1 /* $NetBSD: bt_open.c,v 1.29 2016/09/24 21:31:25 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_open.c,v 1.29 2016/09/24 21:31:25 christos Exp $");
41
42 /*
43 * Implementation of btree access method for 4.4BSD.
44 *
45 * The design here was originally based on that of the btree access method
46 * used in the Postgres database system at UC Berkeley. This implementation
47 * is wholly independent of the Postgres code.
48 */
49
50 #include "namespace.h"
51 #include <sys/stat.h>
52
53 #include <assert.h>
54 #include <errno.h>
55 #include <fcntl.h>
56 #include <limits.h>
57 #include <signal.h>
58 #include <stdio.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <unistd.h>
62 #include <paths.h>
63
64 #include <db.h>
65 #include "btree.h"
66
67 #ifdef DEBUG
68 #undef MINPSIZE
69 #define MINPSIZE 128
70 #endif
71
72 static int byteorder(void);
73 static int nroot(BTREE *);
74
75 /*
76 * __BT_OPEN -- Open a btree.
77 *
78 * Creates and fills a DB struct, and calls the routine that actually
79 * opens the btree.
80 *
81 * Parameters:
82 * fname: filename (NULL for in-memory trees)
83 * flags: open flag bits
84 * mode: open permission bits
85 * b: BTREEINFO pointer
86 *
87 * Returns:
88 * NULL on failure, pointer to DB on success.
89 *
90 */
91 DB *
__bt_open(const char * fname,int flags,mode_t mode,const BTREEINFO * openinfo,int dflags)92 __bt_open(const char *fname, int flags, mode_t mode, const BTREEINFO *openinfo,
93 int dflags)
94 {
95 struct stat sb;
96 BTMETA m;
97 BTREE *t;
98 BTREEINFO b;
99 DB *dbp;
100 pgno_t ncache;
101 ssize_t nr;
102 size_t temp;
103 int machine_lorder;
104
105 t = NULL;
106
107 /*
108 * Intention is to make sure all of the user's selections are okay
109 * here and then use them without checking. Can't be complete, since
110 * we don't know the right page size, lorder or flags until the backing
111 * file is opened. Also, the file's page size can cause the cachesize
112 * to change.
113 */
114 machine_lorder = byteorder();
115 if (openinfo) {
116 b = *openinfo;
117
118 /* Flags: R_DUP. */
119 if (b.flags & ~(R_DUP))
120 goto einval;
121
122 /*
123 * Page size must be indx_t aligned and >= MINPSIZE. Default
124 * page size is set farther on, based on the underlying file
125 * transfer size.
126 */
127 if (b.psize &&
128 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
129 b.psize & (sizeof(indx_t) - 1)))
130 goto einval;
131
132 /* Minimum number of keys per page; absolute minimum is 2. */
133 if (b.minkeypage) {
134 if (b.minkeypage < 2)
135 goto einval;
136 } else
137 b.minkeypage = DEFMINKEYPAGE;
138
139 /* If no comparison, use default comparison and prefix. */
140 if (b.compare == NULL) {
141 b.compare = __bt_defcmp;
142 if (b.prefix == NULL)
143 b.prefix = __bt_defpfx;
144 }
145
146 if (b.lorder == 0)
147 b.lorder = machine_lorder;
148 } else {
149 b.compare = __bt_defcmp;
150 b.cachesize = 0;
151 b.flags = 0;
152 b.lorder = machine_lorder;
153 b.minkeypage = DEFMINKEYPAGE;
154 b.prefix = __bt_defpfx;
155 b.psize = 0;
156 }
157
158 /* Check for the ubiquitous PDP-11. */
159 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
160 goto einval;
161
162 /* Allocate and initialize DB and BTREE structures. */
163 if ((t = malloc(sizeof(*t))) == NULL)
164 goto err;
165 memset(t, 0, sizeof(BTREE));
166 t->bt_fd = -1; /* Don't close unopened fd on error. */
167 t->bt_lorder = b.lorder;
168 t->bt_order = NOT;
169 t->bt_cmp = b.compare;
170 t->bt_pfx = b.prefix;
171 t->bt_rfd = -1;
172
173 if ((t->bt_dbp = dbp = malloc(sizeof(*dbp))) == NULL)
174 goto err;
175 memset(t->bt_dbp, 0, sizeof(DB));
176 if (t->bt_lorder != machine_lorder)
177 F_SET(t, B_NEEDSWAP);
178
179 dbp->type = DB_BTREE;
180 dbp->internal = t;
181 dbp->close = __bt_close;
182 dbp->del = __bt_delete;
183 dbp->fd = __bt_fd;
184 dbp->get = __bt_get;
185 dbp->put = __bt_put;
186 dbp->seq = __bt_seq;
187 dbp->sync = __bt_sync;
188
189 /*
190 * If no file name was supplied, this is an in-memory btree and we
191 * open a backing temporary file. Otherwise, it's a disk-based tree.
