diff options
Diffstat (limited to 'include/tdb.h')
| -rw-r--r-- | include/tdb.h | 1038 |
1 files changed, 1038 insertions, 0 deletions
diff --git a/include/tdb.h b/include/tdb.h new file mode 100644 index 0000000..884171c --- /dev/null +++ b/include/tdb.h @@ -0,0 +1,1038 @@ +#ifndef __TDB_H__ +#define __TDB_H__ + +/* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2004 + + ** 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 + +#include <signal.h> +#include <stdbool.h> + +/* for old gcc releases that don't have the feature test macro __has_attribute */ +#ifndef __has_attribute +#define __has_attribute(x) 0 +#endif + +#ifndef _PUBLIC_ +#if __has_attribute(visibility) +#define _PUBLIC_ __attribute__((visibility("default"))) +#else +#define _PUBLIC_ +#endif +#endif + +/** + * @defgroup tdb The tdb API + * + * tdb is a Trivial database. In concept, it is very much like GDBM, and BSD's + * DB except that it allows multiple simultaneous writers and uses locking + * internally to keep writers from trampling on each other. tdb is also + * extremely small. + * + * @section tdb_interface Interface + * + * The interface is very similar to gdbm except for the following: + * + * <ul> + * <li>different open interface. The tdb_open call is more similar to a + * traditional open()</li> + * <li>no tdbm_reorganise() function</li> + * <li>no tdbm_sync() function. No operations are cached in the library + * anyway</li> + * <li>added a tdb_traverse() function for traversing the whole database</li> + * <li>added transactions support</li> + * </ul> + * + * A general rule for using tdb is that the caller frees any returned TDB_DATA + * structures. Just call free(p.dptr) to free a TDB_DATA return value called p. + * This is the same as gdbm. + * + * @{ + */ + +/** Flags to tdb_store() */ +#define TDB_REPLACE 1 /** Unused */ +#define TDB_INSERT 2 /** Don't overwrite an existing entry */ +#define TDB_MODIFY 3 /** Don't create an existing entry */ + +/** Flags for tdb_open() */ +#define TDB_DEFAULT 0 /** just a readability place holder */ +#define TDB_CLEAR_IF_FIRST 1 /** If this is the first open, wipe the db */ +#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 (internal use) */ +#define TDB_BIGENDIAN 32 /** Header is big-endian (internal use) */ +#define TDB_NOSYNC 64 /** Don't use synchronous transactions */ +#define TDB_SEQNUM 128 /** Maintain a sequence number */ +#define TDB_VOLATILE 256 /** Activate the per-hashchain freelist, default 5 */ +#define TDB_ALLOW_NESTING 512 /** Allow transactions to nest */ +#define TDB_DISALLOW_NESTING 1024 /** Disallow transactions to nest */ +#define TDB_INCOMPATIBLE_HASH 2048 /** Better hashing: can't be opened by tdb < 1.2.6. */ +#define TDB_MUTEX_LOCKING 4096 /** optimized locking using robust mutexes if supported, + only with tdb >= 1.3.0 and TDB_CLEAR_IF_FIRST + after checking tdb_runtime_check_for_robust_mutexes() */ + +/** The tdb error codes */ +enum TDB_ERROR {TDB_SUCCESS=0, TDB_ERR_CORRUPT, TDB_ERR_IO, TDB_ERR_LOCK, + TDB_ERR_OOM, TDB_ERR_EXISTS, TDB_ERR_NOLOCK, TDB_ERR_LOCK_TIMEOUT, + TDB_ERR_NOEXIST, TDB_ERR_EINVAL, TDB_ERR_RDONLY, + TDB_ERR_NESTING}; + +/** Debugging uses one of the following levels */ +enum tdb_debug_level {TDB_DEBUG_FATAL = 0, TDB_DEBUG_ERROR, + TDB_DEBUG_WARNING, TDB_DEBUG_TRACE}; + +/** The tdb data structure */ +typedef struct TDB_DATA { + unsigned char *dptr; + size_t dsize; +} TDB_DATA; + +#ifndef PRINTF_ATTRIBUTE +#if __has_attribute(format) || (__GNUC__ >= 3) +/** Use gcc attribute to check printf fns. a1 is the 1-based index of + * the parameter containing the format, and a2 the index of the first + * argument. Note that some gcc 2.x versions don't handle this + * properly **/ +#define PRINTF_ATTRIBUTE(a1, a2) __attribute__ ((format (__printf__, a1, a2))) +#else +#define PRINTF_ATTRIBUTE(a1, a2) +#endif +#endif + +/** This is the context structure that is returned from a db open. */ +typedef struct tdb_context TDB_CONTEXT; + +typedef int (*tdb_traverse_func)(struct tdb_context *, TDB_DATA, TDB_DATA, void *); +typedef void (*tdb_log_func)(struct tdb_context *, enum tdb_debug_level, const char *, ...) PRINTF_ATTRIBUTE(3, 4); +typedef unsigned int (*tdb_hash_func)(TDB_DATA *key); + +struct tdb_logging_context { + tdb_log_func log_fn; + void *log_private; +}; + +/** + * @brief Open the database and creating it if necessary. + * + * @param[in] name The name of the db to open. + * + * @param[in] hash_size The hash size is advisory, use zero for a default + * value. + * + * @param[in] tdb_flags The flags to use to open the db:\n\n + * TDB_CLEAR_IF_FIRST - Clear database if we are the + * only one with it open\n + * TDB_INTERNAL - Don't use a file, instead store the + * data in memory. The filename is + * ignored in this case.