[Boost-users] multichar_input_filter, what I'm doing wrong?

I'm implementing a base64 decoder using multichar_input_filter, it works well but it doesn't seems to stop, after the last char of the testcase string (which is reads from file), it continues to read, I must be missing something, here is the code: http://codepad.org/YvKREpKS the convert funcion does the actual convert and I don't think it is relevant to the code but if someone thinks it is, I'll include it. I'm banging my head against the wall for a couple of days in this issue... thanks.