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_open.c 8.10 (Berkeley) 8/17/94
33 * $FreeBSD: head/lib/libc/db/btree/bt_open.c 190498 2009-03-28 07:31:02Z delphij $
34 */
35
36 /*
37 * Implementation of btree access method for 4.4BSD.
38 *
39 * The design here was originally based on that of the btree access method
40 * used in the Postgres database system at UC Berkeley. This implementation
41 * is wholly independent of the Postgres code.
42 */
43
44 #include "namespace.h"
45 #include <sys/param.h>
46 #include <sys/stat.h>
47 #include <sys/file.h>
48
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <limits.h>
52 #include <signal.h>
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <string.h>
56 #include <unistd.h>
57 #include "un-namespace.h"
58
59 #include <db.h>
60 #include "btree.h"
61
62 #ifdef DEBUG
63 #undef MINPSIZE
64 #define MINPSIZE 128
65 #endif
66
67 static int byteorder(void);
68 static int nroot(BTREE *);
69 static int tmp(void);
70
71 /*
72 * __BT_OPEN -- Open a btree.
73 *
74 * Creates and fills a DB struct, and calls the routine that actually
75 * opens the btree.
76 *
77 * Parameters:
78 * fname: filename (NULL for in-memory trees)
79 * flags: open flag bits
80 * mode: open permission bits
81 * b: BTREEINFO pointer
82 *
83 * Returns:
84 * NULL on failure, pointer to DB on success.
85 *
86 */
87 DB *
__bt_open(const char * fname,int flags,mode_t mode,const BTREEINFO * openinfo,int dflags)88 __bt_open(const char *fname, int flags, mode_t mode, const BTREEINFO *openinfo,
89 int dflags)
90 {
91 struct stat sb;
92 BTMETA m;
93 BTREE *t;
94 BTREEINFO b;
95 DB *dbp;
96 pgno_t ncache;
97 ssize_t nr;
98 int machine_lorder, saved_errno;
99
100 t = NULL;
101
102 /*
103 * Intention is to make sure all of the user's selections are okay
104 * here and then use them without checking. Can't be complete, since
105 * we don't know the right page size, lorder or flags until the backing
106 * file is opened. Also, the file's page size can cause the cachesize
107 * to change.
108 */
109 machine_lorder = byteorder();
110 if (openinfo) {
111 b = *openinfo;
112
113 /* Flags: R_DUP. */
114 if (b.flags & ~(R_DUP))
115 goto einval;
116
117 /*
118 * Page size must be indx_t aligned and >= MINPSIZE. Default
119 * page size is set farther on, based on the underlying file
120 * transfer size.
121 */
122 if (b.psize &&
123 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
124 b.psize & (sizeof(indx_t) - 1) ))
125 goto einval;
126
127 /* Minimum number of keys per page; absolute minimum is 2. */
128 if (b.minkeypage) {
129 if (b.minkeypage < 2)
130 goto einval;
131 } else
132 b.minkeypage = DEFMINKEYPAGE;
133
134 /* If no comparison, use default comparison and prefix. */
135 if (b.compare == NULL) {
136 b.compare = __bt_defcmp;
137 if (b.prefix == NULL)
138 b.prefix = __bt_defpfx;
139 }
140
141 if (b.lorder == 0)
142 b.lorder = machine_lorder;
143 } else {
144 b.compare = __bt_defcmp;
145 b.cachesize = 0;
146 b.flags = 0;
147 b.lorder = machine_lorder;
148 b.minkeypage = DEFMINKEYPAGE;
149 b.prefix = __bt_defpfx;
150 b.psize = 0;
151 }
152
153 /* Check for the ubiquitous PDP-11. */
154 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
155 goto einval;
156
157 /* Allocate and initialize DB and BTREE structures. */
158 if ((t = (BTREE *)calloc(1, sizeof(BTREE))) == NULL)
159 goto err;
160 t->bt_fd = -1; /* Don't close unopened fd on error. */
161 t->bt_lorder = b.lorder;
162 t->bt_order = NOT;
163 t->bt_cmp = b.compare;
164 t->bt_pfx = b.prefix;
165 t->bt_rfd = -1;
166
167 if ((t->bt_dbp = dbp = (DB *)calloc(1, sizeof(DB))) == NULL)
168 goto err;
169 if (t->bt_lorder != machine_lorder)
170 F_SET(t, B_NEEDSWAP);
171
172 dbp->type = DB_BTREE;
173 dbp->internal = t;
174 dbp->close = __bt_close;
175 dbp->del = __bt_delete;
176 dbp->fd = __bt_fd;
177 dbp->get = __bt_get;
178 dbp->put = __bt_put;
179 dbp->seq = __bt_seq;
180 dbp->sync = __bt_sync;
181
182 /*
183 * If no file name was supplied, this is an in-memory btree and we
184 * open a backing temporary file. Otherwise, it's a disk-based tree.
