php-doc-en/reference/igbinary/functions/igbinary-unserialize.xml

<?xml version="1.0" encoding="utf-8"?>
<refentry xml:id="function.igbinary-unserialize" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>igbinary_unserialize</refname>
  <refpurpose>
   Creates a PHP value from a stored representation from <function>igbinary_serialize</function>
  </refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>igbinary_unserialize</methodname>
   <methodparam><type>string</type><parameter>str</parameter></methodparam>
  </methodsynopsis>
  <simpara>
   <function>igbinary_unserialize</function> takes a single serialized variable from
   <function>igbinary_serialize</function> and converts it back into a PHP value.
  </simpara>
  <warning>
   <para>
    Untrusted user input must not be passed to <function>igbinary_unserialize</function>.
    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
    <function>json_decode</function> and <function>json_encode</function>) should be used,
    if serialized data needs to be passed to a client.
   </para>
   <para>
    If there is the need to unserialize externally-stored serialized data,
    <function>hash_hmac</function> can be used for data validation.
    It is important to ensure that nobody has tampered with the data.
   </para>
  </warning>
  <warning>
   <para>
    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.
   </para>
  </warning>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>str</parameter></term>
    <listitem>
     <para>
      The serialized string generated by <function>igbinary_serialize</function>.
     </para>
     <para>
      If the value being unserialized is an &object;, after successfully
      reconstructing the object igbinary will automatically attempt to call the
      <link linkend="object.unserialize">__unserialize()</link> or
      <link linkend="object.wakeup">__wakeup()</link> methods (if one exists).
     </para>
     <para>
      <note>
       <title>unserialize_callback_func directive</title>
       <para>
        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 <type>object</type> <literal>__PHP_Incomplete_Class</literal>.)
        The &php.ini;, <function>ini_set</function> or &htaccess; can be used
        to define <link linkend="ini.unserialize-callback-func">unserialize_callback_func</link>.
        Everytime an undefined class should be instantiated, it will be called.
        To disable this feature this setting should be emptied.
       </para>
      </note>
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   The converted value is returned, and can be a <type>bool</type>,
   <type>int</type>, <type>float</type>, <type>string</type>,
   <type>array</type>, <type>object</type>, or <type>null</type>.
  </para>
  <para>
   In case the passed string is not unserializeable, &false; is returned and
   <constant>E_NOTICE</constant> or <constant>E_WARNING</constant> is issued.
  </para>
 </refsect1>

 <refsect1 role="errors">
  &reftitle.errors;
  <para>
   Objects may throw <classname>Throwable</classname>s in their unserialization handlers.
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <warning>
   <para>
    &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 <parameter>str</parameter> with
    <code>igbinary_serialize(null)</code> or <code>igbinary_serialize(false)</code>
    or by catching the issued <constant>E_NOTICE</constant>.
   </para>
  </warning>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>unserialize</function></member>
    <member><function>json_encode</function></member>
    <member><function>json_decode</function></member>
    <member><function>hash_hmac</function></member>
    <member><function>igbinary_serialize</function></member>
    <member><link linkend="language.oop5.autoload">Autoloading Classes</link></member>
    <member><link linkend="ini.unserialize-callback-func">unserialize_callback_func</link></member>
    <member><link linkend="object.wakeup">__wakeup()</link></member>
    <member><link linkend="object.serialize">__serialize()</link></member>
    <member><link linkend="object.unserialize">__unserialize()</link></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>
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