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 /*
40 * Implementation of btree access method for 4.4BSD.
41 *
42 * The design here was originally based on that of the btree access method
43 * used in the Postgres database system at UC Berkeley. This implementation
44 * is wholly independent of the Postgres code.
45 */
46
47 #include "namespace.h"
48 #include <sys/param.h>
49 #include <sys/stat.h>
50
51 #include <errno.h>
52 #include <fcntl.h>
53 #include <limits.h>
54 #include <signal.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59 #include "un-namespace.h"
60 #include "libc_private.h"
61
62 #include <db.h>
63 #include "btree.h"
64
65 #ifdef DEBUG
66 #undef MINPSIZE
67 #define MINPSIZE 128
68 #endif
69
70 static int byteorder(void);
71 static int nroot(BTREE *);
72 static int tmp(void);
73
74 /*
75 * __BT_OPEN -- Open a btree.
76 *
77 * Creates and fills a DB struct, and calls the routine that actually
78 * opens the btree.
79 *
80 * Parameters:
81 * fname: filename (NULL for in-memory trees)
82 * flags: open flag bits
83 * mode: open permission bits
84 * b: BTREEINFO pointer
85 *
86 * Returns:
87 * NULL on failure, pointer to DB on success.
88 *
89 */
90 DB *
__bt_open(const char * fname,int flags,int mode,const BTREEINFO * openinfo,int dflags)91 __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, int dflags)
92 {
93 struct stat sb;
94 BTMETA m;
95 BTREE *t;
96 BTREEINFO b;
97 DB *dbp;
98 pgno_t ncache;
99 ssize_t nr;
100 int machine_lorder, saved_errno;
101
102 t = NULL;
103
104 /*
105 * Intention is to make sure all of the user's selections are okay
106 * here and then use them without checking. Can't be complete, since
107 * we don't know the right page size, lorder or flags until the backing
108 * file is opened. Also, the file's page size can cause the cachesize
109 * to change.
110 */
111 machine_lorder = byteorder();
112 if (openinfo) {
113 b = *openinfo;
114
115 /* Flags: R_DUP. */
116 if (b.flags & ~(R_DUP))
117 goto einval;
118
119 /*
120 * Page size must be indx_t aligned and >= MINPSIZE. Default
121 * page size is set farther on, based on the underlying file
122 * transfer size.
123 */
124 if (b.psize &&
125 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
126 b.psize & (sizeof(indx_t) - 1) ))
127 goto einval;
128
129 /* Minimum number of keys per page; absolute minimum is 2. */
130 if (b.minkeypage) {
131 if (b.minkeypage < 2)
132 goto einval;
133 } else
134 b.minkeypage = DEFMINKEYPAGE;
135
136 /* If no comparison, use default comparison and prefix. */
137 if (b.compare == NULL) {
138 b.compare = __bt_defcmp;
139 if (b.prefix == NULL)
140 b.prefix = __bt_defpfx;
141 }
142
143 if (b.lorder == 0)
144 b.lorder = machine_lorder;
145 } else {
146 b.compare = __bt_defcmp;
147 b.cachesize = 0;
148 b.flags = 0;
149 b.lorder = machine_lorder;
150 b.minkeypage = DEFMINKEYPAGE;
151 b.prefix = __bt_defpfx;
152 b.psize = 0;
153 }
154
155 /* Check for the ubiquitous PDP-11. */
156 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
157 goto einval;
158
159 /* Allocate and initialize DB and BTREE structures. */
160 if ((t = (BTREE *)calloc(1, sizeof(BTREE))) == NULL)
161 goto err;
162 t->bt_fd = -1; /* Don't close unopened fd on error. */
163 t->bt_lorder = b.lorder;
164 t->bt_order = NOT;
165 t->bt_cmp = b.compare;
166 t->bt_pfx = b.prefix;
167 t->bt_rfd = -1;
168
169 if ((t->bt_dbp = dbp = (DB *)calloc(1, sizeof(DB))) == NULL)
170 goto err;
171 if (t->bt_lorder != machine_lorder)
172 F_SET(t, B_NEEDSWAP);
173
174 dbp->type = DB_BTREE;
175 dbp->internal = t;
176 dbp->close = __bt_close;
177 dbp->del = __bt_delete;
178 dbp->fd = __bt_fd;
179 dbp->get = __bt_get;
180 dbp->put = __bt_put;
181 dbp->seq = __bt_seq;
182 dbp->sync = __bt_sync;
183
184 /*
185 * If no file name was supplied, this is an in-memory btree and we
186 * open a backing temporary file. Otherwise, it's a disk-based tree.
