Since you have already loaded CGI.pm ... why not use CGI::upload ... it's a whole lot easier. Here is a short example that you can modify (add error checking, etc.).

#!/usr/bin/perl -T

use strict;
use HTML::Entities;
use CGI qw(:standard);

print header,
   start_multipart_form,
   filefield('file'),
   submit('go'),
   end_form,
;

if (param('go')) {
   my $fh = upload('file');
   print hr, pre( map { encode_entities $_ } <$fh>);
}
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jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)