Subject: Re: "less -F" is broken

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Thu, 16 Aug 2018 10:22:11 +0200

On Wed, Aug 15 2018, Linus Torvalds wrote:

> On Wed, Aug 15, 2018 at 2:29 PM Ævar Arnfjörð Bjarmason
> <[email-masked]> wrote:
>>
>> Downloading & trying versions of it locally reveals that it's as of
>> version 520, not 530. The last version before 520 is 487. Presumably
>> it's covered by this item in the changelog:
>>
>>     Don't output terminal init sequence if using -F and file fits on one
>>     screen[1]
>
> Side note: that's sad, because we already use X in the default exactly
> for that reason.

And as another note for those following along (and myself until a short
while ago, I didn't remember how this worked).

We set those default options at compile-time here:
https://github.com/git/git/blob/63749b2dea5d1501ff85bab7b8a7f64911d21dea/Makefile#L1761-L1763

I.e. set LESS=FRX and then when we setup the pager we use that unless we
can find LESS (and LV) set in the env already:
https://github.com/git/git/blob/63749b2dea5d1501ff85bab7b8a7f64911d21dea/pager.c#L71-L96

> So apparently "less" was broken for us to fix something that we
> already had long solved. The code basically tried to do "automatic X
> when F is set".
>
> And all that line_count stuff (which is what breaks) is pointless when
> -X is already given.
>
> That does give a possible fix: just stop doing the line_count thing if
> no_init is set.
>
> So "-F" would continue to be broken, but "-FX" would work.
>
> Something like the attached patch, perhaps?

This works for me under -FX.

>             Linus
>  main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/main.c b/main.c
> index 179bd78..961a9db 100644
> --- a/main.c
> +++ b/main.c
> @@ -59,6 +59,7 @@ extern int	missing_cap;
>  extern int	know_dumb;
>  extern int	pr_type;
>  extern int	quit_if_one_screen;
> +extern int	no_init;
>
>
>  /*
> @@ -274,7 +275,7 @@ main(argc, argv)
>  	{
>  		if (edit_stdin())  /* Edit standard input */
>  			quit(QUIT_ERROR);
> -		if (quit_if_one_screen)
> +		if (quit_if_one_screen && !no_init)
>  			line_count = get_line_count();
>  	} else
>  	{