So--why not designate a portion of their computers for the children to use, and the rest as adult only. Seems pretty uncomplicated to me.
Here's a novel thoguht. Why not let the people who built the libraries decide wheter or not they want to filter out pornography. The Federal snotbox under the States tent again and again.
Now couple this ruling with the last beauty which made virtual child pornography protected speech and guess what becomes available in every library in the country including your childrens?