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/>.
34 #if HAVE_FILE_OFFSET_BITS
35 #define _FILE_OFFSET_BITS 64
38 #include <sys/types.h>
41 /* For sig_atomic_t. */
52 #include <ccan/compiler/compiler.h>
53 #include <ccan/typesafe_cb/typesafe_cb.h>
54 #include <ccan/cast/cast.h>
60 * tdb_open - open a database file
61 * @name: the file name (can be NULL if flags contains TDB_INTERNAL)
62 * @tdb_flags: options for this database
63 * @open_flags: flags argument for tdb's open() call.
64 * @mode: mode argument for tdb's open() call.
65 * @attributes: linked list of extra attributes for this tdb.
67 * This call opens (and potentially creates) a database file.
68 * Multiple processes can have the TDB file open at once.
70 * On failure it will return NULL, and set errno: it may also call
71 * any log attribute found in @attributes.
76 struct tdb_context *tdb_open(const char *name, int tdb_flags,
77 int open_flags, mode_t mode,
78 union tdb_attribute *attributes);
81 /* flags for tdb_open() */
82 #define TDB_DEFAULT 0 /* just a readability place holder */
83 #define TDB_INTERNAL 2 /* don't store on disk */
84 #define TDB_NOLOCK 4 /* don't do any locking */
85 #define TDB_NOMMAP 8 /* don't use mmap */
86 #define TDB_CONVERT 16 /* convert endian */
87 #define TDB_NOSYNC 64 /* don't use synchronous transactions */
88 #define TDB_SEQNUM 128 /* maintain a sequence number */
89 #define TDB_ALLOW_NESTING 256 /* fake nested transactions */
90 #define TDB_RDONLY 512 /* implied by O_RDONLY */
91 #define TDB_VERSION1 1024 /* create/open an old style TDB */
94 * tdb_close - close and free a tdb.
95 * @tdb: the tdb context returned from tdb_open()
97 * This always succeeds, in that @tdb is unusable after this call. But if
98 * some unexpected error occurred while closing, it will return non-zero
99 * (the only clue as to cause will be via the log attribute).
101 int tdb_close(struct tdb_context *tdb);
104 * struct tdb_data - representation of keys or values.
105 * @dptr: the data pointer
106 * @dsize: the size of the data pointed to by dptr.
108 * This is the "blob" representation of keys and data used by TDB.
110 typedef struct tdb_data {
116 * enum TDB_ERROR - error returns for TDB
122 TDB_SUCCESS = 0, /* No error. */
123 TDB_ERR_CORRUPT = -1, /* We read the db, and it was bogus. */
124 TDB_ERR_IO = -2, /* We couldn't read/write the db. */
125 TDB_ERR_LOCK = -3, /* Locking failed. */
126 TDB_ERR_OOM = -4, /* Out of Memory. */
127 TDB_ERR_EXISTS = -5, /* The key already exists. */
128 TDB_ERR_NOEXIST = -6, /* The key does not exist. */
129 TDB_ERR_EINVAL = -7, /* You're using it wrong. */
130 TDB_ERR_RDONLY = -8, /* The database is read-only. */
131 TDB_ERR_LAST = TDB_ERR_RDONLY
135 * tdb_store - store a key/value pair in a tdb.
136 * @tdb: the tdb context returned from tdb_open()
138 * @dbuf: the data to associate with the key.
139 * @flag: TDB_REPLACE, TDB_INSERT or TDB_MODIFY.
141 * This inserts (or overwrites) a key/value pair in the TDB. If flag
142 * is TDB_REPLACE, it doesn't matter whether the key exists or not;
143 * TDB_INSERT means it must not exist (returns TDB_ERR_EXISTS otherwise),
144 * and TDB_MODIFY means it must exist (returns TDB_ERR_NOEXIST otherwise).
146 * On success, this returns TDB_SUCCESS.
149 * tdb_fetch, tdb_transaction_start, tdb_append, tdb_delete.
