Fix Type Casting Issue in Jetpack Boost functions-helpers.php

Hello Support Team,

I am experiencing an issue with the Jetpack Boost plugin related to the file functions-helpers.php located in the /app/lib/minify/ directory. The error log displays the following message:

[18-Feb-2025 03:40:26 UTC] PHP Fatal error:  Uncaught TypeError: Unsupported operand types: int - string in /home/***/public_html/wp-content/plugins/jetpack-boost/app/lib/minify/functions-helpers.php:76
Stack trace:
#0 /home/***/public_html/wp-content/plugins/jetpack-boost/app/lib/minify/functions-helpers.php(32): jetpack_boost_delete_expired_files(Array, '/home/mfkvhsiie...')
#1 /home/***/public_html/wp-includes/class-wp-hook.php(324): jetpack_boost_legacy_minify_cache_cleanup('/home/mfkvhsiie...')
#2 /home/***/public_html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array)
#3 /home/***/public_html/wp-includes/plugin.php(565): WP_Hook->do_action(Array)
#4 /home/***/public_html/wp-cron.php(191): do_action_ref_array('jetpack_boost_m...', Array)
#5 {main}
  thrown in /home/***/public_html/wp-content/plugins/jetpack-boost/app/lib/minify/functions-helpers.php on line 76

It appears that the error occurs because there is an attempt to subtract a string from an integer. The original code is as follows:

if ( ( time() - $file_age ) > fileatime( $file ) ) {
    wp_delete_file( $file );
} elseif ( ( time() - ( 2 * $file_age ) ) > filemtime( $file ) ) {
    wp_delete_file( $file );
}

The problem arises because the variable $file_age is not explicitly cast as a numeric value before the arithmetic operation, leading to a type error when its value is not purely numeric.

The proposed fix is to cast $file_age to an integer, ensuring that arithmetic operations are performed on valid numeric values. The corrected code is:

if ( ( time() - (int) $file_age ) > (int) fileatime( $file ) ) {
    wp_delete_file( $file );
} elseif ( ( time() - ( 2 * (int) $file_age ) ) > (int) filemtime( $file ) ) {
    wp_delete_file( $file );
}

I kindly request that you review this change and update the plugin accordingly in the next release to permanently resolve the issue.

Thank you for your attention and support.

Best regards.

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