patch for issue opencontainers#39:

	runc always shows "container in use" if /var/run/ocf/container exists
	However, there are two cases
		1) case 1: "container in use"
		2) case 2: /var/run/ocf/container still exists after runc was terminated by SIGKILL or abnormal crash
	For case 2, runc should yield "delete the lock dir" instead of "container in use"
	This patch is for this issue using "pid" file in /var/run/ocf/container/task

Signed-off-by: Jin-Hwan Jeong <jhjeong.kr@gmail.com>

    patch for issue opencontainers#39:
        runc always shows "container in use" if /var/run/ocf/container exists
        However, there are two cases
                1) case 1: "container in use"
                2) case 2: /var/run/ocf/container still exists after runc was terminated by SIGKILL or abnormal crash
        For case 2, runc should yield "delete the lock dir" instead of "container in use"
        This patch is for this issue using "pid" file in /var/run/ocf/container/task
	Also, I refined indentation and added code for slice length check

Signed-off-by: Jin-Hwan Jeong <jhjeong.kr@gmail.com>

libcontainer/factory_linux.go

@@ -159,13 +159,30 @@ func (l *LinuxFactory) Create(id string, config *configs.Config) (Container, err
 	}
 	containerRoot := filepath.Join(l.Root, id)
 	if _, err := os.Stat(containerRoot); err == nil {
-		return nil, newGenericError(fmt.Errorf("Container with id exists: %v", id), IdInUse)
+		_, runcName := filepath.Split(os.Args[0])
+		pid, err := ioutil.ReadFile(filepath.Join(containerRoot, "task"))
+		if err != nil {
+			return nil, newGenericError(fmt.Errorf("delete the directory: %s", containerRoot), IdInUse)
+		}
+		procPath := fmt.Sprintf("/proc/%s/cmdline", pid)
+		cmdline, err := ioutil.ReadFile(procPath)
+		if err != nil {
+			return nil, newGenericError(fmt.Errorf("delete the directory: %s", containerRoot), IdInUse)
+		}
+		_, exeName := filepath.Split(string(cmdline))
+		if len(exeName) >= len(runcName) && exeName[0:len(runcName)] == runcName {
+			return nil, newGenericError(fmt.Errorf("Container with id exists: %v", id), IdInUse)
+		}
+		return nil, newGenericError(fmt.Errorf("Container with id by other cli exists: %v", id), IdInUse)
 	} else if !os.IsNotExist(err) {
 		return nil, newGenericError(err, SystemError)
 	}
 	if err := os.MkdirAll(containerRoot, 0700); err != nil {
 		return nil, newGenericError(err, SystemError)
 	}
+	if err := ioutil.WriteFile(filepath.Join(containerRoot, "task"), []byte(fmt.Sprintf("%d", os.Getpid())), 0700); err != nil {
+		return nil, newGenericError(err, SystemError)
+	}
 	return &linuxContainer{
 		id:            id,
 		root:          containerRoot,