Local backend handle canceled steps case (#6008)

pipeline/backend/local/local.go

@@ -179,6 +179,14 @@ func (e *local) WaitStep(_ context.Context, step *types.Step, taskUUID string) (
 		return nil, err
 	}
 
+	if state.cmd == nil {
+		return nil, errors.New("exec: step command not set up")
+	}
+
+	stepState := &types.State{
+		Exited: true,
+	}
+
 	// normally we use cmd.Wait() to wait for *exec.Cmd, but cmd.StdoutPipe() tells us not
 	// as Wait() would close the io pipe even if not all logs where read and send back
 	// so we have to do use the underlying functions
@@ -190,13 +198,19 @@ func (e *local) WaitStep(_ context.Context, step *types.Step, taskUUID string) (
 		if err != nil {
 			return nil, err
 		}
-		state.cmd.ProcessState = cmdState
+		if cmdState == nil {
+			return nil, errors.New("exec: cmd state after Wait() can not be nil but is")
+		}
+		stepState.ExitCode = cmdState.ExitCode()
+		// can be nil if step got canceled
+		if state.cmd != nil {
+			state.cmd.ProcessState = cmdState
+		}
+	} else {
+		stepState.ExitCode = state.cmd.ProcessState.ExitCode()
 	}
 
-	return &types.State{
-		Exited:   true,
-		ExitCode: state.cmd.ProcessState.ExitCode(),
-	}, err
+	return stepState, err
 }
 
 func (e *local) TailStep(_ context.Context, step *types.Step, taskUUID string) (io.ReadCloser, error) {
@@ -217,13 +231,20 @@ func (e *local) DestroyStep(_ context.Context, step *types.Step, taskUUID string
 
 	// As WaitStep can not use cmd.Wait() witch ensures the process already finished and
 	// the io pipe is closed on process end, we make sure it is done.
-	_ = state.output.Close()
-	state.output = nil
-	_ = state.cmd.Cancel()
-	state.cmd = nil
-	workflowState, _ := e.getWorkflowState(taskUUID)
-	workflowState.stepState.Delete(step.UUID)
+	if state.output != nil {
+		_ = state.output.Close()
+		state.output = nil
+	}
+	if state.cmd != nil {
+		_ = state.cmd.Cancel()
+		state.cmd = nil
+	}
+	workflowState, err := e.getWorkflowState(taskUUID)
+	if err != nil {
+		return err
+	}
 
+	workflowState.stepState.Delete(step.UUID)
 	return nil
 }
 
@@ -237,11 +258,16 @@ func (e *local) DestroyWorkflow(_ context.Context, _ *types.Config, taskUUID str
 
 	// clean up steps not cleaned up because of context cancel or detached function
 	state.stepState.Range(func(_, value any) bool {
-		state, _ := value.(*stepState)
-		_ = state.output.Close()
-		state.output = nil
-		_ = state.cmd.Cancel()
-		state.cmd = nil
+		if state, ok := value.(*stepState); ok && state != nil {
+			if state.output != nil {
+				_ = state.output.Close()
+				state.output = nil
+			}
+			if state.cmd != nil {
+				_ = state.cmd.Cancel()
+				state.cmd = nil
+			}
+		}
 		return true
 	})
 
@@ -264,7 +290,7 @@ func (e *local) getWorkflowState(taskUUID string) (*workflowState, error) {
 	}
 
 	s, ok := state.(*workflowState)
-	if !ok {
+	if !ok || s == nil {
 		return nil, fmt.Errorf("could not parse state: %v", state)
 	}
 
@@ -283,7 +309,7 @@ func (e *local) getStepState(taskUUID, stepUUID string) (*stepState, error) {
 	}
 
 	s, ok := state.(*stepState)
-	if !ok {
+	if !ok || s == nil {
 		return nil, fmt.Errorf("could not parse state: %v", state)
 	}