wp-admin/includes/class-wp-site-health-auto-updates.php:317Checks if core files are writable by the web user/group.
array|false public function test_all_files_writable() { global $wp_filesystem; require ABSPATH . WPINC . '/version.php'; // $wp_version; // x.y.z $skin = new Automatic_Upgrader_Skin(); $success = $skin->request_filesystem_credentials( false, ABSPATH ); if ( ! $success ) { return false; } WP_Filesystem(); if ( 'direct' !== $wp_filesystem->method ) { return false; } // Make sure the `get_core_checksums()` function is available during our REST API call. if ( ! function_exists( 'get_core_checksums' ) ) { require_once ABSPATH . 'wp-admin/includes/update.php'; } $checksums = get_core_checksums( $wp_version, 'en_US' ); $dev = ( str_contains( $wp_version, '-' ) ); // Get the last stable version's files and test against that. if ( ! $checksums && $dev ) { $checksums = get_core_checksums( (float) $wp_version - 0.1, 'en_US' ); } // There aren't always checksums for development releases, so just skip the test if we still can't find any. if ( ! $checksums && $dev ) { return false; } if ( ! $checksums ) { $description = sprintf( /* translators: %s: WordPress version. */ __( "Couldn't retrieve a list of the checksums for WordPress %s." ), $wp_version ); $description .= ' ' . __( 'This could mean that connections are failing to WordPress.org.' ); return array( 'description' => $description, 'severity' => 'warning', ); } $unwritable_files = array(); foreach ( array_keys( $checksums ) as $file ) { if ( str_starts_with( $file, 'wp-content' ) ) { continue; } if ( ! file_exists( ABSPATH . $file ) ) { continue; } if ( ! is_writable( ABSPATH . $file ) ) { $unwritable_files[] = $file; } } if ( $unwritable_files ) { if ( count( $unwritable_files ) > 20 ) { $unwritable_files = array_slice( $unwritable_files, 0, 20 ); $unwritable_files[] = '...'; } return array( 'description' => __( 'Some files are not writable by WordPress:' ) . ' <ul><li>' . implode( '</li><li>', $unwritable_files ) . '</li></ul>', 'severity' => 'fail', ); } else { return array( 'description' => __( 'All of your WordPress files are writable.' ), 'severity' => 'pass', ); } }Introduced in 5.2.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-site-health-auto-updates.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.