summaryrefslogtreecommitdiff
path: root/program/include/rcube_db.php
blob: f24e9591355eb87435a9ebbea34dd374a753b2bc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
<?php

/**
 +-----------------------------------------------------------------------+
 | program/include/rcube_db.php                                          |
 |                                                                       |
 | This file is part of the Roundcube Webmail client                     |
 | Copyright (C) 2005-2012, The Roundcube Dev Team                       |
 |                                                                       |
 | Licensed under the GNU General Public License version 3 or            |
 | any later version with exceptions for skins & plugins.                |
 | See the README file for a full license statement.                     |
 |                                                                       |
 | PURPOSE:                                                              |
 |   Database wrapper class that implements PHP PDO functions            |
 |                                                                       |
 +-----------------------------------------------------------------------+
 | Author: Aleksander Machniak <alec@alec.pl>                            |
 +-----------------------------------------------------------------------+
*/


/**
 * Database independent query interface
 *
 * This is a wrapper for the PHP PDO
 *
 * @package Database
 * @version 1.0
 */
class rcube_db
{
    protected $db_dsnw;               // DSN for write operations
    protected $db_dsnr;               // DSN for read operations
    protected $db_connected = false;  // Already connected ?
    protected $db_mode;               // Connection mode
    protected $dbh;                   // Connection handle

    protected $db_error        = false;
    protected $db_error_msg    = '';
    protected $conn_failure    = false;
    protected $a_query_results = array('dummy');
    protected $last_res_id     = 0;
    protected $db_index        = 0;
    protected $tables;
    protected $variables;

    protected $options = array(
        // column/table quotes
        'identifier_start' => '"',
        'identifier_end'   => '"',
    );


    /**
     * Factory, returns driver-specific instance of the class
     *
     * @param string $db_dsnw DSN for read/write operations
     * @param string $db_dsnr Optional DSN for read only operations
     * @param bool   $pconn   Enables persistent connections
     *
     * @return rcube_db Object instance
     */
    public static function factory($db_dsnw, $db_dsnr = '', $pconn = false)
    {
        $driver     = strtolower(substr($db_dsnw, 0, strpos($db_dsnw, ':')));
        $driver_map = array(
            'sqlite2' => 'sqlite',
            'sybase'  => 'mssql',
            'dblib'   => 'mssql',
            'mysqli'  => 'mysql',
        );

        $driver = isset($driver_map[$driver]) ? $driver_map[$driver] : $driver;
        $class  = "rcube_db_$driver";

        if (!class_exists($class)) {
            rcube::raise_error(array('code' => 600, 'type' => 'db',
                'line' => __LINE__, 'file' => __FILE__,
                'message' => "Configuration error. Unsupported database driver: $driver"),
                true, true);
        }

        return new $class($db_dsnw, $db_dsnr, $pconn);
    }

    /**
     * Object constructor
     *
     * @param string $db_dsnw DSN for read/write operations
     * @param string $db_dsnr Optional DSN for read only operations
     * @param bool   $pconn   Enables persistent connections
     */
    public function __construct($db_dsnw, $db_dsnr = '', $pconn = false)
    {
        if (empty($db_dsnr)) {
            $db_dsnr = $db_dsnw;
        }

        $this->db_dsnw  = $db_dsnw;
        $this->db_dsnr  = $db_dsnr;
        $this->db_pconn = $pconn;

        $this->db_dsnw_array = self::parse_dsn($db_dsnw);
        $this->db_dsnr_array = self::parse_dsn($db_dsnr);

        // Initialize driver class
        $this->init();
    }

    /**
     * Initialization of the object with driver specific code
     */
    protected function init()
    {
        // To be used by driver classes
    }

    /**
     * Connect to specific database
     *
     * @param array $dsn DSN for DB connections
     *
     * @return PDO database handle
     */
    protected function dsn_connect($dsn)
    {
        $this->db_error     = false;
        $this->db_error_msg = null;

        // Get database specific connection options
        $dsn_string  = $this->dsn_string($dsn);
        $dsn_options = $this->dsn_options($dsn);

        if ($db_pconn) {
            $dsn_options[PDO::ATTR_PERSISTENT] = true;
        }

