Return 404 for non-existing files instead of 403

web/fs.go

@@ -0,0 +1,54 @@
+package web
+
+import (
+	"io"
+	"net/http"
+	"os"
+)
+
+// Credit: https://stackoverflow.com/questions/49589685/good-way-to-disable-directory-listing-with-http-fileserver-in-go
+type justFilesFilesystem struct {
+	fs http.FileSystem
+	// readDirBatchSize - configuration parameter for `Readdir` func
+	readDirBatchSize int
+}
+
+func (fs justFilesFilesystem) Open(name string) (http.File, error) {
+	f, err := fs.fs.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	return neuteredStatFile{File: f, readDirBatchSize: fs.readDirBatchSize}, nil
+}
+
+type neuteredStatFile struct {
+	http.File
+	readDirBatchSize int
+}
+
+func (e neuteredStatFile) Stat() (os.FileInfo, error) {
+	s, err := e.File.Stat()
+	if err != nil {
+		return nil, err
+	}
+	if s.IsDir() {
+	LOOP:
+		for {
+			fl, err := e.File.Readdir(e.readDirBatchSize)
+			switch err {
+			case io.EOF:
+				break LOOP
+			case nil:
+				for _, f := range fl {
+					if f.Name() == "index.html" {
+						return s, err
+					}
+				}
+			default:
+				return nil, err
+			}
+		}
+		return nil, os.ErrNotExist
+	}
+	return s, err
+}