187 */
188 if (fname) {
189 switch (flags & O_ACCMODE) {
190 case O_RDONLY:
191 F_SET(t, B_RDONLY);
192 break;
193 case O_RDWR:
194 break;
195 case O_WRONLY:
196 default:
197 goto einval;
198 }
199
200 if ((t->bt_fd = _open(fname, flags | O_CLOEXEC, mode)) < 0)
201 goto err;
202
203 } else {
204 if ((flags & O_ACCMODE) != O_RDWR)
205 goto einval;
206 if ((t->bt_fd = tmp()) == -1)
207 goto err;
208 F_SET(t, B_INMEM);
209 }
210
211 if (_fstat(t->bt_fd, &sb))
212 goto err;
213 if (sb.st_size) {
214 if ((nr = _read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
215 goto err;
216 if (nr != sizeof(BTMETA))
217 goto eftype;
218
219 /*
220 * Read in the meta-data. This can change the notion of what
221 * the lorder, page size and flags are, and, when the page size
222 * changes, the cachesize value can change too. If the user
223 * specified the wrong byte order for an existing database, we
224 * don't bother to return an error, we just clear the NEEDSWAP
225 * bit.
226 */
227 if (m.magic == BTREEMAGIC)
228 F_CLR(t, B_NEEDSWAP);
229 else {
230 F_SET(t, B_NEEDSWAP);
231 M_32_SWAP(m.magic);
232 M_32_SWAP(m.version);
233 M_32_SWAP(m.psize);
234 M_32_SWAP(m.free);
235 M_32_SWAP(m.nrecs);
236 M_32_SWAP(m.flags);
237 }
238 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
239 goto eftype;
240 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
241 m.psize & (sizeof(indx_t) - 1) )
242 goto eftype;
243 if (m.flags & ~SAVEMETA)
244 goto eftype;
245 b.psize = m.psize;
246 F_SET(t, m.flags);
247 t->bt_free = m.free;
248 t->bt_nrecs = m.nrecs;
249 } else {
250 /*
251 * Set the page size to the best value for I/O to this file.
252 * Don't overflow the page offset type.
253 */
254 if (b.psize == 0) {
255 b.psize = sb.st_blksize;
256 if (b.psize < MINPSIZE)
257 b.psize = MINPSIZE;
258 if (b.psize > MAX_PAGE_OFFSET + 1)
259 b.psize = MAX_PAGE_OFFSET + 1;
260 }
261
262 /* Set flag if duplicates permitted. */
263 if (!(b.flags & R_DUP))
264 F_SET(t, B_NODUPS);
265
266 t->bt_free = P_INVALID;
267 t->bt_nrecs = 0;
268 F_SET(t, B_METADIRTY);
269 }
270
271 t->bt_psize = b.psize;
272
273 /* Set the cache size; must be a multiple of the page size. */
274 if (b.cachesize && b.cachesize & (b.psize - 1) )
275 b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1;
276 if (b.cachesize < b.psize * MINCACHE)
277 b.cachesize = b.psize * MINCACHE;
278
279 /* Calculate number of pages to cache. */
280 ncache = howmany(b.cachesize, t->bt_psize);
281
282 /*
283 * The btree data structure requires that at least two keys can fit on
284 * a page, but other than that there's no fixed requirement. The user
285 * specified a minimum number per page, and we translated that into the
286 * number of bytes a key/data pair can use before being placed on an
287 * overflow page. This calculation includes the page header, the size
288 * of the index referencing the leaf item and the size of the leaf item
289 * structure. Also, don't let the user specify a minkeypage such that
290 * a key/data pair won't fit even if both key and data are on overflow
291 * pages.
