1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17/*
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
22 */
23
24#ifndef APR_SDBM_H
25#define APR_SDBM_H
26
27#include "apu.h"
28#include "apr_errno.h"
29#include "apr_file_io.h"   /* for apr_fileperms_t */
30
31/**
32 * @file apr_sdbm.h
33 * @brief apr-util SDBM library
34 */
35/**
36 * @defgroup APR_Util_DBM_SDBM SDBM library
37 * @ingroup APR_Util_DBM
38 * @{
39 */
40
41/**
42 * Structure for referencing an sdbm
43 */
44typedef struct apr_sdbm_t apr_sdbm_t;
45
46/**
47 * Structure for referencing the datum record within an sdbm
48 */
49typedef struct {
50    /** pointer to the data stored/retrieved */
51    char *dptr;
52    /** size of data */
53    /* apr_ssize_t for release 2.0??? */
54    int dsize;
55} apr_sdbm_datum_t;
56
57/* The extensions used for the database files */
58/** SDBM Directory file extension */
59#define APR_SDBM_DIRFEXT	".dir"
60/** SDBM page file extension */
61#define APR_SDBM_PAGFEXT	".pag"
62
63/* flags to sdbm_store */
64#define APR_SDBM_INSERT     0   /**< Insert */
65#define APR_SDBM_REPLACE    1   /**< Replace */
66#define APR_SDBM_INSERTDUP  2   /**< Insert with duplicates */
67
68/**
69 * Open an sdbm database by file name
70 * @param db The newly opened database
71 * @param name The sdbm file to open
72 * @param mode The flag values (APR_READ and APR_BINARY flags are implicit)
73 * <PRE>
74 *           APR_WRITE          open for read-write access
75 *           APR_CREATE         create the sdbm if it does not exist
76 *           APR_TRUNCATE       empty the contents of the sdbm
77 *           APR_EXCL           fail for APR_CREATE if the file exists
78 *           APR_DELONCLOSE     delete the sdbm when closed
79 *           APR_SHARELOCK      support locking across process/machines
80 * </PRE>
81 * @param perms Permissions to apply to if created
82 * @param p The pool to use when creating the sdbm
83 * @remark The sdbm name is not a true file name, as sdbm appends suffixes
84 * for seperate data and index files.
85 */
86APU_DECLARE(apr_status_t) apr_sdbm_open(apr_sdbm_t **db, const char *name,
87                                        apr_int32_t mode,
88                                        apr_fileperms_t perms, apr_pool_t *p);
89
90/**
91 * Close an sdbm file previously opened by apr_sdbm_open
92 * @param db The database to close
93 */
94APU_DECLARE(apr_status_t) apr_sdbm_close(apr_sdbm_t *db);
95
96/**
97 * Lock an sdbm database for concurency of multiple operations
98 * @param db The database to lock
99 * @param type The lock type
100 * <PRE>
101 *           APR_FLOCK_SHARED
102 *           APR_FLOCK_EXCLUSIVE
103 * </PRE>
104 * @remark Calls to apr_sdbm_lock may be nested.  All apr_sdbm functions
105 * perform implicit locking.  Since an APR_FLOCK_SHARED lock cannot be
106 * portably promoted to an APR_FLOCK_EXCLUSIVE lock, apr_sdbm_store and
107 * apr_sdbm_delete calls will fail if an APR_FLOCK_SHARED lock is held.
108 * The apr_sdbm_lock call requires the database to be opened with the
109 * APR_SHARELOCK mode value.
110 */
111APU_DECLARE(apr_status_t) apr_sdbm_lock(apr_sdbm_t *db, int type);
112
113/**
114 * Release an sdbm lock previously aquired by apr_sdbm_lock
115 * @param db The database to unlock
116 */
117APU_DECLARE(apr_status_t) apr_sdbm_unlock(apr_sdbm_t *db);
118
119/**
120 * Fetch an sdbm record value by key
121 * @param db The database
122 * @param value The value datum retrieved for this record
123 * @param key The key datum to find this record
124 */
125APU_DECLARE(apr_status_t) apr_sdbm_fetch(apr_sdbm_t *db,
126                                         apr_sdbm_datum_t *value,
127                                         apr_sdbm_datum_t key);
128
129/**
130 * Store an sdbm record value by key
131 * @param db The database
132 * @param key The key datum to store this record by
133 * @param value The value datum to store in this record
134 * @param opt The method used to store the record
135 * <PRE>
136 *           APR_SDBM_INSERT     return an error if the record exists
137 *           APR_SDBM_REPLACE    overwrite any existing record for key
138 * </PRE>
139 */
140APU_DECLARE(apr_status_t) apr_sdbm_store(apr_sdbm_t *db, apr_sdbm_datum_t key,
141                                         apr_sdbm_datum_t value, int opt);
142
143/**
144 * Delete an sdbm record value by key
145 * @param db The database
146 * @param key The key datum of the record to delete
147 * @remark It is not an error to delete a non-existent record.
148 */
149APU_DECLARE(apr_status_t) apr_sdbm_delete(apr_sdbm_t *db,
150                                          const apr_sdbm_datum_t key);
151
152/**
153 * Retrieve the first record key from a dbm
154 * @param db The database
155 * @param key The key datum of the first record
156 * @remark The keys returned are not ordered.  To traverse the list of keys
157 * for an sdbm opened with APR_SHARELOCK, the caller must use apr_sdbm_lock
158 * prior to retrieving the first record, and hold the lock until after the
159 * last call to apr_sdbm_nextkey.
160 */
161APU_DECLARE(apr_status_t) apr_sdbm_firstkey(apr_sdbm_t *db, apr_sdbm_datum_t *key);
162
163/**
164 * Retrieve the next record key from an sdbm
165 * @param db The database
166 * @param key The key datum of the next record
167 */
168APU_DECLARE(apr_status_t) apr_sdbm_nextkey(apr_sdbm_t *db, apr_sdbm_datum_t *key);
169
170/**
171 * Returns true if the sdbm database opened for read-only access
172 * @param db The database to test
173 */
174APU_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db);
175/** @} */
176#endif /* APR_SDBM_H */
177