docker-php-fpm/php_modules/ffi/README.md

ffi

This extension allows the loading of shared libraries (.DLL or .so), calling of C functions and accessing of C data structures in pure PHP, without having to have deep knowledge of the Zend extension API, and without having to learn a third “intermediate” language.

Platform	Url
PHP.net	https://www.php.net/manual/en/book.ffi.php