5 TDB version 2: trivial database library
7 Copyright (C) Andrew Tridgell 1999-2004
8 Copyright (C) Rusty Russell 2010-2011
10 ** NOTE! The following LGPL license applies to the tdb
11 ** library. This does NOT imply that all of Samba is released
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/>.
32 #ifdef HAVE_LIBREPLACE
35 #if HAVE_FILE_OFFSET_BITS
36 #define _FILE_OFFSET_BITS 64
39 #include <sys/types.h>
42 /* For sig_atomic_t. */
53 #include <ccan/compiler/compiler.h>
54 #include <ccan/typesafe_cb/typesafe_cb.h>
55 #include <ccan/cast/cast.h>
57 #ifndef typesafe_cb_preargs
58 /* Failing to have CCAN just mean less typesafe protection, etc. */
59 #define typesafe_cb_preargs(rtype, atype, fn, arg, ...) \
60 ((rtype (*)(__VA_ARGS__, atype))(fn))
63 #if defined(__intptr_t_defined) || defined(HAVE_INTPTR_T)
64 #define cast_const(type, expr) ((type)((intptr_t)(expr)))
66 #define cast_const(type, expr) ((type *)(expr))
69 #endif /* !HAVE_CCAN */
75 * tdb_open - open a database file
76 * @name: the file name (can be NULL if flags contains TDB_INTERNAL)
77 * @tdb_flags: options for this database
78 * @open_flags: flags argument for tdb's open() call.
79 * @mode: mode argument for tdb's open() call.
80 * @attributes: linked list of extra attributes for this tdb.
82 * This call opens (and potentially creates) a database file.
83 * Multiple processes can have the TDB file open at once.
85 * On failure it will return NULL, and set errno: it may also call
86 * any log attribute found in @attributes.
91 struct tdb_context *tdb_open(const char *name, int tdb_flags,
92 int open_flags, mode_t mode,
93 union tdb_attribute *attributes);
96 /* flags for tdb_open() */
97 #define TDB_DEFAULT 0 /* just a readability place holder */
98 #define TDB_INTERNAL 2 /* don't store on disk */
99 #define TDB_NOLOCK 4 /* don't do any locking */
100 #define TDB_NOMMAP 8 /* don't use mmap */
101 #define TDB_CONVERT 16 /* convert endian */
102 #define TDB_NOSYNC 64 /* don't use synchronous transactions */
103 #define TDB_SEQNUM 128 /* maintain a sequence number */
104 #define TDB_ALLOW_NESTING 256 /* fake nested transactions */
105 #define TDB_RDONLY 512 /* implied by O_RDONLY */
106 #define TDB_CANT_CHECK 2048 /* has a feature which we don't understand */
109 * tdb_close - close and free a tdb.
110 * @tdb: the tdb context returned from tdb_open()
112 * This always succeeds, in that @tdb is unusable after this call. But if
113 * some unexpected error occurred while closing, it will return non-zero
114 * (the only clue as to cause will be via the log attribute).
116 int tdb_close(struct tdb_context *tdb);
119 * struct tdb_data - representation of keys or values.
120 * @dptr: the data pointer
121 * @dsize: the size of the data pointed to by dptr.
123 * This is the "blob" representation of keys and data used by TDB.
125 typedef struct tdb_data {
131 * enum TDB_ERROR - error returns for TDB
137 TDB_SUCCESS = 0, /* No error. */
138 TDB_ERR_CORRUPT = -1, /* We read the db, and it was bogus. */
139 TDB_ERR_IO = -2, /* We couldn't read/write the db. */
140 TDB_ERR_LOCK = -3, /* Locking failed. */
141 TDB_ERR_OOM = -4, /* Out of Memory. */
142 TDB_ERR_EXISTS = -5, /* The key already exists. */
143 TDB_ERR_NOEXIST = -6, /* The key does not exist. */
144 TDB_ERR_EINVAL = -7, /* You're using it wrong. */
145 TDB_ERR_RDONLY = -8, /* The database is read-only. */
146 TDB_ERR_LAST = TDB_ERR_RDONLY
150 * tdb_store - store a key/value pair in a tdb.
