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Bug #14266 serialize() doesn't work correcty
Submitted: 2001-11-28 08:32 UTC Modified: 2001-11-28 09:06 UTC
From: lenar at vision dot ee Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 4.2.0-dev OS: Debian Linux
Private report: No CVE-ID: None
View Developer Edit
 [2001-11-28 08:32 UTC] lenar at vision dot ee 
Consider following simple script. It's pretty obvious
that serialize() does not work correctly (at least not as 
expected).

<?php
  $x = new stdClass();
  $x->x =& $x;
  $s = serialize($x) . "\n";

  echo "test on original: "; // OK
  $x->a = "str";
  echo $x->x->a . "\n";
  $o = unserialize($s);

  echo "test on unserialized object: "; // not OK
  $o->a = "str";
  echo $o->x->a . "\n"; 
?>

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 [2001-11-28 08:38 UTC] jmoore@php.net 
Circualar reference here:

$x->x =& $x;
  

These dont work as expected at all.

Bogus bug report as the lang isnt designed to support this.

- James
 [2001-11-28 08:38 UTC] lenar at vision dot ee 
Tested this with current cvs too. No better luck.
Original and unserialized objects have different 
representation in memory.
 [2001-11-28 08:41 UTC] jmoore@php.net 
Your creating a reference to itself this is not allowed.

Therefore the bug is bogus, the behaviour is undefined.

- James
 [2001-11-28 08:43 UTC] lenar at vision dot ee 
I dont' agree. Circular refferences can happen with 
objects (using refferences). Sometimes they are 
intentional. And serialize() doesn't completely ignore 
this. Because it spits out:
O:8:"stdClass":1:{s:1:"x";O:8:"stdClass":1:{s:1:"x";R:2;}}

so it knows about circular refferences.

Now is there any reason why it doesn't generate instead 
something like this:

O:8:"stdClass":1:{s:1:"x";R:1;}

I would understand if it completely ignores circular 
references, but it doesn't. It just misbehaves.
 [2001-11-28 08:59 UTC] zimt@php.net 
Behaviour of Circular / Selfreferencing objects is not defined. 

you could try to do a workarround 
by using defining __sleep() and __wakeup()
in your class, which are called when the object is serialized / unserialized, and could unset those self-references.

but you realy should do those.. if you dont destroy all of those references, you will get memory leaks!

regards, Peter Petermann
 [2001-11-28 09:01 UTC] zimt@php.net 
sorry, i wanted to write:
you realy should *NOT*...
 [2001-11-28 09:06 UTC] lenar at vision dot ee 
Ok, I tested a little bit more
and found that when calling serialize() like serialize(&$x)
it works.
I know about leaks, but those leaks don't kill me (yet).

And btw. Circular references work as expected. There is 
nothing so "undefined" about them in php. They work quite 
logically.
 
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