        // Connect
        try {
            // with this check we skip fatal error on PDO object creation
            if (!class_exists('PDO', false)) {
                throw new Exception('PDO extension not loaded. See http://php.net/manual/en/intro.pdo.php');
            }

            $this->conn_prepare($dsn);

            $dbh = new PDO($dsn_string, $dsn['username'], $dsn['password'], $dsn_options);

            // don't throw exceptions or warnings
            $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT);
        }
        catch (Exception $e) {
            $this->db_error     = true;
            $this->db_error_msg = $e->getMessage();

            rcube::raise_error(array('code' => 500, 'type' => 'db',
                'line' => __LINE__, 'file' => __FILE__,
                'message' => $this->db_error_msg), true, false);

            return null;
        }

        $this->conn_configure($dsn, $dbh);

        return $dbh;
    }

    /**
     * Driver-specific preparation of database connection
     *
     * @param array $dsn DSN for DB connections
     */
    protected function conn_prepare($dsn)
    {
    }

    /**
     * Driver-specific configuration of database connection
     *
     * @param array $dsn DSN for DB connections
     * @param PDO   $dbh Connection handler
     */
    protected function conn_configure($dsn, $dbh)
    {
    }

    /**
     * Driver-specific database character set setting
     *
     * @param string $charset Character set name
     */
    protected function set_charset($charset)
    {
        $this->query("SET NAMES 'utf8'");
    }

    /**
     * Connect to appropiate database depending on the operation
     *
     * @param string $mode Connection mode (r|w)
     */
    public function db_connect($mode)
    {
        // previous connection failed, don't attempt to connect again
        if ($this->conn_failure) {
            return;
        }

        // no replication
        if ($this->db_dsnw == $this->db_dsnr) {
            $mode = 'w';
        }

        // Already connected
        if ($this->db_connected) {
            // connected to db with the same or "higher" mode
            if ($this->db_mode == 'w' || $this->db_mode == $mode) {
                return;
            }
        }

        $dsn = ($mode == 'r') ? $this->db_dsnr_array : $this->db_dsnw_array;

        $this->dbh          = $this->dsn_connect($dsn);
        $this->db_connected = is_object($this->dbh);

        // use write-master when read-only fails
        if (!$this->db_connected && $mode == 'r') {
            $mode = 'w';
            $this->dbh          = $this->dsn_connect($this->db_dsnw_array);
            $this->db_connected = is_object($this->dbh);
        }

        if ($this->db_connected) {
            $this->db_mode = $mode;
            $this->set_charset('utf8');
        }
        else {
            $this->conn_failure = true;
        }
    }

    /**
     * Activate/deactivate debug mode
     *
     * @param boolean $dbg True if SQL queries should be logged
     */
    public function set_debug($dbg = true)
    {
        $this->options['debug_mode'] = $dbg;
    }

    /**
     * Getter for error state
     *
     * @return boolean True on error
     */
    public function is_error()
    {
        return $this->db_error ? $this->db_error_msg : false;
    }

    /**
     * Connection state checker
     *
     * @return boolean True if in connected state
     */
    public function is_connected()
    {
        return !is_object($this->dbh) ? false : $this->db_connected;
    }

    /**
     * Is database replication configured?
     *
     * @return bool Returns true if dsnw != dsnr
     */
    public function is_replicated()
    {
      return !empty($this->db_dsnr) && $this->db_dsnw != $this->db_dsnr;
    }

    /**
     * Get database runtime variables
     *
     * @param string $varname Variable name
     * @param mixed  $default Default value if variable is not set
     *
     * @return mixed Variable value or default
     */
    public function get_variable($varname, $default = null)
    {
        // to be implemented by driver class
        return $default;
    }

    /**
     * Execute a SQL query
     *
     * @param string SQL query to execute
     * @param mixed  Values to be inserted in query
     *
     * @return number  Query handle identifier
     */
    public function query()
    {
        $params = func_get_args();
        $query = array_shift($params);

