4.4 File Server

The following example implements a file server which will serve files from the docroot document root set to the current working directory in this example. Four helper functions are used; ws-in-directory-p is used to check if the requested path is within the document root. If not then ws-send-404 is used to send a default “File Not Found”. If so then the file is served with ws-send-file (which appropriately sets the mime-type of the response based on the extension of the file) if it is a file or is served with ws-send-directory-list if it is a directory.

;;; file-server.el --- serve any files using Emacs Web Server
(lexical-let ((docroot default-directory))
  (ws-start
   (lambda (request)
     (with-slots (process headers) request
       (let ((path (substring (cdr (assoc :GET headers)) 1)))
         (if (ws-in-directory-p docroot path)
             (if (file-directory-p path)
                 (ws-send-directory-list process
                   (expand-file-name path docroot) "^[^\.]")
               (ws-send-file process (expand-file-name path docroot)))
           (ws-send-404 process)))))
   9003))