Protect creation of "dir:" with a mutex

internal/taskfile/task.go

@@ -1,5 +1,8 @@
 package taskfile
 
+import "os"
+import "sync"
+
 // Tasks represents a group of tasks
 type Tasks map[string]*Task
 
@@ -14,6 +17,7 @@ type Task struct {
 	Generates   []string
 	Status      []string
 	Dir         string
+	mkdirMutex  sync.Mutex
 	Vars        Vars
 	Env         Vars
 	Silent      bool
@@ -21,3 +25,22 @@ type Task struct {
 	Prefix      string
 	IgnoreError bool `yaml:"ignore_error"`
 }
+
+// Mkdir creates the directory Task.Dir.
+// Safe to be called concurrently.
+func (t *Task) Mkdir() error {
+	if t.Dir == "" {
+		// No "dir:" attribute, so we do nothing.
+		return nil
+	}
+
+	t.mkdirMutex.Lock()
+	defer t.mkdirMutex.Unlock()
+
+	if _, err := os.Stat(t.Dir); os.IsNotExist(err) {
+		if err := os.MkdirAll(t.Dir, 0755); err != nil {
+			return err
+		}
+	}
+	return nil
+}

task.go

@@ -202,13 +202,8 @@ func (e *Executor) RunTask(ctx context.Context, call taskfile.Call) error {
 
 	// When using the "dir:" attribute it can happen that the directory doesn't exist.
 	// If so, we create it.
-	if t.Dir != "" {
+	if err := t.Mkdir(); err != nil {
-		if _, err := os.Stat(t.Dir); os.IsNotExist(err) {
-			if err := os.MkdirAll(t.Dir, 0755); err != nil {
 		e.Logger.Errf("task: cannot make directory %q: %v", t.Dir, err)
-				return err
-			}
-		}
 	}
 
 	for i := range t.Cmds {