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    unserialize

    (PHP 4, PHP 5, PHP 7, PHP 8)

    unserialize — Cria um valor PHP a partir de uma representação armazenada

    Descrição

    unserialize(string $data, array $options = []): mixed

    unserialize() toma uma única variável serializada e converte-a de volta em um valor PHP.

    Aviso

    Entradas de usuário não confiáveis não devem ser passadas a unserialize() independente dos valores do elemento allowed_classes do parâmetro options. Desserialização pode resultar em um código carregado e executado devido a uma instanciação de objeto e auto-carregamento, e um usuário malicioso pode ser capaz de explorar isto. Use um formato padrão e seguro de troca de dados como JSON (via json_decode() e json_encode()) se for necessário passar dados serializados ao usuário.

    Se for necessário desserializar dados armazenados externamente, considere o uso de hash_hmac() para validação de dados. Certifique-se que os dados não foram modificados por outras pessoas.

    Parâmetros

    data

    A string serializada.

    Se a variável a ser desserializada for um objeto, após a reconstrução bem sucedida do objeto o PHP tentará automaticamente chamar os métodos __unserialize() ou __wakeup() (se existirem).

    Nota: unserialize_callback_func directive

    É possível definir uma função de retorno de chamada, se uma classe indefinida tiver sido instanciada durante a desserialização. (para evitar receber um objeto imcompleto do tipo object "__PHP_Incomplete_Class".) Deve-se usar o php.ini, a função ini_set() ou o arquivo .htaccess para definir unserialize_callback_func. Toda vez que uma classe indefinida precisar ser instanciada, ela será chamada. Para desabilitar este recurso basta esvaziar esta configuração.

    options

    Quaisquer opções podem ser fornecidas a unserialize() como um array associativo.

    Opções válidas
    Nome Tipo Descrição
    allowed_classes mixed Pode ser um array de nomes de classe que devem ser aceitas, false para não aceitar nenhuma classe, ou true para aceitar todas as classes. Se esta opção for definida e unserialize() encontrar um objeto de uma classe que não deve ser aceita, o objeto será instanciado como uma __PHP_Incomplete_Class. Omitir esta opção é o mesmo que defini-la como true: o PHP tentará instanciar objetos de qualquer classe.
    max_depth int A profundidade máxima de estruturas permitidas durante a desserialização, com a intenção de prevenir sobrecarga de pilha. O limite padrão de profundidade é 4096 e pode ser desabilitado definindo-se max_depth para 0.

    Valor Retornado

    O valor convertido é retornado, e pode ser bool, int, float, string, array ou object.

    Caso a string informada não for desserializável, false é retornado e um erro de nível E_WARNING é emitido.

    Erros/Exceções

    Objetos podem disparar exceções da classe Throwable em seus manipuladores de desserialização.

    Registro de Alterações

    Versão Descrição
    8.3.0 Agora emite um E_WARNING quando a string informada não for desserializável; anteriormente um E_NOTICE era emitido.
    7.4.0 Adicionado elemento max_depth do array options para definir a profundidade máxima de estruturas permitidas durante desserialização.
    7.1.0 O elemento allowed_classes de options) agora é estritamente tipado, isto é, se algo que não seja um array ou um bool for fornecido, unserialize() retorna false e emite um erro de nível E_WARNING.

    Exemplos

    Exemplo #1 Exemplo de unserialize()

    <?php
    // Aqui, será usado unserialize() para carregar dados de sessão para o
    // array $session_data a partir de uma string selecionada de um banco de dados.
    // Este exemplo complementa o descrito em serialize().

