Fix some more races

download/download.go

@@ -1,6 +1,7 @@
 package download
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"log"
@@ -61,6 +62,18 @@ func (m *Manager) ManageQueue() {
 	}
 }
 
+func (m *Manager) DownloadsAsJSON() ([]byte, error) {
+
+	m.Lock.Lock()
+	defer m.Lock.Unlock()
+	for _, dl := range m.Downloads {
+		dl.Lock.Lock()
+		defer dl.Lock.Unlock()
+	}
+	b, err := json.Marshal(m.Downloads)
+	return b, err
+}
+
 // startQueued starts any downloads that have been queued, we would not exceed
 // maxRunning. If maxRunning is 0, there is no limit.
 func (m *Manager) startQueued(maxRunning int) {

main.go

@@ -327,7 +327,11 @@ func fetchInfoOneRESTHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// just a get, return the object
+		thisDownload.Lock.Lock()
+		defer thisDownload.Lock.Unlock()
+
 		b, _ := json.Marshal(thisDownload)
+
 		w.Write(b)
 		return
 	} else {
@@ -337,9 +341,10 @@ func fetchInfoOneRESTHandler(w http.ResponseWriter, r *http.Request) {
 
 func fetchInfoRESTHandler(w http.ResponseWriter, r *http.Request) {
 
-	dm.Lock.Lock()
+	b, err := dm.DownloadsAsJSON()
-	defer dm.Lock.Unlock()
+	if err != nil {
-	b, _ := json.Marshal(dm.Downloads)
+		panic(err)
+	}
 	w.Write(b)
 }