192 */
193 if (fname) {
194 switch (flags & O_ACCMODE) {
195 case O_RDONLY:
196 F_SET(t, B_RDONLY);
197 break;
198 case O_RDWR:
199 break;
200 case O_WRONLY:
201 default:
202 goto einval;
203 }
204 if ((t->bt_fd = __dbopen(fname, flags, mode, &sb)) == -1)
205 goto err;
206 } else {
207 if ((flags & O_ACCMODE) != O_RDWR)
208 goto einval;
209 if ((t->bt_fd = __dbtemp("bt.", &sb)) == -1)
210 goto err;
211 F_SET(t, B_INMEM);
212 }
213
214
215 if (sb.st_size) {
216 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
217 goto err;
218 if (nr != sizeof(BTMETA))
219 goto eftype;
220
221 /*
222 * Read in the meta-data. This can change the notion of what
223 * the lorder, page size and flags are, and, when the page size
224 * changes, the cachesize value can change too. If the user
225 * specified the wrong byte order for an existing database, we
226 * don't bother to return an error, we just clear the NEEDSWAP
227 * bit.
228 */
229 if (m.magic == BTREEMAGIC)
230 F_CLR(t, B_NEEDSWAP);
231 else {
232 F_SET(t, B_NEEDSWAP);
233 M_32_SWAP(m.magic);
234 M_32_SWAP(m.version);
235 M_32_SWAP(m.psize);
236 M_32_SWAP(m.free);
237 M_32_SWAP(m.nrecs);
238 M_32_SWAP(m.flags);
239 }
240 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
241 goto eftype;
242 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
243 m.psize & (sizeof(indx_t) - 1))
244 goto eftype;
245 if (m.flags & ~SAVEMETA)
246 goto eftype;
247 b.psize = m.psize;
248 F_SET(t, m.flags);
249 t->bt_free = m.free;
250 t->bt_nrecs = m.nrecs;
251 } else {
252 /*
253 * Set the page size to the best value for I/O to this file.
254 * Don't overflow the page offset type.
255 */
256 if (b.psize == 0) {
257 b.psize = sb.st_blksize;
258 if (b.psize < MINPSIZE)
259 b.psize = MINPSIZE;
260 if (b.psize > MAX_PAGE_OFFSET + 1)
261 b.psize = MAX_PAGE_OFFSET + 1;
262 }
263
264 /* Set flag if duplicates permitted. */
265 if (!(b.flags & R_DUP))
266 F_SET(t, B_NODUPS);
267
268 t->bt_free = P_INVALID;
269 t->bt_nrecs = 0;
270 F_SET(t, B_METADIRTY);
271 }
272
273 t->bt_psize = b.psize;
274
275 /* Set the cache size; must be a multiple of the page size. */
276 if (b.cachesize && b.cachesize & (b.psize - 1))
277 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1;
278 if (b.cachesize < b.psize * MINCACHE)
279 b.cachesize = b.psize * MINCACHE;
280
281 /* Calculate number of pages to cache. */
282 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
283
284 /*
285 * The btree data structure requires that at least two keys can fit on
286 * a page, but other than that there's no fixed requirement. The user
287 * specified a minimum number per page, and we translated that into the
288 * number of bytes a key/data pair can use before being placed on an
289 * overflow page. This calculation includes the page header, the size
290 * of the index referencing the leaf item and the size of the leaf item
291 * structure. Also, don't let the user specify a minkeypage such that
292 * a key/data pair won't fit even if both key and data are on overflow
293 * pages.
