[Toybox] top: pressing SHIFT-RIGHT and RIGHT confuses [sort key column]

[Rob Landley]

On 4/27/26 20:30, Mark Hansen wrote:
> Hi, first up, thanks for toybox. I'm always debugging Android apps
> using Toybox builtins and I appreciate all your work.
> 
> I just had some confusing behaviour in toybox top in Android.
> 
> Background: top lets you press left/right to move the list, and
> shift-left/shift-right to change sort column:

Yup. As documented in the --help output.

https://landley.net/toybox/help.html#top

> ```
>      Cursor UP/DOWN or LEFT/RIGHT to move list, SHIFT LEFT/RIGHT to change sort,
>      space to force update, R to reverse sort, Q to exit.
> ```
> 
> And the intention from the source code looks to be to highlight the
> sort-order column by putting the column name in square brackets:

Left/right lets you scroll the display to see long command lines, shift 
left/right changes which column you're sorting by, yes.

Judging by the title of the email... Ah, normal cursor right is _also_ 
incrementing which field is [bracketed] in the display (although it 
doesn't change which field it's actually sorting by).

Ah, I see the problem: show_pos() (and for that matter get_headers()) is 
skipping TT.scroll many fields, so the display logic needs to subtract 
TT.scroll from TT.sortpos.

Sigh, that was/is stuff looks like sleep deprivation... Ok, fixed up.

> I expect the problem is that here in `get_headers`, we print into a
> string buffer starting at header position `TT.scroll`:

Yup, that was it.

> enh at google.com said: "i tried your suggested fix, and it seems to work":
> ```
> diff --git a/toys/posix/ps.c b/toys/posix/ps.c
> index 86cd2197..8d53e26a 100644
> --- a/toys/posix/ps.c
> +++ b/toys/posix/ps.c
> @@ -1726,7 +1726,7 @@ static void top_common(
>           lines = header_line(lines, 0);
>           // print line of header labels for currently displayed fields
>           get_headers(TT.fields, pos = toybuf, sizeof(toybuf));
> -        for (i = 0, is = ' '; *pos; pos++) {
> +        for (i = TT.scroll, is = ' '; *pos; pos++) {
>             was = is;
>             is = *pos;
>             if (isspace(was) && !isspace(is) && i++==TT.sortpos && pos!=toybuf)
> ```

That would have worked too. (I fixed it before reading down that far.)

I rewrote the loop to advance by word because all it's doing is 
bracketing simple space separated words with no quoting, and declaring 
was/is variables for that says to me that I was VERY sleep deprived when 
I wrote that part...

Actually, your trick makes it slightly smaller, I'll do that too.

Thanks,

Rob