        // Support one argument of type array, instead of n arguments
        if (count($params) == 1 && is_array($params[0])) {
            $params = $params[0];
        }

        return $this->_query($query, 0, 0, $params);
    }

    /**
     * Execute a SQL query with limits
     *
     * @param string SQL query to execute
     * @param int    Offset for LIMIT statement
     * @param int    Number of rows for LIMIT statement
     * @param mixed  Values to be inserted in query
     *
     * @return int Query handle identifier
     */
    public function limitquery()
    {
        $params  = func_get_args();
        $query   = array_shift($params);
        $offset  = array_shift($params);
        $numrows = array_shift($params);

        return $this->_query($query, $offset, $numrows, $params);
    }

    /**
     * Execute a SQL query with limits
     *
     * @param string $query   SQL query to execute
     * @param int    $offset  Offset for LIMIT statement
     * @param int    $numrows Number of rows for LIMIT statement
     * @param array  $params  Values to be inserted in query
     *
     * @return int Query handle identifier
     */
    protected function _query($query, $offset, $numrows, $params)
    {
        // Read or write ?
        $mode = preg_match('/^(select|show)/i', ltrim($query)) ? 'r' : 'w';

        $this->db_connect($mode);

        // check connection before proceeding
        if (!$this->is_connected()) {
            return null;
        }

        if ($numrows || $offset) {
            $query = $this->set_limit($query, $numrows, $offset);
        }

        $params = (array) $params;

        // Because in Roundcube we mostly use queries that are
        // executed only once, we will not use prepared queries
        $pos = 0;
        $idx = 0;

        while ($pos = strpos($query, '?', $pos)) {
            $val = $this->quote($params[$idx++]);
            unset($params[$idx-1]);
            $query = substr_replace($query, $val, $pos, 1);
            $pos += strlen($val);
        }

        $query = rtrim($query, ';');

        if ($this->options['debug_mode']) {
            rcube::write_log('sql', '[' . (++$this->db_index) . '] ' . $query . ';');
        }

        $query = $this->dbh->query($query);

        if ($query === false) {
            $error = $this->dbh->errorInfo();
            $this->db_error = true;
            $this->db_error_msg = sprintf('[%s] %s', $error[1], $error[2]);

            rcube::raise_error(array('code' => 500, 'type' => 'db',
                'line' => __LINE__, 'file' => __FILE__,
                'message' => $this->db_error_msg), true, false);
        }

        // add result, even if it's an error
        return $this->_add_result($query);
    }

    /**
     * Get number of affected rows for the last query
     *
     * @param  number $res_id Optional query handle identifier
     *
     * @return int Number of rows or false on failure
     */
    public function affected_rows($res_id = null)
    {
        if ($result = $this->_get_result($res_id)) {
            return $result->rowCount();
        }

        return 0;
    }

    /**
     * Get last inserted record ID
     * For Postgres databases, a sequence name is required
     *
     * @param string $table Table name (to find the incremented sequence)
     *
     * @return mixed ID or false on failure
     */
    public function insert_id($table = '')
    {
        if (!$this->db_connected || $this->db_mode == 'r') {
            return false;
        }

        if ($table) {
            // resolve table name
            $table = $this->table_name($table);
        }

        $id = $this->dbh->lastInsertId($table);

        return $id;
    }

    /**
     * Get an associative array for one row
     * If no query handle is specified, the last query will be taken as reference
     *
     * @param int $res_id Optional query handle identifier
     *
     * @return mixed Array with col values or false on failure
     */
    public function fetch_assoc($res_id = null)
    {
        $result = $this->_get_result($res_id);
        return $this->_fetch_row($result, PDO::FETCH_ASSOC);
    }

    /**
     * Get an index array for one row
     * If no query handle is specified, the last query will be taken as reference
     *
     * @param int $res_id Optional query handle identifier
     *
     * @return mixed Array with col values or false on failure
     */
    public function fetch_array($res_id = null)
    {
        $result = $this->_get_result($res_id);
        return $this->_fetch_row($result, PDO::FETCH_NUM);
    }