151 * @tdb: the tdb context returned from tdb_open()
153 * @dbuf: the data to associate with the key.
154 * @flag: TDB_REPLACE, TDB_INSERT or TDB_MODIFY.
156 * This inserts (or overwrites) a key/value pair in the TDB. If flag
157 * is TDB_REPLACE, it doesn't matter whether the key exists or not;
158 * TDB_INSERT means it must not exist (returns TDB_ERR_EXISTS otherwise),
159 * and TDB_MODIFY means it must exist (returns TDB_ERR_NOEXIST otherwise).
161 * On success, this returns TDB_SUCCESS.
164 * tdb_fetch, tdb_transaction_start, tdb_append, tdb_delete.
166 enum TDB_ERROR tdb_store(struct tdb_context *tdb,
168 struct tdb_data dbuf,
171 /* flags to tdb_store() */
172 #define TDB_REPLACE 1 /* A readability place holder */
173 #define TDB_INSERT 2 /* Don't overwrite an existing entry */
174 #define TDB_MODIFY 3 /* Don't create an existing entry */
177 * tdb_fetch - fetch a value from a tdb.
178 * @tdb: the tdb context returned from tdb_open()
180 * @data: pointer to data.
182 * This looks up a key in the database and sets it in @data.
184 * If it returns TDB_SUCCESS, the key was found: it is your
185 * responsibility to call free() on @data->dptr.
187 * Otherwise, it returns an error (usually, TDB_ERR_NOEXIST) and @data is
190 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
191 struct tdb_data *data);
194 * tdb_errorstr - map the tdb error onto a constant readable string
195 * @ecode: the enum TDB_ERROR to map.
197 * This is useful for displaying errors to users.
199 const char *tdb_errorstr(enum TDB_ERROR ecode);
202 * tdb_append - append a value to a key/value pair in a tdb.
203 * @tdb: the tdb context returned from tdb_open()
205 * @dbuf: the data to append.
207 * This is equivalent to fetching a record, reallocating .dptr to add the
208 * data, and writing it back, only it's much more efficient. If the key
209 * doesn't exist, it's equivalent to tdb_store (with an additional hint that
210 * you expect to expand the record in future).
213 * tdb_fetch(), tdb_store()
215 enum TDB_ERROR tdb_append(struct tdb_context *tdb,
216 struct tdb_data key, struct tdb_data dbuf);
219 * tdb_delete - delete a key from a tdb.
220 * @tdb: the tdb context returned from tdb_open()
221 * @key: the key to delete.
223 * Returns TDB_SUCCESS on success, or an error (usually TDB_ERR_NOEXIST).
226 * tdb_fetch(), tdb_store()
228 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key);
231 * tdb_exists - does a key exist in the database?
232 * @tdb: the tdb context returned from tdb_open()
233 * @key: the key to search for.
235 * Returns true if it exists, or false if it doesn't or any other error.
237 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key);
240 * tdb_deq - are struct tdb_data equal?
241 * @a: one struct tdb_data
242 * @b: another struct tdb_data
244 static inline bool tdb_deq(struct tdb_data a, struct tdb_data b)
246 return a.dsize == b.dsize && memcmp(a.dptr, b.dptr, a.dsize) == 0;
250 * tdb_mkdata - make a struct tdb_data from const data
251 * @p: the constant pointer
254 * As the dptr member of struct tdb_data is not constant, you need to
255 * cast it. This function keeps thost casts in one place, as well as
256 * suppressing the warning some compilers give when casting away a
257 * qualifier (eg. gcc with -Wcast-qual)
259 static inline struct tdb_data tdb_mkdata(const void *p, size_t len)
262 d.dptr = cast_const(void *, p);
268 * tdb_transaction_start - start a transaction
269 * @tdb: the tdb context returned from tdb_open()
271 * This begins a series of atomic operations. Other processes will be able
272 * to read the tdb, but not alter it (they will block), nor will they see
273 * any changes until tdb_transaction_commit() is called.
