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7a7357dae1
This enables docker cp and ADD/COPY docker build support for LCOW. Originally, the graphdriver.Get() interface returned a local path to the container root filesystem. This does not work for LCOW, so the Get() method now returns an interface that LCOW implements to support copying to and from the container. Signed-off-by: Akash Gupta <akagup@microsoft.com>
132 lines
4.1 KiB
Go
132 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/docker/docker/daemon/graphdriver"
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"github.com/docker/docker/pkg/chrootarchive"
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"github.com/docker/docker/pkg/containerfs"
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"github.com/docker/docker/pkg/idtools"
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"github.com/docker/docker/pkg/system"
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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.NewArchiver(nil).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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idMappings: idtools.NewIDMappingsFromMaps(uidMaps, gidMaps),
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}
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rootIDs := d.idMappings.RootPair()
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if err := idtools.MkdirAllAndChown(home, 0700, rootIDs); 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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idMappings *idtools.IDMappings
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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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// GetMetadata is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any meta data.
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func (d *Driver) GetMetadata(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 string, opts *graphdriver.CreateOpts) error {
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return d.Create(id, parent, opts)
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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 string, opts *graphdriver.CreateOpts) error {
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if opts != nil && len(opts.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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rootIDs := d.idMappings.RootPair()
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if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0700, rootIDs); err != nil {
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return err
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}
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if err := idtools.MkdirAndChown(dir, 0755, rootIDs); err != nil {
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return err
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}
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labelOpts := []string{"level:s0"}
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if _, mountLabel, err := label.InitLabels(labelOpts); 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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return CopyWithTar(parentDir.Path(), dir)
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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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return system.EnsureRemoveAll(d.dir(id))
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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) (containerfs.ContainerFS, 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 nil, err
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} else if !st.IsDir() {
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return nil, fmt.Errorf("%s: not a directory", dir)
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}
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return containerfs.NewLocalContainerFS(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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