(PHP 5 >= 5.1.2, PECL hash >= 1.1)
hash_update_file — Pump data into an active hashing context from a file
$hcontext
   , string $filename
   [, resource $scontext = NULL
  ] )
hcontext
     Hashing context returned by hash_init().
filename
     URL describing location of file to be hashed; Supports fopen wrappers.
scontext
     Stream context as returned by stream_context_create().
   Returns TRUE on success or FALSE on failure.