dolphin/methods-and-how-to/repair-serialized-string.php

<?php

/**
 *  dolphin. Collection of useful PHP skeletons.
 *  Copyright (C) 2013  Johannes 'Banana' Keßler
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the COMMON DEVELOPMENT AND DISTRIBUTION LICENSE
 *
 * You should have received a copy of the
 * COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
 * along with this program.  If not, see http://www.sun.com/cddl/cddl.html
 */

/**
 * how to "repair" an serilized string to get the data back.
 * it can not solve everything but it might help to recover some otherwise lost data
 */

/**
 * the error message "Error at offset"
 * this inticates a malformed string. with the following method you can 
 * find out where and what could be the error
 * At first use the exact offset from the error message and choose a length of 3
 * then you can get backwards and choose a longer range to identify the error
 * if you have utf-8 data, make sure you set the right encoding header.
 */
var_export(substr($serializedStr, OFFSET, LENGTH););

/**
 * there is a better way to store and save the data to avoid malformed data
 */
$toDatabse = base64_encode(serialize($data));  // Save to database
$fromDatabase = unserialize(base64_decode($data)); //Getting Save Format

/**
 * finding the error in the serilized string.
 * based on a idea from stackoverflow
 *
 * @param string The serilized string
 */
function findSerializeError($data1) {
    echo "<pre>";
    $data2 = preg_replace ( '!s:(\d+):"(.*?)";!e', "'s:'.strlen('$2').':\"$2\";'",$data1 );
    $max = (strlen ( $data1 ) > strlen ( $data2 )) ? strlen ( $data1 ) : strlen ( $data2 );

    echo $data1 . PHP_EOL;
    echo $data2 . PHP_EOL;

    for($i = 0; $i < $max; $i ++) {

        if (@$data1 {$i} !== @$data2 {$i}) {

            echo "Diffrence ", @$data1 {$i}, " != ", @$data2 {$i}, PHP_EOL;
            echo "\t-> ORD number ", ord ( @$data1 {$i} ), " != ", ord ( @$data2 {$i} ), PHP_EOL;
            echo "\t-> Line Number = $i" . PHP_EOL;

            $start = ($i - 20);
            $start = ($start < 0) ? 0 : $start;
            $length = 40;

            $point = $max - $i;
            if ($point < 20) {
                $rlength = 1;
                $rpoint = - $point;
            } else {
                $rpoint = $length - 20;
                $rlength = 1;
            }

            echo "\t-> Section Data1  = ", substr_replace ( substr ( $data1, $start, $length ), "<b style=\"color:green\">{$data1 {$i}}</b>", $rpoint, $rlength ), PHP_EOL;
            echo "\t-> Section Data2  = ", substr_replace ( substr ( $data2, $start, $length ), "<b style=\"color:red\">{$data2 {$i}}</b>", $rpoint, $rlength ), PHP_EOL;
        }
    }
}

?>