Bug#4158: pine does not lock mailbox properly - loss of mail is likely

[Ian Jackson <ian@chiark.chu.cam.ac.uk>]

Package: pine
Version: 3.94-3

Pine does not use the proper <mailbox>.lock convention for locking the
mailbox.  It does do this if it has access to the directory to do so,
but if it doesn't it silently uses flock instead.

There are several problems here.

Those which need to be fixed urgently to avoid loss of mail:
 * Pine needs to be made secure when setgid mail (at the moment it
   isn't).
 * Pine needs to be setgid mail.

Those which need to be fixed:
 * Pine needs to have compiled into it the kind of locking it needs,
   to that it doesn't `fall back' to a different locking strategy thus
   creating a silent failure mode.  (A fallback locking strategy is a
   pointless exercise, of course.)

Those which should be fixed for other systems:
 * Pine should never use flock on a Linux system.  It should use fcntl
   instead.

I do believe this locking behaviour has been a persistent problem with
Pine, and I'm sad to see that it's still not right.

Ian.