test.php

<?php

$headerName = 'stdio.h';
$libName = 'libc.so';

try {
    $libc = FFI::load($headerName);
    var_dump($libc);
} catch(FFI\Exception $e)
{
    fprintf(STDERR, '%s on line %s%s', $e->getMessage(),$e->getLine(), PHP_EOL);
    $headerContent = sprintf('#define FFI_LIB "%s"%s', $libName, PHP_EOL);
    $headerContent .= sprintf('#define FFI_SCOPE "_%s"%s', strtoupper($libName), PHP_EOL);

    if(file_put_contents($headerName, $headerContent)) {
        echo exec(sprintf('cpp -P -C -D"__attribute__(ARGS)="$(find $PREFIX -type f -name %s)>>%s', $headerName, $headerName));
    }
}