151 enum TDB_ERROR tdb_store(struct tdb_context *tdb,
153 struct tdb_data dbuf,
156 /* flags to tdb_store() */
157 #define TDB_REPLACE 1 /* A readability place holder */
158 #define TDB_INSERT 2 /* Don't overwrite an existing entry */
159 #define TDB_MODIFY 3 /* Don't create an existing entry */
162 * tdb_fetch - fetch a value from a tdb.
163 * @tdb: the tdb context returned from tdb_open()
165 * @data: pointer to data.
167 * This looks up a key in the database and sets it in @data.
169 * If it returns TDB_SUCCESS, the key was found: it is your
170 * responsibility to call free() on @data->dptr.
172 * Otherwise, it returns an error (usually, TDB_ERR_NOEXIST) and @data is
175 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
176 struct tdb_data *data);
179 * tdb_errorstr - map the tdb error onto a constant readable string
180 * @ecode: the enum TDB_ERROR to map.
182 * This is useful for displaying errors to users.
184 const char *tdb_errorstr(enum TDB_ERROR ecode);
187 * tdb_append - append a value to a key/value pair in a tdb.
188 * @tdb: the tdb context returned from tdb_open()
190 * @dbuf: the data to append.
192 * This is equivalent to fetching a record, reallocating .dptr to add the
193 * data, and writing it back, only it's much more efficient. If the key
194 * doesn't exist, it's equivalent to tdb_store (with an additional hint that
195 * you expect to expand the record in future).
198 * tdb_fetch(), tdb_store()
200 enum TDB_ERROR tdb_append(struct tdb_context *tdb,
201 struct tdb_data key, struct tdb_data dbuf);
204 * tdb_delete - delete a key from a tdb.
205 * @tdb: the tdb context returned from tdb_open()
206 * @key: the key to delete.
208 * Returns TDB_SUCCESS on success, or an error (usually TDB_ERR_NOEXIST).
211 * tdb_fetch(), tdb_store()
213 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key);
216 * tdb_exists - does a key exist in the database?
217 * @tdb: the tdb context returned from tdb_open()
218 * @key: the key to search for.
220 * Returns true if it exists, or false if it doesn't or any other error.
222 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key);
225 * tdb_deq - are struct tdb_data equal?
226 * @a: one struct tdb_data
227 * @b: another struct tdb_data
229 static inline bool tdb_deq(struct tdb_data a, struct tdb_data b)
231 return a.dsize == b.dsize && memcmp(a.dptr, b.dptr, a.dsize) == 0;
235 * tdb_mkdata - make a struct tdb_data from const data
236 * @p: the constant pointer
239 * As the dptr member of struct tdb_data is not constant, you need to
240 * cast it. This function keeps thost casts in one place, as well as
241 * suppressing the warning some compilers give when casting away a
242 * qualifier (eg. gcc with -Wcast-qual)
244 static inline struct tdb_data tdb_mkdata(const void *p, size_t len)
247 d.dptr = cast_const(void *, p);
253 * tdb_transaction_start - start a transaction
254 * @tdb: the tdb context returned from tdb_open()
256 * This begins a series of atomic operations. Other processes will be able
257 * to read the tdb, but not alter it (they will block), nor will they see
258 * any changes until tdb_transaction_commit() is called.
260 * Note that if the TDB_ALLOW_NESTING flag is set, a tdb_transaction_start()
261 * within a transaction will succeed, but it's not a real transaction:
262 * (1) An inner transaction which is committed is not actually committed until
263 * the outer transaction is; if the outer transaction is cancelled, the
264 * inner ones are discarded.
265 * (2) tdb_transaction_cancel() marks the outer transaction as having an error,
266 * so the final tdb_transaction_commit() will fail.
267 * (3) the outer transaction will see the results of the inner transaction.
270 * tdb_transaction_cancel, tdb_transaction_commit.
272 enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb);
275 * tdb_transaction_cancel - abandon a transaction
276 * @tdb: the tdb context returned from tdb_open()
278 * This aborts a transaction, discarding any changes which were made.
279 * tdb_close() does this implicitly.
