Fix bug 8480 - acl_xattr can free an invalid pointer if no blob is loaded.
[Samba.git] / lib / tdb2 / tdb1_lock.c
blob5cc0ad656729c51877aebf5f1fe7489bb11b972a
1 /*
2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 1999-2005
7 Copyright (C) Paul `Rusty' Russell 2000
8 Copyright (C) Jeremy Allison 2000-2003
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
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.
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.
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/>.
28 #include "tdb1_private.h"
30 /* list -1 is the alloc list, otherwise a hash chain. */
31 static tdb1_off_t lock_offset(int list)
33 return TDB1_FREELIST_TOP + 4*list;
36 /* a byte range locking function - return 0 on success
37 this functions locks/unlocks 1 byte at the specified offset.
39 On error, errno is also set so that errors are passed back properly
40 through tdb1_open().
42 note that a len of zero means lock to end of file
44 int tdb1_brlock(struct tdb_context *tdb,
45 int rw_type, tdb1_off_t offset, size_t len,
46 enum tdb_lock_flags flags)
48 enum TDB_ERROR ecode = tdb_brlock(tdb, rw_type, offset, len, flags
49 | TDB_LOCK_NOCHECK);
50 if (ecode == TDB_SUCCESS)
51 return 0;
52 tdb->last_error = ecode;
53 return -1;
56 int tdb1_brunlock(struct tdb_context *tdb,
57 int rw_type, tdb1_off_t offset, size_t len)
59 enum TDB_ERROR ecode = tdb_brunlock(tdb, rw_type, offset, len);
60 if (ecode == TDB_SUCCESS)
61 return 0;
62 tdb->last_error = ecode;
63 return -1;
66 int tdb1_allrecord_upgrade(struct tdb_context *tdb)
68 enum TDB_ERROR ecode = tdb_allrecord_upgrade(tdb, TDB1_FREELIST_TOP);
69 if (ecode == TDB_SUCCESS)
70 return 0;
71 tdb->last_error = ecode;
72 return -1;
75 static struct tdb_lock *tdb1_find_nestlock(struct tdb_context *tdb,
76 tdb1_off_t offset)
78 unsigned int i;
80 for (i=0; i<tdb->file->num_lockrecs; i++) {
81 if (tdb->file->lockrecs[i].off == offset) {
82 return &tdb->file->lockrecs[i];
85 return NULL;
88 /* lock an offset in the database. */
89 int tdb1_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
90 enum tdb_lock_flags flags)
92 enum TDB_ERROR ecode;
94 if (offset >= lock_offset(tdb->tdb1.header.hash_size)) {
95 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
96 "tdb1_lock: invalid offset %u for"
97 " ltype=%d",
98 offset, ltype);
99 return -1;
102 ecode = tdb_nest_lock(tdb, offset, ltype, flags | TDB_LOCK_NOCHECK);
103 if (unlikely(ecode != TDB_SUCCESS)) {
104 tdb->last_error = ecode;
105 return -1;
107 return 0;
110 static int tdb1_lock_and_recover(struct tdb_context *tdb)
112 int ret;
114 /* We need to match locking order in transaction commit. */
115 if (tdb1_brlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0,
116 TDB_LOCK_WAIT|TDB_LOCK_NOCHECK)) {
117 return -1;
120 if (tdb1_brlock(tdb, F_WRLCK, TDB1_OPEN_LOCK, 1,
121 TDB_LOCK_WAIT|TDB_LOCK_NOCHECK)) {
122 tdb1_brunlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0);
123 return -1;
126 ret = tdb1_transaction_recover(tdb);
128 tdb1_brunlock(tdb, F_WRLCK, TDB1_OPEN_LOCK, 1);
129 tdb1_brunlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0);
131 return ret;
134 static bool have_data_locks(const struct tdb_context *tdb)
136 unsigned int i;
138 for (i = 0; i < tdb->file->num_lockrecs; i++) {
139 if (tdb->file->lockrecs[i].off >= lock_offset(-1))
140 return true;
142 return false;
145 static int tdb1_lock_list(struct tdb_context *tdb, int list, int ltype,
146 enum tdb_lock_flags waitflag)
148 int ret;
149 bool check = false;
151 /* a allrecord lock allows us to avoid per chain locks */
152 if (tdb->file->allrecord_lock.count) {
153 if (!check_lock_pid(tdb, "tdb1_lock_list", true)) {
154 tdb->last_error = TDB_ERR_LOCK;
155 return -1;
157 if (tdb->file->allrecord_lock.owner != tdb) {
158 tdb->last_error = owner_conflict(tdb, "tdb1_lock_list");
159 return -1;
161 if (ltype == tdb->file->allrecord_lock.ltype
162 || ltype == F_RDLCK) {