275 * Note that if the TDB_ALLOW_NESTING flag is set, a tdb_transaction_start()
276 * within a transaction will succeed, but it's not a real transaction:
277 * (1) An inner transaction which is committed is not actually committed until
278 * the outer transaction is; if the outer transaction is cancelled, the
279 * inner ones are discarded.
280 * (2) tdb_transaction_cancel() marks the outer transaction as having an error,
281 * so the final tdb_transaction_commit() will fail.
282 * (3) the outer transaction will see the results of the inner transaction.
285 * tdb_transaction_cancel, tdb_transaction_commit.
287 enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb);
290 * tdb_transaction_cancel - abandon a transaction
291 * @tdb: the tdb context returned from tdb_open()
293 * This aborts a transaction, discarding any changes which were made.
294 * tdb_close() does this implicitly.
296 void tdb_transaction_cancel(struct tdb_context *tdb);
299 * tdb_transaction_commit - commit a transaction
300 * @tdb: the tdb context returned from tdb_open()
302 * This completes a transaction, writing any changes which were made.
304 * fsync() is used to commit the transaction (unless TDB_NOSYNC is set),
305 * making it robust against machine crashes, but very slow compared to
306 * other TDB operations.
308 * A failure can only be caused by unexpected errors (eg. I/O or
309 * memory); this is no point looping on transaction failure.
312 * tdb_transaction_prepare_commit()
314 enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb);
317 * tdb_transaction_prepare_commit - prepare to commit a transaction
318 * @tdb: the tdb context returned from tdb_open()
320 * This ensures we have the resources to commit a transaction (using
321 * tdb_transaction_commit): if this succeeds then a transaction will only
322 * fail if the write() or fsync() calls fail.
324 * If this fails you must still call tdb_transaction_cancel() to cancel
328 * tdb_transaction_commit()
330 enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb);
333 * tdb_traverse - traverse a TDB
334 * @tdb: the tdb context returned from tdb_open()
335 * @fn: the function to call for every key/value pair (or NULL)
336 * @p: the pointer to hand to @f
338 * This walks the TDB until all they keys have been traversed, or @fn
339 * returns non-zero. If the traverse function or other processes are
340 * changing data or adding or deleting keys, the traverse may be
341 * unreliable: keys may be skipped or (rarely) visited twice.
343 * There is one specific exception: the special case of deleting the
344 * current key does not undermine the reliability of the traversal.
346 * On success, returns the number of keys iterated. On error returns
347 * a negative enum TDB_ERROR value.
349 #define tdb_traverse(tdb, fn, p) \
350 tdb_traverse_(tdb, typesafe_cb_preargs(int, void *, (fn), (p), \
351 struct tdb_context *, \
352 TDB_DATA, TDB_DATA), (p))
354 int64_t tdb_traverse_(struct tdb_context *tdb,
355 int (*fn)(struct tdb_context *,
356 TDB_DATA, TDB_DATA, void *), void *p);
359 * tdb_parse_record - operate directly on data in the database.
360 * @tdb: the tdb context returned from tdb_open()
361 * @key: the key whose record we should hand to @parse
362 * @parse: the function to call for the data
363 * @data: the private pointer to hand to @parse (types must match).
365 * This avoids a copy for many cases, by handing you a pointer into
366 * the memory-mapped database. It also locks the record to prevent
367 * other accesses at the same time.
369 * Do not alter the data handed to parse()!
371 #define tdb_parse_record(tdb, key, parse, data) \
372 tdb_parse_record_((tdb), (key), \
373 typesafe_cb_preargs(enum TDB_ERROR, void *, \
375 TDB_DATA, TDB_DATA), (data))
377 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
379 enum TDB_ERROR (*parse)(TDB_DATA k,
385 * tdb_get_seqnum - get a database sequence number
386 * @tdb: the tdb context returned from tdb_open()
388 * This returns a sequence number: any change to the database from a
389 * tdb context opened with the TDB_SEQNUM flag will cause that number
390 * to increment. Note that the incrementing is unreliable (it is done
391 * without locking), so this is only useful as an optimization.
