Workaround for corrupted serialized meta data

When database encoding changed from single to multibyte character set
unserialize function fails for data with multibyte characters.

The webmaster should fix this in the database...

We try to get around the error.

include/db/mysql.php

@@ -1436,9 +1436,23 @@ function phorum_db_get_messages($thread, $page=0, $ignore_mod_perms=FALSE, $writ
     foreach ($messages as $id => $message)
     {
         // Unpack the message meta data.
+        if (!empty($message['meta'])) {
+            $fixed_meta = @unserialize($message['meta']);
+            if ($fixed_meta === false) {
+                // When database encoding changed from single to multibyte character set
+                // unserialize function fails for data with multibyte characters.
+                // The webmaster should fix this in the database...
+                // We try to get around the error.
+                $fixed_meta = preg_replace_callback(
+                    '/s:([0-9]+):\"(.*?)\";/',
+                    function ($matches) { return "s:".strlen($matches[2]).':"'.$matches[2].'";'; },
+                    $message['meta']
+                );
+            }
+        }
         $messages[$id]['meta'] = empty($message['meta'])
                                ? array()
-                               : unserialize($message['meta']);
+                               : $fixed_meta;
 
         // Collect all involved users.
         if ($message['user_id']) {