185 */
186 if (fname) {
187 switch (flags & O_ACCMODE) {
188 case O_RDONLY:
189 F_SET(t, B_RDONLY);
190 break;
191 case O_RDWR:
192 break;
193 case O_WRONLY:
194 default:
195 goto einval;
196 }
197
198 if ((t->bt_fd = _open(fname, flags | O_CLOEXEC, mode)) < 0)
199 goto err;
200
201 } else {
202 if ((flags & O_ACCMODE) != O_RDWR)
203 goto einval;
204 if ((t->bt_fd = tmp()) == -1)
205 goto err;
206 F_SET(t, B_INMEM);
207 }
208
209 if (_fcntl(t->bt_fd, F_SETFD, 1) == -1)
210 goto err;
211
212 if (_fstat(t->bt_fd, &sb))
213 goto err;
214 if (sb.st_size) {
215 if ((nr = _read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
216 goto err;
217 if (nr != sizeof(BTMETA))
218 goto eftype;
219
220 /*
221 * Read in the meta-data. This can change the notion of what
222 * the lorder, page size and flags are, and, when the page size
223 * changes, the cachesize value can change too. If the user
224 * specified the wrong byte order for an existing database, we
225 * don't bother to return an error, we just clear the NEEDSWAP
226 * bit.
227 */
228 if (m.magic == BTREEMAGIC)
229 F_CLR(t, B_NEEDSWAP);
230 else {
231 F_SET(t, B_NEEDSWAP);
232 M_32_SWAP(m.magic);
233 M_32_SWAP(m.version);
234 M_32_SWAP(m.psize);
235 M_32_SWAP(m.free);
236 M_32_SWAP(m.nrecs);
237 M_32_SWAP(m.flags);
238 }
239 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
240 goto eftype;
241 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
242 m.psize & (sizeof(indx_t) - 1) )
243 goto eftype;
244 if (m.flags & ~SAVEMETA)
245 goto eftype;
246 b.psize = m.psize;
247 F_SET(t, m.flags);
248 t->bt_free = m.free;
249 t->bt_nrecs = m.nrecs;
250 } else {
251 /*
252 * Set the page size to the best value for I/O to this file.
253 * Don't overflow the page offset type.
254 *
255 * Stop using st_blksize, its meaningless on a modern system
256 * and can cause db to operate inefficiently. Instead we
257 * use NOMPSIZE.
258 */
259 if (b.psize == 0) {
260 b.psize = NOMPSIZE;
261 if (b.psize < MINPSIZE)
262 b.psize = MINPSIZE;
263 if (b.psize > MAX_PAGE_OFFSET + 1)
264 b.psize = MAX_PAGE_OFFSET + 1;
265 }
266
267 /* Set flag if duplicates permitted. */
268 if (!(b.flags & R_DUP))
269 F_SET(t, B_NODUPS);
270
271 t->bt_free = P_INVALID;
272 t->bt_nrecs = 0;
273 F_SET(t, B_METADIRTY);
274 }
275
276 t->bt_psize = b.psize;
277
278 /* Set the cache size; must be a multiple of the page size. */
279 if (b.cachesize && b.cachesize & (b.psize - 1) )
280 b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1;
281 if (b.cachesize < b.psize * MINCACHE)
282 b.cachesize = b.psize * MINCACHE;
283
284 /* Calculate number of pages to cache. */
285 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
286
287 /*
288 * The btree data structure requires that at least two keys can fit on
289 * a page, but other than that there's no fixed requirement. The user
290 * specified a minimum number per page, and we translated that into the
291 * number of bytes a key/data pair can use before being placed on an
292 * overflow page. This calculation includes the page header, the size
293 * of the index referencing the leaf item and the size of the leaf item
294 * structure. Also, don't let the user specify a minkeypage such that
295 * a key/data pair won't fit even if both key and data are on overflow
296 * pages.
