Use compiled in assets for those not in STGUIASSETS dir

cmd/syncthing/gui.go

@@ -15,6 +15,7 @@ import (
 	"mime"
 	"net"
 	"net/http"
+	"os"
 	"path/filepath"
 	"reflect"
 	"runtime"
@@ -128,11 +129,7 @@ func startGUI(cfg config.GUIConfiguration, assetDir string, m *model.Model) erro
 	mux.HandleFunc("/qr/", getQR)
 
 	// Serve compiled in assets unless an asset directory was set (for development)
-	if len(assetDir) > 0 {
+	mux.Handle("/", embeddedStatic(assetDir))
-		mux.Handle("/", http.FileServer(http.Dir(assetDir)))
-	} else {
-		mux.HandleFunc("/", embeddedStatic)
-	}
 
 	// Wrap everything in CSRF protection. The /rest prefix should be
 	// protected, other requests will grant cookies.
@@ -536,7 +533,8 @@ func validAPIKey(k string) bool {
 	return len(apiKey) > 0 && k == apiKey
 }
 
-func embeddedStatic(w http.ResponseWriter, r *http.Request) {
+func embeddedStatic(assetDir string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		file := r.URL.Path
 
 		if file[0] == '/' {
@@ -547,8 +545,18 @@ func embeddedStatic(w http.ResponseWriter, r *http.Request) {
 			file = "index.html"
 		}
 
+		if assetDir != "" {
+			p := filepath.Join(assetDir, filepath.FromSlash(file))
+			_, err := os.Stat(p)
+			if err == nil {
+				http.ServeFile(w, r, p)
+				return
+			}
+		}
+
 		bs, ok := auto.Assets[file]
 		if !ok {
+			http.NotFound(w, r)
 			return
 		}
 
@@ -560,4 +568,5 @@ func embeddedStatic(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Last-Modified", modt)
 
 		w.Write(bs)
+	})
 }