You already have the filehandle. Just read from the filehandle and write to a file in your UPLOAD_DIR.

# after getting $file_handle

my $file = "some_name"; # pick a name
open F, ">" . UPLOAD_DIR . "$file" or die "$!";
while (<$file_handle>) {
    print F;
}
close F;
close $file_handle;
[download]

/prakash