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109 lines
2.4 KiB
Go
109 lines
2.4 KiB
Go
package graphdriver
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import (
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"errors"
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"fmt"
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"github.com/dotcloud/docker/archive"
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"os"
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"path"
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)
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type FsMagic uint64
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const (
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FsMagicBtrfs = FsMagic(0x9123683E)
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FsMagicAufs = FsMagic(0x61756673)
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)
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type InitFunc func(root string) (Driver, error)
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type Driver interface {
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String() string
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Create(id, parent string) error
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Remove(id string) error
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Get(id, mountLabel string) (dir string, err error)
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Put(id string)
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Exists(id string) bool
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Status() [][2]string
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Cleanup() error
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}
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type Differ interface {
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Diff(id string) (archive.Archive, error)
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Changes(id string) ([]archive.Change, error)
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ApplyDiff(id string, diff archive.ArchiveReader) error
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DiffSize(id string) (bytes int64, err error)
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}
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var (
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DefaultDriver string
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// All registred drivers
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drivers map[string]InitFunc
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// Slice of drivers that should be used in an order
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priority = []string{
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"aufs",
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"btrfs",
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"devicemapper",
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"vfs",
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}
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ErrNotSupported = errors.New("driver not supported")
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ErrPrerequisites = errors.New("prerequisites for driver not satisfied (wrong filesystem?)")
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ErrIncompatibleFS = fmt.Errorf("backing file system is unsupported for this graph driver")
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)
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func init() {
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drivers = make(map[string]InitFunc)
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}
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func Register(name string, initFunc InitFunc) error {
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if _, exists := drivers[name]; exists {
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return fmt.Errorf("Name already registered %s", name)
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}
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drivers[name] = initFunc
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return nil
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}
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func GetDriver(name, home string) (Driver, error) {
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if initFunc, exists := drivers[name]; exists {
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return initFunc(path.Join(home, name))
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}
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return nil, ErrNotSupported
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}
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func New(root string) (driver Driver, err error) {
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for _, name := range []string{os.Getenv("DOCKER_DRIVER"), DefaultDriver} {
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if name != "" {
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return GetDriver(name, root)
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}
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}
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// Check for priority drivers first
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for _, name := range priority {
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driver, err = GetDriver(name, root)
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if err != nil {
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if err == ErrNotSupported || err == ErrPrerequisites || err == ErrIncompatibleFS {
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continue
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}
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return nil, err
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}
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return driver, nil
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}
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// Check all registered drivers if no priority driver is found
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for _, initFunc := range drivers {
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if driver, err = initFunc(root); err != nil {
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if err == ErrNotSupported || err == ErrPrerequisites || err == ErrIncompatibleFS {
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continue
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}
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return nil, err
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}
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return driver, nil
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}
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return nil, fmt.Errorf("No supported storage backend found")
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}
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