wrapfs is a Go module which provides wrappers around fs.FS.

This wrapper makes sure calls to fs.FileInfo.Stat and fs.DirEntry.Info always return non-zero ModTime(). In case the wrapped file or entry return non-zero modification time it stays unchanged. In case they return a zero modification time then a static mod time will be used instead.

Usage:

var someFs fs.FS = getFS()
modTimeFS := wrapfs.WithModTime(someFS, time.Now())
http.FileServer(http.FS(modTimeFS))

This is especially helpful for embed.FS file systems when used in conjecture with http.FileServer. When wrapfs.WithModTime is used in this case the HTTP server will be able to handle caches which utilize the "Last-Modified" HTTP headers.

If new interfaces are added in fs they will not be exposed as implemented by the wrappers until the library has been patched.