A Complete PHP/FFI/preloading Example

php.ini

ffi.enable=preload
opcache.preload=preload.php

preload.php

<?phpFFI::load(__DIR__ . "/dummy.h");opcache_compile_file(__DIR__ . "/dummy.php");?>

dummy.h

#define FFI_SCOPE "DUMMY"
#define FFI_LIB "libc.so.6"
 
int printf(const char *format, ...);

dummy.php

<?phpfinal class Dummy {    private static $ffi = null;    function __construct() {        if (is_null(self::$ffi)) {            self::$ffi = FFI::scope("DUMMY");        }    }    function printf($format, ...$args) {       return (int)self::$ffi->printf($format, ...$args);    }}?>

test.php

<?php$d = new Dummy();$d->printf("Hello %s!\n", "world");?>