393 * For example, you may have a regular database backup routine which
394 * does not operate if the sequence number is unchanged. In the
395 * unlikely event of a failed increment, it will be backed up next
398 * Returns an enum TDB_ERROR (ie. negative) on error.
400 int64_t tdb_get_seqnum(struct tdb_context *tdb);
403 * tdb_firstkey - get the "first" key in a TDB
404 * @tdb: the tdb context returned from tdb_open()
405 * @key: pointer to key.
407 * This returns an arbitrary key in the database; with tdb_nextkey() it allows
408 * open-coded traversal of the database, though it is slightly less efficient
411 * It is your responsibility to free @key->dptr on success.
413 * Returns TDB_ERR_NOEXIST if the database is empty.
415 enum TDB_ERROR tdb_firstkey(struct tdb_context *tdb, struct tdb_data *key);
418 * tdb_nextkey - get the "next" key in a TDB
419 * @tdb: the tdb context returned from tdb_open()
420 * @key: a key returned by tdb_firstkey() or tdb_nextkey().
422 * This returns another key in the database; it will free @key.dptr for
425 * Returns TDB_ERR_NOEXIST if there are no more keys.
427 enum TDB_ERROR tdb_nextkey(struct tdb_context *tdb, struct tdb_data *key);
430 * tdb_chainlock - lock a record in the TDB
431 * @tdb: the tdb context returned from tdb_open()
432 * @key: the key to lock.
434 * This prevents any access occurring to a group of keys including @key,
435 * even if @key does not exist. This allows primitive atomic updates of
436 * records without using transactions.
438 * You cannot begin a transaction while holding a tdb_chainlock(), nor can
439 * you do any operations on any other keys in the database. This also means
440 * that you cannot hold more than one tdb_chainlock() at a time.
445 enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
448 * tdb_chainunlock - unlock a record in the TDB
449 * @tdb: the tdb context returned from tdb_open()
450 * @key: the key to unlock.
452 * The key must have previously been locked by tdb_chainlock().
454 void tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
457 * tdb_chainlock_read - lock a record in the TDB, for reading
458 * @tdb: the tdb context returned from tdb_open()
459 * @key: the key to lock.
461 * This prevents any changes from occurring to a group of keys including @key,
462 * even if @key does not exist. This allows primitive atomic updates of
463 * records without using transactions.
465 * You cannot begin a transaction while holding a tdb_chainlock_read(), nor can
466 * you do any operations on any other keys in the database. This also means
467 * that you cannot hold more than one tdb_chainlock()/read() at a time.
472 enum TDB_ERROR tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key);
475 * tdb_chainunlock_read - unlock a record in the TDB for reading
476 * @tdb: the tdb context returned from tdb_open()
477 * @key: the key to unlock.
479 * The key must have previously been locked by tdb_chainlock_read().
481 void tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key);
484 * tdb_lockall - lock the entire TDB
485 * @tdb: the tdb context returned from tdb_open()
487 * You cannot hold a tdb_chainlock while calling this. It nests, so you
488 * must call tdb_unlockall as many times as you call tdb_lockall.
490 enum TDB_ERROR tdb_lockall(struct tdb_context *tdb);
493 * tdb_unlockall - unlock the entire TDB
494 * @tdb: the tdb context returned from tdb_open()
496 void tdb_unlockall(struct tdb_context *tdb);
499 * tdb_lockall_read - lock the entire TDB for reading
500 * @tdb: the tdb context returned from tdb_open()
502 * This prevents others writing to the database, eg. tdb_delete, tdb_store,
503 * tdb_append, but not tdb_fetch.
505 * You cannot hold a tdb_chainlock while calling this. It nests, so you
506 * must call tdb_unlockall_read as many times as you call tdb_lockall_read.
508 enum TDB_ERROR tdb_lockall_read(struct tdb_context *tdb);
511 * tdb_unlockall_read - unlock the entire TDB for reading
512 * @tdb: the tdb context returned from tdb_open()
514 void tdb_unlockall_read(struct tdb_context *tdb);
517 * tdb_wipe_all - wipe the database clean
518 * @tdb: the tdb context returned from tdb_open()
520 * Completely erase the database. This is faster than iterating through
521 * each key and doing tdb_delete.
