net/http: allow customization of FileServer's directory HTML and styling

[rbucker]

go/src/net/http/fs.go

Lines 128 to 165 in e9e0d1e

	func dirList(w ResponseWriter, r *Request, f File) {
	// Prefer to use ReadDir instead of Readdir,
	// because the former doesn't require calling
	// Stat on every entry of a directory on Unix.
	var dirs anyDirs
	var err error
	if d, ok := f.(fs.ReadDirFile); ok {
	var list dirEntryDirs
	list, err = d.ReadDir(-1)
	dirs = list
	} else {
	var list fileInfoDirs
	list, err = f.Readdir(-1)
	dirs = list
	}
	if err != nil {
	logf(r, "http: error reading directory: %v", err)
	Error(w, "Error reading directory", StatusInternalServerError)
	return
	}
	sort.Slice(dirs, func(i, j int) bool { return dirs.name(i) < dirs.name(j) })
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	fmt.Fprintf(w, "<pre>\n")
	for i, n := 0, dirs.len(); i < n; i++ {
	name := dirs.name(i)
	if dirs.isDir(i) {
	name += "/"
	}
	// name may contain '?' or '#', which must be escaped to remain
	// part of the URL path, and not indicate the start of a query
	// string or fragment.
	url := url.URL{Path: name}
	fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", url.String(), htmlReplacer.Replace(name))
	}
	fmt.Fprintf(w, "</pre>\n")
	}

The overarching purpose of the fileserver is to serve files in a safe way. But then it has this side effect of being able to generate a directory list. The directory list is a very basic PRE block with some A links. The code also sets the content-type. However, there is something missing.

• is the HTML that it generates simply the smallest code possible?
• is there a way to style that fragment either with a template or some CSS etc
• since it's just a PRE block should I wrap the handler in a handler and then write a header, then call the handler, then write the footer
• maybe there should be a callback instead of hardcoded
• maybe there should be a template feature

At the very least please update the documentation to set the intent.

[mknyszek]

If I understand correctly, the file server is meant as a very basic server. Very useful for one-offs and non-critical situations, but I don't think that this is ever intended to be a solution that is very customizable.

CC @neild

[mknyszek]

Actually, see #29945. This has been declined more than once. Closing.