How to repair a serialized string which has been corrupted by an incorrect byte count length?

I am using Hotaru CMS with the Image Upload plugin, I get this error if I try to attach an image to a post, otherwise there is no error:

> unserialize() [function.unserialize]: Error at offset

The offending code (error points to line with **):

/**
* Retrieve submission step data
*
* @param $key - empty when setting
* @return bool
*/
public function loadSubmitData($h, $key = '')
{
// delete everything in this table older than 30 minutes:
$this->deleteTempData($h->db);

if (!$key) { return false; }

$cleanKey = preg_replace('/[^a-z0-9]+/','',$key);
if (strcmp($key,$cleanKey) != 0) {
return false;
} else {
$sql = "SELECT tempdata_value FROM " . TABLE_TEMPDATA . " WHERE tempdata_key = %s ORDER BY tempdata_updatedts DESC LIMIT 1";
$submitted_data = $h->db->get_var($h->db->prepare($sql, $key));
**if ($submitted_data) { return unserialize($submitted_data); } else { return false; }**
}
}

Data from the table, notice the end bit has the image info, I am not an expert in PHP so I was wondering what you guys/gals might think?

tempdata_value:

a:10:{s:16:"submit_editorial";b:0;s:15:"submit_orig_url";s:13:"www.bbc.co.uk";s:12:"submit_title";s:14:"No title found";s:14:"submit_content";s:12:"dnfsdkfjdfdf";s:15:"submit_category";i:2;s:11:"submit_tags";s:3:"bbc";s:9:"submit_id";b:0;s:16:"submit_subscribe";i:0;s:15:"submit_comments";s:4:"open";s:5:"image";s:19:"C:fakepath100.jpg";}

Edit: I think I've found the serialize bit...

/**
* Save submission step data
*
* @return bool
*/
public function saveSubmitData($h)
{
// delete everything in this table older than 30 minutes:
$this->deleteTempData($h->db);

$sid = preg_replace('/[^a-z0-9]+/i', '', session_id());
$key = md5(microtime() . $sid . rand());
$sql = "INSERT INTO " . TABLE_TEMPDATA . " (tempdata_key, tempdata_value, tempdata_updateby) VALUES (%s,%s, %d)";
$h->db->query($h->db->prepare($sql, $key, serialize($h->vars['submitted_data']), $h->currentUser->id));
return $key;
}

`unserialize() [function.unserialize]: Error at offset` was dues to `invalid serialization data` due to invalid length

**Quick Fix**

What you can do is is `recalculating the length` of the elements in serialized array

**You current serialized data**

$data = 'a:10:{s:16:"submit_editorial";b:0;s:15:"submit_orig_url";s:13:"www.bbc.co.uk";s:12:"submit_title";s:14:"No title found";s:14:"submit_content";s:12:"dnfsdkfjdfdf";s:15:"submit_category";i:2;s:11:"submit_tags";s:3:"bbc";s:9:"submit_id";b:0;s:16:"submit_subscribe";i:0;s:15:"submit_comments";s:4:"open";s:5:"image";s:19:"C:fakepath100.jpg";}';

**Example without recalculation**


var_dump(unserialize($data));


Output

Notice: unserialize() [function.unserialize]: Error at offset 337 of 338 bytes



**Recalculating**

$data = preg_replace('!s:(\d+):"(.*?)";!e', "'s:'.strlen('$2').':\"$2\";'", $data);
var_dump(unserialize($data));


Output

array
'submit_editorial' => boolean false
'submit_orig_url' => string 'www.bbc.co.uk' (length=13)
'submit_title' => string 'No title found' (length=14)
'submit_content' => string 'dnfsdkfjdfdf' (length=12)
'submit_category' => int 2
'submit_tags' => string 'bbc' (length=3)
'submit_id' => boolean false
'submit_subscribe' => int 0
'submit_comments' => string 'open' (length=4)
'image' => string 'C:fakepath100.jpg' (length=17)



**Recommendation** .. I

Instead of using this kind of quick fix ... i"ll advice you update the question with

- How you are serializing your data

- How you are Saving it ..


