source: vendor/3.5.0/lib/tdb/common/tdb.c

Last change on this file was 414, checked in by Herwig Bauernfeind, 16 years ago

Samba 3.5.0: Initial import
File size: 27.9 KB
Line 
1 /*
2 Unix SMB/CIFS implementation.
3
4 trivial database library
5
6 Copyright (C) Andrew Tridgell 1999-2005
7 Copyright (C) Paul `Rusty' Russell 2000
8 Copyright (C) Jeremy Allison 2000-2003
9
10 ** NOTE! The following LGPL license applies to the tdb
11 ** library. This does NOT imply that all of Samba is released
12 ** under the LGPL
13
14 This library is free software; you can redistribute it and/or
15 modify it under the terms of the GNU Lesser General Public
16 License as published by the Free Software Foundation; either
17 version 3 of the License, or (at your option) any later version.
18
19 This library is distributed in the hope that it will be useful,
20 but WITHOUT ANY WARRANTY; without even the implied warranty of
21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 Lesser General Public License for more details.
23
24 You should have received a copy of the GNU Lesser General Public
25 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26*/
27
28#include "tdb_private.h"
29
30TDB_DATA tdb_null;
31
32/*
33 non-blocking increment of the tdb sequence number if the tdb has been opened using
34 the TDB_SEQNUM flag
35*/
36void tdb_increment_seqnum_nonblock(struct tdb_context *tdb)
37{
38 tdb_off_t seqnum=0;
39
40 if (!(tdb->flags & TDB_SEQNUM)) {
41 return;
42 }
43
44 /* we ignore errors from this, as we have no sane way of
45 dealing with them.
46 */
47 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
48 seqnum++;
49 tdb_ofs_write(tdb, TDB_SEQNUM_OFS, &seqnum);
50}
51
52/*
53 increment the tdb sequence number if the tdb has been opened using
54 the TDB_SEQNUM flag
55*/
56static void tdb_increment_seqnum(struct tdb_context *tdb)
57{
58 if (!(tdb->flags & TDB_SEQNUM)) {
59 return;
60 }
61
62 if (tdb_brlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, F_SETLKW, 1, 1) != 0) {
63 return;
64 }
65
66 tdb_increment_seqnum_nonblock(tdb);
67
68 tdb_brlock(tdb, TDB_SEQNUM_OFS, F_UNLCK, F_SETLKW, 1, 1);
69}
70
71static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
72{
73 return memcmp(data.dptr, key.dptr, data.dsize);
74}
75
76/* Returns 0 on fail. On success, return offset of record, and fills
77 in rec */
78static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, uint32_t hash,
79 struct tdb_record *r)
80{
81 tdb_off_t rec_ptr;
82
83 /* read in the hash top */
84 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
85 return 0;
86
87 /* keep looking until we find the right record */
88 while (rec_ptr) {
89 if (tdb_rec_read(tdb, rec_ptr, r) == -1)
90 return 0;
91
92 if (!TDB_DEAD(r) && hash==r->full_hash
93 && key.dsize==r->key_len
94 && tdb_parse_data(tdb, key, rec_ptr + sizeof(*r),
95 r->key_len, tdb_key_compare,
96 NULL) == 0) {
97 return rec_ptr;
98 }
99 /* detect tight infinite loop */
100 if (rec_ptr == r->next) {
101 tdb->ecode = TDB_ERR_CORRUPT;
102 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_find: loop detected.\n"));
103 return 0;
104 }
105 rec_ptr = r->next;
106 }
107 tdb->ecode = TDB_ERR_NOEXIST;
108 return 0;
109}
110
111/* As tdb_find, but if you succeed, keep the lock */
112tdb_off_t tdb_find_lock_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash, int locktype,
113 struct tdb_record *rec)
114{
115 uint32_t rec_ptr;
116
117 if (tdb_lock(tdb, BUCKET(hash), locktype) == -1)
118 return 0;
119 if (!(rec_ptr = tdb_find(tdb, key, hash, rec)))
120 tdb_unlock(tdb, BUCKET(hash), locktype);
121 return rec_ptr;
122}
123
124static TDB_DATA _tdb_fetch(struct tdb_context *tdb, TDB_DATA key);
125
126/* update an entry in place - this only works if the new data size
127 is <= the old data size and the key exists.
128 on failure return -1.
