xref: /freebsd/lib/libc/db/btree/bt_utils.c (revision ef5d438ed4bc17ad7ece3e40fe4d1f9baf3aadf7)
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.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
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
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
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
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