1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)bt_open.c 8.10 (Berkeley) 8/17/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD: stable/12/lib/libc/db/btree/bt_open.c 326025 2017-11-20 19:49:47Z pfg $");
40
41 /*
42 * Implementation of btree access method for 4.4BSD.
43 *
44 * The design here was originally based on that of the btree access method
45 * used in the Postgres database system at UC Berkeley. This implementation
46 * is wholly independent of the Postgres code.
47 */
48
49 #include "namespace.h"
50 #include <sys/param.h>
51 #include <sys/stat.h>
52
53 #include <errno.h>
54 #include <fcntl.h>
55 #include <limits.h>
56 #include <signal.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <unistd.h>
61 #include "un-namespace.h"
62 #include "libc_private.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 static int tmp(void);
75
76 /*
77 * __BT_OPEN -- Open a btree.
78 *
79 * Creates and fills a DB struct, and calls the routine that actually
80 * opens the btree.
81 *
82 * Parameters:
83 * fname: filename (NULL for in-memory trees)
84 * flags: open flag bits
85 * mode: open permission bits
86 * b: BTREEINFO pointer
87 *
88 * Returns:
89 * NULL on failure, pointer to DB on success.
90 *
91 */
92 DB *
__bt_open(const char * fname,int flags,int mode,const BTREEINFO * openinfo,int dflags)93 __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, 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 int machine_lorder, saved_errno;
103
104 t = NULL;
105
106 /*
107 * Intention is to make sure all of the user's selections are okay
108 * here and then use them without checking. Can't be complete, since
109 * we don't know the right page size, lorder or flags until the backing
110 * file is opened. Also, the file's page size can cause the cachesize
111 * to change.
112 */
113 machine_lorder = byteorder();
114 if (openinfo) {
115 b = *openinfo;
116
117 /* Flags: R_DUP. */
118 if (b.flags & ~(R_DUP))
119 goto einval;
120
121 /*
122 * Page size must be indx_t aligned and >= MINPSIZE. Default
123 * page size is set farther on, based on the underlying file
124 * transfer size.
125 */
126 if (b.psize &&
127 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
128 b.psize & (sizeof(indx_t) - 1) ))
129 goto einval;
130
131 /* Minimum number of keys per page; absolute minimum is 2. */
132 if (b.minkeypage) {
133 if (b.minkeypage < 2)
134 goto einval;
135 } else
136 b.minkeypage = DEFMINKEYPAGE;
137
138 /* If no comparison, use default comparison and prefix. */
139 if (b.compare == NULL) {
140 b.compare = __bt_defcmp;
141 if (b.prefix == NULL)
142 b.prefix = __bt_defpfx;
143 }
144
145 if (b.lorder == 0)
146 b.lorder = machine_lorder;
147 } else {
148 b.compare = __bt_defcmp;
149 b.cachesize = 0;
150 b.flags = 0;
151 b.lorder = machine_lorder;
152 b.minkeypage = DEFMINKEYPAGE;
153 b.prefix = __bt_defpfx;
154 b.psize = 0;
155 }
156
157 /* Check for the ubiquitous PDP-11. */
158 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
159 goto einval;
160
161 /* Allocate and initialize DB and BTREE structures. */
162 if ((t = (BTREE *)calloc(1, sizeof(BTREE))) == NULL)
163 goto err;
164 t->bt_fd = -1; /* Don't close unopened fd on error. */
165 t->bt_lorder = b.lorder;
166 t->bt_order = NOT;
167 t->bt_cmp = b.compare;
168 t->bt_pfx = b.prefix;
169 t->bt_rfd = -1;
170
171 if ((t->bt_dbp = dbp = (DB *)calloc(1, sizeof(DB))) == NULL)
172 goto err;
173 if (t->bt_lorder != machine_lorder)
174 F_SET(t, B_NEEDSWAP);
175
176 dbp->type = DB_BTREE;
177 dbp->internal = t;
178 dbp->close = __bt_close;
179 dbp->del = __bt_delete;
180 dbp->fd = __bt_fd;
181 dbp->get = __bt_get;
182 dbp->put = __bt_put;
183 dbp->seq = __bt_seq;
184 dbp->sync = __bt_sync;
185
186 /*
187 * If no file name was supplied, this is an in-memory btree and we
188 * open a backing temporary file. Otherwise, it's a disk-based tree.
