Disable Attachment Pages on WordPress

<?php
add_action('template_redirect', function () {
    global $post;

    if (
        !is_attachment() ||
        !isset($post->post_parent) ||
        !is_numeric($post->post_parent)
    ) {
        return;
    }

    // Does the attachment have a parent post?
    // If the post is trashed, fallback to redirect to homepage.
    if (
        $post->post_parent !== 0 &&
        get_post_status($post->post_parent) !== 'trash'
    ) {
        // Redirect to the attachment parent
        wp_safe_redirect(get_permalink($post->post_parent), 301);
    } else {
        // For attachment without a parent redirect to homepage
        wp_safe_redirect(get_bloginfo('wpurl'), 302);
    }

    exit;
}, 1);