    /**
     * Get col values for a result row
     *
     * @param PDOStatement $result Result handle
     * @param int          $mode   Fetch mode identifier
     *
     * @return mixed Array with col values or false on failure
     */
    protected function _fetch_row($result, $mode)
    {
        if (!is_object($result) || !$this->is_connected()) {
            return false;
        }

        return $result->fetch($mode);
    }

    /**
     * Adds LIMIT,OFFSET clauses to the query
     *
     * @param string $query  SQL query
     * @param int    $limit  Number of rows
     * @param int    $offset Offset
     *
     * @return string SQL query
     */
    protected function set_limit($query, $limit = 0, $offset = 0)
    {
        if ($limit) {
            $query .= ' LIMIT ' . intval($limit);
        }

        if ($offset) {
            $query .= ' OFFSET ' . intval($offset);
        }

        return $query;
    }

    /**
     * Returns list of tables in a database
     *
     * @return array List of all tables of the current database
     */
    public function list_tables()
    {
        // get tables if not cached
        if ($this->tables === null) {
            $q = $this->query('SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES ORDER BY TABLE_NAME');

            if ($res = $this->_get_result($q)) {
                $this->tables = $res->fetchAll(PDO::FETCH_COLUMN, 0);
            }
            else {
                $this->tables = array();
            }
        }

        return $this->tables;
    }

    /**
     * Returns list of columns in database table
     *
     * @param string $table Table name
     *
     * @return array List of table cols
     */
    public function list_cols($table)
    {
        $q = $this->query('SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = ?',
            array($table));

        if ($res = $this->_get_result($q)) {
            return $res->fetchAll(PDO::FETCH_COLUMN, 0);
        }

        return array();
    }

    /**
     * Formats input so it can be safely used in a query
     *
     * @param mixed  $input Value to quote
     * @param string $type  Type of data
     *
     * @return string Quoted/converted string for use in query
     */
    public function quote($input, $type = null)
    {
        // handle int directly for better performance
        if ($type == 'integer' || $type == 'int') {
            return intval($input);
        }

        // create DB handle if not available
        if (!$this->dbh) {
            $this->db_connect('r');
        }

        if ($this->dbh) {
            $map = array(
                'bool'    => PDO::PARAM_BOOL,
                'integer' => PDO::PARAM_INT,
            );
            $type = isset($map[$type]) ? $map[$type] : PDO::PARAM_STR;
            return $this->dbh->quote($input, $type);
        }

        return 'NULL';
    }

    /**
     * Quotes a string so it can be safely used as a table or column name
     *
     * @param string $str Value to quote
     *
     * @return string Quoted string for use in query
     * @deprecated    Replaced by rcube_db::quote_identifier
     * @see           rcube_db::quote_identifier
     */
    public function quoteIdentifier($str)
    {
        return $this->quote_identifier($str);
    }

    /**
     * Quotes a string so it can be safely used as a table or column name
     *
     * @param string $str Value to quote
     *
     * @return string Quoted string for use in query
     */
    public function quote_identifier($str)
    {
        $start = $this->options['identifier_start'];
        $end   = $this->options['identifier_end'];
        $name  = array();

        foreach (explode('.', $str) as $elem) {
            $elem = str_replace(array($start, $end), '', $elem);
            $name[] = $start . $elem . $end;
        }

        return  implode($name, '.');
    }

    /**
     * Return SQL function for current time and date
     *
     * @return string SQL function to use in query
     */
    public function now()
    {
        return "now()";
    }

    /**
     * Return list of elements for use with SQL's IN clause
     *
     * @param array  $arr  Input array
     * @param string $type Type of data
     *
     * @return string Comma-separated list of quoted values for use in query
     */
    public function array2list($arr, $type = null)
    {
        if (!is_array($arr)) {
            return $this->quote($arr, $type);
        }

        foreach ($arr as $idx => $item) {
            $arr[$idx] = $this->quote($item, $type);
        }

        return implode(',', $arr);
    }

    /**
     * Return SQL statement to convert a field value into a unix timestamp
     *
     * This method is deprecated and should not be used anymore due to limitations
     * of timestamp functions in Mysql (year 2038 problem)
     *
     * @param string $field Field name
     *
     * @return string  SQL statement to use in query
     * @deprecated
     */
    public function unixtimestamp($field)
    {
        return "UNIX_TIMESTAMP($field)";
    }

    /**
     * Return SQL statement to convert from a unix timestamp
     *
     * @param int $timestamp Unix timestamp
     *
     * @return string Date string in db-specific format
     */
    public function fromunixtime($timestamp)
    {
        return date("'Y-m-d H:i:s'", $timestamp);
    }