**================================ EDIT 1 ===============================**

**The Error**

The Error was generated because of use of double quote `"` instead single quote `'` that is why `C:\fakepath\100.png` was converted to `C:fakepath100.jpg`


**To fix the error**


You need to change `$h->vars['submitted_data']` From (Note the singe quite `'` )

Replace

$h->vars['submitted_data']['image'] = "C:\fakepath\100.png" ;


With

$h->vars['submitted_data']['image'] = 'C:\fakepath\100.png' ;



**Additional Filter**

You can also add this simple filter before you call serialize

function satitize(&$value, $key)
{
$value = addslashes($value);
}

array_walk($h->vars['submitted_data'], "satitize");

If you have UTF Characters you can also run

$h->vars['submitted_data'] = array_map("utf8_encode",$h->vars['submitted_data']);

**How to detect the problem in future serialized data**


findSerializeError ( $data1 ) ;


Output


Diffrence 9 != 7
-> ORD number 57 != 55
-> Line Number = 315
-> Section Data1 = pen";s:5:"image";s:19:"C:fakepath100.jpg
-> Section Data2 = pen";s:5:"image";s:17:"C:fakepath100.jpg
^------- The Error (Element Length)




`findSerializeError` Function

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;
}

}

}


**A better way to save to Database**

$toDatabse = base64_encode(serialize($data)); // Save to database
$fromDatabase = unserialize(base64_decode($data)); //Getting Save Format

This error is caused because your charset is wrong.

Set charset after open tag:

header('Content-Type: text/html; charset=utf-8');

And set charset utf8 in your database :

mysql_query("SET NAMES 'utf8'");

There's another reason `unserialize()` failed because you improperly put serialized data into the database see [Official Explanation][1] here. Since `serialize()` returns binary data and php variables don't care encoding methods, so that putting it into TEXT, VARCHAR() will cause this error.

Solution: store serialized data into BLOB in your table.


[1]:

[To see links please register here]

I don't have enough reputation to comment, so I hope this is seen by people using the above "correct" answer:

Since php 5.5 the /e modifier in preg_replace() has been deprecated completely and the preg_match above will error out. The php documentation recommends using preg_match_callback in its place.

Please find the following solution as an alternative to the above proposed preg_match.

$fixed_data = preg_replace_callback ( '!s:(\d+):"(.*?)";!', function($match) {
return ($match[1] == strlen($match[2])) ? $match[0] : 's:' . strlen($match[2]) . ':"' . $match[2] . '";';
},$bad_data );

You will have to alter the collation type to `utf8_unicode_ci` and the problem will be fixed.

the [official docs][1] says it should return false and set E_NOTICE

but since you got error then the error reporting is set to be triggered by E_NOTICE

here is a fix to allow you detect false returned by ```unserialize```

$old_err=error_reporting();
error_reporting($old_err & ~E_NOTICE);
$object = unserialize($serialized_data);
error_reporting($old_err);

you might want to consider use base64 encode/decode

$string=base64_encode(serialize($obj));
unserialize(base64_decode($string));



[1]:

[To see links please register here]

In my case I was storing serialized data in `BLOB` field of MySQL DB which apparently wasn't big enough to contain the whole value and truncated it. Such a string obviously could not be unserialized.
Once converted that field to `MEDIUMBLOB` the problem dissipated.
Also it may be needed to switch in table options `ROW_FORMAT` to `DYNAMIC` or `COMPRESSED`.

Another reason of this problem can be column type of "payload" sessions table. If you have huge data on session, a text column wouldn't be enough. You will need MEDIUMTEXT or even LONGTEXT.

You can fix broken serialize string using following function, with **multibyte character** handling.

function repairSerializeString($value)
{

$regex = '/s:([0-9]+):"(.*?)"/';

return preg_replace_callback(
$regex, function($match) {
return "s:".mb_strlen($match[2]).":\"".$match[2]."\"";
},
$value
);
}