attachment: Support perl 5.8's buggy version of CGI.pm.

This is truely horribly disgusting. CGI::tmpFileName, in current perls, is
an undocumented function (which should be a clue..) that takes the original
filename of an uploaded attachment, and returns the name of the tempfile
that CGI has stored it in.

In old perls, though, CGI::tmpFileName does not take a filename. It takes
a key from the object's {'.tmpfiles'} hash. This key is something
crazy like '*Fh::fh00001group' -- apparently the stringification of a
filehandle object.

Just to add to the fun, tmpFileName doesn't take the key, it expects a
refernce to the key. Argh?!

But the fun doesn't stop there, because in perl 5.8, CGI.pm is also broken
in two other ways. The upload() method is supposed to return a filehandle
to the temp file. It doesn't. The param() method is supposed to return
a filehandle to the temp file, that stringifies to the original filename.
It returns just the original filename, no filehandle.

Combine all these bugs, and you end up with this disgusting commit. Since
I have no way to get the filehandle, I *need* to get the tempfile name.
If I had the filehandle, I could probably pass it into tmpFileName, and
it might strigify to the right key name. But I don't, so the only way to
determine the key is to grub through the .tmpfiles hash ourselves.

And finally, one the temp file name is discovered, a filehandle can finally
be obtained by (re)opening it.

I recommend that this commit be reverted when perl 5.8 is a mercifully
faded memory.

I'm really, really, really glad I'm actually being paid for working on
this right now!

1 files changed, 4 insertions, 0 deletions

diff --git a/doc/bugs/attachment:_failed_to_get_filehandle.mdwn b/doc/bugs/attachment:_failed_to_get_filehandle.mdwn
index 9053e1abf..09546dcb5 100644
--- a/doc/bugs/attachment:_failed_to_get_filehandle.mdwn
+++ b/doc/bugs/attachment:_failed_to_get_filehandle.mdwn
@@ -96,3 +96,7 @@ Is it Ikiwiki bug or my attachment plugin is misconfigured? --[[Paweł|ptecza]]
 
 > I've reproduced the bug, and it does seem to be a bug with the perl in
 > debian stable/ubuntu hardy. Trying to figure it out --[[Joey]]
+
+> This was amazingly disgusting, see commit message for the full horror of
+> the details. I think it's [[done]] -- at least it works on debian stable
+> now. --[[Joey]]