1 /* Copyright 2000-2005 The Apache Software Foundation or its licensors, as
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 * sdbm - ndbm work-alike hashed database library
19 * based on Per-Ake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
20 * author: oz@nexus.yorku.ca
21 * status: ex-public domain
28 #include "apr_errno.h"
29 #include "apr_file_io.h" /* for apr_fileperms_t */
33 * @brief apr-util SDBM library
36 * @defgroup APR_Util_DBM_SDBM SDBM library
37 * @ingroup APR_Util_DBM
42 * Structure for referencing an sdbm
44 typedef struct apr_sdbm_t apr_sdbm_t;
47 * Structure for referencing the datum record within an sdbm
50 /** pointer to the data stored/retrieved */
56 /* The extensions used for the database files */
57 /** SDBM Directory file extension */
58 #define APR_SDBM_DIRFEXT ".dir"
59 /** SDBM page file extension */
60 #define APR_SDBM_PAGFEXT ".pag"
62 /* flags to sdbm_store */
63 #define APR_SDBM_INSERT 0 /**< Insert */
64 #define APR_SDBM_REPLACE 1 /**< Replace */
65 #define APR_SDBM_INSERTDUP 2 /**< Insert with duplicates */
68 * Open an sdbm database by file name
69 * @param db The newly opened database
70 * @param name The sdbm file to open
71 * @param mode The flag values (APR_READ and APR_BINARY flags are implicit)
73 * APR_WRITE open for read-write access
74 * APR_CREATE create the sdbm if it does not exist
75 * APR_TRUNCATE empty the contents of the sdbm
76 * APR_EXCL fail for APR_CREATE if the file exists
77 * APR_DELONCLOSE delete the sdbm when closed
78 * APR_SHARELOCK support locking across process/machines
80 * @param perms Permissions to apply to if created
81 * @param p The pool to use when creating the sdbm
82 * @remark The sdbm name is not a true file name, as sdbm appends suffixes
83 * for seperate data and index files.
85 APU_DECLARE(apr_status_t) apr_sdbm_open(apr_sdbm_t **db, const char *name,
87 apr_fileperms_t perms, apr_pool_t *p);
90 * Close an sdbm file previously opened by apr_sdbm_open
91 * @param db The database to close
93 APU_DECLARE(apr_status_t) apr_sdbm_close(apr_sdbm_t *db);
96 * Lock an sdbm database for concurency of multiple operations
97 * @param db The database to lock
98 * @param type The lock type
101 * APR_FLOCK_EXCLUSIVE
103 * @remark Calls to apr_sdbm_lock may be nested. All apr_sdbm functions
104 * perform implicit locking. Since an APR_FLOCK_SHARED lock cannot be
105 * portably promoted to an APR_FLOCK_EXCLUSIVE lock, apr_sdbm_store and
106 * apr_sdbm_delete calls will fail if an APR_FLOCK_SHARED lock is held.
107 * The apr_sdbm_lock call requires the database to be opened with the
108 * APR_SHARELOCK mode value.
110 APU_DECLARE(apr_status_t) apr_sdbm_lock(apr_sdbm_t *db, int type);
113 * Release an sdbm lock previously aquired by apr_sdbm_lock
114 * @param db The database to unlock
116 APU_DECLARE(apr_status_t) apr_sdbm_unlock(apr_sdbm_t *db);
119 * Fetch an sdbm record value by key
120 * @param db The database
121 * @param value The value datum retrieved for this record
122 * @param key The key datum to find this record
124 APU_DECLARE(apr_status_t) apr_sdbm_fetch(apr_sdbm_t *db,
125 apr_sdbm_datum_t *value,
126 apr_sdbm_datum_t key);
129 * Store an sdbm record value by key
130 * @param db The database
131 * @param key The key datum to store this record by
132 * @param value The value datum to store in this record
133 * @param opt The method used to store the record
135 * APR_SDBM_INSERT return an error if the record exists
136 * APR_SDBM_REPLACE overwrite any existing record for key
139 APU_DECLARE(apr_status_t) apr_sdbm_store(apr_sdbm_t *db, apr_sdbm_datum_t key,
140 apr_sdbm_datum_t value, int opt);
143 * Delete an sdbm record value by key
144 * @param db The database
145 * @param key The key datum of the record to delete
146 * @remark It is not an error to delete a non-existent record.
148 APU_DECLARE(apr_status_t) apr_sdbm_delete(apr_sdbm_t *db,
149 const apr_sdbm_datum_t key);
152 * Retrieve the first record key from a dbm
153 * @param db The database
154 * @param key The key datum of the first record
155 * @remark The keys returned are not ordered. To traverse the list of keys
156 * for an sdbm opened with APR_SHARELOCK, the caller must use apr_sdbm_lock
157 * prior to retrieving the first record, and hold the lock until after the
158 * last call to apr_sdbm_nextkey.
160 APU_DECLARE(apr_status_t) apr_sdbm_firstkey(apr_sdbm_t *db, apr_sdbm_datum_t *key);
163 * Retrieve the next record key from an sdbm
164 * @param db The database
165 * @param key The key datum of the next record
167 APU_DECLARE(apr_status_t) apr_sdbm_nextkey(apr_sdbm_t *db, apr_sdbm_datum_t *key);
170 * Returns true if the sdbm database opened for read-only access
171 * @param db The database to test
173 APU_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db);
175 #endif /* APR_SDBM_H */