    /**
     * Return SQL statement for case insensitive LIKE
     *
     * @param string $column Field name
     * @param string $value  Search value
     *
     * @return string SQL statement to use in query
     */
    public function ilike($column, $value)
    {
        return $this->quote_identifier($column).' LIKE '.$this->quote($value);
    }

    /**
     * Abstract SQL statement for value concatenation
     *
     * @return string SQL statement to be used in query
     */
    public function concat(/* col1, col2, ... */)
    {
        $args = func_get_args();
        if (is_array($args[0])) {
            $args = $args[0];
        }

        return '(' . join(' || ', $args) . ')';
    }

    /**
     * Encodes non-UTF-8 characters in string/array/object (recursive)
     *
     * @param mixed $input Data to fix
     *
     * @return mixed Properly UTF-8 encoded data
     */
    public static function encode($input)
    {
        if (is_object($input)) {
            foreach (get_object_vars($input) as $idx => $value) {
                $input->$idx = self::encode($value);
            }
            return $input;
        }
        else if (is_array($input)) {
            foreach ($input as $idx => $value) {
                $input[$idx] = self::encode($value);
            }
            return $input;
        }

        return utf8_encode($input);
    }

    /**
     * Decodes encoded UTF-8 string/object/array (recursive)
     *
     * @param mixed $input Input data
     *
     * @return mixed Decoded data
     */
    public static function decode($input)
    {
        if (is_object($input)) {
            foreach (get_object_vars($input) as $idx => $value) {
                $input->$idx = self::decode($value);
            }
            return $input;
        }
        else if (is_array($input)) {
            foreach ($input as $idx => $value) {
                $input[$idx] = self::decode($value);
            }
            return $input;
        }

        return utf8_decode($input);
    }

    /**
     * Adds a query result and returns a handle ID
     *
     * @param object $res Query handle
     *
     * @return int Handle ID
     */
    protected function _add_result($res)
    {
        $this->last_res_id = sizeof($this->a_query_results);
        $this->a_query_results[$this->last_res_id] = $res;

        return $this->last_res_id;
    }

    /**
     * Resolves a given handle ID and returns the according query handle
     * If no ID is specified, the last resource handle will be returned
     *
     * @param int $res_id Handle ID
     *
     * @return mixed Resource handle or false on failure
     */
    protected function _get_result($res_id = null)
    {
        if ($res_id == null) {
            $res_id = $this->last_res_id;
        }

        if (!empty($this->a_query_results[$res_id])) {
            return $this->a_query_results[$res_id];
        }

        return false;
    }

    /**
     * Return correct name for a specific database table
     *
     * @param string $table Table name
     *
     * @return string Translated table name
     */
    public function table_name($table)
    {
        $rcube = rcube::get_instance();

        // return table name if configured
        $config_key = 'db_table_'.$table;

        if ($name = $rcube->config->get($config_key)) {
            return $name;
        }

        return $table;
    }

    /**
     * Return correct name for a specific database sequence
     * (used for Postgres only)
     *
     * @param string $sequence Secuence name
     *
     * @return string Translated sequence name
     */
    public function sequence_name($sequence)
    {
        $rcube = rcube::get_instance();

        // return sequence name if configured
        $config_key = 'db_sequence_'.$sequence;

        if ($name = $rcube->config->get($config_key)) {
            return $name;
        }

        return $sequence;
    }

    /**
     * MDB2 DSN string parser
     *
     * @param string $sequence Secuence name
     *
     * @return array DSN parameters
     */
    public static function parse_dsn($dsn)
    {
        if (empty($dsn)) {
            return null;
        }

        // Find phptype and dbsyntax
        if (($pos = strpos($dsn, '://')) !== false) {
            $str = substr($dsn, 0, $pos);
            $dsn = substr($dsn, $pos + 3);
        }
        else {
            $str = $dsn;
            $dsn = null;
        }

