virtcontainers: change container's rootfs from string to mount alike struct

container's rootfs is a string type, which cannot represent a
block storage backed rootfs which hasn't been mounted.
Change it to a mount alike struct as below:
    RootFs struct {
            // Source specify the BlockDevice path
            Source string
            // Target specify where the rootfs is mounted if it has been mounted
            Target string
            // Type specifies the type of filesystem to mount.
            Type string
            // Options specifies zero or more fstab style mount options.
            Options []string
            // Mounted specifies whether the rootfs has be mounted or not
            Mounted bool
     }

If the container's rootfs has been mounted as before, then this struct can be
initialized as: RootFs{Target: <rootfs>, Mounted: true} to be compatible with
previous case.

Fixes:#1158

Signed-off-by: lifupan <lifupan@gmail.com>

pkg/katautils/create.go

@@ -164,7 +164,7 @@ func SetEphemeralStorageType(ociSpec oci.CompatOCISpec) oci.CompatOCISpec {
 }
 
 // CreateSandbox create a sandbox container
-func CreateSandbox(ctx context.Context, vci vc.VC, ociSpec oci.CompatOCISpec, runtimeConfig oci.RuntimeConfig,
+func CreateSandbox(ctx context.Context, vci vc.VC, ociSpec oci.CompatOCISpec, runtimeConfig oci.RuntimeConfig, rootFs vc.RootFs,
 	containerID, bundlePath, console string, disableOutput, systemdCgroup, builtIn bool) (vc.VCSandbox, vc.Process, error) {
 	span, ctx := Trace(ctx, "createSandbox")
 	defer span.Finish()
@@ -178,6 +178,17 @@ func CreateSandbox(ctx context.Context, vci vc.VC, ociSpec oci.CompatOCISpec, ru
 		sandboxConfig.Stateful = true
 	}
 
+	if !rootFs.Mounted && len(sandboxConfig.Containers) == 1 {
+		if rootFs.Source != "" {
+			realPath, err := ResolvePath(rootFs.Source)
+			if err != nil {
+				return nil, vc.Process{}, err
+			}
+			rootFs.Source = realPath
+		}
+		sandboxConfig.Containers[0].RootFs = rootFs
+	}
+
 	// Important to create the network namespace before the sandbox is
 	// created, because it is not responsible for the creation of the
 	// netns if it does not exist.
@@ -218,7 +229,7 @@ func CreateSandbox(ctx context.Context, vci vc.VC, ociSpec oci.CompatOCISpec, ru
 }
 
 // CreateContainer create a container
-func CreateContainer(ctx context.Context, vci vc.VC, sandbox vc.VCSandbox, ociSpec oci.CompatOCISpec, containerID, bundlePath, console string, disableOutput, builtIn bool) (vc.Process, error) {
+func CreateContainer(ctx context.Context, vci vc.VC, sandbox vc.VCSandbox, ociSpec oci.CompatOCISpec, rootFs vc.RootFs, containerID, bundlePath, console string, disableOutput, builtIn bool) (vc.Process, error) {
 	var c vc.VCContainer
 
 	span, ctx := Trace(ctx, "createContainer")
@@ -231,6 +242,17 @@ func CreateContainer(ctx context.Context, vci vc.VC, sandbox vc.VCSandbox, ociSp
 		return vc.Process{}, err
 	}
 
+	if !rootFs.Mounted {
+		if rootFs.Source != "" {
+			realPath, err := ResolvePath(rootFs.Source)
+			if err != nil {
+				return vc.Process{}, err
+			}
+			rootFs.Source = realPath
+		}
+		contConfig.RootFs = rootFs
+	}
+
 	sandboxID, err := ociSpec.SandboxID()
 	if err != nil {
 		return vc.Process{}, err

pkg/katautils/create_test.go

@@ -306,7 +306,9 @@ func TestCreateSandboxConfigFail(t *testing.T) {
 		Quota: &quota,
 	}
 
