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Diffstat (limited to 'lib/tdb2/tdb2.h')
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diff --git a/lib/tdb2/tdb2.h b/lib/tdb2/tdb2.h new file mode 100644 index 00000000000..3f80793d760 --- /dev/null +++ b/lib/tdb2/tdb2.h @@ -0,0 +1,848 @@ +#ifndef CCAN_TDB2_H +#define CCAN_TDB2_H + +/* + TDB version 2: trivial database library + + Copyright (C) Andrew Tridgell 1999-2004 + Copyright (C) Rusty Russell 2010-2011 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#ifdef __cplusplus +extern "C" { +#endif + +#ifndef _SAMBA_BUILD_ +/* For mode_t */ +#include <sys/types.h> +/* For O_* flags. */ +#include <sys/stat.h> +/* For sig_atomic_t. */ +#include <signal.h> +/* For uint64_t */ +#include <stdint.h> +/* For bool */ +#include <stdbool.h> +/* For memcmp */ +#include <string.h> +#else +#include "replace.h" +#endif +#include <ccan/compiler/compiler.h> +#include <ccan/typesafe_cb/typesafe_cb.h> +#include <ccan/cast/cast.h> + +union tdb_attribute; +struct tdb_context; + +/** + * tdb_open - open a database file + * @name: the file name (can be NULL if flags contains TDB_INTERNAL) + * @tdb_flags: options for this database + * @open_flags: flags argument for tdb's open() call. + * @mode: mode argument for tdb's open() call. + * @attributes: linked list of extra attributes for this tdb. + * + * This call opens (and potentially creates) a database file. + * Multiple processes can have the TDB file open at once. + * + * On failure it will return NULL, and set errno: it may also call + * any log attribute found in @attributes. + * + * See also: + * union tdb_attribute + */ +struct tdb_context *tdb_open(const char *name, int tdb_flags, + int open_flags, mode_t mode, + union tdb_attribute *attributes); + + +/* flags for tdb_open() */ +#define TDB_DEFAULT 0 /* just a readability place holder */ +#define TDB_INTERNAL 2 /* don't store on disk */ +#define TDB_NOLOCK 4 /* don't do any locking */ +#define TDB_NOMMAP 8 /* don't use mmap */ +#define TDB_CONVERT 16 /* convert endian */ +#define TDB_NOSYNC 64 /* don't use synchronous transactions */ +#define TDB_SEQNUM 128 /* maintain a sequence number */ +#define TDB_ALLOW_NESTING 256 /* fake nested transactions */ + +/** + * tdb_close - close and free a tdb. + * @tdb: the tdb context returned from tdb_open() + * + * This always succeeds, in that @tdb is unusable after this call. But if + * some unexpected error occurred while closing, it will return non-zero + * (the only clue as to cause will be via the log attribute). + */ +int tdb_close(struct tdb_context *tdb); + +/** + * struct tdb_data - representation of keys or values. + * @dptr: the data pointer + * @dsize: the size of the data pointed to by dptr. + * + * This is the "blob" representation of keys and data used by TDB. + */ +typedef struct tdb_data { + unsigned char *dptr; + size_t dsize; +} TDB_DATA; + +/** + * enum TDB_ERROR - error returns for TDB + * + * See Also: + * tdb_errorstr() + */ +enum TDB_ERROR { + TDB_SUCCESS = 0, /* No error. */ + TDB_ERR_CORRUPT = -1, /* We read the db, and it was bogus. */ + TDB_ERR_IO = -2, /* We couldn't read/write the db. */ + TDB_ERR_LOCK = -3, /* Locking failed. */ + TDB_ERR_OOM = -4, /* Out of Memory. */ + TDB_ERR_EXISTS = -5, /* The key already exists. */ + TDB_ERR_NOEXIST = -6, /* The key does not exist. */ + TDB_ERR_EINVAL = -7, /* You're using it wrong. */ + TDB_ERR_RDONLY = -8, /* The database is read-only. */ + TDB_ERR_LAST = TDB_ERR_RDONLY +}; + +/** + * tdb_store - store a key/value pair in a tdb. + * @tdb: the tdb context returned from tdb_open() + * @key: the key + * @dbuf: the data to associate with the key. + * @flag: TDB_REPLACE, TDB_INSERT or TDB_MODIFY. + * + * This inserts (or overwrites) a key/value pair in the TDB. If flag + * is TDB_REPLACE, it doesn't matter whether the key exists or not; + * TDB_INSERT means it must not exist (returns TDB_ERR_EXISTS otherwise), + * and