    $conn = odbc_connect("webdb", "php", "chicken");
    $stmt = odbc_prepare($conn, "SELECT data FROM sessions WHERE id = ?");
    $sqldata = array($_SERVER['PHP_AUTH_USER']);
    if (!    odbc_execute($stmt, $sqldata) || !odbc_fetch_into($stmt, $tmp)) {
    // se a execute ou fetch falharem, inicializa como um array vazio
    $session_data = array();
    } else {
    // agora os dados serializados devem estar em $tmp[0].
    $session_data = unserialize($tmp[0]);
    if (!    is_array($session_data)) {
    // algo deu errado, inicializa como um array vazio
    $session_data = array();
    }
    }
    ?>

    Exemplo #2 Exemplo de unserialize_callback_func

    <?php
    $serialized_object    ='O:1:"a":1:{s:5:"value";s:3:"100";}';

    ini_set('unserialize_callback_func', 'mycallback'); // define a função de retorno de chamada

    function mycallback($classname)
    {
    // apenas inclua um arquivo contendo sua definição de classe
    // $classname serve para determinar que definição de classe é requerida
    }
    ?>

    Notas

    Aviso

    false é retornado tanto em caso de um erro quanto no caso de desserializar o valor false serializado. É possível capturar este caso especial comparando-se data com serialize(false) ou capturando-se o erro de nível E_NOTICE emitido.

    Veja Também

    add a note add a note

    User Contributed Notes 24 notes

    up
    103
    me+phpnet at unreal4u dot com
    7 years ago
    Just some reminder which may save somebody some time regarding the `$options` array:

    Say you want to be on the safe side and not allow any objects to be unserialized... My first thought was doing the following:

    <?php
    $lol     = unserialize($string, false);
    // This will generate:
    // Warning: unserialize() expects parameter 2 to be array, boolean given
    ?>

    The correct way of doing this is the following:
    <?php
    $lol     = unserialize($string, ['allowed_classes' => false]);
    ?>

    Hope it helps somebody!
    up
    10
    karsten at dambekalns dot de
    3 years ago
    Keep in mind that the allowed_classes does not use inheritance, i.e. allowing an interface is not possible and sub-classes won't pass the check. See https://3v4l.org/tdHfl
    up
    33
    ErnestV
    11 years ago
    Just a note - if the serialized string contains a reference to a class that cannot be instantiated (e.g. being abstract) PHP will immediately die with a fatal error. If the unserialize() statement is preceded with a '@' to avoid cluttering the logs with warns or notices there will be absolutely no clue as to why the script stopped working. Cost me a couple of hours...
    up
    11
    daniel at fourstaples dot com
    14 years ago
    Here's a simple function to get the class of a serialized string (that is, the type of object that will be returned if it's unserialized):

    <?php
    function get_serial_class($serial) {
            $types = array('s' => 'string', 'a' => 'array', 'b' => 'bool', 'i' => 'int', 'd' => 'float', 'N;' => 'NULL');
       
            $parts = explode(':', $serial, 4);
        return isset(    $types[$parts[0]]) ? $types[$parts[0]] : trim($parts[2], '"');
    }
    ?>

    I use this when saving a serialized object to a cookie, to make sure it is the right type when I go to unserialize it.

    The type names are the same format/case as you would see if you did a var_dump().
    up
    9
    hadley8899 at gmail dot com
    4 years ago
    For the people who are getting the error

    PHP Notice:  unserialize(): Error at offset 191 of 285 bytes in ...