297 */
298 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
299 (sizeof(indx_t) + NBLEAFDBT(0, 0));
300 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
301 t->bt_ovflsize =
302 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
303
304 /* Initialize the buffer pool. */
305 if ((t->bt_mp =
306 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
307 goto err;
308 if (!F_ISSET(t, B_INMEM))
309 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
310
311 /* Create a root page if new tree. */
312 if (nroot(t) == RET_ERROR)
313 goto err;
314
315 /* Global flags. */
316 if (dflags & DB_LOCK)
317 F_SET(t, B_DB_LOCK);
318 if (dflags & DB_SHMEM)
319 F_SET(t, B_DB_SHMEM);
320 if (dflags & DB_TXN)
321 F_SET(t, B_DB_TXN);
322
323 return (dbp);
324
325 einval: errno = EINVAL;
326 goto err;
327
328 eftype: errno = EFTYPE;
329 goto err;
330
331 err: saved_errno = errno;
332 if (t) {
333 if (t->bt_dbp)
334 free(t->bt_dbp);
335 if (t->bt_fd != -1)
336 _close(t->bt_fd);
337 free(t);
338 }
339 errno = saved_errno;
340 return (NULL);
341 }
342
343 /*
344 * NROOT -- Create the root of a new tree.
345 *
346 * Parameters:
347 * t: tree
348 *
349 * Returns:
350 * RET_ERROR, RET_SUCCESS
351 */
352 static int
nroot(BTREE * t)353 nroot(BTREE *t)
354 {
355 PAGE *meta, *root;
356 pgno_t npg;
357
358 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
359 if (root->lower == 0 &&
360 root->pgno == 0 &&
361 root->linp[0] == 0) {
362 mpool_delete(t->bt_mp, root);
363 errno = EINVAL;
364 } else {
365 mpool_put(t->bt_mp, root, 0);
366 return (RET_SUCCESS);
367 }
368 }
369 if (errno != EINVAL) /* It's OK to not exist. */
370 return (RET_ERROR);
371 errno = 0;
372
373 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
374 return (RET_ERROR);
375
376 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
377 return (RET_ERROR);
378
379 if (npg != P_ROOT)
380 return (RET_ERROR);
381 root->pgno = npg;
382 root->prevpg = root->nextpg = P_INVALID;
383 root->lower = BTDATAOFF;
384 root->upper = t->bt_psize;
385 root->flags = P_BLEAF;
386 memset(meta, 0, t->bt_psize);
387 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
388 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
389 return (RET_SUCCESS);
390 }
391
392 static int
tmp(void)393 tmp(void)
394 {
395 sigset_t set, oset;
396 int fd, len;
397 char *envtmp = NULL;
398 char path[MAXPATHLEN];
399
400 if (issetugid() == 0)
401 envtmp = getenv("TMPDIR");
402 len = snprintf(path,
403 sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
404 if (len < 0 || len >= (int)sizeof(path)) {
405 errno = ENAMETOOLONG;
406 return(-1);
407 }
408
409 sigfillset(&set);
410 _sigprocmask(SIG_BLOCK, &set, &oset);
411 if ((fd = mkostemp(path, O_CLOEXEC)) != -1)
412 _unlink(path);
413 _sigprocmask(SIG_SETMASK, &oset, NULL);
414 return(fd);
415 }
416
417 static int
byteorder(void)418 byteorder(void)
419 {
420 uint32_t x;
421 unsigned char *p;
422
423 x = 0x01020304;
424 p = (unsigned char *)&x;
425 switch (*p) {
426 case 1:
427 return (BIG_ENDIAN);
428 case 4:
429 return (LITTLE_ENDIAN);
430 default:
431 return (0);
432 }
433 }
434
435 int
__bt_fd(const DB * dbp)436 __bt_fd(const DB *dbp)
437 {
438 BTREE *t;
439
440 t = dbp->internal;
441
442 /* Toss any page pinned across calls. */
443 if (t->bt_pinned != NULL) {
444 mpool_put(t->bt_mp, t->bt_pinned, 0);
445 t->bt_pinned = NULL;
446 }
447
448 /* In-memory database can't have a file descriptor. */
449 if (F_ISSET(t, B_INMEM)) {
450 errno = ENOENT;
451 return (-1);
452 }
453 return (t->bt_fd);
454 }
455