virtcontainers/persist: update GetDriver to support rootless fs

GetDriver returns new PersistDriver according to current needs, a mock fs
driver is returned when mockTesting is enabled, a rootless fs is returned when
rootless is detected, otherwise a fs driver is used.

Signed-off-by: Julio Montes <julio.montes@intel.com>

virtcontainers/persist/manager.go

@@ -1,4 +1,5 @@
 // Copyright (c) 2019 Huawei Corporation
+// Copyright (c) 2020 Intel Corporation
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -9,12 +10,18 @@ import (
 	"fmt"
 
 	exp "github.com/kata-containers/runtime/virtcontainers/experimental"
-	"github.com/kata-containers/runtime/virtcontainers/persist/api"
+	persistapi "github.com/kata-containers/runtime/virtcontainers/persist/api"
 	"github.com/kata-containers/runtime/virtcontainers/persist/fs"
+	"github.com/kata-containers/runtime/virtcontainers/pkg/rootless"
 )
 
 type initFunc (func() (persistapi.PersistDriver, error))
 
+const (
+	RootFSName     = "fs"
+	RootlessFSName = "rootlessfs"
+)
+
 var (
 	// NewStoreFeature is an experimental feature
 	NewStoreFeature = exp.Feature{
@@ -25,16 +32,22 @@ var (
 	expErr           error
 	supportedDrivers = map[string]initFunc{
 
-		"fs": fs.Init,
+		RootFSName:     fs.Init,
+		RootlessFSName: fs.RootlessInit,
 	}
+	mockTesting = false
 )
 
 func init() {
 	expErr = exp.Register(NewStoreFeature)
 }
 
+func EnableMockTesting() {
+	mockTesting = true
+}
+
 // GetDriver returns new PersistDriver according to driver name
-func GetDriver(name string) (persistapi.PersistDriver, error) {
+func GetDriverByName(name string) (persistapi.PersistDriver, error) {
 	if expErr != nil {
 		return nil, expErr
 	}
@@ -45,3 +58,28 @@ func GetDriver(name string) (persistapi.PersistDriver, error) {
 
 	return nil, fmt.Errorf("failed to get storage driver %q", name)
 }
+
+// GetDriver returns new PersistDriver according to current needs.
+// For example, a rootless FS driver is returned if the process is running
+// as unprivileged process.
+func GetDriver() (persistapi.PersistDriver, error) {
+	if expErr != nil {
+		return nil, expErr
+	}
+
+	if mockTesting {
+		return fs.MockFSInit()
+	}
+
+	if rootless.IsRootless() {
+		if f, ok := supportedDrivers[RootlessFSName]; ok {
+			return f()
+		}
+	}
+
+	if f, ok := supportedDrivers[RootFSName]; ok {
+		return f()
+	}
+
+	return nil, fmt.Errorf("Could not find a FS driver")
+}

virtcontainers/persist/manager_test.go

@@ -1,4 +1,5 @@
 // Copyright (c) 2019 Huawei Corporation
+// Copyright (c) 2020 Intel Corporation
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -6,17 +7,51 @@
 package persist
 
 import (
+	"os"
 	"testing"
 
+	persistapi "github.com/kata-containers/runtime/virtcontainers/persist/api"
+	"github.com/kata-containers/runtime/virtcontainers/persist/fs"
 	"github.com/stretchr/testify/assert"
 )
 
-func TestGetDriver(t *testing.T) {
-	nonexist, err := GetDriver("non-exist")
+func TestGetDriverByName(t *testing.T) {
+	nonexist, err := GetDriverByName("non-exist")
 	assert.NotNil(t, err)
 	assert.Nil(t, nonexist)
 
-	fsDriver, err := GetDriver("fs")
+	fsDriver, err := GetDriverByName("fs")
 	assert.Nil(t, err)
 	assert.NotNil(t, fsDriver)
 }
+
+func TestGetDriver(t *testing.T) {
+	assert := assert.New(t)
+	orgMockTesting := mockTesting
+	defer func() {
+		mockTesting = orgMockTesting
+	}()
+
+	mockTesting = false
+
+	fsd, err := GetDriver()
+	assert.NoError(err)
+
+	var expectedFS persistapi.PersistDriver
+	if os.Getuid() != 0 {
+		expectedFS, err = fs.RootlessInit()
+	} else {
+		expectedFS, err = fs.Init()
+	}
+
+	assert.NoError(err)
+	assert.Equal(expectedFS, fsd)
+
+	// Testing mock driver
+	mockTesting = true
+	fsd, err = GetDriver()
+	assert.NoError(err)
+	expectedFS, err = fs.MockFSInit()
+	assert.NoError(err)
+	assert.Equal(expectedFS, fsd)
+}