\n + * TDB_NOLOCK - Don't do any locking\n + * TDB_NOMMAP - Don't use mmap\n + * TDB_NOSYNC - Don't synchronise transactions to disk\n + * TDB_SEQNUM - Maintain a sequence number\n + * TDB_VOLATILE - activate the per-hashchain freelist, + * default 5.\n + * TDB_ALLOW_NESTING - Allow transactions to nest.\n + * TDB_DISALLOW_NESTING - Disallow transactions to nest.\n + * TDB_INCOMPATIBLE_HASH - Better hashing: can't be opened by tdb < 1.2.6.\n + * TDB_MUTEX_LOCKING - Optimized locking using robust mutexes if supported, + * can't be opened by tdb < 1.3.0. + * Only valid in combination with TDB_CLEAR_IF_FIRST + * after checking tdb_runtime_check_for_robust_mutexes()\n + * + * @param[in] open_flags Flags for the open(2) function. + * + * @param[in] mode The mode for the open(2) function. + * + * @return A tdb context structure, NULL on error. + */ +_PUBLIC_ struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags, + int open_flags, mode_t mode); + +/** + * @brief Open the database and creating it if necessary. + * + * This is like tdb_open(), but allows you to pass an initial logging and + * hash function. Be careful when passing a hash function - all users of the + * database must use the same hash function or you will get data corruption. + * + * @param[in] name The name of the db to open. + * + * @param[in] hash_size The hash size is advisory, use zero for a default + * value. + * + * @param[in] tdb_flags The flags to use to open the db:\n\n + * TDB_CLEAR_IF_FIRST - Clear database if we are the + * only one with it open\n + * TDB_INTERNAL - Don't use a file, instead store the + * data in memory. The filename is + * ignored in this case.\n + * TDB_NOLOCK - Don't do any locking\n + * TDB_NOMMAP - Don't use mmap\n + * TDB_NOSYNC - Don't synchronise transactions to disk\n + * TDB_SEQNUM - Maintain a sequence number\n + * TDB_VOLATILE - activate the per-hashchain freelist, + * default 5.\n + * TDB_ALLOW_NESTING - Allow transactions to nest.\n + * TDB_DISALLOW_NESTING - Disallow transactions to nest.\n + * TDB_INCOMPATIBLE_HASH - Better hashing: can't be opened by tdb < 1.2.6.\n + * TDB_MUTEX_LOCKING - Optimized locking using robust mutexes if supported, + * can't be opened by tdb < 1.3.0. + * Only valid in combination with TDB_CLEAR_IF_FIRST + * after checking tdb_runtime_check_for_robust_mutexes()\n + * + * @param[in] open_flags Flags for the open(2) function. + * + * @param[in] mode The mode for the open(2) function. + * + * @param[in] log_ctx The logging function to use. + * + * @param[in] hash_fn The hash function you want to use. + * + * @return A tdb context structure, NULL on error. + * + * @see tdb_open() + */ +_PUBLIC_ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags, + int open_flags, mode_t mode, + const struct tdb_logging_context *log_ctx, + tdb_hash_func hash_fn); + +/** + * @brief Set the maximum number of dead records per hash chain. + * + * @param[in] tdb The database handle to set the maximum. + * + * @param[in] max_dead The maximum number of dead records per hash chain. + */ +_PUBLIC_ void tdb_set_max_dead(struct tdb_context *tdb, int max_dead); + +/** + * @brief Reopen a tdb. + * + * This can be used after a fork to ensure that we have an independent seek + * pointer from our parent and to re-establish locks. + * + * @param[in] tdb The database to reopen. It will be free'd on error! + * + * @return 0 on success, -1 on error. + * + * @note Don't call tdb_error() after this function cause the tdb context will + * be freed on error. + */ +_PUBLIC_ int tdb_reopen(struct tdb_context *tdb); + +/** + * @brief Reopen all tdb's + * + * If the parent is longlived (ie. a parent daemon architecture), we know it + * will keep it's active lock on a tdb opened with CLEAR_IF_FIRST. Thus for + * child processes we don't have to add an active lock. This is essential to + * improve performance on systems that keep POSIX locks as a non-scalable data + * structure