php change str_replace inside serialized data and fix it

replace_serialized_data.php

<?php
$change_from = 'old_string';
$change_to = 'new_string_new_length';
$serialized = file_get_contents('serialized_data.txt');
$serialized = str_replace($change_from, $change_to, $serialized);
function fix_str_length($matches) {
    $string = $matches[2];
    $right_length = strlen($string); // yes, strlen even for UTF-8 characters, PHP wants the mem size, not the char count
    return 's:' . $right_length . ':"' . $string . '";';
}
function fix_serialized($string) {
    // securities
    if ( !preg_match('/^[aOs]:/', $string) ) return $string;
    if ( @unserialize($string) !== false ) return $string;
    $string = preg_replace("%\n%", "", $string);
    // doublequote exploding
    $data = preg_replace('%";%', "µµµ", $string);
    $tab = explode("µµµ", $data);
    $new_data = '';
    foreach ($tab as $line) {
        $new_data .= preg_replace_callback('%\bs:(\d+):"(.*)%', 'fix_str_length', $line);
    }
    return $new_data;
}
$serialized = fix_serialized($serialized);
echo $serialized;

This is great!