292 */
293 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
294 (sizeof(indx_t) + NBLEAFDBT(0, 0));
295 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
296 t->bt_ovflsize =
297 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
298
299 /* Initialize the buffer pool. */
300 if ((t->bt_mp =
301 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
302 goto err;
303 if (!F_ISSET(t, B_INMEM))
304 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
305
306 /* Create a root page if new tree. */
307 if (nroot(t) == RET_ERROR)
308 goto err;
309
310 /* Global flags. */
311 if (dflags & DB_LOCK)
312 F_SET(t, B_DB_LOCK);
313 if (dflags & DB_SHMEM)
314 F_SET(t, B_DB_SHMEM);
315 if (dflags & DB_TXN)
316 F_SET(t, B_DB_TXN);
317
318 return (dbp);
319
320 einval: errno = EINVAL;
321 goto err;
322
323 eftype: errno = EFTYPE;
324 goto err;
325
326 err: saved_errno = errno;
327 if (t) {
328 if (t->bt_dbp)
329 free(t->bt_dbp);
330 if (t->bt_fd != -1)
331 (void)_close(t->bt_fd);
332 free(t);
333 }
334 errno = saved_errno;
335 return (NULL);
336 }
337
338 /*
339 * NROOT -- Create the root of a new tree.
340 *
341 * Parameters:
342 * t: tree
343 *
344 * Returns:
345 * RET_ERROR, RET_SUCCESS
346 */
347 static int
nroot(BTREE * t)348 nroot(BTREE *t)
349 {
350 PAGE *meta, *root;
351 pgno_t npg;
352
353 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
354 if (root->lower == 0 &&
355 root->pgno == 0 &&
356 root->linp[0] == 0) {
357 mpool_delete(t->bt_mp, root);
358 errno = EINVAL;
359 } else {
360 mpool_put(t->bt_mp, root, 0);
361 return (RET_SUCCESS);
362 }
363 }
364 if (errno != EINVAL) /* It's OK to not exist. */
365 return (RET_ERROR);
366 errno = 0;
367
368 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
369 return (RET_ERROR);
370
371 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
372 return (RET_ERROR);
373
374 if (npg != P_ROOT)
375 return (RET_ERROR);
376 root->pgno = npg;
377 root->prevpg = root->nextpg = P_INVALID;
378 root->lower = BTDATAOFF;
379 root->upper = t->bt_psize;
380 root->flags = P_BLEAF;
381 memset(meta, 0, t->bt_psize);
382 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
383 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
384 return (RET_SUCCESS);
385 }
386
387 static int
tmp(void)388 tmp(void)
389 {
390 sigset_t set, oset;
391 int fd, len;
392 char *envtmp = NULL;
393 char path[MAXPATHLEN];
394
395 if (issetugid() == 0)
396 envtmp = getenv("TMPDIR");
397 len = snprintf(path,
398 sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
399 if (len < 0 || len >= (int)sizeof(path)) {
400 errno = ENAMETOOLONG;
401 return(-1);
402 }
403
404 (void)sigfillset(&set);
405 (void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
406 if ((fd = mkostemp(path, O_CLOEXEC)) != -1)
407 (void)unlink(path);
408 (void)__libc_sigprocmask(SIG_SETMASK, &oset, NULL);
409 return(fd);
410 }
411
412 static int
byteorder(void)413 byteorder(void)
414 {
415 u_int32_t x;
416 u_char *p;
417
418 x = 0x01020304;
419 p = (u_char *)&x;
420 switch (*p) {
421 case 1:
422 return (BIG_ENDIAN);
423 case 4:
424 return (LITTLE_ENDIAN);
425 default:
426 return (0);
427 }
428 }
429
430 int
__bt_fd(const DB * dbp)431 __bt_fd(const DB *dbp)
432 {
433 BTREE *t;
434
435 t = dbp->internal;
436
437 /* Toss any page pinned across calls. */
438 if (t->bt_pinned != NULL) {
439 mpool_put(t->bt_mp, t->bt_pinned, 0);
440 t->bt_pinned = NULL;
441 }
442
443 /* In-memory database can't have a file descriptor. */
444 if (F_ISSET(t, B_INMEM)) {
445 errno = ENOENT;
446 return (-1);
447 }
448 return (t->bt_fd);
449 }
450