129*/
130static int tdb_update_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash, TDB_DATA dbuf)
131{
132 struct tdb_record rec;
133 tdb_off_t rec_ptr;
134
135 /* find entry */
136 if (!(rec_ptr = tdb_find(tdb, key, hash, &rec)))
137 return -1;
138
139 /* it could be an exact duplicate of what is there - this is
140 * surprisingly common (eg. with a ldb re-index). */
141 if (rec.key_len == key.dsize &&
142 rec.data_len == dbuf.dsize &&
143 rec.full_hash == hash) {
144 TDB_DATA data = _tdb_fetch(tdb, key);
145 if (data.dsize == dbuf.dsize &&
146 memcmp(data.dptr, dbuf.dptr, data.dsize) == 0) {
147 if (data.dptr) {
148 free(data.dptr);
149 }
150 return 0;
151 }
152 if (data.dptr) {
153 free(data.dptr);
154 }
155 }
156
157
158 /* must be long enough key, data and tailer */
159 if (rec.rec_len < key.dsize + dbuf.dsize + sizeof(tdb_off_t)) {
160 tdb->ecode = TDB_SUCCESS; /* Not really an error */
161 return -1;
162 }
163
164 if (tdb->methods->tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len,
165 dbuf.dptr, dbuf.dsize) == -1)
166 return -1;
167
168 if (dbuf.dsize != rec.data_len) {
169 /* update size */
170 rec.data_len = dbuf.dsize;
171 return tdb_rec_write(tdb, rec_ptr, &rec);
172 }
173
174 return 0;
175}
176
177/* find an entry in the database given a key */
178/* If an entry doesn't exist tdb_err will be set to
179 * TDB_ERR_NOEXIST. If a key has no data attached
180 * then the TDB_DATA will have zero length but
181 * a non-zero pointer
182 */
183static TDB_DATA _tdb_fetch(struct tdb_context *tdb, TDB_DATA key)
184{
185 tdb_off_t rec_ptr;
186 struct tdb_record rec;
187 TDB_DATA ret;
188 uint32_t hash;
189
190 /* find which hash bucket it is in */
191 hash = tdb->hash_fn(&key);
192 if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec)))
193 return tdb_null;
194
195 ret.dptr = tdb_alloc_read(tdb, rec_ptr + sizeof(rec) + rec.key_len,
196 rec.data_len);
197 ret.dsize = rec.data_len;
198 tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
199 return ret;
200}
201
202TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key)
203{
204 TDB_DATA ret = _tdb_fetch(tdb, key);
205
206 tdb_trace_1rec_retrec(tdb, "tdb_fetch", key, ret);
207 return ret;
208}
209
210/*
211 * Find an entry in the database and hand the record's data to a parsing
212 * function. The parsing function is executed under the chain read lock, so it
213 * should be fast and should not block on other syscalls.
214 *
215 * DONT CALL OTHER TDB CALLS FROM THE PARSER, THIS MIGHT LEAD TO SEGFAULTS.
216 *
217 * For mmapped tdb's that do not have a transaction open it points the parsing
218 * function directly at the mmap area, it avoids the malloc/memcpy in this
219 * case. If a transaction is open or no mmap is available, it has to do
220 * malloc/read/parse/free.
221 *
222 * This is interesting for all readers of potentially large data structures in
223 * the tdb records, ldb indexes being one example.
224 */
225
226int tdb_parse_record(struct tdb_context *tdb, TDB_DATA key,
227 int (*parser)(TDB_DATA key, TDB_DATA data,
228 void *private_data),
229 void *private_data)
230{
231 tdb_off_t rec_ptr;
232 struct tdb_record rec;
233 int ret;
234 uint32_t hash;
235
236 /* find which hash bucket it is in */
237 hash = tdb->hash_fn(&key);
238
239 if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec))) {
240 tdb_trace_1rec_ret(tdb, "tdb_parse_record", key, -1);
241 tdb->ecode = TDB_ERR_NOEXIST;
242 return 0;
243 }
244 tdb_trace_1rec_ret(tdb, "tdb_parse_record", key, 0);
245
246 ret = tdb_parse_data(tdb, key, rec_ptr + sizeof(rec) + rec.key_len,
247 rec.data_len, parser, private_data);
248
249 tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
250
251 return ret;
252}
253
254/* check if an entry in the database exists
255
256 note that 1 is returned if the key is found and 0 is returned if not found
