Hex to Base64

#!/usr/bin/php
<?php

/*
 * IN: Base64 encoded string
 * OUT: ACSII HEX
 */

$in='';
while (!feof(STDIN))
{
    $res = fread(STDIN, 1024);
    if (false === $res)
    {
    	fwrite(STDERR, "error reading from stdin");
	    exit(3);
	}
    $in .= $res;
}
$result=hex2bin($in);
if (false===$result)
{
	fwrite(STDERR, "hex2bin failed");
	exit(3);
}

$result=base64_encode($result);

fwrite(STDOUT, $result);

exit(0);