1 #pragma ident "%Z%%M% %I% %E% SMI"
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. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39 #if defined(LIBC_SCCS) && !defined(lint)
40 static char sccsid[] = "@(#)bt_open.c 8.11 (Berkeley) 11/2/95";
41 #endif /* LIBC_SCCS and not lint */
42
43 /*
44 * Implementation of btree access method for 4.4BSD.
45 *
46 * The design here was originally based on that of the btree access method
47 * used in the Postgres database system at UC Berkeley. This implementation
48 * is wholly independent of the Postgres code.
49 */
50
51 #include <sys/param.h>
52 #include <sys/stat.h>
53
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
63 #include "db-int.h"
64 #include "btree.h"
65
66 #ifdef DEBUG
67 #undef MINPSIZE
68 #define MINPSIZE 128
69 #endif
70
71 static int byteorder __P((void));
72 static int nroot __P((BTREE *));
73 static int tmp __P((void));
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(fname,flags,mode,openinfo,dflags)92 __bt_open(fname, flags, mode, openinfo, dflags)
93 const char *fname;
94 int flags, mode, dflags;
95 const BTREEINFO *openinfo;
96 {
97 struct stat sb;
98 BTMETA m;
99 BTREE *t;
100 BTREEINFO b;
101 DB *dbp;
102 db_pgno_t ncache;
103 ssize_t nr;
104 int machine_lorder;
105
106 t = NULL;
107
108 /*
109 * Intention is to make sure all of the user's selections are okay
110 * here and then use them without checking. Can't be complete, since
111 * we don't know the right page size, lorder or flags until the backing
112 * file is opened. Also, the file's page size can cause the cachesize
113 * to change.
114 */
115 machine_lorder = byteorder();
116 if (openinfo) {
117 b = *openinfo;
118
119 /* Flags: R_DUP. */
120 if (b.flags & ~(R_DUP))
121 goto einval;
122
123 /*
124 * Page size must be indx_t aligned and >= MINPSIZE. Default
125 * page size is set farther on, based on the underlying file
126 * transfer size.
127 */
128 if (b.psize &&
129 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
130 b.psize & (sizeof(indx_t) - 1)))
131 goto einval;
132
133 /* Minimum number of keys per page; absolute minimum is 2. */
134 if (b.minkeypage) {
135 if (b.minkeypage < 2)
136 goto einval;
137 } else
138 b.minkeypage = DEFMINKEYPAGE;
139
140 /* If no comparison, use default comparison and prefix. */
141 if (b.compare == NULL) {
142 b.compare = __bt_defcmp;
143 if (b.prefix == NULL)
144 b.prefix = __bt_defpfx;
145 }
146
147 if (b.lorder == 0)
148 b.lorder = machine_lorder;
149 } else {
150 b.compare = __bt_defcmp;
151 b.cachesize = 0;
152 b.flags = 0;
153 b.lorder = machine_lorder;
154 b.minkeypage = DEFMINKEYPAGE;
155 b.prefix = __bt_defpfx;
156 b.psize = 0;
157 }
158
159 /* Check for the ubiquitous PDP-11. */
160 if (b.lorder != DB_BIG_ENDIAN && b.lorder != DB_LITTLE_ENDIAN)
161 goto einval;
162
163 /* Allocate and initialize DB and BTREE structures. */
164 if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
165 goto err;
166 memset(t, 0, sizeof(BTREE));
167 t->bt_fd = -1; /* Don't close unopened fd on error. */
168 t->bt_lorder = b.lorder;
169 t->bt_order = NOT;
170 t->bt_cmp = b.compare;
171 t->bt_pfx = b.prefix;
172 t->bt_rfd = -1;
173
174 if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
175 goto err;
176 memset(t->bt_dbp, 0, sizeof(DB));
177 if (t->bt_lorder != machine_lorder)
178 F_SET(t, B_NEEDSWAP);
179
180 dbp->type = DB_BTREE;
181 dbp->internal = t;
182 dbp->close = __bt_close;
183 dbp->del = __bt_delete;
184 dbp->fd = __bt_fd;
185 dbp->get = __bt_get;
186 dbp->put = __bt_put;
187 dbp->seq = __bt_seq;
188 dbp->sync = __bt_sync;
189
190 /*
191 * If no file name was supplied, this is an in-memory btree and we
192 * open a backing temporary file. Otherwise, it's a disk-based tree.
