FilesystemStore doesn’t truncate session files

[moraes]

From http://code.google.com/p/gorilla/issues/detail?id=53

I’m writing a small web-app and I noticed that during testing, I sometimes got the error message

"2012/09/27 15:25:50 session error: securecookie: the value could not be decoded"

…and my session contents were lost.

After a bit of digging, this happens when you write session contents which are smaller than the previous contents.

It can be easily fixed by using os.O_TRUNC in func (s *FilesystemStore) save(session *Session) (sessions/store.go:198):

fp, err2 := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)

Please apply this fix upstream.

Thanks!