there is no such thing.
227 */
228 len = MIN(a->size, b->size);
229 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
230 if (*p1 != *p2)
231 return ((int)*p1 - (int)*p2);
232 return ((int)a->size - (int)b->size);
233 }
234
235 /*
236 * __BT_DEFPFX -- Default prefix routine.
237 *
238 * Parameters:
239 * a: DBT #1
240 * b: DBT #2
241 *
242 * Returns:
243 * Number of bytes needed to distinguish b from a.
244 */
245 size_t
__bt_defpfx(a,b)246 __bt_defpfx(a, b)
247 const DBT *a, *b;
248 {
249 register u_char *p1, *p2;
250 register size_t cnt, len;
251
252 cnt = 1;
253 len = MIN(a->size, b->size);
254 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
255 if (*p1 != *p2)
256 return (cnt);
257
258 /* a->size must be <= b->size, or they wouldn't be in this order. */
259 return (a->size < b->size ? a->size + 1 : a->size);
260 }
261