HTTP_Spew::Headers

converts a Rack env into an HTTP header buffer If input is a string, this appends input to the header buffer so the client can avoid extra writes. If input is an IO-like object, it is returned as the second element of an array.

This, the following code always works and may be used to clobber input if it is merged into buf

buf, input = env_to_headers(env, input)

regenerates the request_uri from a Rack env