[Toybox] [PATCH] killall should kill scripts too.

[Rob Landley]

On 12/18/2017 07:07 PM, enh wrote:
> On Sun, Dec 17, 2017 at 9:40 AM, Rob Landley <rob at landley.net> wrote:
>> On 12/17/2017 11:20 AM, Rob Landley wrote:
>>> Sigh. You argument that "we can't just do something easily explained but
>>> must copy ubuntu's magic edge cases exactly" implies I need to
>>> understand ubuntu's magic edge cases, which are nonobvious.
>>
>> I should clarify: what I'm uncomfortable with is the need to read
>> multiple /proc files per process, because the speed of lsof is just
>> _sad_ and the cpu usage of top is unpleasant. (Part of the reason I
>> haven't finished cleaning up lsof yet is I still hope to be able to
>> speed it up somehow, which is a largeish time sink every time I turn my
>> attention to it.)
>>
>> Having killall need to do similar grinding over a large number of
>> processes seems unnecessary. That said, it looks like to match ubuntu's
>> killall we would need to read two files _and_ stat /proc/$$/exe.
> 
> that's still a lot lighter weight than all the work pgrep/pkill have
> to do, and it's what everyone's already living with anyway...

That and the "it doesn't have to be right or match a spec, it has to
match the other command's behavior", which is a nonobvious hairball once
I started looking at it:

  $ echo -e '#!/bin/bash\nsleep "$@"' > spleep
  $ chmod +x spleep
  $ spleep 123 &
  [1] 28391
  $ killall $PWD/spleep
  /home/landley/toybox/toy3/sub2/spleep: no process found

Because no process has /proc/*/exe pointing to that file's dev:inode
pair. The existing lib/ plumbing for this is _only_ checking names, not
checking this inode stuff. But this is in lib because it's shared
plumbing, pidof also uses it and the host version of that has -s to
check for scripts...

Sigh. Ok, it's been long enough I'm invoking the "apply the other
person's patch then fiddle on top of it" rule, but this absolute path
business is not what the other one's doing...

Rob