281 void tdb_transaction_cancel(struct tdb_context *tdb);
284 * tdb_transaction_commit - commit a transaction
285 * @tdb: the tdb context returned from tdb_open()
287 * This completes a transaction, writing any changes which were made.
289 * fsync() is used to commit the transaction (unless TDB_NOSYNC is set),
290 * making it robust against machine crashes, but very slow compared to
291 * other TDB operations.
293 * A failure can only be caused by unexpected errors (eg. I/O or
294 * memory); this is no point looping on transaction failure.
297 * tdb_transaction_prepare_commit()
299 enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb);
302 * tdb_transaction_prepare_commit - prepare to commit a transaction
303 * @tdb: the tdb context returned from tdb_open()
305 * This ensures we have the resources to commit a transaction (using
306 * tdb_transaction_commit): if this succeeds then a transaction will only
307 * fail if the write() or fsync() calls fail.
309 * If this fails you must still call tdb_transaction_cancel() to cancel
313 * tdb_transaction_commit()
315 enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb);
318 * tdb_traverse - traverse a TDB
319 * @tdb: the tdb context returned from tdb_open()
320 * @fn: the function to call for every key/value pair (or NULL)
321 * @p: the pointer to hand to @f
323 * This walks the TDB until all they keys have been traversed, or @fn
324 * returns non-zero. If the traverse function or other processes are
325 * changing data or adding or deleting keys, the traverse may be
326 * unreliable: keys may be skipped or (rarely) visited twice.
328 * There is one specific exception: the special case of deleting the
329 * current key does not undermine the reliability of the traversal.
331 * On success, returns the number of keys iterated. On error returns
332 * a negative enum TDB_ERROR value.
334 #define tdb_traverse(tdb, fn, p) \
335 tdb_traverse_(tdb, typesafe_cb_preargs(int, void *, (fn), (p), \
336 struct tdb_context *, \
337 TDB_DATA, TDB_DATA), (p))
339 int64_t tdb_traverse_(struct tdb_context *tdb,
340 int (*fn)(struct tdb_context *,
341 TDB_DATA, TDB_DATA, void *), void *p);
344 * tdb_parse_record - operate directly on data in the database.
345 * @tdb: the tdb context returned from tdb_open()
346 * @key: the key whose record we should hand to @parse
347 * @parse: the function to call for the data
348 * @data: the private pointer to hand to @parse (types must match).
350 * This avoids a copy for many cases, by handing you a pointer into
351 * the memory-mapped database. It also locks the record to prevent
352 * other accesses at the same time.
354 * Do not alter the data handed to parse()!
356 #define tdb_parse_record(tdb, key, parse, data) \
357 tdb_parse_record_((tdb), (key), \
358 typesafe_cb_preargs(enum TDB_ERROR, void *, \
360 TDB_DATA, TDB_DATA), (data))
362 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
364 enum TDB_ERROR (*parse)(TDB_DATA k,
370 * tdb_get_seqnum - get a database sequence number
371 * @tdb: the tdb context returned from tdb_open()
373 * This returns a sequence number: any change to the database from a
374 * tdb context opened with the TDB_SEQNUM flag will cause that number
375 * to increment. Note that the incrementing is unreliable (it is done
376 * without locking), so this is only useful as an optimization.
378 * For example, you may have a regular database backup routine which
379 * does not operate if the sequence number is unchanged. In the
380 * unlikely event of a failed increment, it will be backed up next
383 * Returns an enum TDB_ERROR (ie. negative) on error.
385 int64_t tdb_get_seqnum(struct tdb_context *tdb);
388 * tdb_firstkey - get the "first" key in a TDB
389 * @tdb: the tdb context returned from tdb_open()
390 * @key: pointer to key.
392 * This returns an arbitrary key in the database; with tdb_nextkey() it allows
393 * open-coded traversal of the database, though it is slightly less efficient
396 * It is your responsibility to free @key->dptr on success.
398 * Returns TDB_ERR_NOEXIST if the database is empty.
