#define CCAN_TDB2_H
/*
- Unix SMB/CIFS implementation.
-
- trivial database library
+ 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
#endif
#include <ccan/compiler/compiler.h>
-/* 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 */
+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_CLEAR_IF_FIRST 1
#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_VOLATILE 256 /* Activate the per-hashchain freelist, default 5 */
-/* 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_NOEXIST,
- TDB_ERR_EINVAL, TDB_ERR_RDONLY };
-
-/* flags for tdb_summary. Logical or to combine. */
-enum tdb_summary_flags { TDB_SUMMARY_HISTOGRAMS = 1 };
-
-/* logging uses one of the following levels */
-enum tdb_log_level {TDB_LOG_ERROR = 0, TDB_LOG_USE_ERROR, TDB_LOG_WARNING};
+/**
+ * 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;
-struct tdb_context;
+/**
+ * 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_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.
+ *
+ * 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.
+ *
+ * See Also:
+ * tdb_transaction_commit()
+ */
+enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb);
/* FIXME: Make typesafe */
typedef int (*tdb_traverse_func)(struct tdb_context *, TDB_DATA, TDB_DATA, void *);
+/**
+ * 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.
+ */
+int64_t tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *p);
+
+/**
+ * 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 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(), 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.
+ */
+enum TDB_ERROR tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * 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)
+ * @private_data: pointer for @check
+ *
+ * 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().
+ */
+enum TDB_ERROR tdb_check(struct tdb_context *tdb,
+ enum TDB_ERROR (*check)(TDB_DATA key,
+ TDB_DATA data,
+ void *private_data),
+ void *private_data);
+
+/**
+ * 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);
+
+/**
+ * enum tdb_attribute_type - descriminator for union tdb_attribute.
+ */
enum tdb_attribute_type {
TDB_ATTRIBUTE_LOG = 0,
TDB_ATTRIBUTE_HASH = 1,
TDB_ATTRIBUTE_STATS = 3
};
+/**
+ * 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 (*log_fn)(struct tdb_context *tdb,
void *log_private;
};
+/**
+ * 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 (*hash_fn)(const void *key, size_t len, uint64_t seed,
void *hash_private;
};
+/**
+ * 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.
+ *
+ * New fields will be added at the end, hence the "size" argument which
+ * indicates how large your structure is. If your size is larger than
+ * that known about by this version of tdb, the size will be reduced to
+ * the known structure size. Thus you can detect older versions, and
+ * thus know that newer stats will not be updated.
+ */
struct tdb_attribute_stats {
struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_STATS */
size_t size; /* = sizeof(struct tdb_attribute_stats) */
uint64_t lock_nonblock;
};
+/**
+ * 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.
+ */
union tdb_attribute {
struct tdb_attribute_base base;
struct tdb_attribute_log log;
struct tdb_attribute_seed seed;
struct tdb_attribute_stats stats;
};
-
-struct tdb_context *tdb_open(const char *name, int tdb_flags,
- int open_flags, mode_t mode,
- union tdb_attribute *attributes);
-
-struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key);
-int tdb_delete(struct tdb_context *tdb, struct tdb_data key);
-int tdb_store(struct tdb_context *tdb, struct tdb_data key, struct tdb_data dbuf, int flag);
-int tdb_append(struct tdb_context *tdb, struct tdb_data key, struct tdb_data dbuf);
-int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
-int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
-int64_t tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *p);
-int64_t tdb_traverse_read(struct tdb_context *tdb,
- tdb_traverse_func fn, void *p);
-TDB_DATA tdb_firstkey(struct tdb_context *tdb);
-TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA key);
-int tdb_close(struct tdb_context *tdb);
-int tdb_check(struct tdb_context *tdb,
- int (*check)(TDB_DATA key, TDB_DATA data, void *private_data),
- void *private_data);
-
-enum TDB_ERROR tdb_error(const struct tdb_context *tdb);
-const char *tdb_errorstr(const struct tdb_context *tdb);
-
-int tdb_transaction_start(struct tdb_context *tdb);
-void tdb_transaction_cancel(struct tdb_context *tdb);
-int tdb_transaction_prepare_commit(struct tdb_context *tdb);
-int tdb_transaction_commit(struct tdb_context *tdb);
-
-char *tdb_summary(struct tdb_context *tdb, enum tdb_summary_flags flags);
+/**
+ * tdb_null - a convenient value for errors.
+ */
extern struct tdb_data tdb_null;
#ifdef __cplusplus
projects / ccan / blobdiff