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_open.c 8.11 (Berkeley) 11/2/95";
39 #endif /* LIBC_SCCS and not lint */
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 <sys/param.h>
50 #include <sys/stat.h>
51
52 #include <errno.h>
53 #include <fcntl.h>
54 #include <limits.h>
55 #include <signal.h>
56 #include <stdio.h>
57 #include <stdlib.h>
58 #include <string.h>
59 #include <unistd.h>
60
61 #include "db-int.h"
62 #include "btree.h"
63
64 #ifdef DEBUG
65 #undef MINPSIZE
66 #define MINPSIZE 128
67 #endif
68
69 static int byteorder __P((void));
70 static int nroot __P((BTREE *));
71 static int tmp __P((void));
72
73 /*
74 * __BT_OPEN -- Open a btree.
75 *
76 * Creates and fills a DB struct, and calls the routine that actually
77 * opens the btree.
78 *
79 * Parameters:
80 * fname: filename (NULL for in-memory trees)
81 * flags: open flag bits
82 * mode: open permission bits
83 * b: BTREEINFO pointer
84 *
85 * Returns:
86 * NULL on failure, pointer to DB on success.
87 *
88 */
89 DB *
__bt_open(fname,flags,mode,openinfo,dflags)90 __bt_open(fname, flags, mode, openinfo, dflags)
91 const char *fname;
92 int flags, mode, dflags;
93 const BTREEINFO *openinfo;
94 {
95 struct stat sb;
96 BTMETA m;
97 BTREE *t;
98 BTREEINFO b;
99 DB *dbp;
100 db_pgno_t ncache;
101 ssize_t nr;
102 int machine_lorder;
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 != DB_BIG_ENDIAN && b.lorder != DB_LITTLE_ENDIAN)
159 goto einval;
160
161 /* Allocate and initialize DB and BTREE structures. */
162 if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
163 goto err;
164 memset(t, 0, sizeof(BTREE));
165 t->bt_fd = -1; /* Don't close unopened fd on error. */
166 t->bt_lorder = b.lorder;
167 t->bt_order = NOT;
168 t->bt_cmp = b.compare;
169 t->bt_pfx = b.prefix;
170 t->bt_rfd = -1;
171
172 if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
173 goto err;
174 memset(t->bt_dbp, 0, sizeof(DB));
175 if (t->bt_lorder != machine_lorder)
176 F_SET(t, B_NEEDSWAP);
177
178 dbp->type = DB_BTREE;
179 dbp->internal = t;
180 dbp->close = __bt_close;
181 dbp->del = __bt_delete;
182 dbp->fd = __bt_fd;
183 dbp->get = __bt_get;
184 dbp->put = __bt_put;
185 dbp->seq = __bt_seq;
186 dbp->sync = __bt_sync;
187
188 /*
189 * If no file name was supplied, this is an in-memory btree and we
190 * open a backing temporary file. Otherwise, it's a disk-based tree.
191 */
192 if (fname) {
193 switch (flags & O_ACCMODE) {
194 case O_RDONLY:
195 F_SET(t, B_RDONLY);
196 break;
197 case O_RDWR:
198 break;
199 case O_WRONLY:
200 default:
201 goto einval;
202 }
203
204 if ((t->bt_fd = open(fname, flags | O_BINARY, mode)) < 0)
205 goto err;
206
207 } else {
208 if ((flags & O_ACCMODE) != O_RDWR)
209 goto einval;
210 if ((t->bt_fd = tmp()) == -1)
211 goto err;
212 F_SET(t, B_INMEM);
213 }
214
215 if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
216 goto err;
217
218 if (fstat(t->bt_fd, &sb))
219 goto err;
220 if (sb.st_size) {
221 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
222 goto err;
223 if (nr != sizeof(BTMETA))
224 goto eftype;
225
226 /*
227 * Read in the meta-data. This can change the notion of what
228 * the lorder, page size and flags are, and, when the page size
229 * changes, the cachesize value can change too. If the user
230 * specified the wrong byte order for an existing database, we
231 * don't bother to return an error, we just clear the NEEDSWAP
232 * bit.
233 */
234 if (m.magic == BTREEMAGIC)
235 F_CLR(t, B_NEEDSWAP);
236 else {
237 F_SET(t, B_NEEDSWAP);
238 M_32_SWAP(m.magic);
239 M_32_SWAP(m.version);
240 M_32_SWAP(m.psize);
241 M_32_SWAP(m.free);
242 M_32_SWAP(m.nrecs);
243 M_32_SWAP(m.flags);
244 }
245 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
246 goto eftype;
247 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
248 m.psize & (sizeof(indx_t) - 1))
249 goto eftype;
250 if (m.flags & ~SAVEMETA)
251 goto eftype;
252 b.psize = m.psize;
253 F_SET(t, m.flags);
254 t->bt_free = m.free;
255 t->bt_nrecs = m.nrecs;
256 } else {
257 /*
258 * Set the page size to the best value for I/O to this file.
259 * Don't overflow the page offset type.
