Make ResponseWriter a struct

Make ResponseWriter a struct again so that it can be extended in a
backwards-compatible way.

fs.go

@@ -33,7 +33,7 @@ type fileServer struct {
 	fs.FS
 }
 
-func (fs fileServer) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
+func (fs fileServer) ServeGemini(ctx context.Context, w *ResponseWriter, r *Request) {
 	serveFile(w, r, fs, path.Clean(r.URL.Path), true)
 }
 
@@ -43,11 +43,11 @@ func (fs fileServer) ServeGemini(ctx context.Context, w ResponseWriter, r *Reque
 //
 // ServeContent tries to deduce the type from name's file extension.
 // The name is otherwise unused; it is never sent in the response.
-func ServeContent(w ResponseWriter, r *Request, name string, content io.Reader) {
+func ServeContent(w *ResponseWriter, r *Request, name string, content io.Reader) {
 	serveContent(w, name, content)
 }
 
-func serveContent(w ResponseWriter, name string, content io.Reader) {
+func serveContent(w *ResponseWriter, name string, content io.Reader) {
 	// Detect mimetype from file extension
 	ext := path.Ext(name)
 	mimetype := mime.TypeByExtension(ext)
@@ -75,7 +75,7 @@ func serveContent(w ResponseWriter, name string, content io.Reader) {
 // Outside of those two special cases, ServeFile does not use r.URL.Path for
 // selecting the file or directory to serve; only the file or directory
 // provided in the name argument is used.
-func ServeFile(w ResponseWriter, r *Request, fsys fs.FS, name string) {
+func ServeFile(w *ResponseWriter, r *Request, fsys fs.FS, name string) {
 	if containsDotDot(r.URL.Path) {
 		// Too many programs use r.URL.Path to construct the argument to
 		// serveFile. Reject the request under the assumption that happened
@@ -102,7 +102,7 @@ func containsDotDot(v string) bool {
 
 func isSlashRune(r rune) bool { return r == '/' || r == '\\' }
 
-func serveFile(w ResponseWriter, r *Request, fsys fs.FS, name string, redirect bool) {
+func serveFile(w *ResponseWriter, r *Request, fsys fs.FS, name string, redirect bool) {
 	const indexPage = "/index.gmi"
 
 	// Redirect .../index.gmi to .../
@@ -177,7 +177,7 @@ func serveFile(w ResponseWriter, r *Request, fsys fs.FS, name string, redirect b
 	serveContent(w, name, f)
 }
 
-func dirList(w ResponseWriter, f fs.File) {
+func dirList(w *ResponseWriter, f fs.File) {
 	var entries []fs.DirEntry
 	var err error
 	d, ok := f.(fs.ReadDirFile)

handler.go

@@ -19,23 +19,23 @@ import (
 //
 // Handlers should not modify the provided Request.
 type Handler interface {
-	ServeGemini(context.Context, ResponseWriter, *Request)
+	ServeGemini(context.Context, *ResponseWriter, *Request)
 }
 
 // The HandlerFunc type is an adapter to allow the use of ordinary functions
 // as Gemini handlers. If f is a function with the appropriate signature,
 // HandlerFunc(f) is a Handler that calls f.
-type HandlerFunc func(context.Context, ResponseWriter, *Request)
+type HandlerFunc func(context.Context, *ResponseWriter, *Request)
 
 // ServeGemini calls f(ctx, w, r).
-func (f HandlerFunc) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
+func (f HandlerFunc) ServeGemini(ctx context.Context, w *ResponseWriter, r *Request) {
 	f(ctx, w, r)
 }
 
 // StatusHandler returns a request handler that responds to each request
 // with the provided status code and meta.
 func StatusHandler(status Status, meta string) Handler {
-	return HandlerFunc(func(ctx context.Context, w ResponseWriter, r *Request) {
+	return HandlerFunc(func(ctx context.Context, w *ResponseWriter, r *Request) {
 		w.WriteHeader(status, meta)
 	})
 }
@@ -56,7 +56,7 @@ func StripPrefix(prefix string, h Handler) Handler {
 	if prefix == "" {
 		return h
 	}
-	return HandlerFunc(func(ctx context.Context, w ResponseWriter, r *Request) {
+	return HandlerFunc(func(ctx context.Context, w *ResponseWriter, r *Request) {
 		p := strings.TrimPrefix(r.URL.Path, prefix)
 		rp := strings.TrimPrefix(r.URL.RawPath, prefix)
 		if len(p) < len(r.URL.Path) && (r.URL.RawPath == "" || len(rp) < len(r.URL.RawPath)) {

mux.go

@@ -212,7 +212,7 @@ func (mux *ServeMux) Handler(r *Request) Handler {
 
 // ServeGemini dispatches the request to the handler whose
 // pattern most closely matches the request URL.
-func (mux *ServeMux) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
+func (mux *ServeMux) ServeGemini(ctx context.Context, w *ResponseWriter, r *Request) {
 	h := mux.Handler(r)
 	h.ServeGemini(ctx, w, r)
 }

mux_test.go

@@ -8,7 +8,7 @@ import (
 
 type nopHandler struct{}
 
-func (*nopHandler) ServeGemini(context.Context, ResponseWriter, *Request) {}
+func (*nopHandler) ServeGemini(context.Context, *ResponseWriter, *Request) {}
 
