(PHP 5 >= 5.1.2, PECL hash >= 1.1)
hash_update_stream — Pump data into an active hashing context from an open stream
Hashing context returned by hash_init().
Open file handle as returned by any stream creation function.
Maximum number of characters to copy from handle into the hashing context.
Actual number of bytes added to the hashing context from handle.
Example #1 hash_update_stream() example
<?php
$fp = tmpfile();
fwrite($fp, 'The quick brown fox jumped over the lazy dog.');
rewind($fp);
$ctx = hash_init('md5');
hash_update_stream($ctx, $fp);
echo hash_final($ctx);
?>
以上例程会输出：
5c6ffbdd40d9556b73a21e63c3e0e904