include/apr_sdbm.h

   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  */
  44 typedef struct apr_sdbm_t apr_sdbm_t;
  45
  46 /**
  47  * Structure for referencing the datum record within an sdbm
  48  */
  49 typedef 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  */
  86 APU_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  */
  94 APU_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  */
 111 APU_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  */
 117 APU_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  */
 125 APU_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  */
 140 APU_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  */
 149 APU_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  */
 161 APU_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  */
 168 APU_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  */
 174 APU_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db);
 175 /** @} */
 176 #endif /* APR_SDBM_H */