294 */
295 temp = (t->bt_psize - BTDATAOFF) / b.minkeypage -
296 (sizeof(indx_t) + NBLEAFDBT(0, 0));
297 _DBFIT(temp, indx_t);
298 t->bt_ovflsize = (indx_t)temp;
299 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) {
300 size_t l = NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
301 _DBFIT(l, indx_t);
302 t->bt_ovflsize = (indx_t)l;
303 }
304
305 /* Initialize the buffer pool. */
306 if ((t->bt_mp =
307 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
308 goto err;
309 if (!F_ISSET(t, B_INMEM))
310 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
311
312 /* Create a root page if new tree. */
313 if (nroot(t) == RET_ERROR)
314 goto err;
315
316 /* Global flags. */
317 if (dflags & DB_LOCK)
318 F_SET(t, B_DB_LOCK);
319 if (dflags & DB_SHMEM)
320 F_SET(t, B_DB_SHMEM);
321 if (dflags & DB_TXN)
322 F_SET(t, B_DB_TXN);
323
324 return (dbp);
325
326 einval: errno = EINVAL;
327 goto err;
328
329 eftype: errno = EFTYPE;
330 goto err;
331
332 err: if (t) {
333 if (t->bt_dbp)
334 free(t->bt_dbp);
335 if (t->bt_fd != -1)
336 (void)close(t->bt_fd);
337 free(t);
338 }
339 return (NULL);
340 }
341
342 /*
343 * NROOT -- Create the root of a new tree.
344 *
345 * Parameters:
346 * t: tree
347 *
348 * Returns:
349 * RET_ERROR, RET_SUCCESS
350 */
351 static int
nroot(BTREE * t)352 nroot(BTREE *t)
353 {
354 PAGE *meta, *root;
355 pgno_t npg;
356
357 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
358 if (root->lower == 0 &&
359 root->pgno == 0 &&
360 root->linp[0] == 0) {
361 mpool_delete(t->bt_mp, root);
362 errno = EINVAL;
363 } else {
364 mpool_put(t->bt_mp, root, 0);
365 return RET_SUCCESS;
366 }
367 }
368 if (errno != EINVAL) /* It's OK to not exist. */
369 return (RET_ERROR);
370 errno = 0;
371
372 if ((meta = mpool_newf(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
373 return (RET_ERROR);
374
375 if ((root = mpool_newf(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
376 return (RET_ERROR);
377
378 if (npg != P_ROOT)
379 return (RET_ERROR);
380 root->pgno = npg;
381 root->prevpg = root->nextpg = P_INVALID;
382 root->lower = BTDATAOFF;
383 root->upper = t->bt_psize;
384 root->flags = P_BLEAF;
385 memset(meta, 0, t->bt_psize);
386 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
387 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
388 return (RET_SUCCESS);
389 }
390
391 static int
byteorder(void)392 byteorder(void)
393 {
394 uint32_t x;
395 uint8_t *p;
396
397 x = 0x01020304;
398 p = (uint8_t *)(void *)&x;
399 switch (*p) {
400 case 1:
401 return (BIG_ENDIAN);
402 case 4:
403 return (LITTLE_ENDIAN);
404 default:
405 return (0);
406 }
407 }
408
409 int
__bt_fd(const DB * dbp)410 __bt_fd(const DB *dbp)
411 {
412 BTREE *t;
413
414 t = dbp->internal;
415
416 /* Toss any page pinned across calls. */
417 if (t->bt_pinned != NULL) {
418 mpool_put(t->bt_mp, t->bt_pinned, 0);
419 t->bt_pinned = NULL;
420 }
421
422 /* In-memory database can't have a file descriptor. */
423 if (F_ISSET(t, B_INMEM)) {
424 errno = ENOENT;
425 return (-1);
426 }
427 return (t->bt_fd);
428 }
429