igbinary_unserialize takes a single serialized variable from igbinary_serialize and converts it back into a PHP value.
Untrusted user input must not be passed to igbinary_unserialize. Unserialization can result in code being loaded and executed due to object instantiation and autoloading, and a malicious user may be able to exploit this. Instead a safe, standard data interchange format such as JSON (via json_decode and json_encode) should be used, if serialized data needs to be passed to a client.
If there is the need to unserialize externally-stored serialized data, hash_hmac can be used for data validation. It is important to ensure that nobody has tampered with the data.
The igbinary serialization format does not provide a way to distinguish between different reference groups for the same value. All PHP references to a given value as treated as part of the same reference group when unserialized, even if they were parts of difference reference groups when serialized.
The serialized string generated by igbinary_serialize.
If the value being unserialized is an object, after successfully reconstructing the object igbinary will automatically attempt to call the __unserialize() or __wakeup() methods (if one exists).
It is possible to set a callback function which will be called, if an undefined class should be instantiated during unserializing. (to prevent getting an incomplete object __PHP_Incomplete_Class.) The php.ini, ini_set or .htaccess can be used to define unserialize_callback_func. Everytime an undefined class should be instantiated, it will be called. To disable this feature this setting should be emptied.
The converted value is returned, and can be a bool, int, float, string, array, object, or null.
In case the passed string is not unserializeable, false is returned and E_NOTICE or E_WARNING is issued.
Exceptions and Errors
Objects may throw Throwables in their unserialization handlers.
null or false is returned both in the case of an error and if unserializing
the serialized null or false value. It is possible to catch this special case by
comparing str with
or by catching the issued E_NOTICE.