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Request #36696 __destruct() is called before serialize() when object stored in session
Submitted: 2006-03-11 04:30 UTC Modified: 2013-12-18 00:29 UTC
Votes:2
Avg. Score:2.0 ± 1.0
Reproduced:2 of 2 (100.0%)
Same Version:2 (100.0%)
Same OS:1 (50.0%)
From: iain at iaindooley dot com Assigned: sas (profile)
Status: Closed Package: Scripting Engine problem
PHP Version: * OS: *
Private report: No CVE-ID: None
 [2006-03-11 04:30 UTC] iain at iaindooley dot com
Description:
------------
if an object that impelements Serializable is stored in the session, and implements __destruct, then __destruct is called before serialize() when the script finishes execution.

Reproduce code:
---------------
<?
class SomeClass implements Serializable
{
     function SomeClass()
     {
     }

     public function unserialize($dat)
     {
         echo('called unseriazlize');
     }

     public function serialize()
     {
         echo('called serialize<br />');
     }

     function __destruct()
     {
         echo('called __destruct<br />');
     }
}

session_name('god');
session_start();
$_SESSION['var'] = new SomeClass();

?>


Expected result:
----------------
called serialize
called __destruct

Actual result:
--------------
called __destruct
called serialize

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 [2006-03-13 10:53 UTC] helly@php.net
The solution is easy: close the session before ending your scripts. Otherwise this is a session shutdown issue.

Assigning to primary session maintainer.
 [2006-03-13 11:07 UTC] iain at iaindooley dot com
Just for clarity, i presume you mean using:

session_write_close();

before the scripts conclude.
 [2006-03-13 19:54 UTC] helly@php.net
exactly
 [2006-03-21 15:47 UTC] iliaa@php.net
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

When putting objects into session or serializing them manually put the instantiation result into a variable 1st and then use it.

Ex. $a = new Object();
$_SESSION['obj'] = $a;

Doing so avoids temp var, which gets destroyed right away hence leading to the wrong order of operations.
 [2006-03-21 23:34 UTC] iain at iaindooley dot com
i would say that the fact the order of operations changes for a temp var or an assigned var is a bug.
 [2006-03-22 18:13 UTC] iliaa@php.net
There is nothing wrong with the order here. Temp var gets destroyed as soon as it is created, while session serialization happens at the end of the script.
 [2006-03-23 00:27 UTC] iain at iaindooley dot com
in a garbage collection system, the destructor shouldn't be called on an object until the last reference to it is destroyed. if i do:

$_SESSION['var'] = new Var();

then a reference to that object that was created should be stored in the $_SESSION array, and __destruct() should not be called until the $_SESSION array is destoryed. so clearly the session array must be being destroyed before the objects within it are serialized, which isn't right.
 [2008-06-26 09:38 UTC] margus dot sipria at gmail dot com
duplicate with a bug http://bugs.php.net/bug.php?id=33772
 [2011-02-21 21:29 UTC] jani@php.net
-Package: Feature/Change Request +Package: Session related
 [2013-06-27 22:20 UTC] yohgaki@php.net
-Package: Session related +Package: Scripting Engine problem -PHP Version: 5.1.2 +PHP Version: *
 [2013-06-27 22:20 UTC] yohgaki@php.net
There is exact dup bug report, but I cannot find.
Workaround is call before session_write_close() before shutdown, but __destruct 
should be the last magicmethod to be called, isn't it?
 [2013-08-02 12:25 UTC] info at djdb dot be
/**
 * @param mixed $user
 * @return void
 */
function setsessionuser($user){
	$_SESSION['user']=serialize($user);
}
/**
 * getsessionuser()
 * @return object User
 */ 
function getsessionuser(){
	return(isset($_SESSION['user']))?unserialize($_SESSION['user']):null;
}
class User extends User_data{
test and remake
 [2013-12-18 00:28 UTC] sas@php.net
Hi,

please reopen ticket if this particular issue reoccurs.

Thank you for using PHP.

Best
Sascha
 [2013-12-18 00:29 UTC] sas@php.net
-Status: Assigned +Status: Closed
 
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