257 this doesn't match the conventions in the rest of this module, but is
258 compatible with gdbm
259*/
260static int tdb_exists_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash)
261{
262 struct tdb_record rec;
263
264 if (tdb_find_lock_hash(tdb, key, hash, F_RDLCK, &rec) == 0)
265 return 0;
266 tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
267 return 1;
268}
269
270int tdb_exists(struct tdb_context *tdb, TDB_DATA key)
271{
272 uint32_t hash = tdb->hash_fn(&key);
273 int ret;
274
275 ret = tdb_exists_hash(tdb, key, hash);
276 tdb_trace_1rec_ret(tdb, "tdb_exists", key, ret);
277 return ret;
278}
279
280/* actually delete an entry in the database given the offset */
281int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct tdb_record *rec)
282{
283 tdb_off_t last_ptr, i;
284 struct tdb_record lastrec;
285
286 if (tdb->read_only || tdb->traverse_read) return -1;
287
288 if (((tdb->traverse_write != 0) && (!TDB_DEAD(rec))) ||
289 tdb_write_lock_record(tdb, rec_ptr) == -1) {
290 /* Someone traversing here: mark it as dead */
291 rec->magic = TDB_DEAD_MAGIC;
292 return tdb_rec_write(tdb, rec_ptr, rec);
293 }
294 if (tdb_write_unlock_record(tdb, rec_ptr) != 0)
295 return -1;
296
297 /* find previous record in hash chain */
298 if (tdb_ofs_read(tdb, TDB_HASH_TOP(rec->full_hash), &i) == -1)
299 return -1;
300 for (last_ptr = 0; i != rec_ptr; last_ptr = i, i = lastrec.next)
301 if (tdb_rec_read(tdb, i, &lastrec) == -1)
302 return -1;
303
304 /* unlink it: next ptr is at start of record. */
305 if (last_ptr == 0)
306 last_ptr = TDB_HASH_TOP(rec->full_hash);
307 if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1)
308 return -1;
309
310 /* recover the space */
311 if (tdb_free(tdb, rec_ptr, rec) == -1)
312 return -1;
313 return 0;
314}
315
316static int tdb_count_dead(struct tdb_context *tdb, uint32_t hash)
317{
318 int res = 0;
319 tdb_off_t rec_ptr;
320 struct tdb_record rec;
321
322 /* read in the hash top */
323 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
324 return 0;
325
326 while (rec_ptr) {
327 if (tdb_rec_read(tdb, rec_ptr, &rec) == -1)
328 return 0;
329
330 if (rec.magic == TDB_DEAD_MAGIC) {
331 res += 1;
332 }
333 rec_ptr = rec.next;
334 }
335 return res;
336}
337
338/*
339 * Purge all DEAD records from a hash chain
340 */
341static int tdb_purge_dead(struct tdb_context *tdb, uint32_t hash)
342{
343 int res = -1;
344 struct tdb_record rec;
345 tdb_off_t rec_ptr;
346
347 if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
348 return -1;
349 }
350
351 /* read in the hash top */
352 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
353 goto fail;
354
355 while (rec_ptr) {
356 tdb_off_t next;
357
358 if (tdb_rec_read(tdb, rec_ptr, &rec) == -1) {
359 goto fail;
360 }
361
362 next = rec.next;
363
364 if (rec.magic == TDB_DEAD_MAGIC
365 && tdb_do_delete(tdb, rec_ptr, &rec) == -1) {
366 goto fail;
367 }
368 rec_ptr = next;
369 }
370 res = 0;
371 fail:
372 tdb_unlock(tdb, -1, F_WRLCK);
373 return res;
374}
375
376/* delete an entry in the database given a key */
377static int tdb_delete_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash)
378{
379 tdb_off_t rec_ptr;
380 struct tdb_record rec;
381 int ret;
382
383 if (tdb->max_dead_records != 0) {
384
385 /*
386 * Allow for some dead records per hash chain, mainly for
387 * tdb's with a very high create/delete rate like locking.tdb.
388 */
389
390 if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
391 return -1;
392
393 if (tdb_count_dead(tdb, hash) >= tdb->max_dead_records) {
394 /*
395 * Don't let the per-chain freelist grow too large,
396 * delete all existing dead records
397 */
398 tdb_purge_dead(tdb, hash);
399 }
400
401 if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) {
402 tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
403 return -1;
404 }
405
406 /*
407 * Just mark the record as dead.