    and are getting the data from a database, Make sure that you have the database set the the correct encoding, I had the database set as latin1_swedish_ci and all of the data looked perfect, Infact when i copied it into a online unserialize it worked fine. I changed the collation to utf8mb4_unicode_ci and all worked fine.
    up
    7
    bjd
    7 years ago
    Talk on Exploiting PHP7 Unserialize here: https://media.ccc.de/v/33c3-7858-exploiting_php7_unserialize
    up
    5
    chris at pollett dot org
    9 years ago
    When you serialize an object of a class from a particular namespace, the namespace is recorded as part of the serialization. If you decide to change this namespace's name, it can be hard to read in old serialized objects. I.e., suppose you had serialized an object of type foo\A, you change the namespace of your project to goo but otherwise leave the class definition of A unchanged. You would like to be able to unserialize the object as goo\A, instead unserialization will only create a partial object. To fix this in the case where you don't have nested objects in your class definition, you can use the following simple rename function:
    /**
    * Used to change the namespace of a serialized php object (assumes doesn't
    * have nested subobjects)
    *
    * @param string $class_name new fully qualified name with namespace
    * @param string $object_string serialized object
    *
    * @return string serialized object with new name
    */
    function renameSerializedObject($class_name, $object_string)
    {
        /*  number of digits in the length of name of the object needs to be
            less than 12 digits (probably more like 4) for this to work.
        */
        $name_length = intval(substr($object_string, 2, 14));
        $name_space_info_length = strlen("O:".$name_length.":") +
            $name_length + 2; // 2 for quotes;
        $object_string = 'O:' .
            strlen($class_name) . ':"'. $class_name.'"' .
            substr($object_string, $name_space_info_length);
        return $object_string;
    }
    up
    10
    Ray.Paseur often uses Gmail
    11 years ago
    In the Classes and Objects docs, there is this: In order to be able to unserialize() an object, the class of that object needs to be defined.

    Prior to PHP 5.3, this was not an issue.  But after PHP 5.3 an object made by SimpleXML_Load_String() cannot be serialized.  An attempt to do so will result in a run-time failure, throwing an exception.  If you store such an object in $_SESSION, you will get a post-execution error that says this:

    Fatal error: Uncaught exception 'Exception' with message 'Serialization of 'SimpleXMLElement' is not allowed' in [no active file]:0 Stack trace: #0 {main} thrown in [no active file] on line 0

    The entire contents of the session will be lost.  Hope this saves someone some time!

    <?php // RAY_temp_ser.php
    error_reporting(E_ALL);
    session_start();
    var_dump($_SESSION);
    $_SESSION['hello'] = 'World';
    var_dump($_SESSION);

    // AN XML STRING FOR TEST DATA
    $xml = '<?xml version="1.0"?>
    <families>
      <parent>
        <child index="1" value="Category 1">Child One</child>
      </parent>
    </families>'    ;

    // MAKE AN OBJECT (GIVES SimpleXMLElement)
    $obj = SimpleXML_Load_String($xml);

    // STORE THE OBJECT IN THE SESSION
    $_SESSION['obj'] = $obj;
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    8
    arbie samong
    15 years ago
    __PHP_Incomplete_Class Object Demystified

    1. First take note of the output. A simple example:

    __PHP_Incomplete_Class Object (
    [__PHP_Incomplete_Class_Name] => SomeObject1
    [obj1property1] => somevalue1 [obj1property2] => __PHP_Incomplete_Class Object ( [__PHP_Incomplete_Class_Name] => SomeObject2 [obj2property1] => somevalue1 [obj2property2] => Array (
    ['key1'] => somevalue3, ['key2'] => somevalue4 ) ) )

    2. We analyze this and break it down.
    __PHP_Incomplete_Class Object tells you there is an object that needs to be declared somehow.
    __PHP_Incomplete_Class_Name simply tells you the expected class name. It is just one of the properties for now.

    So we have:
    a) an unknown object that has a class name SomeObject1 (first class)
    b) it has 2 properties, namely obj1property1 and obj2property2
    c) obj2property2 is itself an object whose class name is SomeObject2 (the second class)
    d) SomeObject2 has two properties, obj2property1 and obj2property2
    e) obj2property2 is an array that contains two elements

    3. Now that we have an idea of the structure, we shall create class definitions based from it. We will just create properties for now, methods are not required as a minimum.

    <?php
    class SomeObject1 {
            public     $obj1property1;
            public     $obj1property2;
    }
    class     SomeObject2 {
            public     $obj2property1;
            public     $obj2property2;
    }
    ?>

    4. Have that accessible to your script and it will solve the __PHP_Incomplete_Class Object problem as far as the output is concerned. Now you will have:

    SomeObject1 ( [obj1property1] => somevalue1 [obj1property2] => SomeObject2 ( [obj2property1] => somevalue1 [obj2property2] => Array ( ['key1'] => somevalue3, ['key2'] => somevalue4 ) ) )

    As you will notice, __PHP_Incomplete_Class Object is gone and replaced by the class name. The property __PHP_Incomplete_Class_Name is also removed.

