virtcontainers: move GetDevicePathAndFsType to utils_linux

`GetDevicePathAndFsType` is a function to get the path and filesystem type
of a mount point from `/proc/mounts`.
Move `GetDevicePathAndFsType` to utils_linux since it's linux specific
and that way it can be used in other subpackages.

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

virtcontainers/container.go

@@ -1323,7 +1323,7 @@ func (c *Container) hotplugDrive() error {
 			c.rootfsSuffix = ""
 		}
 		// If device mapper device, then fetch the full path of the device
-		devicePath, fsType, err = GetDevicePathAndFsType(dev.mountPoint)
+		devicePath, fsType, err = utils.GetDevicePathAndFsType(dev.mountPoint)
 		if err != nil {
 			return err
 		}

virtcontainers/mount.go

@@ -6,17 +6,16 @@
 package virtcontainers
 
 import (
-	"bufio"
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"os"
 	"path/filepath"
 	"strings"
 	"syscall"
 
 	merr "github.com/hashicorp/go-multierror"
+	"github.com/kata-containers/runtime/virtcontainers/utils"
 	"github.com/sirupsen/logrus"
 )
 
@@ -187,59 +186,6 @@ func getDeviceForPath(path string) (device, error) {
 	return dev, nil
 }
 
-const (
-	procMountsFile = "/proc/mounts"
-
-	fieldsPerLine = 6
-)
-
-const (
-	procDeviceIndex = iota
-	procPathIndex
-	procTypeIndex
-)
-
-// GetDevicePathAndFsType gets the device for the mount point and the file system type
-// of the mount.
-func GetDevicePathAndFsType(mountPoint string) (devicePath, fsType string, err error) {
-	if mountPoint == "" {
-		err = fmt.Errorf("Mount point cannot be empty")
-		return
-	}
-
-	var file *os.File
-
-	file, err = os.Open(procMountsFile)
-	if err != nil {
-		return
-	}
-
-	defer file.Close()
-
-	reader := bufio.NewReader(file)
-	for {
-		var line string
-
-		line, err = reader.ReadString('\n')
-		if err == io.EOF {
-			err = fmt.Errorf("Mount %s not found", mountPoint)
-			return
-		}
-
-		fields := strings.Fields(line)
-		if len(fields) != fieldsPerLine {
-			err = fmt.Errorf("Incorrect no of fields (expected %d, got %d)) :%s", fieldsPerLine, len(fields), line)
-			return
-		}
-
-		if mountPoint == fields[procPathIndex] {
-			devicePath = fields[procDeviceIndex]
-			fsType = fields[procTypeIndex]
-			return
-		}
-	}
-}
-
 var blockFormatTemplate = "/sys/dev/block/%d:%d/dm"
 
 var checkStorageDriver = isDeviceMapper
@@ -445,7 +391,7 @@ func IsEphemeralStorage(path string) bool {
 		return false
 	}
 
-	if _, fsType, _ := GetDevicePathAndFsType(path); fsType == "tmpfs" {
+	if _, fsType, _ := utils.GetDevicePathAndFsType(path); fsType == "tmpfs" {
 		return true
 	}
 
@@ -460,7 +406,7 @@ func Isk8sHostEmptyDir(path string) bool {
 		return false
 	}
 
-	if _, fsType, _ := GetDevicePathAndFsType(path); fsType != "tmpfs" {
+	if _, fsType, _ := utils.GetDevicePathAndFsType(path); fsType != "tmpfs" {
 		return true
 	}
 	return false

virtcontainers/mount_test.go

@@ -206,22 +206,6 @@ func TestGetDeviceForPathBindMount(t *testing.T) {
 	assert.Equal(sourceDev, destDev)
 }
 
-func TestGetDevicePathAndFsTypeEmptyMount(t *testing.T) {
-	assert := assert.New(t)
-	_, _, err := GetDevicePathAndFsType("")
-	assert.Error(err)
-}
-
-func TestGetDevicePathAndFsTypeSuccessful(t *testing.T) {
-	assert := assert.New(t)
-
-	path, fstype, err := GetDevicePathAndFsType("/proc")
-	assert.NoError(err)
-
-	assert.Equal(path, "proc")
-	assert.Equal(fstype, "proc")
-}
-
 func TestIsDeviceMapper(t *testing.T) {
 	assert := assert.New(t)
 

virtcontainers/utils/utils_linux.go

@@ -6,10 +6,13 @@
 package utils
 
 import (
+	"bufio"
 	"crypto/rand"
 	"fmt"
+	"io"
 	"math/big"
 	"os"
+	"strings"
 	"syscall"
 	"unsafe"
 
@@ -85,3 +88,56 @@ func FindContextID() (*os.File, uint64, error) {
 	vsockFd.Close()
 	return nil, 0, fmt.Errorf("Could not get a unique context ID for the vsock : %s", err)
 }
+
+const (
+	procMountsFile = "/proc/mounts"
+
+	fieldsPerLine = 6
+)
+
+const (
+	procDeviceIndex = iota
+	procPathIndex
+	procTypeIndex
+)
+
+// GetDevicePathAndFsType gets the device for the mount point and the file system type
+// of the mount.
+func GetDevicePathAndFsType(mountPoint string) (devicePath, fsType string, err error) {
+	if mountPoint == "" {
+		err = fmt.Errorf("Mount point cannot be empty")
+		return
+	}
+
+	var file *os.File
+
+	file, err = os.Open(procMountsFile)
+	if err != nil {
+		return
+	}
+
+	defer file.Close()
+
+	reader := bufio.NewReader(file)
+	for {
+		var line string
+
+		line, err = reader.ReadString('\n')
+		if err == io.EOF {
+			err = fmt.Errorf("Mount %s not found", mountPoint)
+			return
+		}
+
+		fields := strings.Fields(line)
+		if len(fields) != fieldsPerLine {
+			err = fmt.Errorf("Incorrect no of fields (expected %d, got %d)) :%s", fieldsPerLine, len(fields), line)
+			return
+		}
+
+		if mountPoint == fields[procPathIndex] {
+			devicePath = fields[procDeviceIndex]
+			fsType = fields[procTypeIndex]
+			return
+		}
+	}
+}

virtcontainers/utils/utils_linux_test.go

@@ -33,3 +33,19 @@ func TestFindContextID(t *testing.T) {
 	assert.Zero(cid)
 	assert.Error(err)
 }
+
+func TestGetDevicePathAndFsTypeEmptyMount(t *testing.T) {
+	assert := assert.New(t)
+	_, _, err := GetDevicePathAndFsType("")
+	assert.Error(err)
+}
+
+func TestGetDevicePathAndFsTypeSuccessful(t *testing.T) {
+	assert := assert.New(t)
+
+	path, fstype, err := GetDevicePathAndFsType("/proc")
+	assert.NoError(err)
+
+	assert.Equal(path, "proc")
+	assert.Equal(fstype, "proc")
+}