corrected archivefs Set() function so that it works in Windows

Windows volume names confused the Set() function

archivefs.Async no longer exits async goroutine on errors from Path
functions. exiting meant that the channels were no longer being
serviced, causing GUI deadlocks

archivefs/async.go

@@ -68,12 +68,16 @@ func NewAsyncPath(setter FilenameSetter) AsyncPath {
 				afs.Close()
 
 			case path := <-pth.Set:
-				afs.Set(path)
+				err := afs.Set(path)
+				if err != nil {
+					pth.err <- err
+					continue // for loop
+				}
 
 				entries, err := afs.List()
 				if err != nil {
 					pth.err <- err
-					return
+					continue // for loop
 				}
 
 				pth.results <- AsyncResults{

archivefs/path.go

@@ -223,8 +223,12 @@ func (afs *Path) List() ([]Node, error) {
 func (afs *Path) Set(path string) error {
 	afs.Close()
 
-	// clean path and split into parts
+	// clean path and and remove volume name. volume name is not something we
+	// typically have to worry about in unix type systems
 	path = filepath.Clean(path)
+	path = strings.TrimPrefix(path, filepath.VolumeName(path))
+
+	// split path into parts
 	lst := strings.Split(path, string(filepath.Separator))
 
 	// strings.Split will remove a leading filepath.Separator. we need to add
@@ -284,6 +288,14 @@ func (afs *Path) Set(path string) error {
 		}
 	}
 
+	// we want the absolute path. this restores any volume name that may have
+	// been trimmed off at the start of the function
+	var err error
+	afs.current, err = filepath.Abs(path)
+	if err != nil {
+		return fmt.Errorf("archivefs: set: %v", err)
+	}
+
 	// make sure path is clean
 	afs.current = filepath.Clean(path)