TDB_MODIFY means it must exist (returns TDB_ERR_NOEXIST otherwise). + * + * On success, this returns TDB_SUCCESS. + * + * See also: + * tdb_fetch, tdb_transaction_start, tdb_append, tdb_delete. + */ +enum TDB_ERROR tdb_store(struct tdb_context *tdb, + struct tdb_data key, + struct tdb_data dbuf, + int flag); + +/* flags to tdb_store() */ +#define TDB_REPLACE 1 /* A readability place holder */ +#define TDB_INSERT 2 /* Don't overwrite an existing entry */ +#define TDB_MODIFY 3 /* Don't create an existing entry */ + +/** + * tdb_fetch - fetch a value from a tdb. + * @tdb: the tdb context returned from tdb_open() + * @key: the key + * @data: pointer to data. + * + * This looks up a key in the database and sets it in @data. + * + * If it returns TDB_SUCCESS, the key was found: it is your + * responsibility to call free() on @data->dptr. + * + * Otherwise, it returns an error (usually, TDB_ERR_NOEXIST) and @data is + * undefined. + */ +enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key, + struct tdb_data *data); + +/** + * tdb_errorstr - map the tdb error onto a constant readable string + * @ecode: the enum TDB_ERROR to map. + * + * This is useful for displaying errors to users. + */ +const char *tdb_errorstr(enum TDB_ERROR ecode); + +/** + * tdb_append - append a value to a key/value pair in a tdb. + * @tdb: the tdb context returned from tdb_open() + * @key: the key + * @dbuf: the data to append. + * + * This is equivalent to fetching a record, reallocating .dptr to add the + * data, and writing it back, only it's much more efficient. If the key + * doesn't exist, it's equivalent to tdb_store (with an additional hint that + * you expect to expand the record in future). + * + * See Also: + * tdb_fetch(), tdb_store() + */ +enum TDB_ERROR tdb_append(struct tdb_context *tdb, + struct tdb_data key, struct tdb_data dbuf); + +/** + * tdb_delete - delete a key from a tdb. + * @tdb: the tdb context returned from tdb_open() + * @key: the key to delete. + * + * Returns TDB_SUCCESS on success, or an error (usually TDB_ERR_NOEXIST). + * + * See Also: + * tdb_fetch(), tdb_store() + */ +enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key); + +/** + * tdb_exists - does a key exist in the database? + * @tdb: the tdb context returned from tdb_open() + * @key: the key to search for. + * + * Returns true if it exists, or false if it doesn't or any other error. + */ +bool tdb_exists(struct tdb_context *tdb, TDB_DATA key); + +/** + * tdb_deq - are struct tdb_data equal? + * @a: one struct tdb_data + * @b: another struct tdb_data + */ +static inline bool tdb_deq(struct tdb_data a, struct tdb_data b) +{ + return a.dsize == b.dsize && memcmp(a.dptr, b.dptr, a.dsize) == 0; +} + +/** + * tdb_mkdata - make a struct tdb_data from const data + * @p: the constant pointer + * @len: the length + * + * As the dptr member of struct tdb_data is not constant, you need to + * cast it. This function keeps thost casts in one place, as well as + * suppressing the warning some compilers give when casting away a + * qualifier (eg. gcc with -Wcast-qual) + */ +static inline struct tdb_data tdb_mkdata(const void *p, size_t len) +{ + struct tdb_data d; + d.dptr = cast_const(void *, p); + d.dsize = len; + return d; +} + +/** + * tdb_transaction_start - start a transaction + * @tdb: the tdb context returned from tdb_open() + * + * This begins a series of atomic operations. Other processes will be able + * to read the tdb, but not alter it (they will block), nor will they see + * any changes until tdb_transaction_commit() is called. + * + * Note that if the TDB_ALLOW_NESTING flag is set, a tdb_transaction_start() + * within a transaction will succeed, but it's not a real transaction: + * (1) An inner transaction which is committed is not actually committed until + * the outer transaction is; if the outer transaction is cancelled, the + * inner ones are discarded. + * (2) tdb_transaction_cancel() marks