Re: [gpsd-dev] Something screwy (qqq-ewy?) with gpsmon

[Eric S. Raymond]

Hal Murray <address@hidden>:
> What sort of things are likely to get it into that mode?

Binary garbage going to the tty that happens to look like one of the
emulator's mode switches can do it. Also, if you interrupt a curses-using
program at *exactly* the wrong time and for some reason the normal endwin()
sequence never gets shipped.

This used to happen a lot when I ran gdb on curses programs, but years
ago someone over there got smart and started doing a tty parameter
save plus the equivalent of endwin() unconditionally on each debugger
stop.

And all this is assuming the terminfo entry for the emulator is perfect - 
there are subtle ways it can be buggy that don't show up in normal use but
do in this sort of edge case (that is, being interrupted at the wrong time). 
The effect of such bugs is to make the qqqqqq effect more likely.

I wrote large portions of ncurses, and used to be more intimate with
this kind of problem than anybody.  But that was more than 20 years ago
and I have forgotten some of what I knew then, which is why my answer
is a bit lacking in detail; sorry.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>