Add Exec to process states

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

linux/proc/deleted_state.go

@@ -48,3 +48,7 @@ func (s *deletedState) Kill(ctx context.Context, sig uint32, all bool) error {
 func (s *deletedState) SetExited(status int) {
 	// no op
 }
+
+func (s *deletedState) Exec(ctx context.Context, path string, r *ExecConfig) (Process, error) {
+	return nil, errors.Errorf("cannot exec in a deleted state")
+}

linux/proc/init.go

@@ -346,8 +346,8 @@ func (p *Init) Runtime() *runc.Runc {
 	return p.runtime
 }
 
-// Exec returns a new exec'd process
+// exec returns a new exec'd process
-func (p *Init) Exec(context context.Context, path string, r *ExecConfig) (Process, error) {
+func (p *Init) exec(context context.Context, path string, r *ExecConfig) (Process, error) {
 	// process exec request
 	var spec specs.Process
 	if err := json.Unmarshal(r.Spec.Value, &spec); err != nil {

linux/proc/init_state.go

@@ -22,6 +22,7 @@ type initState interface {
 	Resume(context.Context) error
 	Update(context.Context, *google_protobuf.Any) error
 	Checkpoint(context.Context, *CheckpointConfig) error
+	Exec(context.Context, string, *ExecConfig) (Process, error)
 }
 
 type createdState struct {
@@ -113,6 +114,12 @@ func (s *createdState) SetExited(status int) {
 	}
 }
 
+func (s *createdState) Exec(ctx context.Context, path string, r *ExecConfig) (Process, error) {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+	return s.p.exec(ctx, path, r)
+}
+
 type createdCheckpointState struct {
 	p    *Init
 	opts *runc.RestoreOpts
@@ -227,6 +234,13 @@ func (s *createdCheckpointState) SetExited(status int) {
 	}
 }
 
+func (s *createdCheckpointState) Exec(ctx context.Context, path string, r *ExecConfig) (Process, error) {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+
+	return nil, errors.Errorf("cannot exec in a created state")
+}
+
 type runningState struct {
 	p *Init
 }
@@ -312,6 +326,12 @@ func (s *runningState) SetExited(status int) {
 	}
 }
 
+func (s *runningState) Exec(ctx context.Context, path string, r *ExecConfig) (Process, error) {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+	return s.p.exec(ctx, path, r)
+}
+
 type pausedState struct {
 	p *Init
 }
@@ -396,7 +416,13 @@ func (s *pausedState) SetExited(status int) {
 	if err := s.transition("stopped"); err != nil {
 		panic(err)
 	}
+}
 
+func (s *pausedState) Exec(ctx context.Context, path string, r *ExecConfig) (Process, error) {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+
+	return nil, errors.Errorf("cannot exec in a paused state")
 }
 
 type stoppedState struct {
@@ -471,3 +497,10 @@ func (s *stoppedState) Kill(ctx context.Context, sig uint32, all bool) error {
 func (s *stoppedState) SetExited(status int) {
 	// no op
 }
+
+func (s *stoppedState) Exec(ctx context.Context, path string, r *ExecConfig) (Process, error) {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+
+	return nil, errors.Errorf("cannot exec in a stopped state")
+}