    5. As for the array property obj2property2, we can directly access that and just assume that it is an array and loop through it:

    <?php

    // this will be SomeObject1
    $data = unserialize($serialized_data);

    // this will be SomeObject2
    $data2 = $data->obj1property2();

    foreach(    $data2->obj2property2 as $key => $value):
             print     $key.' : '. $value .'<br>';
    endforeach;

    ?>

    Outputs:
    key1 : somevalue3
    key2 : somevalue4

    That's it. You can add more methods on the class declarations for the given properties, provided you keep your original output as basis for the data types.
    up
    3
    m.m.j.kronenburg
    8 years ago
    You can use the following code to use the php 7 unserialize function in php 5.3 and upwards. This adds the $option argument.

    <?php

    namespace
    {

    /**
    * PHP 7 unserialize function for PHP 5.3 upwards.
    * Added the $option argument (allowed_classes).
    * See php unserialize manual for more detail.
    **/
    function php7_unserialize($str, $options = array())
    {
      if(    version_compare(PHP_VERSION, '7.0.0', '>='))
      { return     unserialize($str, $options); }

          $allowed_classes = isset($options['allowed_classes']) ?
            $options['allowed_classes'] : true;
      if(    is_array($allowed_classes) || !$allowed_classes)
      {
            $str = preg_replace_callback(
              '/(?=^|:)(O|C):\d+:"([^"]*)":(\d+):{/',
          function(    $matches) use ($allowed_classes)
          {
            if(    is_array($allowed_classes) &&
                  in_array($matches[2], $allowed_classes))
            { return     $matches[0]; }
            else
            {
              return     $matches[1].':22:"__PHP_Incomplete_Class":'.
                (    $matches[3] + 1).
                    ':{s:27:"__PHP_Incomplete_Class_Name";'.
                    serialize($matches[2]);
            }
          },
              $str
            );
      }
      unset(    $allowed_classes);
      return     unserialize($str);
    }

    }     // namespace

    namespace my_name_space
    {
          /**
       * Use the new php7 unserialize in your namespace without
       * renaming all unserialize(...) function calls to
       * php7_unserialize(...).
       **/
          function unserialize($str, $options = array())
      { return     php7_unserialize($str, $options); }
    }

    ?>
    up
    8
    chris AT cmbuckley DOT co DOT uk
    16 years ago
    As mentioned in the notes, unserialize returns false in the event of an error and for boolean false. Here is the first solution mentioned, without using error handling:

    <?php
    function isSerialized($str) {
        return (    $str == serialize(false) || @unserialize($str) !== false);
    }

    var_dump(isSerialized('s:6:"foobar";')); // bool(true)
    var_dump(isSerialized('foobar'));        // bool(false)
    var_dump(isSerialized('b:0;'));          // bool(true)
    ?>
    up
    2
    w dot laurencine at teknoa dot net
    15 years ago
    When dealing with a string which contain "\r", it seems that the length is not evaluated correctly. The following solves the problem for me :

    <?php
    // remove the \r caracters from the $unserialized string
    $unserialized = str_replace("\r","",$unserialized);

    // and then unserialize()
    unserialize($unserialized);
    ?>
    up
    2
    chris at colourlovers dot com
    13 years ago
    Anyone having trouble serializing data with SimpleXMLElement objects stored within it, check this out:

    This will traverse $data looking for any children which are instances of SimpleXMLElement, and will run ->asXML() on them, turning them into a string and making them serializable. Other data will be left alone.