523 enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb);
526 * tdb_repack - repack the database
527 * @tdb: the tdb context returned from tdb_open()
529 * This repacks the database; if it is suffering from a great deal of
530 * fragmentation this might help. However, it can take twice the
531 * memory of the existing TDB.
533 enum TDB_ERROR tdb_repack(struct tdb_context *tdb);
536 * tdb_check - check a TDB for consistency
537 * @tdb: the tdb context returned from tdb_open()
538 * @check: function to check each key/data pair (or NULL)
539 * @data: argument for @check, must match type.
541 * This performs a consistency check of the open database, optionally calling
542 * a check() function on each record so you can do your own data consistency
543 * checks as well. If check() returns an error, that is returned from
546 * Note that the TDB uses a feature which we don't understand which
547 * indicates we can't run tdb_check(), this will log a warning to that
548 * effect and return TDB_SUCCESS. You can detect this condition by
549 * looking for TDB_CANT_CHECK in tdb_get_flags().
551 * Returns TDB_SUCCESS or an error.
553 #define tdb_check(tdb, check, data) \
554 tdb_check_((tdb), typesafe_cb_preargs(enum TDB_ERROR, void *, \
560 enum TDB_ERROR tdb_check_(struct tdb_context *tdb,
561 enum TDB_ERROR (*check)(struct tdb_data k,
567 * tdb_error - get the last error (not threadsafe)
568 * @tdb: the tdb context returned from tdb_open()
570 * Returns the last error returned by a TDB function.
572 * This makes porting from TDB1 easier, but note that the last error is not
573 * reliable in threaded programs.
575 enum TDB_ERROR tdb_error(struct tdb_context *tdb);
578 * enum tdb_summary_flags - flags for tdb_summary.
580 enum tdb_summary_flags {
581 TDB_SUMMARY_HISTOGRAMS = 1 /* Draw graphs in the summary. */
585 * tdb_summary - return a string describing the TDB state
586 * @tdb: the tdb context returned from tdb_open()
587 * @flags: flags to control the summary output.
588 * @summary: pointer to string to allocate.
590 * This returns a developer-readable string describing the overall
591 * state of the tdb, such as the percentage used and sizes of records.
592 * It is designed to provide information about the tdb at a glance
593 * without displaying any keys or data in the database.
595 * On success, sets @summary to point to a malloc()'ed nul-terminated
596 * multi-line string. It is your responsibility to free() it.
598 enum TDB_ERROR tdb_summary(struct tdb_context *tdb,
599 enum tdb_summary_flags flags,
604 * tdb_get_flags - return the flags for a tdb
605 * @tdb: the tdb context returned from tdb_open()
607 * This returns the flags on the current tdb. Some of these are caused by
608 * the flags argument to tdb_open(), others (such as TDB_CONVERT) are
611 unsigned int tdb_get_flags(struct tdb_context *tdb);
614 * tdb_add_flag - set a flag for a tdb
615 * @tdb: the tdb context returned from tdb_open()
616 * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING.
618 * You can use this to set a flag on the TDB. You cannot set these flags
619 * on a TDB_INTERNAL tdb.
621 void tdb_add_flag(struct tdb_context *tdb, unsigned flag);
624 * tdb_remove_flag - unset a flag for a tdb
625 * @tdb: the tdb context returned from tdb_open()
626 * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING.
628 * You can use this to clear a flag on the TDB. You cannot clear flags
629 * on a TDB_INTERNAL tdb.
631 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag);
634 * enum tdb_attribute_type - descriminator for union tdb_attribute.
636 enum tdb_attribute_type {
637 TDB_ATTRIBUTE_LOG = 0,
638 TDB_ATTRIBUTE_HASH = 1,
639 TDB_ATTRIBUTE_SEED = 2,
640 TDB_ATTRIBUTE_STATS = 3,
641 TDB_ATTRIBUTE_OPENHOOK = 4,
642 TDB_ATTRIBUTE_FLOCK = 5,
646 * tdb_get_attribute - get an attribute for an existing tdb
647 * @tdb: the tdb context returned from tdb_open()
648 * @attr: the union tdb_attribute to set.
