Convert io.ReadCloser into io.Reader in Go

I am using the archive/zip library and I need to make a modification to a file inside a zip archive on the fly before I upload it to s3. Currently I am getting back an io.ReadCloser but the function I am using to modify the user requires an io.Reader:

//Function Signature:
Convert(r io.Reader, w io.Writer, ...)

I also need an io.Writer... Bonus points if you can help me determine how to create a writer as well. Here is some example code that may give some context:

for _, f := range r.File {
    if filepath.Ext(f.Name) != ".txt" {

      _, filename := path.Split(f.Name)
      var rc io.ReadCloser
      if rc, err = f.Open(); err == nil {

        // FIXME: Convert
        if err = Convert(rc.Reader, *zip.Writer.Create(f.Name), ...); err != nil {
          errStr := fmt.Sprintf("Unable to convert")
          log.Println(errStr)

        } else {

          log.Println("Success!")

        }

        // Upload to s3
        .....
      }   
    }   
  }

Solution

To convert an io.ReadCloser to an io.Reader you do:

NOTHING!

An io.ReadCloser is already an io.Reader by virtue of the fact that all methods of the io.Reader interface (specifically a Read(p []byte) (n int, err error) method) are also provided by io.ReadCloser.
Converting an io.Reader into an io.Writer is an entirely different matter. You can't really do that in any general way. You'll need to elaborate on what you're trying to do.

Convert io.ReadCloser into io.Reader in Go

NOTHING!