WP_REST_Attachments_Controller::get_attachment_filesize( int $attachment_id ): int|null

2487	protected function get_attachment_filesize( int $attachment_id ): ?int {2488		$meta = wp_get_attachment_metadata( $attachment_id );2489 2490		if ( isset( $meta['filesize'] ) && is_numeric( $meta['filesize'] ) && $meta['filesize'] > 0 ) {2491			return (int) $meta['filesize'];2492		}2493 2494		$original_path = wp_get_original_image_path( $attachment_id );2495		$attached_file = $original_path ? $original_path : get_attached_file( $attachment_id );2496 2497		if ( is_string( $attached_file ) && is_readable( $attached_file ) ) {2498			return wp_filesize( $attached_file );2499		}2500 2501		return null;2502	}