408 */
409 rec.magic = TDB_DEAD_MAGIC;
410 ret = tdb_rec_write(tdb, rec_ptr, &rec);
411 }
412 else {
413 if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK,
414 &rec)))
415 return -1;
416
417 ret = tdb_do_delete(tdb, rec_ptr, &rec);
418 }
419
420 if (ret == 0) {
421 tdb_increment_seqnum(tdb);
422 }
423
424 if (tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK) != 0)
425 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_delete: WARNING tdb_unlock failed!\n"));
426 return ret;
427}
428
429int tdb_delete(struct tdb_context *tdb, TDB_DATA key)
430{
431 uint32_t hash = tdb->hash_fn(&key);
432 int ret;
433
434 ret = tdb_delete_hash(tdb, key, hash);
435 tdb_trace_1rec_ret(tdb, "tdb_delete", key, ret);
436 return ret;
437}
438
439/*
440 * See if we have a dead record around with enough space
441 */
442static tdb_off_t tdb_find_dead(struct tdb_context *tdb, uint32_t hash,
443 struct tdb_record *r, tdb_len_t length)
444{
445 tdb_off_t rec_ptr;
446
447 /* read in the hash top */
448 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
449 return 0;
450
451 /* keep looking until we find the right record */
452 while (rec_ptr) {
453 if (tdb_rec_read(tdb, rec_ptr, r) == -1)
454 return 0;
455
456 if (TDB_DEAD(r) && r->rec_len >= length) {
457 /*
458 * First fit for simple coding, TODO: change to best
459 * fit
460 */
461 return rec_ptr;
462 }
463 rec_ptr = r->next;
464 }
465 return 0;
466}
467
468static int _tdb_store(struct tdb_context *tdb, TDB_DATA key,
469 TDB_DATA dbuf, int flag, uint32_t hash)
470{
471 struct tdb_record rec;
472 tdb_off_t rec_ptr;
473 char *p = NULL;
474 int ret = -1;
475
476 /* check for it existing, on insert. */
477 if (flag == TDB_INSERT) {
478 if (tdb_exists_hash(tdb, key, hash)) {
479 tdb->ecode = TDB_ERR_EXISTS;
480 goto fail;
481 }
482 } else {
483 /* first try in-place update, on modify or replace. */
484 if (tdb_update_hash(tdb, key, hash, dbuf) == 0) {
485 goto done;
486 }
487 if (tdb->ecode == TDB_ERR_NOEXIST &&
488 flag == TDB_MODIFY) {
489 /* if the record doesn't exist and we are in TDB_MODIFY mode then
490 we should fail the store */
491 goto fail;
492 }
493 }
494 /* reset the error code potentially set by the tdb_update() */
495 tdb->ecode = TDB_SUCCESS;
496
497 /* delete any existing record - if it doesn't exist we don't
498 care. Doing this first reduces fragmentation, and avoids
499 coalescing with `allocated' block before it's updated. */
500 if (flag != TDB_INSERT)
501 tdb_delete_hash(tdb, key, hash);
502
503 /* Copy key+value *before* allocating free space in case malloc
504 fails and we are left with a dead spot in the tdb. */
505
506 if (!(p = (char *)malloc(key.dsize + dbuf.dsize))) {
507 tdb->ecode = TDB_ERR_OOM;
508 goto fail;
509 }
510
511 memcpy(p, key.dptr, key.dsize);
512 if (dbuf.dsize)
513 memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize);
514
515 if (tdb->max_dead_records != 0) {
516 /*
517 * Allow for some dead records per hash chain, look if we can
518 * find one that can hold the new record. We need enough space
519 * for key, data and tailer. If we find one, we don't have to
520 * consult the central freelist.
521 */
522 rec_ptr = tdb_find_dead(
523 tdb, hash, &rec,
524 key.dsize + dbuf.dsize + sizeof(tdb_off_t));
525
526 if (rec_ptr != 0) {
527 rec.key_len = key.dsize;
528 rec.data_len = dbuf.dsize;
529 rec.full_hash = hash;
530 rec.magic = TDB_MAGIC;
531 if (tdb_rec_write(tdb, rec_ptr, &rec) == -1
532 || tdb->methods->tdb_write(
533 tdb, rec_ptr + sizeof(rec),
534 p, key.dsize + dbuf.dsize) == -1) {
535 goto fail;
536 }
537 goto done;
538 }
539 }
540
541 /*
542 * We have to allocate some space from the freelist, so this means we
543 * have to lock it. Use the chance to purge all the DEAD records from
544 * the hash chain under the freelist lock.