in the kernel. + * + * @param[in] parent_longlived Whether the parent is longlived or not. + * + * @return 0 on success, -1 on error. + */ +_PUBLIC_ int tdb_reopen_all(int parent_longlived); + +/** + * @brief Set a different tdb logging function. + * + * @param[in] tdb The tdb to set the logging function. + * + * @param[in] log_ctx The logging function to set. + */ +_PUBLIC_ void tdb_set_logging_function(struct tdb_context *tdb, const struct tdb_logging_context *log_ctx); + +/** + * @brief Get the tdb last error code. + * + * @param[in] tdb The tdb to get the error code from. + * + * @return A TDB_ERROR code. + * + * @see TDB_ERROR + */ +_PUBLIC_ enum TDB_ERROR tdb_error(struct tdb_context *tdb); + +/** + * @brief Get a error string for the last tdb error + * + * @param[in] tdb The tdb to get the error code from. + * + * @return An error string. + */ +_PUBLIC_ const char *tdb_errorstr(struct tdb_context *tdb); + +/** + * @brief Fetch an entry in the database given a key. + * + * The caller must free the resulting data. + * + * @param[in] tdb The tdb to fetch the key. + * + * @param[in] key The key to fetch. + * + * @return The key entry found in the database, NULL on error with + * TDB_ERROR set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key); + +/** + * @brief Hand a record to a parser function without allocating it. + * + * This function is meant as a fast tdb_fetch alternative for large records + * that are frequently read. The "key" and "data" arguments point directly + * into the tdb shared memory, they are not aligned at any boundary. + * + * @warning The parser is called while tdb holds a lock on the record. DO NOT + * call other tdb routines from within the parser. Also, for good performance + * you should make the parser fast to allow parallel operations. + * + * @param[in] tdb The tdb to parse the record. + * + * @param[in] key The key to parse. + * + * @param[in] parser The parser to use to parse the data. + * + * @param[in] private_data A private data pointer which is passed to the parser + * function. + * + * @return -1 if the record was not found. If the record was found, + * the return value of "parser" is passed up to the caller. + */ +_PUBLIC_ int tdb_parse_record(struct tdb_context *tdb, TDB_DATA key, + int (*parser)(TDB_DATA key, TDB_DATA data, + void *private_data), + void *private_data); + +/** + * @brief Delete an entry in the database given a key. + * + * @param[in] tdb The tdb to delete the key. + * + * @param[in] key The key to delete. + * + * @return 0 on success, -1 if the key doesn't exist. + */ +_PUBLIC_ int tdb_delete(struct tdb_context *tdb, TDB_DATA key); + +/** + * @brief Store an element in the database. + * + * This replaces any existing element with the same key. + * + * @param[in] tdb The tdb to store the entry. + * + * @param[in] key The key to use to store the entry. + * + * @param[in] dbuf The data to store under the key. + * + * @param[in] flag The flags to store the key:\n\n + * TDB_INSERT: Don't overwrite an existing entry.\n + * TDB_MODIFY: Don't create a new entry\n + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag); + + +/** + * @brief Store an element in the database. + * + * This replaces any existing element with the same key. + * + * @param[in] tdb The tdb to store the entry. + * + * @param[in] key The key to use to store the entry. + * + * @param[in] dbufs A vector of memory chunks to write + * + * @param[in] num_dbufs Length of the dbufs vector + * + * @param[in] flag The flags to store the key:\n\n + * TDB_INSERT: Don't overwrite an existing entry.\n + * TDB_MODIFY: Don't create a new entry\n + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_storev(struct tdb_context *tdb, TDB_DATA key, + const TDB_DATA *dbufs, int num_dbufs, int flag); + +/** + * @brief Append data to an entry. + * + * If the entry doesn't exist, it will create a new one. + * + * @param[in] tdb The database to use. + * + * @param[in] key The key to append the data. + * + * @param[in] new_dbuf The data to append to the key. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf); + +/** + * @brief Close a database. + * + * @param[in] tdb The database to close. The context will be free'd. + * + * @return 0 for success, -1 on error. + * + * @note Don't call tdb_error() after this function cause the tdb context will + * be freed on error. + */ +_PUBLIC_ int tdb_close(struct tdb_context *tdb); + +/** + * @brief Find the first entry in the database and return its key. + * + * The caller must free the returned data. + * + * @param[in] tdb The database to use. + * + * @return The first entry of the database, an empty TDB_DATA entry + * if the database is empty. + */ +_PUBLIC_ TDB_DATA tdb_firstkey(struct tdb_context *tdb); + +/** + * @brief Find the next entry in the database, returning its key. + * + * The caller must free the returned data. + * + * @param[in] tdb The database to use. + * + * @param[in] key The key from which you want the next key. + * + * @return The next entry of the current key, an empty TDB_DATA + * entry if there is no entry. + */ +_PUBLIC_ TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA key); + +/** + * @brief Traverse the entire database. + * + * While traversing the function fn(tdb, key, data, state) is called on each + * element. If fn is NULL then it is not called. A non-zero return value from + * fn() indicates that the traversal should stop. Traversal callbacks may not + * start transactions. + * + * @warning The data buffer given to the callback fn does NOT meet the alignment + * restrictions malloc gives you. + * + * @param[in] tdb The database to traverse. + * + * @param[in] fn The function to call on each entry. + * + * @param[in] private_data The private data which should be passed to the + * traversing function. + * + * @return The record count traversed, -1 on error. + */ +_PUBLIC_ int tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *private_data); + +/** + * @brief Traverse the entire database. + * + * While traversing the database the function fn(tdb, key, data, state) is + * called on each element, but marking the database read only during the + * traversal, so any write operations will fail. This allows tdb to use read + * locks, which increases the parallelism possible during the traversal. + * + * @param[in] tdb The database to traverse. + * + * @param[in] fn The function to call on each entry. + * + * @param[in] private_data The private data which should be passed to the + * traversing function. + * + * @return The record count traversed, -1 on error. + */ +_PUBLIC_ int tdb_traverse_read(struct tdb_context *tdb, tdb_traverse_func fn, void *private_data); + +/** + * @brief Traverse a single hash chain + * + * Traverse a single hash chain under a single lock operation. No + * database modification is possible in the callback. + * + * This exists for background cleanup of databases. In normal + * operations, traversing a complete database can be much too + * expensive. Databases can have many chains, which will all have to + * be looked at before tdb_traverse finishes. Also tdb_traverse does a + * lot of fcntl activity to protect against concurrent record deletes. + * + * With this you can walk a fraction of the whole tdb, collect the + * entries you want to prune, leave the traverse, and then modify or + * delete the records in a subsequent step. + * + * To walk the entire database, call this function tdb_hash_size() + * times, with 0<=chain<tdb_hash_size(tdb). + * + * @param[in] tdb The database to traverse. + * + * @param[in] chain The hash chain number to traverse. + * + * @param[in] fn The function to call on each entry. + * + * @param[in] private_data The private data which should be passed to the + * traversing function. + * + * @return The record count traversed, -1 on error. + */ + +_PUBLIC_ int tdb_traverse_chain(struct tdb_context *tdb, + unsigned chain, + tdb_traverse_func fn, + void *private_data); + +/** + * @brief Traverse a single hash chain + * + * This is like tdb_traverse_chain(), but for all records that are in + * the same chain as the record corresponding to the key parameter. + * + * Use it for ongoing database maintenance under a lock. Whenever you + * are about to modify a database, you know which record you are going + * to write to. For that tdb_store(), an exclusive chainlock is taken + * behind the scenes. To utilize this exclusive lock for incremental + * database cleanup as well, tdb_chainlock() the key you are about to + * modify, then tdb_traverse_key_chain() to do the incremental + * maintenance, modify your record and tdb_chainunlock() the key + * again. + * + * @param[in] tdb The database to traverse. + * + * @param[in] key