[TUHS] v3 pipes

[Paul Winalski]

On 4/25/20, Paul Ruizendaal <pnr at planet.nl> wrote:
>
> I just tried making both pipe ends readable+writeable in my “V6.5” kernel
> and that appears to work. It allows for bi-directional communication in a
> half-duplex sense (i.e communicating walky-talky style). The other benefit
> is using just one file descriptor, at a time when a process had just 15 to
> work with.

If both pipe ends are readable+writeable, you have the Unix equivalent
of VMS mailboxes.  There's lots of opportunity for both deadlock and
livelock, and some "broken pipe" situations become difficult or
impossible to detect.

-Paul W.