Add a file existence check in class-wp-theme-json-resolver to avoid…

[pbearne]

… potential errors.

Trac ticket: https://core.trac.wordpress.org/ticket/64620

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[westonruter]

@pbearne It's still not clear how to reproduce this issue. I wonder if wrapping the code in an is_readable() will just make it harder to debug. Should there be an else statement to say the expected file is missing? Again, having a way to reproduce this would be helpful, and thus could be added as a test.

[pbearne]

@westonruter what would you like in the else
an error
an empty array is already returned as default

[Copilot]

Pull request overview

This PR adjusts WP_Theme_JSON_Resolver::read_json_file() to avoid calling wp_json_file_decode() when the passed path is not readable, preventing avoidable errors/warnings when theme.json (or similar JSON files) are missing or inaccessible.

Changes:

• Add a readability check before decoding JSON files in WP_Theme_JSON_Resolver::read_json_file().
• Preserve existing caching behavior for successfully decoded theme.json-shaped arrays.

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[pbearne]

fixed

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

src/wp-includes/class-wp-theme-json-resolver.php:114

• is_readable() is true for directories, which would still allow wp_json_file_decode() to run. That function calls json_decode( file_get_contents( $filename ) ...); if file_get_contents() returns false (e.g., path is a directory), PHP 8+ can throw a TypeError because json_decode() requires a string. Consider requiring a regular file as well as readability before decoding.

			if ( is_readable( $file_path ) ) {
				$decoded_file = wp_json_file_decode( $file_path, array( 'associative' => true ) );
				if ( is_array( $decoded_file ) ) {
					static::$theme_json_file_cache[ $file_path ] = $decoded_file;
					return static::$theme_json_file_cache[ $file_path ];
				}

[pbearne]

fix

[t-hamano]

@pbearne Can you address the feedback from Copilot? Both seem like reasonable points to me.

[pbearne]

@t-hamano fixed
But it has an error suppression warning
Not sure how to fix it other than removing the @

[mukeshpanchal27]

Thanks for working on this. The guard stops the PHP warning, but I have a concern about where the check lives and what it hides.

How I reproduced the original warning on trunk

get_style_variations() is the only caller of read_json_file() that does not check is_readable() first. The other callers check it at lines 256, 310 and 725. So the trigger is a file in a theme's styles/ folder that exists but cannot be read:

cd wp-content/themes/twentytwentyfive/styles
echo '{"version":3,"title":"Broken"}' > broken.json
chmod 000 broken.json
# or: mkdir fake.json

With WP_DEBUG on, open Appearance > Editor > Styles. Trunk logs file_get_contents(...): Failed to open stream: Permission denied and then a JSON decode notice. A directory named fake.json gives errno=21 Is a directory. With this PR, nothing is logged and the variation disappears from the list.

Smaller points

• The new check repeats the is_readable() check that three of the four callers already do. This adds extra stat calls on those paths.
• Failed reads are not cached. A broken file is checked and decoded again on every call to get_style_variations() in the same request.

Note: Claude fine this.

[mukeshpanchal27]

This check returns array() without any message. Before this change, wp_json_file_decode() reported the problem through wp_trigger_error(). Now a theme author with a broken or unreadable variation file gets no hint on a WP_DEBUG site.

I think the fix belongs inside wp_json_file_decode() instead. That function has two related bugs that other callers also hit, such as block.json registration:

1. It overwrites $filename with wp_normalize_path( realpath( $filename ) ). realpath() returns false for a missing file, so the notice prints an empty path: File doesn't exist!. You can see this with wp_json_file_decode( '/does/not/exist.json' );.
2. It calls file_get_contents() without checking is_file() and is_readable(). An unreadable file or a directory raises a PHP warning.

A check there, with a wp_trigger_error() call that keeps the original path, would fix every caller and keep the diagnostic.

[mukeshpanchal27]

This one method covers six scenarios. The first failing assertion hides the rest. Could you split it into separate test methods or use a data provider?

The unreadable-file case also skips itself without telling PHPUnit. On Windows, without the posix extension, or when tests run as root, it reports a pass for code it never ran. $this->markTestSkipped() in its own method would show this.

[mukeshpanchal27]

If the assertion below fails, chmod() and unlink() never run. A file with mode 0000 then stays in the system temp folder. The invalid-JSON temp file has the same problem. Moving cleanup into tear_down() or a try/finally block would fix this.

[mukeshpanchal27]

The @ hides the decode notice instead of checking that it fires. If the error reporting broke later, this test would still pass. Could you assert the notice with expectNotice() or the wp_trigger_error_run action? A matching assertion for the missing and unreadable cases would also cover the behavior change in the resolver.