0004620: Quercus passes 'by value object' as 'reference'

Viewing Issue Simple Details [ Jump to Notes ]

[ View Advanced ] [ Issue History ] [ Print ]

Category

Severity

Reproducibility

Date Submitted

Last Update

0004620

[Quercus]

minor

always

06-16-11 08:56

03-12-13 12:22

Reporter

thr

View Status

public

Assigned To

nam

Priority

normal

Resolution

unable to reproduce

Status

closed

Product Version

4.0.14

Summary

0004620: Quercus passes 'by value object' as 'reference'

Description

Setting up Wordpress 3.1.3 on Quercus after making some quirks to get it run (Issue 0004568 and Issue 0004612) I get it working. Only if I signed in as admin and Under the menu Item where all articels are listed, I found a difference to a 'normal' php wordpress installation. All the links below the artikel list, which will allow you to edit, delete, etc, the articels, all my links where gone, like I do not have permission to edit.

Investigating the problem I found that Wordpress is using a function called 'wp_list_pluck' to reduce a big array of article-type definitions to a single value.

Thru some calls Wordpress passed the object $wp_post_types to this function.
This function then returns one field out of this object.
As this list is assigning a new value to one of the function parameters and returning it to the callee, I found after thre calls the original $wp_post_types was modfied/damaged.
As php is passing the object by value, this should not be possible. Under some circumstances Quercus seems to pass this object as reference.

To fix this, I changed the funtion in Wordpress to use a new variable to return the result instead of the function parameter.

Unfortunately I could not simulate the behaviour in a simple test script. But anyway I might want to have a look to understand the principle problem ...
but there must be happening more in wordpress to cause this .....

Additional Information

/**
* Pluck a certain field out of each object in a list
*
* @since 3.1.0
*
* @param array $list A list of objects or arrays
* @param int|string $field A field from the object to place instead of the entire object
* @return array
*/
function wp_list_pluck( $list, $field ) {
    foreach ( $list as $key => $value ) {
        $value = (array) $value;
        $list[ $key ] = $value[ $field ];
    }

    return $list;
}

CHANEGED To:

function wp_list_pluck( $list, $field ) {
    foreach ( $list as $key => $value ) {
        $value = (array) $value;
        $new_list[ $key ] = $value[ $field ];
    }

    return $new_list;
}

Attached Files

test_array_ref.php [^] (11,500 bytes) 06-16-11 08:56

Relationships

Notes
(0005684) krystian 01-30-12 11:35	I can also confirm it is still the case in Resin 4.0.24

(0006130) nam 12-30-12 00:13	Unable to reproduce in 4.0.33. Tried wordpress-3.1.3, wordpress-3.5, and your attached script. We did fix a few value-vs-reference issues starting over the course of the last 6 months.

Issue History
Date Modified	Username	Field	Change
06-16-11 08:56	thr	New Issue
06-16-11 08:56	thr	File Added: test_array_ref.php
06-18-11 06:02	kdecherf	Issue Monitored: kdecherf
01-30-12 11:35	krystian	Note Added: 0005684
12-30-12 00:13	nam	Note Added: 0006130
03-12-13 12:22	nam	Status	new => assigned
03-12-13 12:22	nam	Assigned To	=> nam
03-12-13 12:22	nam	Status	assigned => closed
03-12-13 12:22	nam	Resolution	open => unable to reproduce

Mantis 1.0.0rc3[^]

35 total queries executed.
29 unique queries executed.