    <?php
    function exportNestedSimpleXML($data) {
        if (    is_scalar($data) === false) {
            foreach (    $data as $k => $v) {
                if (    $v instanceof SimpleXMLElement) {
                        $v = str_replace("&#13;","\r",$v->asXML());
                } else {
                        $v = exportNestedSimpleXML($v);
                }

                if (    is_array($data)) {
                        $data[$k] = $v;
                } else if (    is_object($data)) {
                        $data->$k = $v;
                }
            }
        }

        return     $data;
    }

    $data = array (
            "baz" => array (
                "foo" => new stdClass(),
                "int" => 123,
                "str" => "asdf",
                "bar" => new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><foo>bar</foo>'),
        )
    );

    var_dump($data);
    /*array(1) {
      ["baz"]=>
      array(4) {
        ["foo"]=>
        object(stdClass)#3 (0) {
        }
        ["int"]=>
        int(123)
        ["str"]=>
        string(4) "asdf"
        ["bar"]=>
        object(SimpleXMLElement)#4 (1) {
          [0]=>
          string(3) "bar"
        }
      }
    }*/

    var_dump(exportNestedSimpleXML($data));
    /*array(1) {
      ["baz"]=>
      array(4) {
        ["foo"]=>
        object(stdClass)#3 (0) {
        }
        ["int"]=>
        int(123)
        ["str"]=>
        string(4) "asdf"
        ["bar"]=>
        string(54) "<?xml version="1.0" encoding="UTF-8"?>
    <foo>bar</foo>
    "
      }
    }
    */
    ?>
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    3
    BenBE at omorphia dot de
    17 years ago
    When trying to serialize or unserialize recursive arrays or otherwise linked data you might find the undocumented R data type quite useful.

    If you want a array like the one produced with
    <?
    $a     = array();
    $a[0] =& $a;
    ?>
    serialized you can store it using a string simular to this one:
    <?
    $a     = unserialize("a:1:{i:0;R:1;}");
    ?>

    Both sources will make $a hold an array that self-references itself in index 0.

    The argument for R is the index of the created sub-variable of the serialize-string beginning with 1.
    up
    2
    Are Pedersen
    18 years ago
    Be aware that if useing serialize/unserialize in a serverfarm with both 32bit and 64bit servers you can get unexpected results.

    Ex: if you serialize an integer with value of 2147483648 on a 64bit system and then unserialize it on a 32bit system you will get the value -2147483648 instead. This is because an integer on 32bit cannot be above 2147483647 so it wraps.
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    2
    double at dumpit dot com
    17 years ago
    This little function will check whether the serialized string is well formed.

    PHP < 6 because i'd heard changes will be made in this php-intern function,
    maybe it could be edited easy for it.

    <?php

    function wd_check_serialization( $string, &$errmsg )
    {

            $str = 's';
            $array = 'a';
            $integer = 'i';
            $any = '[^}]*?';
            $count = '\d+';
            $content = '"(?:\\\";|.)*?";';
            $open_tag = '\{';
            $close_tag = '\}';
            $parameter = "($str|$array|$integer|$any):($count)" . "(?:[:]($open_tag|$content)|[;])";           
            $preg = "/$parameter|($close_tag)/";
        if( !    preg_match_all( $preg, $string, $matches ) )
        {           
                $errmsg = 'not a serialized string';
            return     false;
        }   
            $open_arrays = 0;
        foreach(     $matches[1] AS $key => $value )
        {
            if( !empty(     $value ) && ( $value != $array xor $value != $str xor $value != $integer ) )
            {
                    $errmsg = 'undefined datatype';
                return     false;
            }
            if(     $value == $array )
            {
                    $open_arrays++;                               
                if(     $matches[3][$key] != '{' )
                {
                        $errmsg = 'open tag expected';
                    return     false;
                }
            }
            if(     $value == '' )
            {
                if(     $matches[4][$key] != '}' )
                {
                        $errmsg = 'close tag expected';
                    return     false;
                }
                    $open_arrays--;
            }
            if(     $value == $str )
            {
                    $aVar = ltrim( $matches[3][$key], '"' );
                    $aVar = rtrim( $aVar, '";' );
                if(     strlen( $aVar ) != $matches[2][$key] )
                {
                        $errmsg = 'stringlen for string not match';
                    return     false;
                }
            }
            if(     $value == $integer )
            {
                if( !empty(     $matches[3][$key] ) )
                {
                        $errmsg = 'unexpected data';
                    return     false;
                }
                if( !    is_integer( (int)$matches[2][$key] ) )
                {
                        $errmsg = 'integer expected';
                    return     false;
                }
            }
        }       
        if(     $open_arrays != 0 )
        {
                $errmsg = 'wrong setted arrays';
            return     false;
        }
        return     true;
    }

