Like io.MultiReader, but using a channel (unknown number of input readers)

channelreader.go

package main

import "io"

type channelReader struct {
	c chan []byte
	b []byte
}

func NewChannelReader(c chan []byte) io.Reader {
	return &channelReader{c: c}
}

func (r *channelReader) Read(p []byte) (n int, err error) {
	// drain buffer
	if len(r.b) > 0 {
		n = copy(p, r.b)
		r.b = r.b[n:]
		return
	}

	// get next from channel
	var ok bool
	if r.b, ok = <-r.c; !ok {
		err = io.EOF
		return
	}
	return r.Read(p)
}