25 Apr
2020
25 Apr
'20
11:54 p.m.
On 4/25/20, Paul Ruizendaal <pnr(a)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.