includes/utils/Cdb.php

   1 <?php
   2 /**
   3  * Native CDB file reader and writer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * Read from a CDB file.
  25  * Native and pure PHP implementations are provided.
  26  * http://cr.yp.to/cdb.html
  27  */
  28 abstract class CdbReader {
  29         /**
  30          * The file handle
  31          */
  32         protected $handle;
  33
  34         /**
  35          * Open a file and return a subclass instance
  36          *
  37          * @param string $fileName
  38          *
  39          * @return CdbReader
  40          */
  41         public static function open( $fileName ) {
  42                 return self::haveExtension() ?
  43                         new CdbReaderDBA( $fileName ) :
  44                         new CdbReaderPHP( $fileName );
  45         }
  46
  47         /**
  48          * Returns true if the native extension is available
  49          *
  50          * @return bool
  51          */
  52         public static function haveExtension() {
  53                 if ( !function_exists( 'dba_handlers' ) ) {
  54                         return false;
  55                 }
  56                 $handlers = dba_handlers();
  57                 if ( !in_array( 'cdb', $handlers ) || !in_array( 'cdb_make', $handlers ) ) {
  58                         return false;
  59                 }
  60
  61                 return true;
  62         }
  63
  64         /**
  65          * Create the object and open the file
  66          *
  67          * @param string $fileName
  68          */
  69         abstract public function __construct( $fileName );
  70
  71         /**
  72          * Close the file. Optional, you can just let the variable go out of scope.
  73          */
  74         abstract public function close();
  75
  76         /**
  77          * Get a value with a given key. Only string values are supported.
  78          *
  79          * @param string $key
  80          */
  81         abstract public function get( $key );
  82 }
  83
  84 /**
  85  * Write to a CDB file.
  86  * Native and pure PHP implementations are provided.
  87  */
  88 abstract class CdbWriter {
  89         /**
  90          * The file handle
  91          */
  92         protected $handle;
  93
  94         /**
  95          * File we'll be writing to when we're done
  96          * @var string
  97          */
  98         protected $realFileName;
  99
 100         /**
 101          * File we write to temporarily until we're done
 102          * @var string
 103          */
 104         protected $tmpFileName;
 105
 106         /**
 107          * Open a writer and return a subclass instance.
 108          * The user must have write access to the directory, for temporary file creation.
 109          *
 110          * @param string $fileName
 111          *
 112          * @return CdbWriterDBA|CdbWriterPHP
 113          */
 114         public static function open( $fileName ) {
 115                 return CdbReader::haveExtension() ?
 116                         new CdbWriterDBA( $fileName ) :
 117                         new CdbWriterPHP( $fileName );
 118         }
 119
 120         /**
 121          * Create the object and open the file
 122          *
 123          * @param string $fileName
 124          */
 125         abstract public function __construct( $fileName );
 126
 127         /**
 128          * Set a key to a given value. The value will be converted to string.
 129          * @param string $key
 130          * @param string $value
 131          */
 132         abstract public function set( $key, $value );
 133
 134         /**
 135          * Close the writer object. You should call this function before the object
 136          * goes out of scope, to write out the final hashtables.
 137          */
 138         abstract public function close();
 139
 140         /**
 141          * If the object goes out of scope, close it for sanity
 142          */
 143         public function __destruct() {
 144                 if ( isset( $this->handle ) ) {
 145                         $this->close();
 146                 }
 147         }
 148
 149         /**
 150          * Are we running on Windows?
 151          * @return bool
 152          */
 153         protected function isWindows() {
 154                 return substr( php_uname(), 0, 7 ) == 'Windows';
 155         }
 156 }
 157
 158 /**
 159  * Exception for Cdb errors.
 160  * This explicitly doesn't subclass MWException to encourage reuse.
 161  */
 162 class CdbException extends Exception {
 163 }