Since you seem to be running Windows you might ask the system what is the content type according to it:

use Win32::Registry;
use strict;

{
my %cache;
sub GetContentType {
    my $ext = shift(); # well it's a filename at this point
    for ($ext) {
        s/^.*\.//; # now we extract the extension
        $_ = lc $_;
    }
    return $cache{$ext} if exists $cache{$ext};

    my $key;
    $HKCR->Open('.'.$ext, $key)
        or return;
    my ($type, $value);
    $key->QueryValueEx('Content Type', $type, $value)
        or return;
    $cache{$ext} = $value;
    return $value;
}
}

print "Foo.exe: " . GetContentType('Foo.exe') . "\n";
print "Foo.gif: " . GetContentType('Foo.gif') . "\n";
print "bar.exe: " . GetContentType('bar.exe') . "\n";
[download]

(If the code doesn't work for you it might be because I tested it with Win32::Registry2 installed.)

Jenda
Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.
   -- Rick Osborne

Edit by castaway: Closed small tag in signature