    ?>
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    -1
    OscarZarrus
    2 years ago
    For those who are looking for an efficient solution for handling controversial "FALSE", they can use this function which in case of non-unserializable string, instead of a "FALSE", throws an Exception. Vice versa it returns the unserialized variable.
    <?php
            /**
         * @param string $serializedString
         * @param array $options
         * @return mixed
         * @throws Exception
         */
            function UnSerialize(string $serializedString, array $options = []) {
                $_unserialized = @unserialize($serializedString, $options);
            if (    $serializedString === serialize(false) || $_unserialized !== false){
                return     $_unserialized;
            }
            throw new     Exception("Non-unserializable string");

        }

    ?>
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    1
    Chris Hayes (chris at hypersites dot com)
    20 years ago
    In reply to the earlier post about having to include object definitions *before* using unserialize.  There is a workaround for this.

    When an object is serialized, the first bit of the string is actually the name of the class.  When an unknown object is unserialized, this is maintained as a property.  So if you serialize it again, you get back the exact same string as if you'd serialized the original object.  Basically, to cut to the point...

    If you use

    $_SESSION['my_object'] = unserialize(serialize($_SESSION['my_object']))

    then you get back an object of the correct type, even if the session had originally loaded it as an object of type stdClass.
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    1
    suman dot jis at gmail dot com
    12 years ago
    I was getting unserialize()  Error at offset error.

    If you face similar problem  then use the following procedure

    $auctionDetails = preg_replace('!s:(\d+):"(.*?)";!se', "'s:'.strlen('$2').':\"$2\";'", $dataArr[$i]['auction_details'] );
    $auctionDetails = unserialize($auctionDetails);
    up
    -3
    aderyn at nowhere dot tld
    21 years ago
    A quick note:
    If you store a serialized object in a session, you have to include the class _before_ you initialize (session_start()) the session.
    up
    -3
    Anonymous
    5 years ago
    If serialize() is the answer, you're almost certainly asking the wrong question.

    JSON is widely available. The only thing it does not do, is the very thing that makes serialization immensely dangerous. All it takes is a crafty hacker to pass a crafted payload to a supposedly 'secured' serialize call, for a database driver to be overwritten with malicious code, for example.

    Recreate the object. Normally. With actual data, and a source file, not with serialize. To do otherwise is laziness bordering on malice.
    up
    -6
    MBa
    13 years ago
    To check if a string is serialized:

    $blSerialized=(@unserialize($sText)||$sText=='b:0;');
    up
    -6
    walf
    13 years ago
    a replacement for unserialize that returns whether it worked and populates the unserialized variable by reference:
    <?php
    function funserialize($serialized, &$into) {
        static     $sfalse;
        if (    $sfalse === null)
                $sfalse = serialize(false);
            $into = @unserialize($serialized);
        return     $into !== false || rtrim($serialized) === $sfalse;//whitespace at end of serialized var is ignored by PHP
    }

    $s_foo = 'b:0;';
    var_dump(funserialize($s_foo, $foo), $foo);

    $s_bar = 'bar';
    var_dump(funserialize($s_bar, $bar), $bar);

    $s_foo = 'a:0:{};';
    var_dump(funserialize($s_foo, $foo), $foo);

    ?>
    gives:

    bool(true)
    bool(false)

    bool(false)
    bool(false)

    bool(true)
    array(0) {
    }
    up
    -11
    Fagzal
    14 years ago
    To all who have problem with quoting and slashes when storing serialized data in MySQL: you are probably doing it wrong.

    Use e.g. PDO with placeholders and the blob column type, and it will Just Work.
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