545 */
546
547 if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
548 goto fail;
549 }
550
551 if ((tdb->max_dead_records != 0)
552 && (tdb_purge_dead(tdb, hash) == -1)) {
553 tdb_unlock(tdb, -1, F_WRLCK);
554 goto fail;
555 }
556
557 /* we have to allocate some space */
558 rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec);
559
560 tdb_unlock(tdb, -1, F_WRLCK);
561
562 if (rec_ptr == 0) {
563 goto fail;
564 }
565
566 /* Read hash top into next ptr */
567 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec.next) == -1)
568 goto fail;
569
570 rec.key_len = key.dsize;
571 rec.data_len = dbuf.dsize;
572 rec.full_hash = hash;
573 rec.magic = TDB_MAGIC;
574
575 /* write out and point the top of the hash chain at it */
576 if (tdb_rec_write(tdb, rec_ptr, &rec) == -1
577 || tdb->methods->tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1
578 || tdb_ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) {
579 /* Need to tdb_unallocate() here */
580 goto fail;
581 }
582
583 done:
584 ret = 0;
585 fail:
586 if (ret == 0) {
587 tdb_increment_seqnum(tdb);
588 }
589
590 SAFE_FREE(p);
591 return ret;
592}
593
594/* store an element in the database, replacing any existing element
595 with the same key
596
597 return 0 on success, -1 on failure
598*/
599int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag)
600{
601 uint32_t hash;
602 int ret;
603
604 if (tdb->read_only || tdb->traverse_read) {
605 tdb->ecode = TDB_ERR_RDONLY;
606 tdb_trace_2rec_flag_ret(tdb, "tdb_store", key, dbuf, flag, -1);
607 return -1;
608 }
609
610 /* find which hash bucket it is in */
611 hash = tdb->hash_fn(&key);
612 if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
613 return -1;
614
615 ret = _tdb_store(tdb, key, dbuf, flag, hash);
616 tdb_trace_2rec_flag_ret(tdb, "tdb_store", key, dbuf, flag, ret);
617 tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
618 return ret;
619}
620
621/* Append to an entry. Create if not exist. */
622int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf)
623{
624 uint32_t hash;
625 TDB_DATA dbuf;
626 int ret = -1;
627
628 /* find which hash bucket it is in */
629 hash = tdb->hash_fn(&key);
630 if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
631 return -1;
632
633 dbuf = _tdb_fetch(tdb, key);
634
635 if (dbuf.dptr == NULL) {
636 dbuf.dptr = (unsigned char *)malloc(new_dbuf.dsize);
637 } else {
638 unsigned int new_len = dbuf.dsize + new_dbuf.dsize;
639 unsigned char *new_dptr;
640
641 /* realloc '0' is special: don't do that. */
642 if (new_len == 0)
643 new_len = 1;
644 new_dptr = (unsigned char *)realloc(dbuf.dptr, new_len);
645 if (new_dptr == NULL) {
646 free(dbuf.dptr);
647 }
648 dbuf.dptr = new_dptr;
649 }
650
651 if (dbuf.dptr == NULL) {
652 tdb->ecode = TDB_ERR_OOM;
653 goto failed;
654 }
655
656 memcpy(dbuf.dptr + dbuf.dsize, new_dbuf.dptr, new_dbuf.dsize);
657 dbuf.dsize += new_dbuf.dsize;
658
659 ret = _tdb_store(tdb, key, dbuf, 0, hash);
660 tdb_trace_2rec_retrec(tdb, "tdb_append", key, new_dbuf, dbuf);
661
662failed:
663 tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
664 SAFE_FREE(dbuf.dptr);
665 return ret;
666}
667
668
669/*
670 return the name of the current tdb file
671 useful for external logging functions
672*/
673const char *tdb_name(struct tdb_context *tdb)
674{
675 return tdb->name;
676}
677
678/*
679 return the underlying file descriptor being used by tdb, or -1
680 useful for external routines that want to check the device/inode
681 of the fd
682*/
683int tdb_fd(struct tdb_context *tdb)
684{
685 return tdb->fd;
686}
687
688/*
689 return the current logging function
690 useful for external tdb routines that wish to log tdb errors
691*/
692tdb_log_func tdb_log_fn(struct tdb_context *tdb)
693{
694 return tdb->log.log_fn;
695}
696
697
698/*
699 get the tdb sequence number. Only makes sense if the writers opened
700 with TDB_SEQNUM set. Note that this sequence number will wrap quite
701 quickly, so it should only be used for a 'has something changed'
702 test, not for code that relies on the count of the number of changes
703 made. If you want a counter then use a tdb record.
704
705 The aim of this sequence number is to allow for a very lightweight
706 test of a possible tdb change.
