And Stat_t.PID and Stat_t.Name while we're at it. Then use the new
.State property in runType to distinguish between running and
zombie/dead processes, since kill(2) does not [1]. With this change
we no longer claim Running status for zombie/dead processes.
I've also removed the kill(2) call from runType. It was originally
added in 13841ef3 (new-api: return the Running state only if the init
process is alive, 2014-12-23), but we've been accessing
/proc/[pid]/stat since 14e95b2a (Make state detection precise,
2016-07-05, #930), and with the /stat access the kill(2) check is
redundant.
I also don't see much point to the previously-separate
doesInitProcessExist, so I've inlined that logic in runType.
It would be nice to distinguish between "/proc/[pid]/stat doesn't
exist" and errors parsing its contents, but I've skipped that for the
moment.
The Running -> Stopped change in checkpoint_test.go is because the
post-checkpoint process is a zombie, and with this commit zombie
processes are Stopped (and no longer Running).
[1]: https://github.com/opencontainers/runc/pull/1483#issuecomment-307527789
Signed-off-by: W. Trevor King <wking@tremily.us>
2bea4c897e