(PHP 4 >= 4.2.0, PHP 5 <= 5.0.5, PHP 7)
dio_read — Reads bytes from a file descriptor
$fd
   [, int $len = 1024
  ] )
   The function dio_read() reads and returns
   len bytes from file with descriptor
   fd. 
  
fdThe file descriptor returned by dio_open().
lenThe number of bytes to read. If not specified, dio_read() reads 1K sized block.
   The bytes read from fd.