400 enum TDB_ERROR tdb_firstkey(struct tdb_context *tdb, struct tdb_data *key);
403 * tdb_nextkey - get the "next" key in a TDB
404 * @tdb: the tdb context returned from tdb_open()
405 * @key: a key returned by tdb_firstkey() or tdb_nextkey().
407 * This returns another key in the database; it will free @key.dptr for
410 * Returns TDB_ERR_NOEXIST if there are no more keys.
412 enum TDB_ERROR tdb_nextkey(struct tdb_context *tdb, struct tdb_data *key);
415 * tdb_chainlock - lock a record in the TDB
416 * @tdb: the tdb context returned from tdb_open()
417 * @key: the key to lock.
419 * This prevents any access occurring to a group of keys including @key,
420 * even if @key does not exist. This allows primitive atomic updates of
421 * records without using transactions.
423 * You cannot begin a transaction while holding a tdb_chainlock(), nor can
424 * you do any operations on any other keys in the database. This also means
425 * that you cannot hold more than one tdb_chainlock() at a time.
430 enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
433 * tdb_chainunlock - unlock a record in the TDB
434 * @tdb: the tdb context returned from tdb_open()
435 * @key: the key to unlock.
437 * The key must have previously been locked by tdb_chainlock().
439 void tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
442 * tdb_chainlock_read - lock a record in the TDB, for reading
443 * @tdb: the tdb context returned from tdb_open()
444 * @key: the key to lock.
446 * This prevents any changes from occurring to a group of keys including @key,
447 * even if @key does not exist. This allows primitive atomic updates of
448 * records without using transactions.
450 * You cannot begin a transaction while holding a tdb_chainlock_read(), nor can
451 * you do any operations on any other keys in the database. This also means
452 * that you cannot hold more than one tdb_chainlock()/read() at a time.
457 enum TDB_ERROR tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key);
460 * tdb_chainunlock_read - unlock a record in the TDB for reading
461 * @tdb: the tdb context returned from tdb_open()
462 * @key: the key to unlock.
464 * The key must have previously been locked by tdb_chainlock_read().
466 void tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key);
469 * tdb_lockall - lock the entire TDB
470 * @tdb: the tdb context returned from tdb_open()
472 * You cannot hold a tdb_chainlock while calling this. It nests, so you
473 * must call tdb_unlockall as many times as you call tdb_lockall.
475 enum TDB_ERROR tdb_lockall(struct tdb_context *tdb);
478 * tdb_unlockall - unlock the entire TDB
479 * @tdb: the tdb context returned from tdb_open()
481 void tdb_unlockall(struct tdb_context *tdb);
484 * tdb_lockall_read - lock the entire TDB for reading
485 * @tdb: the tdb context returned from tdb_open()
487 * This prevents others writing to the database, eg. tdb_delete, tdb_store,
488 * tdb_append, but not tdb_fetch.
490 * You cannot hold a tdb_chainlock while calling this. It nests, so you
491 * must call tdb_unlockall_read as many times as you call tdb_lockall_read.
493 enum TDB_ERROR tdb_lockall_read(struct tdb_context *tdb);
496 * tdb_unlockall_read - unlock the entire TDB for reading
497 * @tdb: the tdb context returned from tdb_open()
499 void tdb_unlockall_read(struct tdb_context *tdb);
502 * tdb_wipe_all - wipe the database clean
503 * @tdb: the tdb context returned from tdb_open()
505 * Completely erase the database. This is faster than iterating through
506 * each key and doing tdb_delete.
508 enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb);
511 * tdb_repack - repack the database
512 * @tdb: the tdb context returned from tdb_open()
514 * This repacks the database; if it is suffering from a great deal of
515 * fragmentation this might help. However, it can take twice the
516 * memory of the existing TDB.
518 enum TDB_ERROR tdb_repack(struct tdb_context *tdb);
521 * tdb_check - check a TDB for consistency
522 * @tdb: the tdb context returned from tdb_open()
523 * @check: function to check each key/data pair (or NULL)
524 * @data: argument for @check, must match type.
