[Toybox] weird ps truncation

[Rob Landley]

On 01/30/2017 04:20 PM, enh wrote:
> On Sat, Jan 28, 2017 at 4:16 PM, Rob Landley <rob at landley.net> wrote:
>> On 01/27/2017 06:00 PM, enh wrote:
>>> Android has a lot of long usernames. the bluetooth code, for example,
>>> runs as "bluetooth", and the camera code as "cameraserver". ideally
>>> the USER column would grow to fit (especially when the tty is very
>>> wide), but right now it's kind of narrow, doesn't grow, and truncates
>>> from left rather than the right:
>>
>> The -w flag disables this, it doesn't just ignore screen width but
>> disables truncation of all fields. (I.E. all strings print at their full
>> length.)
> 
> (yes, though it can be hard to read because the columns get shifted about.)
> 
>> As for changing the default behavior: I already made the numeric fields
>> leak. Now it sounds like you want the string values to leak and reclaim
>> space, which is a less bounded problem. (The numbers aren't going to
>> leak _that_ much, but each string could be wider than the screen.)
> 
> no, that wasn't actually what i was thinking about. i was thinking
> about sizing each column to contain its widest value. sort of more
> like how columnated ls works.

Doable, but expensive. top is already taking 5% cpu on my netbook as
opposed to ubuntu top's 1.6%. I have a todo item to profile what it's
spending its time on and trying to streamline that a bit, but it's a
ways down the todo list. :)

>> So what behavior do you _want_ here: swap in numbers, leak/reclaim, or
>> preread all preread all the entries and calculate column values like ls
>> does? Or just truncate from left instead of from right?
> 
> what you've already checked in, fixing the truncation to be
> consistent, gets us back to where we were.
> 
> beyond that i'm not sure...

Me neither.

> the "+" to show we did truncate seems helpful.

Fiddly to implement though. The STIME field is truncated during normal
display, having that _not_ turn the last digit into + every time
requires a special case. And that's sounding like I need to audit all
the fields to see which ones need this...

(I found a bug while I was working on that, it didn't copy the null
terminator when stripping /dev off the tty name so the display could
have trailing garbage.)

Also I've now been staring at the code long enough I don't remember why
I only did the utf8 parsing when we a tty? We jump through hoops to find
the controlling tty, including checking /dev/tty, because ps without -a
only shows processes attached to the current terminal. But that doesn't
involve our OUTPUT being to a tty, ala "ps | cat"... So why was I making
that distinction again? Hmmm...

It's 2 am, I should go to bed.

> switching from USER to UID seems like a clever special case, .

Yes, but what's expected behavior here?

> doing the "+" is at least an obvious signal that something's going on
> here. i'm surprised no one's noticed before now that "bluetooth" gets
> truncated. actually, here's the list of usernames that get truncated
> on a Pixel:
...
> 9 u0_a10000
> 
> (that last one is the start of a block of generated usernames of
> length 9, corresponding to installed apps.)
> 
> maybe Android should just default to 12?

In ps, in top, or in both? And would you still want the +?

Rob