the outer transaction as having an error, + * so the final tdb_transaction_commit() will fail. + * (3) the outer transaction will see the results of the inner transaction. + * + * See Also: + * tdb_transaction_cancel, tdb_transaction_commit. + */ +enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb); + +/** + * tdb_transaction_cancel - abandon a transaction + * @tdb: the tdb context returned from tdb_open() + * + * This aborts a transaction, discarding any changes which were made. + * tdb_close() does this implicitly. + */ +void tdb_transaction_cancel(struct tdb_context *tdb); + +/** + * tdb_transaction_commit - commit a transaction + * @tdb: the tdb context returned from tdb_open() + * + * This completes a transaction, writing any changes which were made. + * + * fsync() is used to commit the transaction (unless TDB_NOSYNC is set), + * making it robust against machine crashes, but very slow compared to + * other TDB operations. + * + * A failure can only be caused by unexpected errors (eg. I/O or + * memory); this is no point looping on transaction failure. + * + * See Also: + * tdb_transaction_prepare_commit() + */ +enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb); + +/** + * tdb_transaction_prepare_commit - prepare to commit a transaction + * @tdb: the tdb context returned from tdb_open() + * + * This ensures we have the resources to commit a transaction (using + * tdb_transaction_commit): if this succeeds then a transaction will only + * fail if the write() or fsync() calls fail. + * + * If this fails you must still call tdb_transaction_cancel() to cancel + * the transaction. + * + * See Also: + * tdb_transaction_commit() + */ +enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb); + +/** + * tdb_traverse - traverse a TDB + * @tdb: the tdb context returned from tdb_open() + * @fn: the function to call for every key/value pair (or NULL) + * @p: the pointer to hand to @f + * + * This walks the TDB until all they keys have been traversed, or @fn + * returns non-zero. If the traverse function or other processes are + * changing data or adding or deleting keys, the traverse may be + * unreliable: keys may be skipped or (rarely) visited twice. + * + * There is one specific exception: the special case of deleting the + * current key does not undermine the reliability of the traversal. + * + * On success, returns the number of keys iterated. On error returns + * a negative enum TDB_ERROR value. + */ +#define tdb_traverse(tdb, fn, p) \ + tdb_traverse_(tdb, typesafe_cb_preargs(int, void *, (fn), (p), \ + struct tdb_context *, \ + TDB_DATA, TDB_DATA), (p)) + +int64_t tdb_traverse_(struct tdb_context *tdb, + int (*fn)(struct tdb_context *, + TDB_DATA, TDB_DATA, void *), void *p); + +/** + * tdb_parse_record - operate directly on data in the database. + * @tdb: the tdb context returned from tdb_open() + * @key: the key whose record we should hand to @parse + * @parse: the function to call for the data + * @data: the private pointer to hand to @parse (types must match). + * + * This avoids a copy for many cases, by handing you a pointer into + * the memory-mapped database. It also locks the record to prevent + * other accesses at the same time. + * + * Do not alter the data handed to parse()! + */ +#define tdb_parse_record(tdb, key, parse, data) \ + tdb_parse_record_((tdb), (key), \ + typesafe_cb_preargs(enum TDB_ERROR, void *, \ + (parse), (data), \ + TDB_DATA, TDB_DATA), (data)) + +enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb, + TDB_DATA key, + enum TDB_ERROR (*parse)(TDB_DATA k, + TDB_DATA d, + void *data), + void *data); + +/** + * tdb_get_seqnum - get a database sequence number + * @tdb: the tdb context returned from tdb_open() + * + * This returns a sequence number: any change to the database from a + * tdb context opened with the TDB_SEQNUM flag will cause that number + * to increment. Note that the incrementing is unreliable (it