193 */
194 if (fname) {
195 switch (flags & O_ACCMODE) {
196 case O_RDONLY:
197 F_SET(t, B_RDONLY);
198 break;
199 case O_RDWR:
200 break;
201 case O_WRONLY:
202 default:
203 goto einval;
204 }
205
206 if ((t->bt_fd = open(fname, flags | O_BINARY, mode)) < 0)
207 goto err;
208
209 } else {
210 if ((flags & O_ACCMODE) != O_RDWR)
211 goto einval;
212 if ((t->bt_fd = tmp()) == -1)
213 goto err;
214 F_SET(t, B_INMEM);
215 }
216
217 if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
218 goto err;
219
220 if (fstat(t->bt_fd, &sb))
221 goto err;
222 if (sb.st_size) {
223 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
224 goto err;
225 if (nr != sizeof(BTMETA))
226 goto eftype;
227
228 /*
229 * Read in the meta-data. This can change the notion of what
230 * the lorder, page size and flags are, and, when the page size
231 * changes, the cachesize value can change too. If the user
232 * specified the wrong byte order for an existing database, we
233 * don't bother to return an error, we just clear the NEEDSWAP
234 * bit.
235 */
236 if (m.magic == BTREEMAGIC)
237 F_CLR(t, B_NEEDSWAP);
238 else {
239 F_SET(t, B_NEEDSWAP);
240 M_32_SWAP(m.magic);
241 M_32_SWAP(m.version);
242 M_32_SWAP(m.psize);
243 M_32_SWAP(m.free);
244 M_32_SWAP(m.nrecs);
245 M_32_SWAP(m.flags);
246 }
247 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
248 goto eftype;
249 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
250 m.psize & (sizeof(indx_t) - 1))
251 goto eftype;
252 if (m.flags & ~SAVEMETA)
253 goto eftype;
254 b.psize = m.psize;
255 F_SET(t, m.flags);
256 t->bt_free = m.free;
257 t->bt_nrecs = m.nrecs;
258 } else {
259 /*
260 * Set the page size to the best value for I/O to this file.
261 * Don't overflow the page offset type.
262 */
263 if (b.psize == 0) {
264 b.psize = sb.st_blksize;
265 if (b.psize < MINPSIZE)
266 b.psize = MINPSIZE;
267 if (b.psize > MAX_PAGE_OFFSET + 1)
268 b.psize = MAX_PAGE_OFFSET + 1;
269 }
270
271 /* Set flag if duplicates permitted. */
272 if (!(b.flags & R_DUP))
273 F_SET(t, B_NODUPS);
274
275 t->bt_free = P_INVALID;
276 t->bt_nrecs = 0;
277 F_SET(t, B_METADIRTY);
278 }
279
280 t->bt_psize = b.psize;
281
282 /* Set the cache size; must be a multiple of the page size. */
283 if (b.cachesize && b.cachesize & (b.psize - 1))
284 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1;
285 if (b.cachesize < b.psize * MINCACHE)
286 b.cachesize = b.psize * MINCACHE;
287
288 /* Calculate number of pages to cache. */
289 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
290
291 /*
292 * The btree data structure requires that at least two keys can fit on
293 * a page, but other than that there's no fixed requirement. The user
294 * specified a minimum number per page, and we translated that into the
295 * number of bytes a key/data pair can use before being placed on an
296 * overflow page. This calculation includes the page header, the size
297 * of the index referencing the leaf item and the size of the leaf item
298 * structure. Also, don't let the user specify a minkeypage such that
299 * a key/data pair won't fit even if both key and data are on overflow
300 * pages.
301 */
302 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
303 (sizeof(indx_t) + NBLEAFDBT(0, 0));
304 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
305 t->bt_ovflsize =
306 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
307
308 /* Initialize the buffer pool. */
309 if ((t->bt_mp =
310 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
311 goto err;
312 if (!F_ISSET(t, B_INMEM))
313 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
314
315 /* Create a root page if new tree. */
316 if (nroot(t) == RET_ERROR)
317 goto err;
318
319 /* Global flags. */
320 if (dflags & DB_LOCK)
321 F_SET(t, B_DB_LOCK);
322 if (dflags & DB_SHMEM)
323 F_SET(t, B_DB_SHMEM);
324 if (dflags & DB_TXN)
325 F_SET(t, B_DB_TXN);
326
327 return (dbp);
328
329 einval: errno = EINVAL;
330 goto err;
331
332 eftype: errno = EFTYPE;
333 goto err;
334
335 err: if (t) {
336 if (t->bt_dbp)
337 free(t->bt_dbp);
338 if (t->bt_fd != -1)
339 (void)close(t->bt_fd);
340 free(t);
341 }
342 return (NULL);
343 }
344
345 /*
346 * NROOT -- Create the root of a new tree.
