Docserver: Add support for viewing docs with a codereview patch applied

chrome/common/extensions/docs/server2/patch_servlet.py

+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from appengine_wrappers import IsDevServer
+from render_servlet import RenderServlet
+from rietveld_patcher import RietveldPatcherError
+from server_instance import ServerInstance
+from servlet import Request, Response, Servlet
+
+class PatchServlet(Servlet):
+  '''Servlet which renders patched docs.
+  '''
+
+  def Get(self):
+    path_with_issue = self._request.path
+    if '/' in path_with_issue:

[not at google - send to devlin, 2013/05/07 05:45:40]

well if there isn't a '/' then it's a malformed, so we can return NotFound right
away.

[方觉(Fang Jue), 2013/05/07 06:03:55]

Done.

+      issue, real_path = path_with_issue.split('/', 1)
+    else:
+      issue, real_path = path_with_issue, ''
+
+    constructor = (ServerInstance.CreateOnline if IsDevServer() else
+                   ServerInstance.GetOrCreateOffline)
+    server_instance = constructor('trunk',
+                                  '/_patch/%s/static' % issue,
+                                  issue)
+    fake_path = '/trunk/%s' % real_path
+
+    try:
+      response = RenderServlet(Request(
+          fake_path,
+          self._request.headers)).Get(server_instance)
+      # Disable cache for patched content.

[not at google - send to devlin, 2013/05/07 05:45:40]

you can do "response.headers.pop('cache-control', None)"

[方觉(Fang Jue), 2013/05/07 06:03:55]

Done.

+      if response.headers.get('cache-control'):
+        del response.headers['cache-control']
+    except RietveldPatcherError as e:
+      response = Response.NotFound(e.message, {'Content-Type': 'text/plain'})

[not at google - send to devlin, 2013/05/07 05:45:40]

would kind of rather prefer to leave the content-type out of here, it's
hopefully unnecessary.

[方觉(Fang Jue), 2013/05/07 06:03:55]

I just don't want any HTML injected in URL to be returned here and intepreted in
the browser.

[not at google - send to devlin, 2013/05/07 06:17:21]

Ok cool. We should either enforce that there's a content type specified in the
response (probably via separating it out into a separate parameter) or make it
default to text/plain, or both.

+
+    if response.IsRedirect():
+      url = response.headers['Location']
+      if url.startswith('/trunk/'):
+        url = url.split('/trunk', 1)[1]
+      response.headers['Location'] = '/_patch/%s%s' % (issue, url)
+    return response