Sun, 29 Mar 2009
The Oldest Real Bug
I occasionally complain about bugs remaining unfixed for a long time in the Open Source Software, and it really hurts when I spend several hours trying to solve a problem, which turns out to be a known problem reported many years ago, still unfixed.
In our archive of graduate theses, we had a problem that some PDF file could not been displayed when being accessed through the
public part of theses.cz. Displaying it from the authenticated
part of this site or downloading it from either part and then displaying
it locally was OK. Later we have found that even displaying the file from
the public part was OK, provided that the HTTPS instead of HTTP has been used.
The problem is caused by caching: Mozilla thinks it cannot cache the
files downloaded over HTTPS, while it can cache the files downloaded
over HTTP. Mozplugger then does a shortcut of running the PDF viewer
with the file name from the Mozilla cache for the HTTP case, but
downloading the file separately into /tmp directory for
the HTTPS case. Now when the PDF file is bigger than the cache size
limit, Mozilla deletes it from the cache just before Mozplugger starts
the PDF viewer.
This has been reported to the Mozilla Bugzilla in March 2003, six years ago. The latest comment was from May 2004, and the bug is still there. The bug has a "QA Contact" field pointing to a non-existent address, so there is even nobody to complain to. We have worked around the bug by adding an HTTP header which causes Mozilla to avoid caching of the PDF file altogether. I have also reported it downstream, to the Fedora bugzilla, hoping they would know better than me how to push it upstream.