Handle external mounts outside of lxc

graphdriver/driver.go

@@ -6,6 +6,8 @@ import (
 	"github.com/dotcloud/docker/utils"
 	"os"
 	"path"
+	"strings"
+	"syscall"
 )
 
 type InitFunc func(root string) (Driver, error)
@@ -31,6 +33,13 @@ type Differ interface {
 	DiffSize(id string) (bytes int64, err error)
 }
 
+type Mount struct {
+	Device  string
+	Target  string
+	Type    string
+	Options string
+}
+
 var (
 	DefaultDriver string
 	// All registred drivers
@@ -88,3 +97,91 @@ func New(root string) (driver Driver, err error) {
 	}
 	return nil, err
 }
+
+func (m *Mount) Mount(root string) error {
+	var (
+		flag   int
+		data   []string
+		target = path.Join(root, m.Target)
+	)
+
+	if mounted, err := Mounted(target); err != nil || mounted {
+		return err
+	}
+
+	flags := map[string]struct {
+		clear bool
+		flag  int
+	}{
+		"defaults":      {false, 0},
+		"ro":            {false, syscall.MS_RDONLY},
+		"rw":            {true, syscall.MS_RDONLY},
+		"suid":          {true, syscall.MS_NOSUID},
+		"nosuid":        {false, syscall.MS_NOSUID},
+		"dev":           {true, syscall.MS_NODEV},
+		"nodev":         {false, syscall.MS_NODEV},
+		"exec":          {true, syscall.MS_NOEXEC},
+		"noexec":        {false, syscall.MS_NOEXEC},
+		"sync":          {false, syscall.MS_SYNCHRONOUS},
+		"async":         {true, syscall.MS_SYNCHRONOUS},
+		"dirsync":       {false, syscall.MS_DIRSYNC},
+		"remount":       {false, syscall.MS_REMOUNT},
+		"mand":          {false, syscall.MS_MANDLOCK},
+		"nomand":        {true, syscall.MS_MANDLOCK},
+		"atime":         {true, syscall.MS_NOATIME},
+		"noatime":       {false, syscall.MS_NOATIME},
+		"diratime":      {true, syscall.MS_NODIRATIME},
+		"nodiratime":    {false, syscall.MS_NODIRATIME},
+		"bind":          {false, syscall.MS_BIND},
+		"rbind":         {false, syscall.MS_BIND | syscall.MS_REC},
+		"relatime":      {false, syscall.MS_RELATIME},
+		"norelatime":    {true, syscall.MS_RELATIME},
+		"strictatime":   {false, syscall.MS_STRICTATIME},
+		"nostrictatime": {true, syscall.MS_STRICTATIME},
+	}
+
+	for _, o := range strings.Split(m.Options, ",") {
+		// If the option does not exist in the flags table then it is a
+		// data value for a specific fs type
+		if f, exists := flags[o]; exists {
+			if f.clear {
+				flag &= ^f.flag
+			} else {
+				flag |= f.flag
+			}
+		} else {
+			data = append(data, o)
+		}
+	}
+
+	if err := syscall.Mount(m.Device, target, m.Type, uintptr(flag), strings.Join(data, ",")); err != nil {
+		panic(err)
+	}
+	return nil
+}
+
+func (m *Mount) Unmount(root string) error {
+	target := path.Join(root, m.Target)
+	if mounted, err := Mounted(target); err != nil || !mounted {
+		return err
+	}
+	return syscall.Unmount(target, 0)
+}
+
+func Mounted(mountpoint string) (bool, error) {
+	mntpoint, err := os.Stat(mountpoint)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	parent, err := os.Stat(path.Join(mountpoint, ".."))
+	if err != nil {
+		return false, err
+	}
+	mntpointSt := mntpoint.Sys().(*syscall.Stat_t)
+	parentSt := parent.Sys().(*syscall.Stat_t)
+
+	return mntpointSt.Dev != parentSt.Dev, nil
+}