Add support for kpod kill

Kill one or more containers using a user-provided signal.  If not signal
is provided, KILL is used.

Signed-off-by: baude <bbaude@redhat.com>

libkpod/kill.go

@@ -0,0 +1,45 @@
+package libkpod
+
+import (
+	"github.com/docker/docker/pkg/signal"
+	"github.com/kubernetes-incubator/cri-o/oci"
+	"github.com/kubernetes-incubator/cri-o/utils"
+	"github.com/pkg/errors"
+	"os"
+	"syscall"
+)
+
+// Reverse lookup signal string from its map
+func findStringInSignalMap(killSignal syscall.Signal) (string, error) {
+	for k, v := range signal.SignalMap {
+		if v == killSignal {
+			return k, nil
+		}
+	}
+	return "", errors.Errorf("unable to convert signal to string")
+
+}
+
+// ContainerKill sends the user provided signal to the containers primary process.
+func (c *ContainerServer) ContainerKill(container string, killSignal syscall.Signal) (string, error) { // nolint
+	ctr, err := c.LookupContainer(container)
+	if err != nil {
+		return "", errors.Wrapf(err, "failed to find container %s", container)
+	}
+	c.runtime.UpdateStatus(ctr)
+	cStatus := c.runtime.ContainerStatus(ctr)
+
+	// If the container is not running, error and move on.
+	if cStatus.Status != oci.ContainerStateRunning {
+		return "", errors.Errorf("cannot kill container %s: it is not running", container)
+	}
+	signalString, err := findStringInSignalMap(killSignal)
+	if err != nil {
+		return "", err
+	}
+	if err := utils.ExecCmdWithStdStreams(os.Stdin, os.Stdout, os.Stderr, c.runtime.Path(ctr), "kill", ctr.ID(), signalString); err != nil {
+		return "", err
+	}
+	c.ContainerStateToDisk(ctr)
+	return ctr.ID(), nil
+}