707*/
708int tdb_get_seqnum(struct tdb_context *tdb)
709{
710 tdb_off_t seqnum=0;
711
712 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
713 return seqnum;
714}
715
716int tdb_hash_size(struct tdb_context *tdb)
717{
718 return tdb->header.hash_size;
719}
720
721size_t tdb_map_size(struct tdb_context *tdb)
722{
723 return tdb->map_size;
724}
725
726int tdb_get_flags(struct tdb_context *tdb)
727{
728 return tdb->flags;
729}
730
731void tdb_add_flags(struct tdb_context *tdb, unsigned flags)
732{
733 if ((flags & TDB_ALLOW_NESTING) &&
734 (flags & TDB_DISALLOW_NESTING)) {
735 tdb->ecode = TDB_ERR_NESTING;
736 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_add_flags: "
737 "allow_nesting and disallow_nesting are not allowed together!"));
738 return;
739 }
740
741 if (flags & TDB_ALLOW_NESTING) {
742 tdb->flags &= ~TDB_DISALLOW_NESTING;
743 }
744 if (flags & TDB_DISALLOW_NESTING) {
745 tdb->flags &= ~TDB_ALLOW_NESTING;
746 }
747
748 tdb->flags |= flags;
749}
750
751void tdb_remove_flags(struct tdb_context *tdb, unsigned flags)
752{
753 if ((flags & TDB_ALLOW_NESTING) &&
754 (flags & TDB_DISALLOW_NESTING)) {
755 tdb->ecode = TDB_ERR_NESTING;
756 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_remove_flags: "
757 "allow_nesting and disallow_nesting are not allowed together!"));
758 return;
759 }
760
761 if (flags & TDB_ALLOW_NESTING) {
762 tdb->flags |= TDB_DISALLOW_NESTING;
763 }
764 if (flags & TDB_DISALLOW_NESTING) {
765 tdb->flags |= TDB_ALLOW_NESTING;
766 }
767
768 tdb->flags &= ~flags;
769}
770
771
772/*
773 enable sequence number handling on an open tdb
774*/
775void tdb_enable_seqnum(struct tdb_context *tdb)
776{
777 tdb->flags |= TDB_SEQNUM;
778}
779
780
781/*
782 add a region of the file to the freelist. Length is the size of the region in bytes,
783 which includes the free list header that needs to be added
784 */
785static int tdb_free_region(struct tdb_context *tdb, tdb_off_t offset, ssize_t length)
786{
787 struct tdb_record rec;
788 if (length <= sizeof(rec)) {
789 /* the region is not worth adding */
790 return 0;
791 }
792 if (length + offset > tdb->map_size) {
793 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_free_region: adding region beyond end of file\n"));
794 return -1;
795 }
796 memset(&rec,'\0',sizeof(rec));
797 rec.rec_len = length - sizeof(rec);
798 if (tdb_free(tdb, offset, &rec) == -1) {
799 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_free_region: failed to add free record\n"));
800 return -1;
801 }
802 return 0;
803}
804
805/*
806 wipe the entire database, deleting all records. This can be done
807 very fast by using a global lock. The entire data portion of the
808 file becomes a single entry in the freelist.
809
810 This code carefully steps around the recovery area, leaving it alone
811 */
812int tdb_wipe_all(struct tdb_context *tdb)
813{
814 int i;
815 tdb_off_t offset = 0;
816 ssize_t data_len;
817 tdb_off_t recovery_head;
818 tdb_len_t recovery_size = 0;
819
820 if (tdb_lockall(tdb) != 0) {
821 return -1;
822 }
823
824 tdb_trace(tdb, "tdb_wipe_all");
825
826 /* see if the tdb has a recovery area, and remember its size
827 if so. We don't want to lose this as otherwise each
828 tdb_wipe_all() in a transaction will increase the size of
829 the tdb by the size of the recovery area */
830 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
831 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_wipe_all: failed to read recovery head\n"));
832 goto failed;
833 }
834
835 if (recovery_head != 0) {
836 struct tdb_record rec;
837 if (tdb->methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
838 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_wipe_all: failed to read recovery record\n"));
839 return -1;
840 }
841 recovery_size = rec.rec_len + sizeof(rec);
842 }
843
844 /* wipe the hashes */
845 for (i=0;i<tdb->header.hash_size;i++) {
846 if (tdb_ofs_write(tdb, TDB_HASH_TOP(i), &offset) == -1) {
847 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to write hash %d\n", i));
848 goto failed;
849 }
850 }
851