526 * This performs a consistency check of the open database, optionally calling
527 * a check() function on each record so you can do your own data consistency
528 * checks as well. If check() returns an error, that is returned from
531 * Returns TDB_SUCCESS or an error.
533 #define tdb_check(tdb, check, data) \
534 tdb_check_((tdb), typesafe_cb_preargs(enum TDB_ERROR, void *, \
540 enum TDB_ERROR tdb_check_(struct tdb_context *tdb,
541 enum TDB_ERROR (*check)(struct tdb_data k,
547 * tdb_error - get the last error (not threadsafe)
548 * @tdb: the tdb context returned from tdb_open()
550 * Returns the last error returned by a TDB function.
552 * This makes porting from TDB1 easier, but note that the last error is not
553 * reliable in threaded programs.
555 enum TDB_ERROR tdb_error(struct tdb_context *tdb);
558 * enum tdb_summary_flags - flags for tdb_summary.
560 enum tdb_summary_flags {
561 TDB_SUMMARY_HISTOGRAMS = 1 /* Draw graphs in the summary. */
565 * tdb_summary - return a string describing the TDB state
566 * @tdb: the tdb context returned from tdb_open()
567 * @flags: flags to control the summary output.
568 * @summary: pointer to string to allocate.
570 * This returns a developer-readable string describing the overall
571 * state of the tdb, such as the percentage used and sizes of records.
572 * It is designed to provide information about the tdb at a glance
573 * without displaying any keys or data in the database.
575 * On success, sets @summary to point to a malloc()'ed nul-terminated
576 * multi-line string. It is your responsibility to free() it.
578 enum TDB_ERROR tdb_summary(struct tdb_context *tdb,
579 enum tdb_summary_flags flags,
584 * tdb_get_flags - return the flags for a tdb
585 * @tdb: the tdb context returned from tdb_open()
587 * This returns the flags on the current tdb. Some of these are caused by
588 * the flags argument to tdb_open(), others (such as TDB_CONVERT) are
591 unsigned int tdb_get_flags(struct tdb_context *tdb);
594 * tdb_add_flag - set a flag for a tdb
595 * @tdb: the tdb context returned from tdb_open()
596 * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING.
598 * You can use this to set a flag on the TDB. You cannot set these flags
599 * on a TDB_INTERNAL tdb.
601 void tdb_add_flag(struct tdb_context *tdb, unsigned flag);
604 * tdb_remove_flag - unset a flag for a tdb
605 * @tdb: the tdb context returned from tdb_open()
606 * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING.
608 * You can use this to clear a flag on the TDB. You cannot clear flags
609 * on a TDB_INTERNAL tdb.
611 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag);
614 * enum tdb_attribute_type - descriminator for union tdb_attribute.
616 enum tdb_attribute_type {
617 TDB_ATTRIBUTE_LOG = 0,
618 TDB_ATTRIBUTE_HASH = 1,
619 TDB_ATTRIBUTE_SEED = 2,
620 TDB_ATTRIBUTE_STATS = 3,
621 TDB_ATTRIBUTE_OPENHOOK = 4,
622 TDB_ATTRIBUTE_FLOCK = 5,
623 TDB_ATTRIBUTE_TDB1_HASHSIZE = 128,
627 * tdb_get_attribute - get an attribute for an existing tdb
628 * @tdb: the tdb context returned from tdb_open()
629 * @attr: the union tdb_attribute to set.
631 * This gets an attribute from a TDB which has previously been set (or
632 * may return the default values). Set @attr.base.attr to the
633 * attribute type you want get.
635 enum TDB_ERROR tdb_get_attribute(struct tdb_context *tdb,
636 union tdb_attribute *attr);
639 * tdb_set_attribute - set an attribute for an existing tdb
640 * @tdb: the tdb context returned from tdb_open()
641 * @attr: the union tdb_attribute to set.
643 * This sets an attribute on a TDB, overriding any previous attribute
644 * of the same type. It returns TDB_ERR_EINVAL if the attribute is
645 * unknown or invalid.