The record key to walk the chain for. + * + * @param[in] fn The function to call on each entry. + * + * @param[in] private_data The private data which should be passed to the + * traversing function. + * + * @return The record count traversed, -1 on error. + */ + +_PUBLIC_ int tdb_traverse_key_chain(struct tdb_context *tdb, + TDB_DATA key, + tdb_traverse_func fn, + void *private_data); +/** + * @brief Check if an entry in the database exists. + * + * @note 1 is returned if the key is found and 0 is returned if not found this + * doesn't match the conventions in the rest of this module, but is compatible + * with gdbm. + * + * @param[in] tdb The database to check if the entry exists. + * + * @param[in] key The key to check if the entry exists. + * + * @return 1 if the key is found, 0 if not. + */ +_PUBLIC_ int tdb_exists(struct tdb_context *tdb, TDB_DATA key); + +/** + * @brief Lock entire database with a write lock. + * + * @param[in] tdb The database to lock. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_lockall(struct tdb_context *tdb); + +/** + * @brief Lock entire database with a write lock. + * + * This is the non-blocking call. + * + * @param[in] tdb The database to lock. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_lockall() + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_lockall_nonblock(struct tdb_context *tdb); + +/** + * @brief Unlock entire database with write lock. + * + * @param[in] tdb The database to unlock. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_lockall() + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_unlockall(struct tdb_context *tdb); + +/** + * @brief Lock entire database with a read lock. + * + * @param[in] tdb The database to lock. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_lockall_read(struct tdb_context *tdb); + +/** + * @brief Lock entire database with a read lock. + * + * This is the non-blocking call. + * + * @param[in] tdb The database to lock. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_lockall_read() + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_lockall_read_nonblock(struct tdb_context *tdb); + +/** + * @brief Unlock entire database with read lock. + * + * @param[in] tdb The database to unlock. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_lockall_read() + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_unlockall_read(struct tdb_context *tdb); + +/** + * @brief Lock entire database with write lock - mark only. + * + * @todo Add more details. + * + * @param[in] tdb The database to mark. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_lockall_mark(struct tdb_context *tdb); + +/** + * @brief Lock entire database with write lock - unmark only. + * + * @todo Add more details. + * + * @param[in] tdb The database to mark. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_lockall_unmark(struct tdb_context *tdb); + +/** + * @brief Get the name of the current tdb file. + * + * This is useful for external logging functions. + * + * @param[in] tdb The database to get the name from. + * + * @return The name of the database. + */ +_PUBLIC_ const char *tdb_name(struct tdb_context *tdb); + +/** + * @brief Get the underlying file descriptor being used by tdb. + * + * This is useful for external routines that want to check the device/inode + * of the fd. + * + * @param[in] tdb The database to get the fd from. + * + * @return The file descriptor or -1. + */ +_PUBLIC_ int tdb_fd(struct tdb_context *tdb); + +/** + * @brief Get the current logging function. + * + * This is useful for external tdb routines that wish to log tdb errors. + * + * @param[in] tdb The database to get the logging function from. + * + * @return The logging function of the database. + * + * @see tdb_get_logging_private() + */ +_PUBLIC_ tdb_log_func tdb_log_fn(struct tdb_context *tdb); + +/** + * @brief Get the private data of the logging function. + * + * @param[in] tdb The database to get the data from. + * + * @return The private data pointer of the logging function. + * + * @see tdb_log_fn() + */ +_PUBLIC_ void *tdb_get_logging_private(struct tdb_context *tdb); + +/** + * @brief Is a transaction active? + * + * It is helpful for the application to know if a transaction is + * active, rather than needing to maintain an application-level reference + * count. + * + * @param[in] tdb The database