852 /* wipe the freelist */
853 if (tdb_ofs_write(tdb, FREELIST_TOP, &offset) == -1) {
854 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to write freelist\n"));
855 goto failed;
856 }
857
858 /* add all the rest of the file to the freelist, possibly leaving a gap
859 for the recovery area */
860 if (recovery_size == 0) {
861 /* the simple case - the whole file can be used as a freelist */
862 data_len = (tdb->map_size - TDB_DATA_START(tdb->header.hash_size));
863 if (tdb_free_region(tdb, TDB_DATA_START(tdb->header.hash_size), data_len) != 0) {
864 goto failed;
865 }
866 } else {
867 /* we need to add two freelist entries - one on either
868 side of the recovery area
869
870 Note that we cannot shift the recovery area during
871 this operation. Only the transaction.c code may
872 move the recovery area or we risk subtle data
873 corruption
874 */
875 data_len = (recovery_head - TDB_DATA_START(tdb->header.hash_size));
876 if (tdb_free_region(tdb, TDB_DATA_START(tdb->header.hash_size), data_len) != 0) {
877 goto failed;
878 }
879 /* and the 2nd free list entry after the recovery area - if any */
880 data_len = tdb->map_size - (recovery_head+recovery_size);
881 if (tdb_free_region(tdb, recovery_head+recovery_size, data_len) != 0) {
882 goto failed;
883 }
884 }
885
886 if (tdb_unlockall(tdb) != 0) {
887 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to unlock\n"));
888 goto failed;
889 }
890
891 return 0;
892
893failed:
894 tdb_unlockall(tdb);
895 return -1;
896}
897
898struct traverse_state {
899 bool error;
900 struct tdb_context *dest_db;
901};
902
903/*
904 traverse function for repacking
905 */
906static int repack_traverse(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *private_data)
907{
908 struct traverse_state *state = (struct traverse_state *)private_data;
909 if (tdb_store(state->dest_db, key, data, TDB_INSERT) != 0) {
910 state->error = true;
911 return -1;
912 }
913 return 0;
914}
915
916/*
917 repack a tdb
918 */
919int tdb_repack(struct tdb_context *tdb)
920{
921 struct tdb_context *tmp_db;
922 struct traverse_state state;
923
924 tdb_trace(tdb, "tdb_repack");
925
926 if (tdb_transaction_start(tdb) != 0) {
927 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to start transaction\n"));
928 return -1;
929 }
930
931 tmp_db = tdb_open("tmpdb", tdb_hash_size(tdb), TDB_INTERNAL, O_RDWR|O_CREAT, 0);
932 if (tmp_db == NULL) {
933 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to create tmp_db\n"));
934 tdb_transaction_cancel(tdb);
935 return -1;
936 }
937
938 state.error = false;
939 state.dest_db = tmp_db;
940
941 if (tdb_traverse_read(tdb, repack_traverse, &state) == -1) {
942 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to traverse copying out\n"));
943 tdb_transaction_cancel(tdb);
944 tdb_close(tmp_db);
945 return -1;
946 }
947
948 if (state.error) {
949 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Error during traversal\n"));
950 tdb_transaction_cancel(tdb);
951 tdb_close(tmp_db);
952 return -1;
953 }
954
955 if (tdb_wipe_all(tdb) != 0) {
956 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to wipe database\n"));
957 tdb_transaction_cancel(tdb);
958 tdb_close(tmp_db);
959 return -1;
960 }
961
962 state.error = false;
963 state.dest_db = tdb;
964
965 if (tdb_traverse_read(tmp_db, repack_traverse, &state) == -1) {
966 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to traverse copying back\n"));
967 tdb_transaction_cancel(tdb);
968 tdb_close(tmp_db);
969 return -1;
970 }
971
972 if (state.error) {
973 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Error during second traversal\n"));
974 tdb_transaction_cancel(tdb);
975 tdb_close(tmp_db);
976 return -1;
977 }
978
979 tdb_close(tmp_db);
980
981 if (tdb_transaction_commit(tdb) != 0) {
982 TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to commit\n"));
983 return -1;
984 }
985
986 return 0;
987}
988
989#ifdef TDB_TRACE
990static void tdb_trace_write(struct tdb_context *tdb, const char *str)
991{
992 if (write(tdb->tracefd, str, strlen(str)) != strlen(str)) {