163 return 0;
165 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK,
166 TDB_LOG_USE_ERROR,
167 "tdb1_lock_list:"
168 " already have read lock");
169 return -1;
172 /* Only check when we grab first data lock. */
173 check = !have_data_locks(tdb);
174 ret = tdb1_nest_lock(tdb, lock_offset(list), ltype, waitflag);
176 if (ret == 0 && check) {
177 tdb_bool_err berr = tdb1_needs_recovery(tdb);
179 if (berr < 0) {
180 return -1;
182 if (berr == true) {
183 tdb1_nest_unlock(tdb, lock_offset(list), ltype);
185 if (tdb1_lock_and_recover(tdb) == -1) {
186 return -1;
188 return tdb1_lock_list(tdb, list, ltype, waitflag);
191 return ret;
194 /* lock a list in the database. list -1 is the alloc list */
195 int tdb1_lock(struct tdb_context *tdb, int list, int ltype)
197 int ret;
199 ret = tdb1_lock_list(tdb, list, ltype, TDB_LOCK_WAIT);
200 /* Don't log for EAGAIN and EINTR: they could have overridden lock fns */
201 if (ret && errno != EAGAIN && errno != EINTR) {
202 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
203 "tdb1_lock failed on list %d "
204 "ltype=%d (%s)", list, ltype, strerror(errno));
206 return ret;
209 int tdb1_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype)
211 enum TDB_ERROR ecode;
213 /* Sanity checks */
214 if (offset >= lock_offset(tdb->tdb1.header.hash_size)) {
215 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
216 "tdb1_unlock: offset %u invalid (%d)",
217 offset, tdb->tdb1.header.hash_size);
218 return -1;
221 ecode = tdb_nest_unlock(tdb, offset, ltype);
222 if (unlikely(ecode != TDB_SUCCESS)) {
223 tdb->last_error = ecode;
224 return -1;
226 return 0;
229 int tdb1_unlock(struct tdb_context *tdb, int list, int ltype)
231 /* a global lock allows us to avoid per chain locks */
232 if (tdb->file->allrecord_lock.count &&
233 (ltype == tdb->file->allrecord_lock.ltype || ltype == F_RDLCK)) {
234 if (tdb->file->allrecord_lock.owner != tdb) {
235 tdb->last_error = owner_conflict(tdb, "tdb1_unlock");
236 return -1;
238 return 0;
241 if (tdb->file->allrecord_lock.count) {
242 tdb->last_error = TDB_ERR_LOCK;
243 return -1;
246 return tdb1_nest_unlock(tdb, lock_offset(list), ltype);
250 get the transaction lock
252 int tdb1_transaction_lock(struct tdb_context *tdb, int ltype,
253 enum tdb_lock_flags lockflags)
255 return tdb1_nest_lock(tdb, TDB1_TRANSACTION_LOCK, ltype, lockflags);
259 release the transaction lock
261 int tdb1_transaction_unlock(struct tdb_context *tdb, int ltype)
263 return tdb1_nest_unlock(tdb, TDB1_TRANSACTION_LOCK, ltype);
266 /* lock/unlock entire database. It can only be upgradable if you have some
267 * other way of guaranteeing exclusivity (ie. transaction write lock).
268 * We do the locking gradually to avoid being starved by smaller locks. */
269 int tdb1_allrecord_lock(struct tdb_context *tdb, int ltype,
270 enum tdb_lock_flags flags, bool upgradable)
272 enum TDB_ERROR ecode;
273 tdb_bool_err berr;
275 /* tdb_lock_gradual() doesn't know about tdb->tdb1.traverse_read. */
276 if (tdb->tdb1.traverse_read && !(tdb->flags & TDB_NOLOCK)) {
277 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK,
278 TDB_LOG_USE_ERROR,
279 "tdb1_allrecord_lock during"
280 " tdb1_read_traverse");
281 return -1;
284 if (tdb->file->allrecord_lock.count
285 && tdb->file->allrecord_lock.ltype == ltype) {
286 tdb->file->allrecord_lock.count++;
287 return 0;
290 if (tdb1_have_extra_locks(tdb)) {
291 /* can't combine global and chain locks */
292 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK,
293 TDB_LOG_USE_ERROR,
294 "tdb1_allrecord_lock holding"
295 " other locks");
296 return -1;
299 if (upgradable && ltype != F_RDLCK) {
300 /* tdb error: you can't upgrade a write lock! */
301 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK,
302 TDB_LOG_ERROR,
303 "tdb1_allrecord_lock cannot"
304 " have upgradable write lock");
305 return -1;
308 /* We cover two kinds of locks:
309 * 1) Normal chain locks. Taken for almost all operations.
