staticfiles: remove mapFSRootOpenErr because Go stdlib has fixed the relevant issue (#1919)

caddyhttp/staticfiles/fileserver.go

@@ -66,9 +66,6 @@ func (fs FileServer) serveFile(w http.ResponseWriter, r *http.Request) (int, err
 	// open the requested file
 	f, err := fs.Root.Open(reqPath)
 	if err != nil {
-		// TODO: remove when http.Dir handles this (Go 1.9?)
-		// Go issue #18984
-		err = mapFSRootOpenErr(err)
 		if os.IsNotExist(err) {
 			return http.StatusNotFound, nil
 		} else if os.IsPermission(err) {
@@ -280,35 +277,3 @@ var staticEncodingPriority = []string{
 	"br",
 	"gzip",
 }
-
-// mapFSRootOpenErr maps the provided non-nil error
-// to a possibly better non-nil error. In particular, it turns OS-specific errors
-// about opening files in non-directories into os.ErrNotExist.
-//
-// TODO: remove when http.Dir handles this (slated for Go 1.9)
-// Go issue #18984
-func mapFSRootOpenErr(originalErr error) error {
-	if os.IsNotExist(originalErr) || os.IsPermission(originalErr) {
-		return originalErr
-	}
-
-	perr, ok := originalErr.(*os.PathError)
-	if !ok {
-		return originalErr
-	}
-	name := perr.Path
-	parts := strings.Split(name, string(filepath.Separator))
-	for i := range parts {
-		if parts[i] == "" {
-			continue
-		}
-		fi, err := os.Stat(strings.Join(parts[:i+1], string(filepath.Separator)))
-		if err != nil {
-			return originalErr
-		}
-		if !fi.IsDir() {
-			return os.ErrNotExist
-		}
-	}
-	return originalErr
-}