650 * This gets an attribute from a TDB which has previously been set (or
651 * may return the default values). Set @attr.base.attr to the
652 * attribute type you want get.
654 enum TDB_ERROR tdb_get_attribute(struct tdb_context *tdb,
655 union tdb_attribute *attr);
658 * tdb_set_attribute - set an attribute for an existing tdb
659 * @tdb: the tdb context returned from tdb_open()
660 * @attr: the union tdb_attribute to set.
662 * This sets an attribute on a TDB, overriding any previous attribute
663 * of the same type. It returns TDB_ERR_EINVAL if the attribute is
664 * unknown or invalid.
666 * Note that TDB_ATTRIBUTE_HASH, TDB_ATTRIBUTE_SEED, and
667 * TDB_ATTRIBUTE_OPENHOOK cannot currently be set after tdb_open.
669 enum TDB_ERROR tdb_set_attribute(struct tdb_context *tdb,
670 const union tdb_attribute *attr);
673 * tdb_unset_attribute - reset an attribute for an existing tdb
674 * @tdb: the tdb context returned from tdb_open()
675 * @type: the attribute type to unset.
677 * This unsets an attribute on a TDB, returning it to the defaults
678 * (where applicable).
680 * Note that it only makes sense for TDB_ATTRIBUTE_LOG and TDB_ATTRIBUTE_FLOCK
683 void tdb_unset_attribute(struct tdb_context *tdb,
684 enum tdb_attribute_type type);
687 * tdb_name - get the name of a tdb
688 * @tdb: the tdb context returned from tdb_open()
690 * This returns a copy of the name string, made at tdb_open() time. If that
691 * argument was NULL (possible for a TDB_INTERNAL db) this will return NULL.
693 * This is mostly useful for logging.
695 const char *tdb_name(const struct tdb_context *tdb);
698 * tdb_fd - get the file descriptor of a tdb
699 * @tdb: the tdb context returned from tdb_open()
701 * This returns the file descriptor for the underlying database file, or -1
704 int tdb_fd(const struct tdb_context *tdb);
707 * tdb_foreach - iterate through every open TDB.
708 * @fn: the function to call for every TDB
709 * @p: the pointer to hand to @fn
711 * TDB internally keeps track of all open TDBs; this function allows you to
712 * iterate through them. If @fn returns non-zero, traversal stops.
714 #define tdb_foreach(fn, p) \
715 tdb_foreach_(typesafe_cb_preargs(int, void *, (fn), (p), \
716 struct tdb_context *), (p))
718 void tdb_foreach_(int (*fn)(struct tdb_context *, void *), void *p);
721 * struct tdb_attribute_base - common fields for all tdb attributes.
723 struct tdb_attribute_base {
724 enum tdb_attribute_type attr;
725 union tdb_attribute *next;
729 * enum tdb_log_level - log levels for tdb_attribute_log
730 * @TDB_LOG_ERROR: used to log unrecoverable errors such as I/O errors
731 * or internal consistency failures.
732 * @TDB_LOG_USE_ERROR: used to log usage errors such as invalid parameters
733 * or writing to a read-only database.
734 * @TDB_LOG_WARNING: used for informational messages on issues which
735 * are unusual but handled by TDB internally, such
736 * as a failure to mmap or failure to open /dev/urandom.
745 * struct tdb_attribute_log - log function attribute
747 * This attribute provides a hook for you to log errors.
749 struct tdb_attribute_log {
750 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_LOG */
751 void (*fn)(struct tdb_context *tdb,
752 enum tdb_log_level level,
753 enum TDB_ERROR ecode,
760 * struct tdb_attribute_hash - hash function attribute
762 * This attribute allows you to provide an alternative hash function.
763 * This hash function will be handed keys from the database; it will also
764 * be handed the 8-byte TDB_HASH_MAGIC value for checking the header (the
765 * tdb_open() will fail if the hash value doesn't match the header).
