libct: replace runType with hasInit

The semantics of runType is slightly complicated, and the only place
where we need to distinguish between Created and Running is
refreshState.

Replace runType with simpler hasInit, simplifying its users (except the
refreshState, which now figures out on its own whether the container is
Created or Running).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/container_linux.go

@@ -115,7 +115,7 @@ func (c *Container) ignoreCgroupError(err error) error {
 	if err == nil {
 		return nil
 	}
-	if errors.Is(err, os.ErrNotExist) && c.runType() == Stopped && !c.cgroupManager.Exists() {
+	if errors.Is(err, os.ErrNotExist) && !c.hasInit() && !c.cgroupManager.Exists() {
 		return nil
 	}
 	return err
@@ -1006,34 +1006,31 @@ func (c *Container) refreshState() error {
 	if paused {
 		return c.state.transition(&pausedState{c: c})
 	}
-	t := c.runType()
-	switch t {
-	case Created:
-		return c.state.transition(&createdState{c: c})
-	case Running:
-		return c.state.transition(&runningState{c: c})
+	if !c.hasInit() {
+		return c.state.transition(&stoppedState{c: c})
 	}
-	return c.state.transition(&stoppedState{c: c})
+	// The presence of exec fifo helps to distinguish between
+	// the created and the running states.
+	if _, err := os.Stat(filepath.Join(c.stateDir, execFifoFilename)); err == nil {
+		return c.state.transition(&createdState{c: c})
+	}
+	return c.state.transition(&runningState{c: c})
 }
 
-func (c *Container) runType() Status {
+// hasInit tells whether the container init process exists.
+func (c *Container) hasInit() bool {
 	if c.initProcess == nil {
-		return Stopped
+		return false
 	}
 	pid := c.initProcess.pid()
 	stat, err := system.Stat(pid)
 	if err != nil {
-		return Stopped
+		return false
 	}
 	if stat.StartTime != c.initProcessStartTime || stat.State == system.Zombie || stat.State == system.Dead {
-		return Stopped
+		return false
 	}
-	// We'll create exec fifo and blocking on it after container is created,
-	// and delete it after start container.
-	if _, err := os.Stat(filepath.Join(c.stateDir, execFifoFilename)); err == nil {
-		return Created
-	}
-	return Running
+	return true
 }
 
 func (c *Container) isPaused() (bool, error) {

libcontainer/state_linux.go

@@ -103,7 +103,7 @@ func (r *runningState) status() Status {
 func (r *runningState) transition(s containerState) error {
 	switch s.(type) {
 	case *stoppedState:
-		if r.c.runType() == Running {
+		if r.c.hasInit() {
 			return ErrRunning
 		}
 		r.c.state = s
@@ -118,7 +118,7 @@ func (r *runningState) transition(s containerState) error {
 }
 
 func (r *runningState) destroy() error {
-	if r.c.runType() == Running {
+	if r.c.hasInit() {
 		return ErrRunning
 	}
 	return destroy(r.c)
@@ -170,14 +170,13 @@ func (p *pausedState) transition(s containerState) error {
 }
 
 func (p *pausedState) destroy() error {
-	t := p.c.runType()
-	if t != Running && t != Created {
-		if err := p.c.cgroupManager.Freeze(configs.Thawed); err != nil {
-			return err
-		}
-		return destroy(p.c)
+	if p.c.hasInit() {
+		return ErrPaused
 	}
-	return ErrPaused
+	if err := p.c.cgroupManager.Freeze(configs.Thawed); err != nil {
+		return err
+	}
+	return destroy(p.c)
 }
 
 // restoredState is the same as the running state but also has associated checkpoint