993 close(tdb->tracefd);
994 tdb->tracefd = -1;
995 }
996}
997
998static void tdb_trace_start(struct tdb_context *tdb)
999{
1000 tdb_off_t seqnum=0;
1001 char msg[sizeof(tdb_off_t) * 4 + 1];
1002
1003 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
1004 snprintf(msg, sizeof(msg), "%u ", seqnum);
1005 tdb_trace_write(tdb, msg);
1006}
1007
1008static void tdb_trace_end(struct tdb_context *tdb)
1009{
1010 tdb_trace_write(tdb, "\n");
1011}
1012
1013static void tdb_trace_end_ret(struct tdb_context *tdb, int ret)
1014{
1015 char msg[sizeof(ret) * 4 + 4];
1016 snprintf(msg, sizeof(msg), " = %i\n", ret);
1017 tdb_trace_write(tdb, msg);
1018}
1019
1020static void tdb_trace_record(struct tdb_context *tdb, TDB_DATA rec)
1021{
1022 char msg[20 + rec.dsize*2], *p;
1023 unsigned int i;
1024
1025 /* We differentiate zero-length records from non-existent ones. */
1026 if (rec.dptr == NULL) {
1027 tdb_trace_write(tdb, " NULL");
1028 return;
1029 }
1030
1031 /* snprintf here is purely cargo-cult programming. */
1032 p = msg;
1033 p += snprintf(p, sizeof(msg), " %zu:", rec.dsize);
1034 for (i = 0; i < rec.dsize; i++)
1035 p += snprintf(p, 2, "%02x", rec.dptr[i]);
1036
1037 tdb_trace_write(tdb, msg);
1038}
1039
1040void tdb_trace(struct tdb_context *tdb, const char *op)
1041{
1042 tdb_trace_start(tdb);
1043 tdb_trace_write(tdb, op);
1044 tdb_trace_end(tdb);
1045}
1046
1047void tdb_trace_seqnum(struct tdb_context *tdb, uint32_t seqnum, const char *op)
1048{
1049 char msg[sizeof(tdb_off_t) * 4 + 1];
1050
1051 snprintf(msg, sizeof(msg), "%u ", seqnum);
1052 tdb_trace_write(tdb, msg);
1053 tdb_trace_write(tdb, op);
1054 tdb_trace_end(tdb);
1055}
1056
1057void tdb_trace_open(struct tdb_context *tdb, const char *op,
1058 unsigned hash_size, unsigned tdb_flags, unsigned open_flags)
1059{
1060 char msg[128];
1061
1062 snprintf(msg, sizeof(msg),
1063 "%s %u 0x%x 0x%x", op, hash_size, tdb_flags, open_flags);
1064 tdb_trace_start(tdb);
1065 tdb_trace_write(tdb, msg);
1066 tdb_trace_end(tdb);
1067}
1068
1069void tdb_trace_ret(struct tdb_context *tdb, const char *op, int ret)
1070{
1071 tdb_trace_start(tdb);
1072 tdb_trace_write(tdb, op);
1073 tdb_trace_end_ret(tdb, ret);
1074}
1075
1076void tdb_trace_retrec(struct tdb_context *tdb, const char *op, TDB_DATA ret)
1077{
1078 tdb_trace_start(tdb);
1079 tdb_trace_write(tdb, op);
1080 tdb_trace_write(tdb, " =");
1081 tdb_trace_record(tdb, ret);
1082 tdb_trace_end(tdb);
1083}
1084
1085void tdb_trace_1rec(struct tdb_context *tdb, const char *op,
1086 TDB_DATA rec)
1087{
1088 tdb_trace_start(tdb);
1089 tdb_trace_write(tdb, op);
1090 tdb_trace_record(tdb, rec);
1091 tdb_trace_end(tdb);
1092}
1093
1094void tdb_trace_1rec_ret(struct tdb_context *tdb, const char *op,
1095 TDB_DATA rec, int ret)
1096{
1097 tdb_trace_start(tdb);
1098 tdb_trace_write(tdb, op);
1099 tdb_trace_record(tdb, rec);
1100 tdb_trace_end_ret(tdb, ret);
1101}
1102
1103void tdb_trace_1rec_retrec(struct tdb_context *tdb, const char *op,
1104 TDB_DATA rec, TDB_DATA ret)
1105{
1106 tdb_trace_start(tdb);
1107 tdb_trace_write(tdb, op);
1108 tdb_trace_record(tdb, rec);
1109 tdb_trace_write(tdb, " =");
1110 tdb_trace_record(tdb, ret);
1111 tdb_trace_end(tdb);
1112}
1113
1114void tdb_trace_2rec_flag_ret(struct tdb_context *tdb, const char *op,
1115 TDB_DATA rec1, TDB_DATA rec2, unsigned flag,
1116 int ret)
1117{
1118 char msg[1 + sizeof(ret) * 4];
1119
1120 snprintf(msg, sizeof(msg), " %#x", flag);
1121 tdb_trace_start(tdb);
1122 tdb_trace_write(tdb, op);
1123 tdb_trace_record(tdb, rec1);
1124 tdb_trace_record(tdb, rec2);
1125 tdb_trace_write(tdb, msg);
1126 tdb_trace_end_ret(tdb, ret);
1127}
1128
1129void tdb_trace_2rec_retrec(struct tdb_context *tdb, const char *op,
1130 TDB_DATA rec1, TDB_DATA rec2, TDB_DATA ret)
1131{
1132 tdb_trace_start(tdb);
1133 tdb_trace_write(tdb, op);
1134 tdb_trace_record(tdb, rec1);
1135 tdb_trace_record(tdb, rec2);
1136 tdb_trace_write(tdb, " =");
1137 tdb_trace_record(tdb, ret);
1138 tdb_trace_end(tdb);
1139}
1140#endif
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