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

Johannes Ruthenberg tech at johannes-ruthenberg.de
Mon Feb 15 18:10:04 UTC 2010


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:

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: 

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.

Johannes Ruthenberg

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