647 * Note that TDB_ATTRIBUTE_HASH, TDB_ATTRIBUTE_SEED,
648 * TDB_ATTRIBUTE_OPENHOOK and TDB_ATTRIBUTE_TDB1_HASHSIZE cannot
649 * currently be set after tdb_open.
651 enum TDB_ERROR tdb_set_attribute(struct tdb_context *tdb,
652 const union tdb_attribute *attr);
655 * tdb_unset_attribute - reset an attribute for an existing tdb
656 * @tdb: the tdb context returned from tdb_open()
657 * @type: the attribute type to unset.
659 * This unsets an attribute on a TDB, returning it to the defaults
660 * (where applicable).
662 * Note that it only makes sense for TDB_ATTRIBUTE_LOG and TDB_ATTRIBUTE_FLOCK
665 void tdb_unset_attribute(struct tdb_context *tdb,
666 enum tdb_attribute_type type);
669 * tdb_name - get the name of a tdb
670 * @tdb: the tdb context returned from tdb_open()
672 * This returns a copy of the name string, made at tdb_open() time. If that
673 * argument was NULL (possible for a TDB_INTERNAL db) this will return NULL.
675 * This is mostly useful for logging.
677 const char *tdb_name(const struct tdb_context *tdb);
680 * tdb_fd - get the file descriptor of a tdb
681 * @tdb: the tdb context returned from tdb_open()
683 * This returns the file descriptor for the underlying database file, or -1
686 int tdb_fd(const struct tdb_context *tdb);
689 * tdb_foreach - iterate through every open TDB.
690 * @fn: the function to call for every TDB
691 * @p: the pointer to hand to @fn
693 * TDB internally keeps track of all open TDBs; this function allows you to
694 * iterate through them. If @fn returns non-zero, traversal stops.
696 #define tdb_foreach(fn, p) \
697 tdb_foreach_(typesafe_cb_preargs(int, void *, (fn), (p), \
698 struct tdb_context *), (p))
700 void tdb_foreach_(int (*fn)(struct tdb_context *, void *), void *p);
703 * struct tdb_attribute_base - common fields for all tdb attributes.
705 struct tdb_attribute_base {
706 enum tdb_attribute_type attr;
707 union tdb_attribute *next;
711 * enum tdb_log_level - log levels for tdb_attribute_log
712 * @TDB_LOG_ERROR: used to log unrecoverable errors such as I/O errors
713 * or internal consistency failures.
714 * @TDB_LOG_USE_ERROR: used to log usage errors such as invalid parameters
715 * or writing to a read-only database.
716 * @TDB_LOG_WARNING: used for informational messages on issues which
717 * are unusual but handled by TDB internally, such
718 * as a failure to mmap or failure to open /dev/urandom.
727 * struct tdb_attribute_log - log function attribute
729 * This attribute provides a hook for you to log errors.
731 struct tdb_attribute_log {
732 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_LOG */
733 void (*fn)(struct tdb_context *tdb,
734 enum tdb_log_level level,
735 enum TDB_ERROR ecode,
742 * struct tdb_attribute_hash - hash function attribute
744 * This attribute allows you to provide an alternative hash function.
745 * This hash function will be handed keys from the database; it will also
746 * be handed the 8-byte TDB_HASH_MAGIC value for checking the header (the
747 * tdb_open() will fail if the hash value doesn't match the header).
749 * Note that if your hash function gives different results on
750 * different machine endians, your tdb will no longer work across
751 * different architectures!
753 struct tdb_attribute_hash {
754 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_HASH */
755 uint64_t (*fn)(const void *key, size_t len, uint64_t seed,
761 * struct tdb_attribute_seed - hash function seed attribute
763 * The hash function seed is normally taken from /dev/urandom (or equivalent)
764 * but can be set manually here. This is mainly for testing purposes.
766 struct tdb_attribute_seed {
767 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_SEED */
772 * struct tdb_attribute_stats - tdb operational statistics
774 * This attribute records statistics of various low-level TDB operations.