260 */
261 if (b.psize == 0) {
262 b.psize = sb.st_blksize;
263 if (b.psize < MINPSIZE)
264 b.psize = MINPSIZE;
265 if (b.psize > MAX_PAGE_OFFSET + 1)
266 b.psize = MAX_PAGE_OFFSET + 1;
267 }
268
269 /* Set flag if duplicates permitted. */
270 if (!(b.flags & R_DUP))
271 F_SET(t, B_NODUPS);
272
273 t->bt_free = P_INVALID;
274 t->bt_nrecs = 0;
275 F_SET(t, B_METADIRTY);
276 }
277
278 t->bt_psize = b.psize;
279
280 /* Set the cache size; must be a multiple of the page size. */
281 if (b.cachesize && b.cachesize & (b.psize - 1))
282 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1;
283 if (b.cachesize < b.psize * MINCACHE)
284 b.cachesize = b.psize * MINCACHE;
285
286 /* Calculate number of pages to cache. */
287 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
288
289 /*
290 * The btree data structure requires that at least two keys can fit on
291 * a page, but other than that there's no fixed requirement. The user
292 * specified a minimum number per page, and we translated that into the
293 * number of bytes a key/data pair can use before being placed on an
294 * overflow page. This calculation includes the page header, the size
295 * of the index referencing the leaf item and the size of the leaf item
296 * structure. Also, don't let the user specify a minkeypage such that
297 * a key/data pair won't fit even if both key and data are on overflow
298 * pages.
299 */
300 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
301 (sizeof(indx_t) + NBLEAFDBT(0, 0));
302 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
303 t->bt_ovflsize =
304 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
305
306 /* Initialize the buffer pool. */
307 if ((t->bt_mp =
308 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
309 goto err;
310 if (!F_ISSET(t, B_INMEM))
311 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
312
313 /* Create a root page if new tree. */
314 if (nroot(t) == RET_ERROR)
315 goto err;
316
317 /* Global flags. */
318 if (dflags & DB_LOCK)
319 F_SET(t, B_DB_LOCK);
320 if (dflags & DB_SHMEM)
321 F_SET(t, B_DB_SHMEM);
322 if (dflags & DB_TXN)
323 F_SET(t, B_DB_TXN);
324
325 return (dbp);
326
327 einval: errno = EINVAL;
328 goto err;
329
330 eftype: errno = EFTYPE;
331 goto err;
332
333 err: if (t) {
334 if (t->bt_dbp)
335 free(t->bt_dbp);
336 if (t->bt_fd != -1)
337 (void)close(t->bt_fd);
338 free(t);
339 }
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(t)353 nroot(t)
354 BTREE *t;
355 {
356 PAGE *meta, *root;
357 db_pgno_t npg;
358
359 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
360 if (root->lower == 0 &&
361 root->pgno == 0 &&
362 root->linp[0] == 0) {
363 mpool_delete(t->bt_mp, root);
364 errno = EINVAL;
365 } else {
366 mpool_put(t->bt_mp, root, 0);
367 return (RET_SUCCESS);
368 }
369 }
370 if (errno != EINVAL) /* It's OK to not exist. */
371 return (RET_ERROR);
372 errno = 0;
373
374 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
375 return (RET_ERROR);
376
377 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
378 return (RET_ERROR);
379
380 if (npg != P_ROOT)
381 return (RET_ERROR);
382 root->pgno = npg;
383 root->prevpg = root->nextpg = P_INVALID;
384 root->lower = BTDATAOFF;
385 root->upper = t->bt_psize;
386 root->flags = P_BLEAF;
387 memset(meta, 0, t->bt_psize);
388 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
389 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
390 return (RET_SUCCESS);
391 }
392
393 static int
tmp()394 tmp()
395 {
396 #ifdef SIG_BLOCK
397 sigset_t set, oset;
398 #else
399 int oset;
400 #endif
401 int fd;
402 char *envtmp;
403 char path[MAXPATHLEN];
404 static char fn[] = "/bt.XXXXXX";
405
406 envtmp = getenv("TMPDIR");
407
408 /* this used to be done with snprintf(), but since snprintf
409 isn't in most operating systems, and overflow checking in
410 this case is easy, this is what is done */
411
412 if (envtmp && ((strlen(envtmp)+sizeof(fn)+1) > sizeof(path)))
413 return(-1);
414
415 (void)sprintf(path, "%s%s", (envtmp ? envtmp : "/tmp"), fn);
416
417 #ifdef SIG_BLOCK
418 (void)sigfillset(&set);
419 (void)sigprocmask(SIG_BLOCK, &set, &oset);
420 #else
421 oset = sigblock(~0);
422 #endif
423 if ((fd = mkstemp(path)) != -1)
424 (void)unlink(path);
425 #ifdef SIG_BLOCK
426 (void)sigprocmask(SIG_SETMASK, &oset, NULL);
427 #else
428 sigsetmask(oset);
429 #endif
430 #ifdef __CYGWIN32__
431 /* Ensure the fd is in binary mode. */
432 setmode(fd, O_BINARY);
433 #endif /* __CYGWIN32__ */
434
435 return(fd);
436 }
437
438 static int
byteorder()439 byteorder()
440 {
441 u_int32_t x;
442 u_char *p;
443
444 x = 0x01020304;
445 p = (u_char *)&x;
446 switch (*p) {
447 case 1:
448 return (DB_BIG_ENDIAN);
449 case 4:
450 return (DB_LITTLE_ENDIAN);
451 default:
452 return (0);
453 }
454 }
455
456 int
__bt_fd(dbp)457 __bt_fd(dbp)
458 const DB *dbp;
459 {
460 BTREE *t;
461
462 t = dbp->internal;
463
464 /* Toss any page pinned across calls. */
465 if (t->bt_pinned != NULL) {
466 mpool_put(t->bt_mp, t->bt_pinned, 0);
467 t->bt_pinned = NULL;
468 }
469
470 /* In-memory database can't have a file descriptor. */
471 if (F_ISSET(t, B_INMEM)) {
472 errno = ENOENT;
473 return (-1);
474 }
475 return (t->bt_fd);
476 }
477