func connectCmdsById(s *server, fromId, toId liblush.CmdId, streamname string) error {
var stream liblush.OutStream
var to, from liblush.Cmd
from = s.session.GetCommand(fromId)
if from == nil {
return errors.New("unknown command in from")
}
switch streamname {
case "stdout":
stream = from.Stdout()
case "stderr":
stream = from.Stderr()
default:
return errors.New("unknown stream")
}
if toId == 0 {
return disconnectStream(stream)
}
to = s.session.GetCommand(toId)
if to == nil {
return errors.New("unknown command in to")
}
if pipedcmd(stream) != nil {
// not strictly necessary but makes for simpler API. service to the
// user! because that is how we roll. EaaS.
return errors.New("already connected to another command")
}
stream.SetListener(to.Stdin())
return nil
}