[9fans] QTCTL?

["Francisco J Ballesteros" <nemo@lsub.org>]

Hi,

while hunting yet another bug in the octopus, I´ve been thinking that
one problem that we have in general, in Plan 9,
 is that there are files that behave like files, and files that
do not.

For example, append only files do not, offsets are ignored on writes.
ctl files are not, either. You write a ctl string, and reading the file reports
something else. Clone files are different files, each time they are open.

This is a problem when (like we do in the octopus) you try to cache files.
But it´s also a problem for things like tar and to whoever tries to use the
file as a plain one.

Why don´t add a QTCTL bit to Qid.type?
It would mean "this file does not behave like a regular file, do not cache and
handle with care).

I think the change can be incorporated without causing a nightmare and
it would make things more clean, regarding what can one expect from a file
after looking at its directory entry.