189 */
190 if (fname) {
191 switch (flags & O_ACCMODE) {
192 case O_RDONLY:
193 F_SET(t, B_RDONLY);
194 break;
195 case O_RDWR:
196 break;
197 case O_WRONLY:
198 default:
199 goto einval;
200 }
201
202 if ((t->bt_fd = _open(fname, flags | O_CLOEXEC, mode)) < 0)
203 goto err;
204
205 } else {
206 if ((flags & O_ACCMODE) != O_RDWR)
207 goto einval;
208 if ((t->bt_fd = tmp()) == -1)
209 goto err;
210 F_SET(t, B_INMEM);
211 }
212
213 if (_fstat(t->bt_fd, &sb))
214 goto err;
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 = howmany(b.cachesize, 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 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
296 (sizeof(indx_t) + NBLEAFDBT(0, 0));
297 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
298 t->bt_ovflsize =
299 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
300
301 /* Initialize the buffer pool. */
302 if ((t->bt_mp =
303 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
304 goto err;
305 if (!F_ISSET(t, B_INMEM))
306 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
307
308 /* Create a root page if new tree. */
309 if (nroot(t) == RET_ERROR)
310 goto err;
311
312 /* Global flags. */
313 if (dflags & DB_LOCK)
314 F_SET(t, B_DB_LOCK);
315 if (dflags & DB_SHMEM)
316 F_SET(t, B_DB_SHMEM);
317 if (dflags & DB_TXN)
318 F_SET(t, B_DB_TXN);
319
320 return (dbp);
321
322 einval: errno = EINVAL;
323 goto err;
324
325 eftype: errno = EFTYPE;
326 goto err;
327
328 err: saved_errno = errno;
329 if (t) {
330 if (t->bt_dbp)
331 free(t->bt_dbp);
332 if (t->bt_fd != -1)
333 (void)_close(t->bt_fd);
334 free(t);
335 }
336 errno = saved_errno;
337 return (NULL);
338 }
339
340 /*
341 * NROOT -- Create the root of a new tree.
342 *
343 * Parameters:
344 * t: tree
345 *
346 * Returns:
347 * RET_ERROR, RET_SUCCESS
348 */
349 static int
nroot(BTREE * t)350 nroot(BTREE *t)
351 {
352 PAGE *meta, *root;
353 pgno_t npg;
354
355 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
356 if (root->lower == 0 &&
357 root->pgno == 0 &&
358 root->linp[0] == 0) {
359 mpool_delete(t->bt_mp, root);
360 errno = EINVAL;
361 } else {
362 mpool_put(t->bt_mp, root, 0);
363 return (RET_SUCCESS);
364 }
365 }
366 if (errno != EINVAL) /* It's OK to not exist. */
367 return (RET_ERROR);
368 errno = 0;
369
370 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
371 return (RET_ERROR);
372
373 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
374 return (RET_ERROR);
375
376 if (npg != P_ROOT)
377 return (RET_ERROR);
378 root->pgno = npg;
379 root->prevpg = root->nextpg = P_INVALID;
380 root->lower = BTDATAOFF;
381 root->upper = t->bt_psize;
382 root->flags = P_BLEAF;
383 memset(meta, 0, t->bt_psize);
384 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
385 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
386 return (RET_SUCCESS);
387 }
388
389 static int
tmp(void)390 tmp(void)
391 {
392 sigset_t set, oset;
393 int fd, len;
394 char *envtmp = NULL;
395 char path[MAXPATHLEN];
396
397 if (issetugid() == 0)
398 envtmp = getenv("TMPDIR");
399 len = snprintf(path,
400 sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
401 if (len < 0 || len >= (int)sizeof(path)) {
402 errno = ENAMETOOLONG;
403 return(-1);
404 }
405
406 (void)sigfillset(&set);
407 (void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
408 if ((fd = mkostemp(path, O_CLOEXEC)) != -1)
409 (void)unlink(path);
410 (void)__libc_sigprocmask(SIG_SETMASK, &oset, NULL);
411 return(fd);
412 }
413
414 static int
byteorder(void)415 byteorder(void)
416 {
417 u_int32_t x;
418 u_char *p;
419
420 x = 0x01020304;
421 p = (u_char *)&x;
422 switch (*p) {
423 case 1:
424 return (BIG_ENDIAN);
425 case 4:
426 return (LITTLE_ENDIAN);
427 default:
428 return (0);
429 }
430 }
431
432 int
__bt_fd(const DB * dbp)433 __bt_fd(const DB *dbp)
434 {
435 BTREE *t;
436
437 t = dbp->internal;
438
439 /* Toss any page pinned across calls. */
440 if (t->bt_pinned != NULL) {
441 mpool_put(t->bt_mp, t->bt_pinned, 0);
442 t->bt_pinned = NULL;
443 }
444
445 /* In-memory database can't have a file descriptor. */
446 if (F_ISSET(t, B_INMEM)) {
447 errno = ENOENT;
448 return (-1);
449 }
450 return (t->bt_fd);
451 }
452