[wp-hackers] possible small bug in widgets.php

[Casey Bisson]

I remember getting this error on a dev server. After a lot of poking around,
I ascribed it to a PHP bug.

The server running MacOS X 10.4 and Marc Liyanage's PHP package. I no longer
remember which version of PHP that was at the time, but the problem was
unique to that environment.

On Tue, Feb 16, 2010 at 9:08 AM, Aaron D. Campbell <aaron at xavisys.com>wrote:

> Or an array like array($someObject, 'someMethod') which still doesn't seem
> like it would have the recursion issue.
>
> Otto wrote:
>
>> Callback shouldn't be an object. It should be a function name.
>> Basically, a string.
>>
>> -Otto
>>
>>
>>
>> On Mon, Feb 15, 2010 at 12:10 PM, Johannes Ruthenberg
>> <tech at johannes-ruthenberg.de> wrote:
>>
>>
>>> Hi!
>>>
>>> There's a possible bug in wp-includes/widgets.php. Since I don't really
>>> understand all the details I wanted to ask here what everyone else thinks
>>> before opening a trac ticket.
>>>
>>> The bug was found in this discussion on the German WordPress forum:
>>>
>>> http://forum.wordpress-deutschland.org/konfiguration/62484-error-bei-den-widgets.html
>>>
>>> A user got a PHP error when opening the backend widgets page: "Nesting
>>> level
>>> too deep – recursive dependency" The error originates in widgets.php, in
>>> function is_active_widget, what is now line 924.
>>>
>>> Apparently, you get this message in newer PHP versions (5.2+) when PHP
>>> compares two objects with == instead ob ===. It compares all properties
>>> of
>>> the objects, which can lead to a loop if the objects have circular
>>> dependencies. Details for example here:
>>>
>>> http://www.richardlord.net/blog/php-nesting-level-too-deep-recursive-dependency
>>>
>>> So, line 924 looks like this:
>>>
>>> if ( ( $callback && isset($wp_registered_widgets[$widget]['callback']) &&
>>> $wp_registered_widgets[$widget]['callback'] == $callback ) || ( $id_base
>>> &&
>>> _get_widget_id_base($widget) == $id_base ) ) {
>>>
>>> The second comparison should be harmless, that would always be a String.
>>> But
>>> I'm not really sure what's inside
>>> $wp_registered_widgets[$widget]['callback']. It seems to be an object
>>> which
>>> can cause this problem, at least with some widgets. The poster in above
>>> mentioned thread changed both comparisons to === and the PHP error
>>> vanished.
>>> Of course, he doesn't want to change this with every WP upgrade, so I
>>> promised to bring this to attention. ;-)
>>>
>>> So, do you think I should just open a trac ticket for this? Could the
>>> stricter comparison have possible side effects? As I said, I'm not quite
>>> sure what's actually compared there.
>>>
>>> Regards,
>>> Johannes Ruthenberg
>>>
>>>
>>
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