to start the transaction. + * + * @return true if there is a transaction active, false otherwise + * + * @see tdb_transaction_start() + * @see tdb_transaction_prepare_commit() + * @see tdb_transaction_commit() + * @see tdb_transaction_cancel() + */ +_PUBLIC_ bool tdb_transaction_active(struct tdb_context *tdb); + +/** + * @brief Start a transaction. + * + * All operations after the transaction start can either be committed with + * tdb_transaction_commit() or cancelled with tdb_transaction_cancel(). + * + * If (the default) TDB_ALLOW_NESTING was specified or + * TDB_DISALLOW_NESTING was not specified as a flag via tdb_open() or + * tdb_open_ex(), you call tdb_transaction_start() again on the same + * tdb context while a transaction is in progress, then the same + * transaction buffer is re-used. The number of + * tdb_transaction_{commit,cancel} operations must match the number of + * successful tdb_transaction_start() calls. + * + * Note that transactions are by default disk synchronous, and use a recover + * area in the database to automatically recover the database on the next open + * if the system crashes during a transaction. You can disable the synchronous + * transaction recovery setup using the TDB_NOSYNC flag, which will greatly + * speed up operations at the risk of corrupting your database if the system + * crashes. + * + * Operations made within a transaction are not visible to other users of the + * database until a successful commit. + * + * @param[in] tdb The database to start the transaction. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_transaction_start(struct tdb_context *tdb); + +/** + * @brief Start a transaction, non-blocking. + * + * @param[in] tdb The database to start the transaction. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + * @see tdb_transaction_start() + */ +_PUBLIC_ int tdb_transaction_start_nonblock(struct tdb_context *tdb); + +/** + * @brief Prepare to commit a current transaction, for two-phase commits. + * + * Once prepared for commit, the only allowed calls are tdb_transaction_commit() + * or tdb_transaction_cancel(). Preparing allocates disk space for the pending + * updates, so a subsequent commit should succeed (barring any hardware + * failures). + * + * @param[in] tdb The database to prepare the commit. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_transaction_prepare_commit(struct tdb_context *tdb); + +/** + * @brief Commit a current transaction. + * + * This updates the database and releases the current transaction locks. + * + * @param[in] tdb The database to commit the transaction. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_transaction_commit(struct tdb_context *tdb); + +/** + * @brief Cancel a current transaction. + * + * This discards all write and lock operations that have been made since the + * transaction started. + * + * @param[in] tdb The tdb to cancel the transaction on. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_transaction_cancel(struct tdb_context *tdb); + +/** + * @brief Get the tdb sequence number. + * + * Only makes sense if the writers opened with TDB_SEQNUM set. Note that this + * sequence number will wrap quite quickly, so it should only be used for a + * 'has something changed' test, not for code that relies on the count of the + * number of changes made. If you want a counter then use a tdb record. + * + * The aim of this sequence number is to allow for a very lightweight test of a + * possible tdb change. + * + * @param[in] tdb The database to get the sequence number from. + * + * @return The sequence number or 0. + * + * @see tdb_open() + * @see tdb_enable_seqnum() + */ +_PUBLIC_ int tdb_get_seqnum(struct tdb_context *tdb); + +/** + * @brief Get the hash size. + * + * @param[in] tdb The database to get the hash size from. + * + * @return The hash size. + */ +_PUBLIC_ int tdb_hash_size(struct tdb_context *tdb); + +/** + * @brief Get the map size. + * + * @param[in] tdb The database to get the map size from. + * + * @return The map size. + */ +_PUBLIC_ size_t tdb_map_size(struct tdb_context *tdb); + +/** + * @brief Get the tdb flags set during open. + * + * @param[in] tdb The database to get the flags form. + * + * @return The flags set to on the database. + */ +_PUBLIC_ int tdb_get_flags(struct tdb_context *tdb); + +/** + * @brief Add flags to the