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176 lines
4.6 KiB
Go
176 lines
4.6 KiB
Go
package image // import "github.com/docker/docker/image"
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import (
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"sync"
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"github.com/docker/docker/pkg/ioutils"
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"github.com/opencontainers/go-digest"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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)
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// DigestWalkFunc is function called by StoreBackend.Walk
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type DigestWalkFunc func(id digest.Digest) error
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// StoreBackend provides interface for image.Store persistence
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type StoreBackend interface {
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Walk(f DigestWalkFunc) error
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Get(id digest.Digest) ([]byte, error)
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Set(data []byte) (digest.Digest, error)
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Delete(id digest.Digest) error
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SetMetadata(id digest.Digest, key string, data []byte) error
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GetMetadata(id digest.Digest, key string) ([]byte, error)
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DeleteMetadata(id digest.Digest, key string) error
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}
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// fs implements StoreBackend using the filesystem.
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type fs struct {
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sync.RWMutex
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root string
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}
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const (
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contentDirName = "content"
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metadataDirName = "metadata"
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)
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// NewFSStoreBackend returns new filesystem based backend for image.Store
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func NewFSStoreBackend(root string) (StoreBackend, error) {
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return newFSStore(root)
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}
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func newFSStore(root string) (*fs, error) {
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s := &fs{
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root: root,
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}
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if err := os.MkdirAll(filepath.Join(root, contentDirName, string(digest.Canonical)), 0700); err != nil {
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return nil, errors.Wrap(err, "failed to create storage backend")
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}
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if err := os.MkdirAll(filepath.Join(root, metadataDirName, string(digest.Canonical)), 0700); err != nil {
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return nil, errors.Wrap(err, "failed to create storage backend")
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}
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return s, nil
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}
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func (s *fs) contentFile(dgst digest.Digest) string {
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return filepath.Join(s.root, contentDirName, string(dgst.Algorithm()), dgst.Hex())
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}
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func (s *fs) metadataDir(dgst digest.Digest) string {
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return filepath.Join(s.root, metadataDirName, string(dgst.Algorithm()), dgst.Hex())
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}
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// Walk calls the supplied callback for each image ID in the storage backend.
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func (s *fs) Walk(f DigestWalkFunc) error {
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// Only Canonical digest (sha256) is currently supported
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s.RLock()
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dir, err := ioutil.ReadDir(filepath.Join(s.root, contentDirName, string(digest.Canonical)))
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s.RUnlock()
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if err != nil {
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return err
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}
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for _, v := range dir {
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dgst := digest.NewDigestFromHex(string(digest.Canonical), v.Name())
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if err := dgst.Validate(); err != nil {
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logrus.Debugf("skipping invalid digest %s: %s", dgst, err)
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continue
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}
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if err := f(dgst); err != nil {
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return err
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}
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}
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return nil
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}
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// Get returns the content stored under a given digest.
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func (s *fs) Get(dgst digest.Digest) ([]byte, error) {
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s.RLock()
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defer s.RUnlock()
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return s.get(dgst)
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}
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func (s *fs) get(dgst digest.Digest) ([]byte, error) {
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content, err := ioutil.ReadFile(s.contentFile(dgst))
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if err != nil {
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return nil, errors.Wrapf(err, "failed to get digest %s", dgst)
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}
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// todo: maybe optional
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if digest.FromBytes(content) != dgst {
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return nil, fmt.Errorf("failed to verify: %v", dgst)
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}
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return content, nil
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}
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// Set stores content by checksum.
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func (s *fs) Set(data []byte) (digest.Digest, error) {
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s.Lock()
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defer s.Unlock()
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if len(data) == 0 {
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return "", fmt.Errorf("invalid empty data")
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}
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dgst := digest.FromBytes(data)
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if err := ioutils.AtomicWriteFile(s.contentFile(dgst), data, 0600); err != nil {
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return "", errors.Wrap(err, "failed to write digest data")
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}
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return dgst, nil
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}
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// Delete removes content and metadata files associated with the digest.
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func (s *fs) Delete(dgst digest.Digest) error {
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s.Lock()
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defer s.Unlock()
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if err := os.RemoveAll(s.metadataDir(dgst)); err != nil {
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return err
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}
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return os.Remove(s.contentFile(dgst))
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}
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// SetMetadata sets metadata for a given ID. It fails if there's no base file.
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func (s *fs) SetMetadata(dgst digest.Digest, key string, data []byte) error {
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s.Lock()
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defer s.Unlock()
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if _, err := s.get(dgst); err != nil {
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return err
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}
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baseDir := filepath.Join(s.metadataDir(dgst))
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if err := os.MkdirAll(baseDir, 0700); err != nil {
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return err
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}
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return ioutils.AtomicWriteFile(filepath.Join(s.metadataDir(dgst), key), data, 0600)
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}
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// GetMetadata returns metadata for a given digest.
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func (s *fs) GetMetadata(dgst digest.Digest, key string) ([]byte, error) {
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s.RLock()
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defer s.RUnlock()
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if _, err := s.get(dgst); err != nil {
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return nil, err
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}
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bytes, err := ioutil.ReadFile(filepath.Join(s.metadataDir(dgst), key))
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if err != nil {
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return nil, errors.Wrap(err, "failed to read metadata")
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}
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return bytes, nil
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}
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// DeleteMetadata removes the metadata associated with a digest.
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func (s *fs) DeleteMetadata(dgst digest.Digest, key string) error {
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s.Lock()
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defer s.Unlock()
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return os.RemoveAll(filepath.Join(s.metadataDir(dgst), key))
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}
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