<?php
  
  define('ERR_SELECT_FAILED', 1);
  define('ERR_TIMEOUT', 2);
  define('ERR_READ_FAILED', 3);
  define('ERR_WRITE_FAILED', 4);
  
  $read = array(STDIN);
  $write = array(STDOUT, STDERR);
  
  stream_set_blocking(STDIN, 0);
  stream_set_blocking(STDOUT, 0);
  stream_set_blocking(STDERR, 0);
  
  $out = $err = '';
  while ($read || $write) {
      $r = $read;
      $w = $write;
      $e = null;
      $n = stream_select($r, $w, $e, 5);
  
      if (false === $n) {
          die(ERR_SELECT_FAILED);
      } elseif ($n < 1) {
          die(ERR_TIMEOUT);
      }
  
      if (in_array(STDOUT, $w) && strlen($out) > 0) {
           $written = fwrite(STDOUT, (binary) $out, 32768);
           if (false === $written) {
               die(ERR_WRITE_FAILED);
           }
           $out = (binary) substr($out, $written);
      }
      if (null === $read && strlen($out) < 1) {
          $write = array_diff($write, array(STDOUT));
      }
  
      if (in_array(STDERR, $w) && strlen($err) > 0) {
           $written = fwrite(STDERR, (binary) $err, 32768);
           if (false === $written) {
               die(ERR_WRITE_FAILED);
           }
           $err = (binary) substr($err, $written);
      }
      if (null === $read && strlen($err) < 1) {
          $write = array_diff($write, array(STDERR));
      }
  
      if ($r) {
          $str = fread(STDIN, 32768);
          if (false !== $str) {
              $out .= $str;
              $err .= $str;
          }
          if (false === $str || feof(STDIN)) {
              $read = null;
              if (!feof(STDIN)) {
                  die(ERR_READ_FAILED);
              }
          }
      }
  }