database. + * + * @param[in] tdb The database to add the flags. + * + * @param[in] flag The tdb flags to add. + */ +_PUBLIC_ void tdb_add_flags(struct tdb_context *tdb, unsigned flag); + +/** + * @brief Remove flags from the database. + * + * @param[in] tdb The database to remove the flags. + * + * @param[in] flag The tdb flags to remove. + */ +_PUBLIC_ void tdb_remove_flags(struct tdb_context *tdb, unsigned flag); + +/** + * @brief Enable sequence number handling on an open tdb. + * + * @param[in] tdb The database to enable sequence number handling. + * + * @see tdb_get_seqnum() + */ +_PUBLIC_ void tdb_enable_seqnum(struct tdb_context *tdb); + +/** + * @brief Increment the tdb sequence number. + * + * This only works if the tdb has been opened using the TDB_SEQNUM flag or + * enabled using tdb_enable_seqnum(). + * + * @param[in] tdb The database to increment the sequence number. + * + * @see tdb_enable_seqnum() + * @see tdb_get_seqnum() + */ +_PUBLIC_ void tdb_increment_seqnum_nonblock(struct tdb_context *tdb); + +/** + * @brief Create a hash of the key. + * + * @param[in] key The key to hash + * + * @return The hash. + */ +_PUBLIC_ unsigned int tdb_jenkins_hash(TDB_DATA *key); + +/** + * @brief Check the consistency of the database. + * + * This check the consistency of the database calling back the check function + * (if non-NULL) on each record. If some consistency check fails, or the + * supplied check function returns -1, tdb_check returns -1, otherwise 0. + * + * @note The logging function (if set) will be called with additional + * information on the corruption found. + * + * @param[in] tdb The database to check. + * + * @param[in] check The check function to use. + * + * @param[in] private_data the private data to pass to the check function. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_check(struct tdb_context *tdb, + int (*check) (TDB_DATA key, TDB_DATA data, void *private_data), + void *private_data); + +/** + * @brief Dump all possible records in a corrupt database. + * + * This is the only way to get data out of a database where tdb_check() fails. + * It will call walk() with anything which looks like a database record; this + * may well include invalid, incomplete or duplicate records. + * + * @param[in] tdb The database to check. + * + * @param[in] walk The walk function to use. + * + * @param[in] private_data the private data to pass to the walk function. + * + * @return 0 on success, -1 on error with error code set. + * + * @see tdb_error() + * @see tdb_errorstr() + */ +_PUBLIC_ int tdb_rescue(struct tdb_context *tdb, + void (*walk) (TDB_DATA key, TDB_DATA data, void *private_data), + void *private_data); + +/** + * @brief Check if support for TDB_MUTEX_LOCKING is available at runtime. + * + * On some systems the API for pthread_mutexattr_setrobust() is not available. + * On other systems there are some bugs in the interaction between glibc and + * the linux kernel. + * + * This function provides a runtime check if robust mutexes are really + * available. + * + * This needs to be called and return true before TDB_MUTEX_LOCKING + * can be used at runtime. + * + * @note This calls fork(), but the SIGCHILD handling should be transparent. + * + * @return true if supported, false otherwise. + * + * @see TDB_MUTEX_LOCKING + */ +_PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void); + +/* @} ******************************************************************/ + +/* Low level locking functions: use with care */ +_PUBLIC_ int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainlock_read_nonblock(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key); +_PUBLIC_ int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key); + +_PUBLIC_ void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *sigptr); + +/* wipe and repack */ +_PUBLIC_ int tdb_wipe_all(struct tdb_context *tdb); +_PUBLIC_ int tdb_repack(struct tdb_context *tdb); + +/* Debug functions. Not used in production. */ +_PUBLIC_ void tdb_dump_all(struct tdb_context *tdb); +_PUBLIC_ int tdb_printfreelist(struct tdb_context *tdb); +_PUBLIC_ int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries); +_PUBLIC_ int tdb_freelist_size(struct tdb_context *tdb); +_PUBLIC_ char *tdb_summary(struct tdb_context *tdb); + +_PUBLIC_ extern TDB_DATA tdb_null; + +#ifdef __cplusplus +} +#endif + +#endif /* tdb.h */ |