Remove container on load if it exited

If the shim gets sigkilled while containerd is down we need to be able
to remove the container correctly so that it does not stay in a stopped
state forever.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

runtime/process.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"syscall"
 
 	"github.com/docker/containerd/specs"
 )
@@ -36,6 +37,8 @@ type Process interface {
 	Stdio() Stdio
 	// SystemPid is the pid on the system
 	SystemPid() int
+	// State returns if the process is running or not
+	State() State
 }
 
 type processConfig struct {
@@ -178,6 +181,17 @@ func (p *process) Close() error {
 	return p.exitPipe.Close()
 }
 
+func (p *process) State() State {
+	if p.pid == 0 {
+		return Stopped
+	}
+	err := syscall.Kill(p.pid, 0)
+	if err != nil && err == syscall.ESRCH {
+		return Stopped
+	}
+	return Running
+}
+
 func (p *process) getPidFromFile() (int, error) {
 	data, err := ioutil.ReadFile(filepath.Join(p.root, "pid"))
 	if err != nil {