Exception while rendering a diff file

[Ryan J Ollos]

I was investigating ​Bloodhound issue #308, and trying to determine why .patch files rendered with syntax highlighting, but .diff files did not. The issue I'm reporting here appears to be unrelated. During the rendering of .diff files I saw the following traceback:

Traceback (most recent call last):
  File "/home/user/Workspace/bloodhound/trac/trac/web/main.py", line 497, in _dispatch_request
    dispatcher.dispatch(req)
  File "/home/user/Workspace/bloodhound/trac/trac/web/main.py", line 236, in dispatch
    self._post_process_request(req)
  File "/home/user/Workspace/bloodhound/trac/trac/web/main.py", line 340, in _post_process_request
    f.post_process_request(req, *(None,)*extra_arg_count)
  File "/home/user/Workspace/trac-hacks/permredirectplugin/trunk/permredirect/filter.py", line 59, in post_process_request
    if issubclass(exctype, PermissionError):
TypeError: issubclass() arg 1 must be a class

Full traceback is attached. To reproduce, attach a file ending in .diff to a ticket and then view the file. You may be able to reproduce under other circumstances as well ... I haven't investigated thoroughly.

I'm not sure what the correct fix is, but the following patch makes the exception go away:

permredirectplugin/trunk/permredirect/filter.py

@@ -56 +56 @@
                 ref_url = ref_url + "?" + req.query_string
             login_url = req.href.login(referer=ref_url)
 
-            if issubclass(exctype, PermissionError):
+            if exctype and issubclass(exctype, PermissionError):
                 req.redirect(login_url)
             
             try:

[Ryan J Ollos]

The issue was confirmed with the latest version of the trunk code.

[ejucovy]

(In [12446]) fixes #10709 -- don't explode with a system error if sys.exc_info()[0] is None. also, add some logging code in that situation, because i don't understand when it happens.

[ejucovy]

I can't reproduce this on a fresh Trac environment (trunk@11483 with no custom components other than permredirect) so let me know if this doesn't fix the issue for you.

[Ryan J Ollos]

Thanks for the fix. I'll do some testing soon and get back to you.

[Ryan J Ollos]

The issue seems to be fixed now. Sorry I don't have more info on what the cause might have been. I'll let you know if I come across a case where the debug info you added gets logged.