347 *
348 * Parameters:
349 * t: tree
350 *
351 * Returns:
352 * RET_ERROR, RET_SUCCESS
353 */
354 static int
nroot(t)355 nroot(t)
356 BTREE *t;
357 {
358 PAGE *meta, *root;
359 db_pgno_t npg;
360
361 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
362 if (root->lower == 0 &&
363 root->pgno == 0 &&
364 root->linp[0] == 0) {
365 mpool_delete(t->bt_mp, root);
366 errno = EINVAL;
367 } else {
368 mpool_put(t->bt_mp, root, 0);
369 return (RET_SUCCESS);
370 }
371 }
372 if (errno != EINVAL) /* It's OK to not exist. */
373 return (RET_ERROR);
374 errno = 0;
375
376 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
377 return (RET_ERROR);
378
379 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
380 return (RET_ERROR);
381
382 if (npg != P_ROOT)
383 return (RET_ERROR);
384 root->pgno = npg;
385 root->prevpg = root->nextpg = P_INVALID;
386 root->lower = BTDATAOFF;
387 root->upper = t->bt_psize;
388 root->flags = P_BLEAF;
389 memset(meta, 0, t->bt_psize);
390 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
391 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
392 return (RET_SUCCESS);
393 }
394
395 static int
tmp()396 tmp()
397 {
398 #ifdef SIG_BLOCK
399 sigset_t set, oset;
400 #else
401 int oset;
402 #endif
403 int fd;
404 char *envtmp;
405 char path[MAXPATHLEN];
406 static char fn[] = "/bt.XXXXXX";
407
408 envtmp = getenv("TMPDIR");
409
410 /* this used to be done with snprintf(), but since snprintf
411 isn't in most operating systems, and overflow checking in
412 this case is easy, this is what is done */
413
414 if (envtmp && ((strlen(envtmp)+sizeof(fn)+1) > sizeof(path)))
415 return(-1);
416
417 (void)sprintf(path, "%s%s", (envtmp ? envtmp : "/tmp"), fn);
418
419 #ifdef SIG_BLOCK
420 (void)sigfillset(&set);
421 (void)sigprocmask(SIG_BLOCK, &set, &oset);
422 #else
423 oset = sigblock(~0);
424 #endif
425 if ((fd = mkstemp(path)) != -1)
426 (void)unlink(path);
427 #ifdef SIG_BLOCK
428 (void)sigprocmask(SIG_SETMASK, &oset, NULL);
429 #else
430 sigsetmask(oset);
431 #endif
432 #ifdef __CYGWIN32__
433 /* Ensure the fd is in binary mode. */
434 setmode(fd, O_BINARY);
435 #endif /* __CYGWIN32__ */
436
437 return(fd);
438 }
439
440 static int
byteorder()441 byteorder()
442 {
443 u_int32_t x;
444 u_char *p;
445
446 x = 0x01020304;
447 p = (u_char *)&x;
448 switch (*p) {
449 case 1:
450 return (DB_BIG_ENDIAN);
451 case 4:
452 return (DB_LITTLE_ENDIAN);
453 default:
454 return (0);
455 }
456 }
457
458 int
__bt_fd(dbp)459 __bt_fd(dbp)
460 const DB *dbp;
461 {
462 BTREE *t;
463
464 t = dbp->internal;
465
466 /* Toss any page pinned across calls. */
467 if (t->bt_pinned != NULL) {
468 mpool_put(t->bt_mp, t->bt_pinned, 0);
469 t->bt_pinned = NULL;
470 }
471
472 /* In-memory database can't have a file descriptor. */
473 if (F_ISSET(t, B_INMEM)) {
474 errno = ENOENT;
475 return (-1);
476 }
477 return (t->bt_fd);
478 }
479