Re: fix for readline terminal size problems when window is resized with open pager

Merlin Moncure <mmoncure(at)gmail(dot)com> writes:
> On Wed, Dec 16, 2015 at 1:29 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> So I now think that print.c shouldn't be involved at all, and the right
>> thing to do is just have gets_interactive() invoke the resize function
>> immediately before calling readline(). That will still leave a window
>> for SIGWINCH to be missed, but it's a pretty tiny one.

> right -- agreed.

I tried that and found out that the first call dumps core because readline
hasn't been initialized yet. To fix that, we need an explicit call to
rl_initialize() instead of depending on readline() to do it for us.
So I arrive at the attached modified patch.

>> And somebody oughta report this as a libreadline bug ...

> See https://bugs.python.org/issue23735 for background. Apparently
> this is expected behavior (and we are far from the only ones
> complaining about it):

> "And so we reach where we are. If a SIGWINCH arrives while readline is
> not active, and the application using callback mode does not catch it and
> tell readline about the updated screen dimensions (rl_set_screen_size()
> exists for this purpose), readline will not know about the new size."

Meh. At the very least, this is a serious documentation failure on their
part, because their docs about interrupt handling look exactly the same
as before, to wit saying exactly the opposite of this.

regards, tom lane