Allow POSIX platforms only to stop downloads. Windows is another ball of wax, as usual.

download/download.go

@@ -36,6 +36,8 @@ type Download struct {
 
 type Downloads []*Download
 
+var CanStopDownload = false
+
 // StartQueued starts any downloads that have been queued, we would not exceed
 // maxRunning. If maxRunning is 0, there is no limit.
 func (dls Downloads) StartQueued(maxRunning int) {
@@ -99,6 +101,10 @@ func (dl *Download) Queue() {
 }
 
 func (dl *Download) Stop() {
+	if !CanStopDownload {
+		log.Print("attempted to stop download on a platform that it is not currently supported on - please report this as a bug")
+		os.Exit(1)
+	}
 	log.Printf("stopping the download")
 	dl.mutex.Lock()
 	dl.Log = append(dl.Log, "aborted by user")

main.go

@@ -296,7 +296,7 @@ func fetchHandler(w http.ResponseWriter, r *http.Request) {
 					panic(err)
 				}
 
-				templateData := map[string]interface{}{"dl": dl, "config": conf}
+				templateData := map[string]interface{}{"dl": dl, "config": conf, "canStop": download.CanStopDownload}
 
 				err = t.ExecuteTemplate(w, "layout", templateData)
 				if err != nil {
@@ -353,7 +353,7 @@ func fetchHandler(w http.ResponseWriter, r *http.Request) {
 			panic(err)
 		}
 
-		templateData := map[string]interface{}{"dl": newDownload, "config": conf}
+		templateData := map[string]interface{}{"dl": newDownload, "config": conf, "canStop": download.CanStopDownload}
 
 		err = t.ExecuteTemplate(w, "layout", templateData)
 		if err != nil {

web/popup.html

@@ -21,7 +21,9 @@
             
         </table>
         <p>You can close this window and your download will continue. Check the <a href="/" target="_gropple_status">Status page</a> to see all downloads in progress.</p>
+        {{ if .canStop }}
         <button x-show="state=='downloading'" class="pure-button" @click="stop()">stop</button>
+        {{ end }}
         <div>
             <h4>Logs</h4>
             <pre x-text="log">