-	_, _, err = CreateSandbox(context.Background(), testingImpl, spec, runtimeConfig, testContainerID, bundlePath, testConsole, true, true, false)
+	rootFs := vc.RootFs{Mounted: true}
+
+	_, _, err = CreateSandbox(context.Background(), testingImpl, spec, runtimeConfig, rootFs, testContainerID, bundlePath, testConsole, true, true, false)
 	assert.Error(err)
 }
 
@@ -340,7 +342,9 @@ func TestCreateSandboxFail(t *testing.T) {
 	spec, err := readOCIConfigFile(ociConfigFile)
 	assert.NoError(err)
 
-	_, _, err = CreateSandbox(context.Background(), testingImpl, spec, runtimeConfig, testContainerID, bundlePath, testConsole, true, true, false)
+	rootFs := vc.RootFs{Mounted: true}
+
+	_, _, err = CreateSandbox(context.Background(), testingImpl, spec, runtimeConfig, rootFs, testContainerID, bundlePath, testConsole, true, true, false)
 	assert.Error(err)
 	assert.True(vcmock.IsMockError(err))
 }
@@ -377,8 +381,10 @@ func TestCreateContainerContainerConfigFail(t *testing.T) {
 	err = writeOCIConfigFile(spec, ociConfigFile)
 	assert.NoError(err)
 
+	rootFs := vc.RootFs{Mounted: true}
+
 	for _, disableOutput := range []bool{true, false} {
-		_, err = CreateContainer(context.Background(), testingImpl, nil, spec, testContainerID, bundlePath, testConsole, disableOutput, false)
+		_, err = CreateContainer(context.Background(), testingImpl, nil, spec, rootFs, testContainerID, bundlePath, testConsole, disableOutput, false)
 		assert.Error(err)
 		assert.False(vcmock.IsMockError(err))
 		assert.True(strings.Contains(err.Error(), containerType))
@@ -418,8 +424,10 @@ func TestCreateContainerFail(t *testing.T) {
 	err = writeOCIConfigFile(spec, ociConfigFile)
 	assert.NoError(err)
 
+	rootFs := vc.RootFs{Mounted: true}
+
 	for _, disableOutput := range []bool{true, false} {
-		_, err = CreateContainer(context.Background(), testingImpl, nil, spec, testContainerID, bundlePath, testConsole, disableOutput, false)
+		_, err = CreateContainer(context.Background(), testingImpl, nil, spec, rootFs, testContainerID, bundlePath, testConsole, disableOutput, false)
 		assert.Error(err)
 		assert.True(vcmock.IsMockError(err))
 		os.RemoveAll(path)
@@ -466,8 +474,10 @@ func TestCreateContainer(t *testing.T) {
 	err = writeOCIConfigFile(spec, ociConfigFile)
 	assert.NoError(err)
 
+	rootFs := vc.RootFs{Mounted: true}
+
 	for _, disableOutput := range []bool{true, false} {
-		_, err = CreateContainer(context.Background(), testingImpl, nil, spec, testContainerID, bundlePath, testConsole, disableOutput, false)
+		_, err = CreateContainer(context.Background(), testingImpl, nil, spec, rootFs, testContainerID, bundlePath, testConsole, disableOutput, false)
 		assert.NoError(err)
 		os.RemoveAll(path)
 	}

pkg/katautils/utils.go

@@ -8,6 +8,7 @@ package katautils
 
 import (
 	"fmt"
+	"golang.org/x/sys/unix"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -78,6 +79,29 @@ func ResolvePath(path string) (string, error) {
 	return resolved, nil
 }
 
+// IsBlockDevice returns true if the give path is a block device
+func IsBlockDevice(filePath string) bool {
+	var stat unix.Stat_t
+
+	if filePath == "" {
+		return false
+	}
+
+	devicePath, err := ResolvePath(filePath)
+	if err != nil {
+		return false
+	}
+
+	if err := unix.Stat(devicePath, &stat); err != nil {
+		return false
+	}
+
+	if stat.Mode&unix.S_IFBLK == unix.S_IFBLK {
+		return true
+	}
+	return false
+}
+
 // fileSize returns the number of bytes in the specified file
 func fileSize(file string) (int64, error) {
 	st := syscall.Stat_t{}