Cleanup cio.FIFOSet interface

Remove duplication with cio.Config
unexport newFIFOSetTempDir() since it includes hardcoded paths
Expose os.RemoveAll() as part of FIFOSet instead of a Dir

Signed-off-by: Daniel Nephin <dnephin@gmail.com>

container.go

@@ -3,6 +3,7 @@ package containerd
 import (
 	"context"
 	"encoding/json"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -288,20 +289,23 @@ func (c *container) get(ctx context.Context) (containers.Container, error) {
 	return c.client.ContainerService().Get(ctx, c.id)
 }
 
+// get the existing fifo paths from the task information stored by the daemon
 func attachExistingIO(response *tasks.GetResponse, ioAttach cio.Attach) (cio.IO, error) {
-	// get the existing fifo paths from the task information stored by the daemon
-	paths := &cio.FIFOSet{
-		Dir: getFifoDir([]string{
-			response.Process.Stdin,
-			response.Process.Stdout,
-			response.Process.Stderr,
-		}),
-		In:       response.Process.Stdin,
-		Out:      response.Process.Stdout,
-		Err:      response.Process.Stderr,
-		Terminal: response.Process.Terminal,
+	path := getFifoDir([]string{
+		response.Process.Stdin,
+		response.Process.Stdout,
+		response.Process.Stderr,
+	})
+	closer := func() error {
+		return os.RemoveAll(path)
 	}
-	return ioAttach(paths)
+	fifoSet := cio.NewFIFOSet(cio.Config{
+		Stdin:    response.Process.Stdin,
+		Stdout:   response.Process.Stdout,
+		Stderr:   response.Process.Stderr,
+		Terminal: response.Process.Terminal,
+	}, closer)
+	return ioAttach(fifoSet)
 }
 
 // getFifoDir looks for any non-empty path for a stdio fifo