310 * 3) Individual records locks. Taken after normal or free
311 * chain locks.
313 * It is (1) which cause the starvation problem, so we're only
314 * gradual for that. */
315 ecode = tdb_lock_gradual(tdb, ltype, flags | TDB_LOCK_NOCHECK,
316 TDB1_FREELIST_TOP, tdb->tdb1.header.hash_size * 4);
317 if (ecode != TDB_SUCCESS) {
318 tdb->last_error = ecode;
319 return -1;
322 /* Grab individual record locks. */
323 if (tdb1_brlock(tdb, ltype, lock_offset(tdb->tdb1.header.hash_size), 0,
324 flags) == -1) {
325 tdb1_brunlock(tdb, ltype, TDB1_FREELIST_TOP,
326 tdb->tdb1.header.hash_size * 4);
327 return -1;
330 tdb->file->allrecord_lock.owner = tdb;
331 tdb->file->allrecord_lock.count = 1;
332 tdb->file->locker = getpid();
333 /* If it's upgradable, it's actually exclusive so we can treat
334 * it as a write lock. */
335 tdb->file->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
336 tdb->file->allrecord_lock.off = upgradable;
338 berr = tdb1_needs_recovery(tdb);
339 if (berr < 0) {
340 return -1;
343 if (berr == true) {
344 tdb1_allrecord_unlock(tdb, ltype);
345 if (tdb1_lock_and_recover(tdb) == -1) {
346 return -1;
348 return tdb1_allrecord_lock(tdb, ltype, flags, upgradable);
351 return 0;
356 /* unlock entire db */
357 int tdb1_allrecord_unlock(struct tdb_context *tdb, int ltype)
359 /* Don't try this during r/o traversal! */
360 if (tdb->tdb1.traverse_read) {
361 tdb->last_error = TDB_ERR_LOCK;
362 return -1;
365 if (tdb->file->allrecord_lock.count == 0) {
366 tdb->last_error = TDB_ERR_LOCK;
367 return -1;
370 /* Upgradable locks are marked as write locks. */
371 if (tdb->file->allrecord_lock.ltype != ltype
372 && (!tdb->file->allrecord_lock.off || ltype != F_RDLCK)) {
373 tdb->last_error = TDB_ERR_LOCK;
374 return -1;
377 if (tdb->file->allrecord_lock.count > 1) {
378 if (tdb->file->allrecord_lock.owner != tdb) {
379 tdb->last_error
380 = owner_conflict(tdb, "tdb1_allrecord_unlock");
381 return -1;
383 tdb->file->allrecord_lock.count--;
384 return 0;
387 tdb->file->allrecord_lock.count = 0;
388 tdb->file->allrecord_lock.ltype = 0;
390 if (tdb1_brunlock(tdb, ltype, TDB1_FREELIST_TOP, 0)) {
391 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
392 "tdb1_unlockall failed (%s)", strerror(errno));
393 return -1;
396 return 0;
399 /* lock/unlock one hash chain. This is meant to be used to reduce
400 contention - it cannot guarantee how many records will be locked */
401 int tdb1_chainlock(struct tdb_context *tdb, TDB_DATA key)
403 int ret = tdb1_lock(tdb,
404 TDB1_BUCKET(tdb_hash(tdb, key.dptr, key.dsize)),
405 F_WRLCK);
406 return ret;
409 int tdb1_chainunlock(struct tdb_context *tdb, TDB_DATA key)
411 return tdb1_unlock(tdb, TDB1_BUCKET(tdb_hash(tdb, key.dptr, key.dsize)),
412 F_WRLCK);
415 int tdb1_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
417 int ret;
418 ret = tdb1_lock(tdb, TDB1_BUCKET(tdb_hash(tdb, key.dptr, key.dsize)),
419 F_RDLCK);
420 return ret;
423 int tdb1_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
425 return tdb1_unlock(tdb, TDB1_BUCKET(tdb_hash(tdb, key.dptr, key.dsize)),
426 F_RDLCK);
429 /* record lock stops delete underneath */
430 int tdb1_lock_record(struct tdb_context *tdb, tdb1_off_t off)
432 if (tdb->file->allrecord_lock.count) {
433 if (!check_lock_pid(tdb, "tdb1_lock_record", true)) {
434 tdb->last_error = TDB_ERR_LOCK;
435 return -1;
437 if (tdb->file->allrecord_lock.owner != tdb) {
438 tdb->last_error = owner_conflict(tdb,
439 "tdb1_lock_record");
440 return -1;
442 return 0;
