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

[Rob Landley]

On 12/16/2017 09:43 PM, enh wrote:
> I don't think the world is helped by having two different imperfect
> heuristics, and I do think it will cause bug reports for us.

We _do_ have two imperfect heuristics. Checking the patch you sent
you're checking an exact match for argv[0] before looking at comm, and
your basename() logic only kicks in for absolute paths. So a command run
at a relative path won't do what ubuntu's does:

  $ ln -s $(which sleep) sleep
  $ sleep 999 &
  [1] 19487
  $ ./sleep 1000 &
  [2] 19490
  $ killall ./sleep
  [1]-  Terminated              sleep 999
  [2]+  Terminated              ./sleep 1000

Hmmm. What _is_ it doing?

  $ $PWD/sleep 998 &
  [1] 19916
  $ sleep 1001 &
  [2] 19917
  $ killall $PWD/sleep
  [1]-  Terminated              $PWD/sleep 998
  [2]+  Terminated              sleep 1001

Yeah, it doesn't look like it's ever taking the $PATH into account? But
then why...

  $ $PWD/sleep 998 &
  [1] 19945
  $ sleep 1001 &
  [2] 19946
  $ $PWD/../sleep 998 &
  bash: /home/landley/toybox/toy3/../sleep: No such file or directory

It's because it's a symlink, isn't it?

  $ killall sleep
  [1]-  Terminated              $PWD/sleep 998
  [2]+  Terminated              sleep 1001
  $ sleep 1001 &
  [1] 21634
  $ $PWD/sleep 998 &
  [2] 21637
  $ killall $PWD/sleep
  [2]+  Terminated              $PWD/sleep 998

Yes it is. It's comparing the inode.

  $ sleep 1001 &
  [1] 21738
  $ ./sleep 999 &
  [2] 21739
  $ killall sleep
  [1]-  Terminated              sleep 1001
  [2]+  Terminated              ./sleep 999

But ONLY for paths, not for simple names.

  $ sleep 1001 & ./sleep 999 &
  [1] 21758
  [2] 21759
  $ killall ./sleep
  [2]+  Terminated              ./sleep 999

Including relative paths, so the x[0] == '/' test is still wrong.

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.

Rob