 func TestServeMuxMatch(t *testing.T) {
 	type Match struct {

response.go

@@ -157,44 +157,7 @@ func (r *Response) TLS() *tls.ConnectionState {
 //
 // A ResponseWriter may not be used after the Handler.ServeGemini method
 // has returned.
-type ResponseWriter interface {
+type ResponseWriter struct {
-	// SetMediaType sets the media type that will be sent by Write for a
-	// successful response. If no media type is set, a default of
-	// "text/gemini; charset=utf-8" will be used.
-	//
-	// Setting the media type after a call to Write or WriteHeader has
-	// no effect.
-	SetMediaType(string)
-
-	// Write writes the data to the connection as part of a Gemini response.
-	//
-	// If WriteHeader has not yet been called, Write calls WriteHeader with
-	// StatusSuccess and the media type set in SetMediaType before writing the data.
-	// If no media type was set, Write uses a default media type of
-	// "text/gemini; charset=utf-8".
-	Write([]byte) (int, error)
-
-	// WriteHeader sends a Gemini response header with the provided
-	// status code and meta.
-	//
-	// If WriteHeader is not called explicitly, the first call to Write
-	// will trigger an implicit call to WriteHeader with a successful
-	// status code and the media type set in SetMediaType.
-	//
-	// The provided code must be a valid Gemini status code.
-	// The provided meta must not be longer than 1024 bytes.
-	// Only one header may be written.
-	WriteHeader(status Status, meta string)
-
-	// Flush sends any buffered data to the client.
-	Flush() error
-
-	// Close closes the connection.
-	// Any blocked Read or Write operations will be unblocked and return errors.
-	Close() error
-}
-
-type responseWriter struct {
 	b           *bufio.Writer
 	closer      io.Closer
 	mediatype   string
@@ -203,22 +166,30 @@ type responseWriter struct {
 }
 
 // NewResponseWriter returns a ResponseWriter that uses the provided io.WriteCloser.
-func NewResponseWriter(wc io.WriteCloser) ResponseWriter {
+func NewResponseWriter(wc io.WriteCloser) *ResponseWriter {
-	return newResponseWriter(wc)
+	return &ResponseWriter{
-}
-
-func newResponseWriter(wc io.WriteCloser) *responseWriter {
-	return &responseWriter{
 		b:      bufio.NewWriter(wc),
 		closer: wc,
 	}
 }
 
-func (w *responseWriter) SetMediaType(mediatype string) {
+// SetMediaType sets the media type that will be sent by Write for a
+// successful response. If no media type is set, a default of
+// "text/gemini; charset=utf-8" will be used.
+//
+// Setting the media type after a call to Write or WriteHeader has
+// no effect.
+func (w *ResponseWriter) SetMediaType(mediatype string) {
 	w.mediatype = mediatype
 }
 
-func (w *responseWriter) Write(b []byte) (int, error) {
+// Write writes the data to the connection as part of a Gemini response.
+//
+// If WriteHeader has not yet been called, Write calls WriteHeader with
+// StatusSuccess and the media type set in SetMediaType before writing the data.
+// If no media type was set, Write uses a default media type of
+// "text/gemini; charset=utf-8".
+func (w *ResponseWriter) Write(b []byte) (int, error) {
 	if !w.wroteHeader {
 		meta := w.mediatype
 		if meta == "" {
@@ -233,7 +204,17 @@ func (w *responseWriter) Write(b []byte) (int, error) {
 	return w.b.Write(b)
 }
 
-func (w *responseWriter) WriteHeader(status Status, meta string) {
+// WriteHeader sends a Gemini response header with the provided
+// status code and meta.
+//
+// If WriteHeader is not called explicitly, the first call to Write
+// will trigger an implicit call to WriteHeader with a successful
+// status code and the media type set in SetMediaType.
+//
+// The provided code must be a valid Gemini status code.
+// The provided meta must not be longer than 1024 bytes.
+// Only one header may be written.
+func (w *ResponseWriter) WriteHeader(status Status, meta string) {
 	if w.wroteHeader {
 		return
 	}
@@ -249,7 +230,8 @@ func (w *responseWriter) WriteHeader(status Status, meta string) {
 	w.wroteHeader = true
 }
 
-func (w *responseWriter) Flush() error {
+// Flush sends any buffered data to the client.
+func (w *ResponseWriter) Flush() error {
 	if !w.wroteHeader {
 		w.WriteHeader(StatusTemporaryFailure, "Temporary failure")
 	}
@@ -257,6 +239,8 @@ func (w *responseWriter) Flush() error {
 	return w.b.Flush()
 }
 
-func (w *responseWriter) Close() error {
+// Close closes the connection.
+// Any blocked Write operations will be unblocked and return errors.
+func (w *ResponseWriter) Close() error {
 	return w.closer.Close()
 }

server.go

@@ -359,7 +359,7 @@ func (srv *Server) serveConn(ctx context.Context, conn net.Conn) error {
 		rc:     conn,
 	}
 
-	w := newResponseWriter(cw)
+	w := NewResponseWriter(cw)
 
 	req, err := ReadRequest(r)
 	if err != nil {

timeout.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 package gemini
 
 import (