775 * This can be used to assist performance evaluation. This is only
776 * useful for tdb_get_attribute().
778 * New fields will be added at the end, hence the "size" argument which
779 * indicates how large your structure is: it must be filled in before
780 * calling tdb_get_attribute(), which will overwrite it with the size
783 struct tdb_attribute_stats {
784 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_STATS */
785 size_t size; /* = sizeof(struct tdb_attribute_stats) */
787 uint64_t alloc_subhash;
788 uint64_t alloc_chain;
789 uint64_t alloc_bucket_exact;
790 uint64_t alloc_bucket_max;
791 uint64_t alloc_leftover;
792 uint64_t alloc_coalesce_tried;
793 uint64_t alloc_coalesce_iterate_clash;
794 uint64_t alloc_coalesce_lockfail;
795 uint64_t alloc_coalesce_race;
796 uint64_t alloc_coalesce_succeeded;
797 uint64_t alloc_coalesce_num_merged;
799 uint64_t compare_wrong_bucket;
800 uint64_t compare_wrong_offsetbits;
801 uint64_t compare_wrong_keylen;
802 uint64_t compare_wrong_rechash;
803 uint64_t compare_wrong_keycmp;
804 uint64_t transactions;
805 uint64_t transaction_cancel;
806 uint64_t transaction_nest;
807 uint64_t transaction_expand_file;
808 uint64_t transaction_read_direct;
809 uint64_t transaction_read_direct_fail;
810 uint64_t transaction_write_direct;
811 uint64_t transaction_write_direct_fail;
815 uint64_t lock_lowlevel;
816 uint64_t lock_nonblock;
817 uint64_t lock_nonblock_fail;
821 * struct tdb_attribute_openhook - tdb special effects hook for open
823 * This attribute contains a function to call once we have the OPEN_LOCK
824 * for the tdb, but before we've examined its contents. If this succeeds,
825 * the tdb will be populated if it's then zero-length.
827 * This is a hack to allow support for TDB1-style TDB_CLEAR_IF_FIRST
830 struct tdb_attribute_openhook {
831 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_OPENHOOK */
832 enum TDB_ERROR (*fn)(int fd, void *data);
837 * struct tdb_attribute_flock - tdb special effects hook for file locking
839 * This attribute contains function to call to place locks on a file; it can
840 * be used to support non-blocking operations or lock proxying.
842 * They should return 0 on success, -1 on failure and set errno.
844 * An error will be logged on error if errno is neither EAGAIN nor EINTR
845 * (normally it would only return EAGAIN if waitflag is false, and
846 * loop internally on EINTR).
848 struct tdb_attribute_flock {
849 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_FLOCK */
850 int (*lock)(int fd,int rw, off_t off, off_t len, bool waitflag, void *);
851 int (*unlock)(int fd, int rw, off_t off, off_t len, void *);
856 * struct tdb_attribute_tdb1_hashsize - tdb1 hashsize
858 * This attribute allows setting the TDB1 hashsize; it only makes sense with
859 * O_CREAT and TDB_VERSION1.
861 * Hashsize should generally be a prime, such as 10007.
863 struct tdb_attribute_tdb1_hashsize {
864 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_TDB1_HASHSIZE */
869 * union tdb_attribute - tdb attributes.
871 * This represents all the known attributes.
874 * struct tdb_attribute_log, struct tdb_attribute_hash,
875 * struct tdb_attribute_seed, struct tdb_attribute_stats,
876 * struct tdb_attribute_openhook, struct tdb_attribute_flock.
878 union tdb_attribute {
879 struct tdb_attribute_base base;
880 struct tdb_attribute_log log;
881 struct tdb_attribute_hash hash;
882 struct tdb_attribute_seed seed;
883 struct tdb_attribute_stats stats;
884 struct tdb_attribute_openhook openhook;
885 struct tdb_attribute_flock flock;
886 struct tdb_attribute_tdb1_hashsize tdb1_hashsize;