package vfs import ( "fmt" "os" "path/filepath" "github.com/docker/docker/daemon/graphdriver" "github.com/docker/docker/pkg/chrootarchive" "github.com/docker/docker/pkg/idtools" "github.com/docker/docker/pkg/system" "github.com/opencontainers/selinux/go-selinux/label" ) var ( // CopyWithTar defines the copy method to use. CopyWithTar = chrootarchive.NewArchiver(nil).CopyWithTar ) func init() { graphdriver.Register("vfs", Init) } // Init returns a new VFS driver. // This sets the home directory for the driver and returns NaiveDiffDriver. func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) { d := &Driver{ home: home, idMappings: idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), } rootIDs := d.idMappings.RootPair() if err := idtools.MkdirAllAndChown(home, 0700, rootIDs); err != nil { return nil, err } return graphdriver.NewNaiveDiffDriver(d, uidMaps, gidMaps), nil } // Driver holds information about the driver, home directory of the driver. // Driver implements graphdriver.ProtoDriver. It uses only basic vfs operations. // In order to support layering, files are copied from the parent layer into the new layer. There is no copy-on-write support. // Driver must be wrapped in NaiveDiffDriver to be used as a graphdriver.Driver type Driver struct { home string idMappings *idtools.IDMappings } func (d *Driver) String() string { return "vfs" } // Status is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any status information. func (d *Driver) Status() [][2]string { return nil } // GetMetadata is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any meta data. func (d *Driver) GetMetadata(id string) (map[string]string, error) { return nil, nil } // Cleanup is used to implement graphdriver.ProtoDriver. There is no cleanup required for this driver. func (d *Driver) Cleanup() error { return nil } // CreateReadWrite creates a layer that is writable for use as a container // file system. func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error { return d.Create(id, parent, opts) } // Create prepares the filesystem for the VFS driver and copies the directory for the given id under the parent. func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error { if opts != nil && len(opts.StorageOpt) != 0 { return fmt.Errorf("--storage-opt is not supported for vfs") } dir := d.dir(id) rootIDs := d.idMappings.RootPair() if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0700, rootIDs); err != nil { return err } if err := idtools.MkdirAndChown(dir, 0755, rootIDs); err != nil { return err } labelOpts := []string{"level:s0"} if _, mountLabel, err := label.InitLabels(labelOpts); err == nil { label.SetFileLabel(dir, mountLabel) } if parent == "" { return nil } parentDir, err := d.Get(parent, "") if err != nil { return fmt.Errorf("%s: %s", parent, err) } return CopyWithTar(parentDir, dir) } func (d *Driver) dir(id string) string { return filepath.Join(d.home, "dir", filepath.Base(id)) } // Remove deletes the content from the directory for a given id. func (d *Driver) Remove(id string) error { if err := system.EnsureRemoveAll(d.dir(id)); err != nil { return err } return nil } // Get returns the directory for the given id. func (d *Driver) Get(id, mountLabel string) (string, error) { dir := d.dir(id) if st, err := os.Stat(dir); err != nil { return "", err } else if !st.IsDir() { return "", fmt.Errorf("%s: not a directory", dir) } return dir, nil } // Put is a noop for vfs that return nil for the error, since this driver has no runtime resources to clean up. func (d *Driver) Put(id string) error { // The vfs driver has no runtime resources (e.g. mounts) // to clean up, so we don't need anything here return nil } // Exists checks to see if the directory exists for the given id. func (d *Driver) Exists(id string) bool { _, err := os.Stat(d.dir(id)) return err == nil }