444 return off ? tdb1_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
448 Write locks override our own fcntl readlocks, so check it here.
449 Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
450 an error to fail to get the lock here.
452 int tdb1_write_lock_record(struct tdb_context *tdb, tdb1_off_t off)
454 struct tdb1_traverse_lock *i;
455 for (i = &tdb->tdb1.travlocks; i; i = i->next)
456 if (i->off == off)
457 return -1;
458 if (tdb->file->allrecord_lock.count) {
459 if (!check_lock_pid(tdb, "tdb1_write_lock_record", true)) {
460 tdb->last_error = TDB_ERR_LOCK;
461 return -1;
463 if (tdb->file->allrecord_lock.owner != tdb) {
464 tdb->last_error
465 = owner_conflict(tdb, "tdb1_write_lock_record");
466 return -1;
468 if (tdb->file->allrecord_lock.ltype == F_WRLCK) {
469 return 0;
471 return -1;
473 return tdb1_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
476 int tdb1_write_unlock_record(struct tdb_context *tdb, tdb1_off_t off)
478 if (tdb->file->allrecord_lock.count) {
479 if (tdb->file->allrecord_lock.owner != tdb) {
480 tdb->last_error
481 = owner_conflict(tdb,
482 "tdb1_write_unlock_record");
483 return -1;
485 return 0;
487 return tdb1_brunlock(tdb, F_WRLCK, off, 1);
490 /* fcntl locks don't stack: avoid unlocking someone else's */
491 int tdb1_unlock_record(struct tdb_context *tdb, tdb1_off_t off)
493 struct tdb1_traverse_lock *i;
494 uint32_t count = 0;
496 if (tdb->file->allrecord_lock.count) {
497 if (tdb->file->allrecord_lock.owner != tdb) {
498 tdb->last_error = owner_conflict(tdb,
499 "tdb1_unlock_record");
500 return -1;
502 return 0;
505 if (off == 0)
506 return 0;
507 for (i = &tdb->tdb1.travlocks; i; i = i->next)
508 if (i->off == off)
509 count++;
510 return (count == 1 ? tdb1_brunlock(tdb, F_RDLCK, off, 1) : 0);
513 bool tdb1_have_extra_locks(struct tdb_context *tdb)
515 unsigned int extra = tdb->file->num_lockrecs;
517 /* A transaction holds the lock for all records. */
518 if (!tdb->tdb1.transaction && tdb->file->allrecord_lock.count) {
519 return true;
522 /* We always hold the active lock if CLEAR_IF_FIRST. */
523 if (tdb1_find_nestlock(tdb, TDB1_ACTIVE_LOCK)) {
524 extra--;
527 /* In a transaction, we expect to hold the transaction lock */
528 if (tdb->tdb1.transaction
529 && tdb1_find_nestlock(tdb, TDB1_TRANSACTION_LOCK)) {
530 extra--;
533 return extra;
536 /* The transaction code uses this to remove all locks. */
537 void tdb1_release_transaction_locks(struct tdb_context *tdb)
539 unsigned int i, active = 0;
541 if (tdb->file->allrecord_lock.count != 0) {
542 tdb1_brunlock(tdb, tdb->file->allrecord_lock.ltype, TDB1_FREELIST_TOP, 0);
543 tdb->file->allrecord_lock.count = 0;
546 for (i=0;i<tdb->file->num_lockrecs;i++) {
547 struct tdb_lock *lck = &tdb->file->lockrecs[i];
549 /* Don't release the active lock! Copy it to first entry. */
550 if (lck->off == TDB1_ACTIVE_LOCK) {
551 tdb->file->lockrecs[active++] = *lck;
552 } else {
553 tdb1_brunlock(tdb, lck->ltype, lck->off, 1);
556 tdb->file->num_lockrecs = active;
557 if (tdb->file->num_lockrecs == 0) {
558 SAFE_FREE(tdb->file->lockrecs);