fopen and getting system file descriptor

Question

I want to get a system file descriptor of the returned resource when I open a file using open. I assume the descriptor is an INT value which is normally inside /dev/fd/

I know that I can read from the descriptor by doing something like:

fread("php://fd/$descriptor", $buflen);

But now I want to get the descriptor for a resource opened by PHP's fopen(). Is there a way?

Answer 1

This is a rather hacky way around it but it works!

function fd($realpath) {
  $dir = '/proc/self/fd/';
  if ($dh = opendir($dir)) {
      while (($file = readdir($dh)) !== false) {
          $filename = $dir . $file;
          if (filetype($filename) == 'link' && realpath($filename) == $realpath) {
            closedir($dh);
            return $file;
          }
      }
      closedir($dh);
  }
  return FALSE;
}

Answer 2

Because you're writing a fuse wrapper, consider not duplicating the effort of this PECL extension. Of course, it also doesn't have any freaking documentation, so this is a stab in the dark at best.