On a lark I took a quick trip out to CPAN - here's my suggestion written down as probably-useable code (meaning I didn't test it). It installs a filter on the STDOUT filehandle before script execution so no tainted data is allowed to print. Obviously if you start handling user-input prior to this INIT block then that isn't covered but you shouldn't do that anyway.
This can be enhanced by using an exception
package Filter::Handle::Tainted;
# Put this code into the package just to have a reasonable
# place to live.
use Filter::Handle qw(subs);
use Taint qw(tainted);
use Exception::Class qw(Filter::Handle::Tainted::TaintException);
INIT {
Filter
\ *STDOUT,
sub {
for (@_) {
next unless tainted( $_ );
# Tainted data was about to be printed to
# the handle. Throw an exception instead.
Filter::Handle::Tainted::TaintException
-> throw( error =>
"Tainted data may not be written to this
+io handle." );
}
};
}
Fun Fun Fun in the Fluffy Chair