        // Get phptype and dbsyntax
        // $str => phptype(dbsyntax)
        if (preg_match('|^(.+?)\((.*?)\)$|', $str, $arr)) {
            $parsed['phptype']  = $arr[1];
            $parsed['dbsyntax'] = !$arr[2] ? $arr[1] : $arr[2];
        }
        else {
            $parsed['phptype']  = $str;
            $parsed['dbsyntax'] = $str;
        }

        if (empty($dsn)) {
            return $parsed;
        }

        // Get (if found): username and password
        // $dsn => username:password@protocol+hostspec/database
        if (($at = strrpos($dsn,'@')) !== false) {
            $str = substr($dsn, 0, $at);
            $dsn = substr($dsn, $at + 1);
            if (($pos = strpos($str, ':')) !== false) {
                $parsed['username'] = rawurldecode(substr($str, 0, $pos));
                $parsed['password'] = rawurldecode(substr($str, $pos + 1));
            }
            else {
                $parsed['username'] = rawurldecode($str);
            }
        }

        // Find protocol and hostspec

        // $dsn => proto(proto_opts)/database
        if (preg_match('|^([^(]+)\((.*?)\)/?(.*?)$|', $dsn, $match)) {
            $proto       = $match[1];
            $proto_opts  = $match[2] ? $match[2] : false;
            $dsn         = $match[3];
        }
        // $dsn => protocol+hostspec/database (old format)
        else {
            if (strpos($dsn, '+') !== false) {
                list($proto, $dsn) = explode('+', $dsn, 2);
            }
            if (   strpos($dsn, '//') === 0
                && strpos($dsn, '/', 2) !== false
                && $parsed['phptype'] == 'oci8'
            ) {
                //oracle's "Easy Connect" syntax:
                //"username/password@[//]host[:port][/service_name]"
                //e.g. "scott/tiger@//mymachine:1521/oracle"
                $proto_opts = $dsn;
                $pos = strrpos($proto_opts, '/');
                $dsn = substr($proto_opts, $pos + 1);
                $proto_opts = substr($proto_opts, 0, $pos);
            }
            else if (strpos($dsn, '/') !== false) {
                list($proto_opts, $dsn) = explode('/', $dsn, 2);
            }
            else {
                $proto_opts = $dsn;
                $dsn = null;
            }
        }

        // process the different protocol options
        $parsed['protocol'] = (!empty($proto)) ? $proto : 'tcp';
        $proto_opts = rawurldecode($proto_opts);
        if (strpos($proto_opts, ':') !== false) {
            list($proto_opts, $parsed['port']) = explode(':', $proto_opts);
        }
        if ($parsed['protocol'] == 'tcp') {
            $parsed['hostspec'] = $proto_opts;
        }
        else if ($parsed['protocol'] == 'unix') {
            $parsed['socket'] = $proto_opts;
        }

        // Get dabase if any
        // $dsn => database
        if ($dsn) {
            // /database
            if (($pos = strpos($dsn, '?')) === false) {
                $parsed['database'] = rawurldecode($dsn);
            // /database?param1=value1&param2=value2
            }
            else {
                $parsed['database'] = rawurldecode(substr($dsn, 0, $pos));
                $dsn = substr($dsn, $pos + 1);
                if (strpos($dsn, '&') !== false) {
                    $opts = explode('&', $dsn);
                }
                else { // database?param1=value1
                    $opts = array($dsn);
                }
                foreach ($opts as $opt) {
                    list($key, $value) = explode('=', $opt);
                    if (!array_key_exists($key, $parsed) || false === $parsed[$key]) {
                        // don't allow params overwrite
                        $parsed[$key] = rawurldecode($value);
                    }
                }
            }
        }

        return $parsed;
    }

    /**
     * Returns PDO DSN string from DSN array
     *
     * @param array $dsn DSN parameters
     *
     * @return string DSN string
     */
    protected function dsn_string($dsn)
    {
        $params = array();
        $result = $dsn['phptype'] . ':';

        if ($dsn['hostspec']) {
            $params[] = 'host=' . $dsn['hostspec'];
        }

        if ($dsn['port']) {
            $params[] = 'port=' . $dsn['port'];
        }

        if ($dsn['database']) {
            $params[] = 'dbname=' . $dsn['database'];
        }

        if (!empty($params)) {
            $result .= implode(';', $params);
        }

        return $result;
    }

    /**
     * Returns driver-specific connection options
     *
     * @param array $dsn DSN parameters
     *
     * @return array Connection options
     */
    protected function dsn_options($dsn)
    {
        $result = array();

        return $result;
    }
}