is done + * without locking), so this is only useful as an optimization. + * + * For example, you may have a regular database backup routine which + * does not operate if the sequence number is unchanged. In the + * unlikely event of a failed increment, it will be backed up next + * time any way. + * + * Returns an enum TDB_ERROR (ie. negative) on error. + */ +int64_t tdb_get_seqnum(struct tdb_context *tdb); + +/** + * tdb_firstkey - get the "first" key in a TDB + * @tdb: the tdb context returned from tdb_open() + * @key: pointer to key. + * + * This returns an arbitrary key in the database; with tdb_nextkey() it allows + * open-coded traversal of the database, though it is slightly less efficient + * than tdb_traverse. + * + * It is your responsibility to free @key->dptr on success. + * + * Returns TDB_ERR_NOEXIST if the database is empty. + */ +enum TDB_ERROR tdb_firstkey(struct tdb_context *tdb, struct tdb_data *key); + +/** + * tdb_nextkey - get the "next" key in a TDB + * @tdb: the tdb context returned from tdb_open() + * @key: a key returned by tdb_firstkey() or tdb_nextkey(). + * + * This returns another key in the database; it will free @key.dptr for + * your convenience. + * + * Returns TDB_ERR_NOEXIST if there are no more keys. + */ +enum TDB_ERROR tdb_nextkey(struct tdb_context *tdb, struct tdb_data *key); + +/** + * tdb_chainlock - lock a record in the TDB + * @tdb: the tdb context returned from tdb_open() + * @key: the key to lock. + * + * This prevents any access occurring to a group of keys including @key, + * even if @key does not exist. This allows primitive atomic updates of + * records without using transactions. + * + * You cannot begin a transaction while holding a tdb_chainlock(), nor can + * you do any operations on any other keys in the database. This also means + * that you cannot hold more than one tdb_chainlock() at a time. + * + * See Also: + * tdb_chainunlock() + */ +enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key); + +/** + * tdb_chainunlock - unlock a record in the TDB + * @tdb: the tdb context returned from tdb_open() + * @key: the key to unlock. + * + * The key must have previously been locked by tdb_chainlock(). + */ +void tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key); + +/** + * tdb_chainlock_read - lock a record in the TDB, for reading + * @tdb: the tdb context returned from tdb_open() + * @key: the key to lock. + * + * This prevents any changes from occurring to a group of keys including @key, + * even if @key does not exist. This allows primitive atomic updates of + * records without using transactions. + * + * You cannot begin a transaction while holding a tdb_chainlock_read(), nor can + * you do any operations on any other keys in the database. This also means + * that you cannot hold more than one tdb_chainlock()/read() at a time. + * + * See Also: + * tdb_chainlock() + */ +enum TDB_ERROR tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key); + +/** + * tdb_chainunlock_read - unlock a record in the TDB for reading + * @tdb: the tdb context returned from tdb_open() + * @key: the key to unlock. + * + * The key must have previously been locked by tdb_chainlock_read(). + */ +void tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key); + +/** + * tdb_lockall - lock the entire TDB + * @tdb: the tdb context returned from tdb_open() + * + * You cannot hold a tdb_chainlock while calling this. It nests, so you + * must call tdb_unlockall as many times as you call tdb_lockall. + */ +enum TDB_ERROR tdb_lockall(struct tdb_context *tdb); + +/** + * tdb_unlockall - unlock the entire TDB + * @tdb: the tdb context returned from tdb_open() + */ +void tdb_unlockall(struct tdb_context *tdb); + +/** + * tdb_lockall_read - lock the entire TDB for reading + * @tdb: the tdb context returned from tdb_open() + * + * This prevents others writing to the database, eg. tdb_delete, tdb_store, + * tdb_append, but not