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