Issue 2678 - Don't consider local files and Windows registry when guessing mime types

cms/bin/test_server.py

 # coding: utf-8
 
 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-2015 Eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
@@ skipping 28 matching lines @@
     {% set code = status.split()|first|int %}
     {% if code == 404 %}
       <p>No page found for the address {{uri}}.</p>
     {% elif code == 500 %}
       <p>An error occurred while processing the request for {{uri}}:</p>
       <pre>{{error}}</pre>
     {% endif %}
   </body>
 </html>"""
 
-# Create our own instance, the default one will introduce "random" host-specific
-# behavior by parsing local config files.
-mime_types = mimetypes.MimeTypes()
+# Initilize the mimetypes modules manually for consistent behavior,
+# ignoring local files and Windows Registry.
+mimetypes.init([])

[Wladimir Palant, 2015/06/29 10:42:32]

Re-reading the source code I can see the issue - MimeTypes class actually calls
mimetypes.init() implicitly, without parameters. It merely allows specifying
*additional* file names, these won't replace the default ones however. It seems
that we cannot avoid changing global state here, and we have to accept that
things will fail badly if somebody else initializes mimetypes module before us.
That module is seriously misdesigned, maybe somebody wants to file a bug on it.

 
 def get_page(path):
   path = path.strip("/")
   if path == "":
     path = source.read_config().get("general", "defaultlocale")
   if "/" in path:
     locale, page = path.split("/", 1)
   else:
     locale, page = path, ""
 
@@ skipping 36 matching lines @@
   for fragment in template.stream(status=status, **kwargs):
     yield fragment.encode(UNICODE_ENCODING)
 
 def handler(environ, start_response):
   path = environ.get("PATH_INFO")
 
   data = get_data(path)
   if data is None:
     return show_error(start_response, "404 Not Found", uri=path)
 
-  mime = mime_types.guess_type(path)[0] or "text/html"
+  mime = mimetypes.guess_type(path)[0] or "text/html"
 
   if isinstance(data, unicode):
     data = data.encode(UNICODE_ENCODING)
     mime = "%s; charset=%s" % (mime, UNICODE_ENCODING)
 
   start_response("200 OK", [("Content-Type", mime)])
   return [data]
 
 if __name__ == "__main__":
   if len(sys.argv) < 2:
@@ skipping 24 matching lines @@
           return app(environ, start_response)
         except Exception, e:
           return show_error(start_response, "500 Internal Server Error",
               uri=environ.get("PATH_INFO"), error=e)
 
       server = make_server(host, port, wrapper)
       print " * Running on http://%s:%i/" % server.server_address
       server.serve_forever()
 
   run("localhost", 5000, handler, use_reloader=True, use_debugger=True)