Re: [9front] rio consctl behaviour

["Ethan Gardener" <eekee57@fastmail.fm>]

On Tue, Jun 2, 2020, at 9:25 PM, umbraticus@prosimetrum.com wrote:
> from rio(4):
> > consctl controls interpretation of console input.  Writing
> > strings to it sets these modes: rawon turns on raw
> > mode; rawoff turns off raw mode; holdon turns on
> > hold mode; holdoff turns off hold mode.  Closing the
> > file makes the window revert to default state (raw
> > off, hold off).
> 
> I am wondering if there is a reason for the behaviour described in the
> last sentence.  It seems like it would be convenient to be able to
> just echo holdon > /dev/consctl rather than do the dance in eg.
> /rc/bin/hold to keep the fd open.  I have commented out
> /sys/src/cmd/rio/xfid.c:328,335 in my local copy and nothing seems to
> have broken...

There is a good reason applicable to raw mode. When a program exits, however it exits - crashes or whatever, you want the console restored to cooked mode. The way it is now is a simple way to do this, an open file will be closed by the OS if the program crashes. How reasonable it is to apply this same logic to hold mode is perhaps debateable.

I briefly thought failure to end hold mode would confuse users, but then I realised I only thought that because I'm used to 9pm, which has no color. ;) It doesn't indicate hold mode at all. This former lack of color might be why hold mode is tied to keeping the fd open. (9pm was ported in 2002.)