tdb_fetch. + * + * You cannot hold a tdb_chainlock while calling this. It nests, so you + * must call tdb_unlockall_read as many times as you call tdb_lockall_read. + */ +enum TDB_ERROR tdb_lockall_read(struct tdb_context *tdb); + +/** + * tdb_unlockall_read - unlock the entire TDB for reading + * @tdb: the tdb context returned from tdb_open() + */ +void tdb_unlockall_read(struct tdb_context *tdb); + +/** + * tdb_wipe_all - wipe the database clean + * @tdb: the tdb context returned from tdb_open() + * + * Completely erase the database. This is faster than iterating through + * each key and doing tdb_delete. + */ +enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb); + +/** + * tdb_check - check a TDB for consistency + * @tdb: the tdb context returned from tdb_open() + * @check: function to check each key/data pair (or NULL) + * @data: argument for @check, must match type. + * + * This performs a consistency check of the open database, optionally calling + * a check() function on each record so you can do your own data consistency + * checks as well. If check() returns an error, that is returned from + * tdb_check(). + * + * Returns TDB_SUCCESS or an error. + */ +#define tdb_check(tdb, check, data) \ + tdb_check_((tdb), typesafe_cb_preargs(enum TDB_ERROR, void *, \ + (check), (data), \ + struct tdb_data, \ + struct tdb_data), \ + (data)) + +enum TDB_ERROR tdb_check_(struct tdb_context *tdb, + enum TDB_ERROR (*check)(struct tdb_data k, + struct tdb_data d, + void *data), + void *data); + +/** + * tdb_error - get the last error (not threadsafe) + * @tdb: the tdb context returned from tdb_open() + * + * Returns the last error returned by a TDB function. + * + * This makes porting from TDB1 easier, but note that the last error is not + * reliable in threaded programs. + */ +enum TDB_ERROR tdb_error(struct tdb_context *tdb); + +/** + * enum tdb_summary_flags - flags for tdb_summary. + */ +enum tdb_summary_flags { + TDB_SUMMARY_HISTOGRAMS = 1 /* Draw graphs in the summary. */ +}; + +/** + * tdb_summary - return a string describing the TDB state + * @tdb: the tdb context returned from tdb_open() + * @flags: flags to control the summary output. + * @summary: pointer to string to allocate. + * + * This returns a developer-readable string describing the overall + * state of the tdb, such as the percentage used and sizes of records. + * It is designed to provide information about the tdb at a glance + * without displaying any keys or data in the database. + * + * On success, sets @summary to point to a malloc()'ed nul-terminated + * multi-line string. It is your responsibility to free() it. + */ +enum TDB_ERROR tdb_summary(struct tdb_context *tdb, + enum tdb_summary_flags flags, + char **summary); + + +/** + * tdb_get_flags - return the flags for a tdb + * @tdb: the tdb context returned from tdb_open() + * + * This returns the flags on the current tdb. Some of these are caused by + * the flags argument to tdb_open(), others (such as TDB_CONVERT) are + * intuited. + */ +unsigned int tdb_get_flags(struct tdb_context *tdb); + +/** + * tdb_add_flag - set a flag for a tdb + * @tdb: the tdb context returned from tdb_open() + * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING. + * + * You can use this to set a flag on the TDB. You cannot set these flags + * on a TDB_INTERNAL tdb. + */ +void tdb_add_flag(struct tdb_context *tdb, unsigned flag); + +/** + * tdb_remove_flag - unset a flag for a tdb + * @tdb: the tdb context returned from tdb_open() + * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING. + * + * You can use this to clear a flag on the TDB. You cannot clear flags + * on a TDB_INTERNAL tdb. + */ +void tdb_remove_flag(struct tdb_context *tdb, unsigned flag); + +/** + * enum tdb_attribute_type - descriminator for union tdb_attribute. + */ +enum tdb_attribute_type { + TDB_ATTRIBUTE_LOG = 0, + TDB_ATTRIBUTE_HASH = 1, + TDB_ATTRIBUTE_SEED = 2, + TDB_ATTRIBUTE_STATS = 3, + TDB_ATTRIBUTE_OPENHOOK = 4, + TDB_ATTRIBUTE_FLOCK = 5 +}; + +/** + * tdb_get_attribute - get an attribute for an existing tdb + * @tdb: the tdb context returned from tdb_open() + * @attr: the union tdb_attribute to set. + * + * This gets an attribute from a TDB which has previously been set (or + * may return the default values). Set @attr.base.attr to the + * attribute type you want get. + * + * Currently this does not work for TDB_ATTRIBUTE_OPENHOOK. + */ +enum TDB_ERROR tdb_get_attribute(struct tdb_context *tdb, + union tdb_attribute *attr); + +/** + * tdb_set_attribute - set an attribute for an existing tdb + * @tdb: the tdb context returned from tdb_open() + * @attr: the union tdb_attribute to set. + * + * This sets an attribute on a TDB, overriding any previous attribute + * of the same type. It returns TDB_ERR_EINVAL if the attribute is + * unknown or invalid. + * + * Note that TDB_ATTRIBUTE_HASH, TDB_ATTRIBUTE_SEED and + * TDB_ATTRIBUTE_OPENHOOK cannot currently be set after tdb_open. + */ +enum TDB_ERROR tdb_set_attribute(struct tdb_context *tdb, + const union tdb_attribute *attr); + +/** + * tdb_unset_attribute - reset an attribute for an existing tdb + * @tdb: the tdb context returned from tdb_open() + * @type: the attribute type to unset. + * + * This unsets an attribute on a TDB, returning it to the defaults + * (where applicable). + * + * Note that it only makes sense for TDB_ATTRIBUTE_LOG and TDB_ATTRIBUTE_FLOCK + * to be unset. + */ +void tdb_unset_attribute(struct tdb_context *tdb, + enum tdb_attribute_type type); + +/** + * tdb_name - get the name of a tdb + * @tdb: the tdb context returned from tdb_open() + * + * This returns a copy of the name string, made at tdb_open() time. If that + * argument was NULL (possible for a TDB_INTERNAL db) this will return NULL. + * + * This is mostly useful for logging. + */ +const char *tdb_name(const struct tdb_context *tdb); + +/** + * tdb_fd - get the file descriptor of a tdb + * @tdb: the tdb context returned from tdb_open() + * + * This returns the file descriptor for the underlying database file, or -1 + * for TDB_INTERNAL. + */ +int tdb_fd(const struct tdb_context *tdb); + +/** + * struct tdb_attribute_base - common fields for all tdb attributes. + */ +struct tdb_attribute_base { + enum tdb_attribute_type attr; + union tdb_attribute *next; +}; + +/** + * enum tdb_log_level - log levels for tdb_attribute_log + * @TDB_LOG_ERROR: used to log unrecoverable errors such as I/O errors + * or internal consistency failures. + * @TDB_LOG_USE_ERROR: used to log usage errors such as invalid parameters + * or writing to a read-only database. + * @TDB_LOG_WARNING: used for informational messages on issues which + * are unusual but handled by TDB internally, such + * as a failure to mmap or failure to open /dev/urandom. + */ +enum tdb_log_level { + TDB_LOG_ERROR, + TDB_LOG_USE_ERROR, + TDB_LOG_WARNING +}; + +/** + * struct tdb_attribute_log - log function attribute + * + * This attribute provides a hook for you to log errors. + */ +struct tdb_attribute_log { + struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_LOG */ + void (*fn)(struct tdb_context *tdb, + enum tdb_log_level level, + const char *message, + void *data); + void *data; +}; + +/** + * struct tdb_attribute_hash - hash function attribute + * + * This attribute allows you to provide an alternative hash function. + * This hash function will be handed keys from the database; it will also + * be handed the 8-byte TDB_HASH_MAGIC value for checking the header (the + * tdb_open() will fail if the hash value doesn't match the header). + * + * Note that if your hash function gives different results on + * different machine endians, your tdb will no longer work across + * different architectures! + */ +struct tdb_attribute_hash { + struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_HASH */ + uint64_t (*fn)(const void *key, size_t len, uint64_t