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Opened 7 months ago

Closed 5 months ago

Last modified 5 months ago

#52814 closed defect (bug) (fixed)

Avoid notices in `get_post_comments_feed_link()`

Reported by: dd32 Owned by: SergeyBiryukov
Milestone: 5.8 Priority: low
Severity: trivial Version:
Component: Feeds Keywords: has-patch has-unit-tests has-testing-info commit
Focuses: Cc:

Description

When an atom feed request is made to a non-existent page, get_post_comments_feed_link() produces PHP Notices such as the following:

E_NOTICE: Trying to get property 'post_type' of non-object in wp-includes/link-template.php:752

Example of a URLs which can trigger this is:

OPTIONS /2021/01/feed/atom/atom/
GET /404-page/feed/atom/

(Options bypasses the canonical redirect, and outputs a post-comments feed for the page "2021/01/feed/atom")

While the code path that results in this function being called without a valid post is unexpected and the resulting url generated in the atom feed is invalid, it silences these notices, which is good for sites that log/monitor these things (Such as WordPress.org)

Attachments (2)

52814.diff (1.8 KB) - added by dd32 7 months ago.
testing-52814.gif (836.4 KB) - added by hellofromTonya 5 months ago.
Testing before and after applying the patch. Before: Warning in PHP 8. After: No notice or warning.

Download all attachments as: .zip

Change History (12)

@dd32
7 months ago

#1 @dd32
7 months ago

  • Keywords has-patch added

#2 @SergeyBiryukov
7 months ago

  • Milestone changed from Awaiting Review to 5.8
  • Owner set to SergeyBiryukov
  • Status changed from new to reviewing

#3 @mukesh27
7 months ago

  • Keywords needs-refresh added

Hi there!

I checked the 52814.diff and found one doc block change.

* @return string|false The permalink for the comments feed for the given post.

Replace to

* @return string|false The permalink for the comments feed for the given post. False if the post does not exist.

This ticket was mentioned in PR #1354 on WordPress/wordpress-develop by hellofromtonya.


5 months ago

  • Keywords has-unit-tests added; needs-refresh removed

Trac ticket: https://core.trac.wordpress.org/ticket/52814

  • Adds unit test
  • Applies 52814.diff props to @dd32
  • Replaces implicit loose comparison in guard clause to bail out if not an instance of WP_Post. Why? WP_Post is the expected data type _if_ the post exists.

@hellofromTonya
5 months ago

Testing before and after applying the patch. Before: Warning in PHP 8. After: No notice or warning.

#5 @hellofromTonya
5 months ago

  • Keywords has-testing-info added

Testing Instructions

Setup:

Create a must-use file in wp-content/mu-plugins/test.php and paste this code into the file:

<?php

add_action( 'loop_start', function() {
    if ( is_admin() ) {
        return;
    }

    $post_id = PHP_INT_MAX;
    $link    = get_post_comments_feed_link( $post_id );
} );

Test

  • Load the home page
  • In less than PHP 8, a notice is generated. In PHP 8, a warning is generated like this one:
[08-Jun-2021 20:51:04 UTC] PHP Warning:  Attempt to read property "post_type" on null in /[path to your project]/wp-includes/link-template.php on line 752
[08-Jun-2021 20:51:04 UTC] PHP Stack trace:
[08-Jun-2021 20:51:04 UTC] PHP   1. {main}() /[path to your project]/index.php:0
[08-Jun-2021 20:51:04 UTC] PHP   2. require() /[path to your project]/index.php:17
[08-Jun-2021 20:51:04 UTC] PHP   3. require_once() /U[path to your project]/wp-blog-header.php:19
[08-Jun-2021 20:51:04 UTC] PHP   4. include() /[path to your project]/wp-includes/template-loader.php:106
[08-Jun-2021 20:51:04 UTC] PHP   5. the_post() /[path to your project]/wp-content/themes/twentytwenty/index.php:88
[08-Jun-2021 20:51:04 UTC] PHP   6. WP_Query->the_post() /[path to your project]/wp-includes/query.php:975
[08-Jun-2021 20:51:04 UTC] PHP   7. do_action_ref_array() /[path to your project]/wp-includes/class-wp-query.php:3326
[08-Jun-2021 20:51:04 UTC] PHP   8. WP_Hook->do_action() /[path to your project]/wp-includes/plugin.php:518
[08-Jun-2021 20:51:04 UTC] PHP   9. WP_Hook->apply_filters() /[path to your project]/wp-includes/class-wp-hook.php:327
[08-Jun-2021 20:51:04 UTC] PHP  10. {closure:/[path to your project]/wp-content/mu-plugins/test.php:3-10}() /[path to your project]/wp-includes/class-wp-hook.php:303
[08-Jun-2021 20:51:04 UTC] PHP  11. get_post_comments_feed_link() /[path to your project]/wp-content/mu-plugins/test.php:9
  • Apply the PR
  • Retest => Result: Page should render and no warning/notice generated

#6 @hellofromTonya
5 months ago

  • Keywords commit added

Marking for commit.

A few enhancements to Dion's patch:

  • Unit test added
  • Checks for the instance of WP_Post which is the expected data type if the post exists
  • Retains the return signature of string data type for backwards compatibility, documentation, etc by returning an empty string if the post does not exist

This ticket was mentioned in Slack in #core by hellofromtonya. View the logs.


5 months ago

This ticket was mentioned in Slack in #core by hellofromtonya. View the logs.


5 months ago

#9 @antpb
5 months ago

  • Resolution set to fixed
  • Status changed from reviewing to closed

In 51121:

Feeds: Avoid notices in get_post_comments_feed_link().

When an feed request is made to a non-existent page, surpress the notice.

Props dd32, SergeyBiryukov, mukesh27, hellofromTonya.
Fixes #52814.

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