767 * Note that if your hash function gives different results on
768 * different machine endians, your tdb will no longer work across
769 * different architectures!
771 struct tdb_attribute_hash {
772 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_HASH */
773 uint64_t (*fn)(const void *key, size_t len, uint64_t seed,
779 * struct tdb_attribute_seed - hash function seed attribute
781 * The hash function seed is normally taken from /dev/urandom (or equivalent)
782 * but can be set manually here. This is mainly for testing purposes.
784 struct tdb_attribute_seed {
785 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_SEED */
790 * struct tdb_attribute_stats - tdb operational statistics
792 * This attribute records statistics of various low-level TDB operations.
793 * This can be used to assist performance evaluation. This is only
794 * useful for tdb_get_attribute().
796 * New fields will be added at the end, hence the "size" argument which
797 * indicates how large your structure is: it must be filled in before
798 * calling tdb_get_attribute(), which will overwrite it with the size
801 struct tdb_attribute_stats {
802 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_STATS */
803 size_t size; /* = sizeof(struct tdb_attribute_stats) */
805 uint64_t alloc_subhash;
806 uint64_t alloc_chain;
807 uint64_t alloc_bucket_exact;
808 uint64_t alloc_bucket_max;
809 uint64_t alloc_leftover;
810 uint64_t alloc_coalesce_tried;
811 uint64_t alloc_coalesce_iterate_clash;
812 uint64_t alloc_coalesce_lockfail;
813 uint64_t alloc_coalesce_race;
814 uint64_t alloc_coalesce_succeeded;
815 uint64_t alloc_coalesce_num_merged;
817 uint64_t compare_wrong_bucket;
818 uint64_t compare_wrong_offsetbits;
819 uint64_t compare_wrong_keylen;
820 uint64_t compare_wrong_rechash;
821 uint64_t compare_wrong_keycmp;
822 uint64_t transactions;
823 uint64_t transaction_cancel;
824 uint64_t transaction_nest;
825 uint64_t transaction_expand_file;
826 uint64_t transaction_read_direct;
827 uint64_t transaction_read_direct_fail;
828 uint64_t transaction_write_direct;
829 uint64_t transaction_write_direct_fail;
833 uint64_t lock_lowlevel;
834 uint64_t lock_nonblock;
835 uint64_t lock_nonblock_fail;
839 * struct tdb_attribute_openhook - tdb special effects hook for open
841 * This attribute contains a function to call once we have the OPEN_LOCK
842 * for the tdb, but before we've examined its contents. If this succeeds,
843 * the tdb will be populated if it's then zero-length.
845 * This is a hack to allow support for TDB1-style TDB_CLEAR_IF_FIRST
848 struct tdb_attribute_openhook {
849 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_OPENHOOK */
850 enum TDB_ERROR (*fn)(int fd, void *data);
855 * struct tdb_attribute_flock - tdb special effects hook for file locking
857 * This attribute contains function to call to place locks on a file; it can
858 * be used to support non-blocking operations or lock proxying.
860 * They should return 0 on success, -1 on failure and set errno.
862 * An error will be logged on error if errno is neither EAGAIN nor EINTR
863 * (normally it would only return EAGAIN if waitflag is false, and
864 * loop internally on EINTR).
866 struct tdb_attribute_flock {
867 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_FLOCK */
868 int (*lock)(int fd,int rw, off_t off, off_t len, bool waitflag, void *);
869 int (*unlock)(int fd, int rw, off_t off, off_t len, void *);
874 * union tdb_attribute - tdb attributes.
876 * This represents all the known attributes.
879 * struct tdb_attribute_log, struct tdb_attribute_hash,
880 * struct tdb_attribute_seed, struct tdb_attribute_stats,
881 * struct tdb_attribute_openhook, struct tdb_attribute_flock.
883 union tdb_attribute {
884 struct tdb_attribute_base base;
885 struct tdb_attribute_log log;
886 struct tdb_attribute_hash hash;
887 struct tdb_attribute_seed seed;
888 struct tdb_attribute_stats stats;
889 struct tdb_attribute_openhook openhook;
890 struct tdb_attribute_flock flock;