seed, + void *data); + void *data; +}; + +/** + * struct tdb_attribute_seed - hash function seed attribute + * + * The hash function seed is normally taken from /dev/urandom (or equivalent) + * but can be set manually here. This is mainly for testing purposes. + */ +struct tdb_attribute_seed { + struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_SEED */ + uint64_t seed; +}; + +/** + * struct tdb_attribute_stats - tdb operational statistics + * + * This attribute records statistics of various low-level TDB operations. + * This can be used to assist performance evaluation. This is only + * useful for tdb_get_attribute(). + * + * New fields will be added at the end, hence the "size" argument which + * indicates how large your structure is: it must be filled in before + * calling tdb_get_attribute(), which will overwrite it with the size + * tdb knows about. + */ +struct tdb_attribute_stats { + struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_STATS */ + size_t size; /* = sizeof(struct tdb_attribute_stats) */ + uint64_t allocs; + uint64_t alloc_subhash; + uint64_t alloc_chain; + uint64_t alloc_bucket_exact; + uint64_t alloc_bucket_max; + uint64_t alloc_leftover; + uint64_t alloc_coalesce_tried; + uint64_t alloc_coalesce_iterate_clash; + uint64_t alloc_coalesce_lockfail; + uint64_t alloc_coalesce_race; + uint64_t alloc_coalesce_succeeded; + uint64_t alloc_coalesce_num_merged; + uint64_t compares; + uint64_t compare_wrong_bucket; + uint64_t compare_wrong_offsetbits; + uint64_t compare_wrong_keylen; + uint64_t compare_wrong_rechash; + uint64_t compare_wrong_keycmp; + uint64_t transactions; + uint64_t transaction_cancel; + uint64_t transaction_nest; + uint64_t transaction_expand_file; + uint64_t transaction_read_direct; + uint64_t transaction_read_direct_fail; + uint64_t transaction_write_direct; + uint64_t transaction_write_direct_fail; + uint64_t expands; + uint64_t frees; + uint64_t locks; + uint64_t lock_lowlevel; + uint64_t lock_nonblock; + uint64_t lock_nonblock_fail; +}; + +/** + * struct tdb_attribute_openhook - tdb special effects hook for open + * + * This attribute contains a function to call once we have the OPEN_LOCK + * for the tdb, but before we've examined its contents. If this succeeds, + * the tdb will be populated if it's then zero-length. + * + * This is a hack to allow support for TDB1-style TDB_CLEAR_IF_FIRST + * behaviour. + */ +struct tdb_attribute_openhook { + struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_OPENHOOK */ + enum TDB_ERROR (*fn)(int fd, void *data); + void *data; +}; + +/** + * struct tdb_attribute_flock - tdb special effects hook for file locking + * + * This attribute contains function to call to place locks on a file; it can + * be used to support non-blocking operations or lock proxying. + * + * They should return 0 on success, -1 on failure and set errno. + * + * An error will be logged on error if errno is neither EAGAIN nor EINTR + * (normally it would only return EAGAIN if waitflag is false, and + * loop internally on EINTR). + */ +struct tdb_attribute_flock { + struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_FLOCK */ + int (*lock)(int fd,int rw, off_t off, off_t len, bool waitflag, void *); + int (*unlock)(int fd, int rw, off_t off, off_t len, void *); + void *data; +}; + +/** + * union tdb_attribute - tdb attributes. + * + * This represents all the known attributes. + * + * See also: + * struct tdb_attribute_log, struct tdb_attribute_hash, + * struct tdb_attribute_seed, struct tdb_attribute_stats, + * struct tdb_attribute_openhook, struct tdb_attribute_flock. + */ +union tdb_attribute { + struct tdb_attribute_base base; + struct tdb_attribute_log log; + struct tdb_attribute_hash hash; + struct tdb_attribute_seed seed; + struct tdb_attribute_stats stats; + struct tdb_attribute_openhook openhook; + struct tdb_attribute_flock flock; +}; + +#ifdef __cplusplus +} +#endif + +#endif /* tdb2.h */ |