Initial commit

vendor/github.com/hyperhq/hypercli/image/fs.go

@@ -0,0 +1,184 @@
+package image
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution/digest"
+)
+
+// IDWalkFunc is function called by StoreBackend.Walk
+type IDWalkFunc func(id ID) error
+
+// StoreBackend provides interface for image.Store persistence
+type StoreBackend interface {
+	Walk(f IDWalkFunc) error
+	Get(id ID) ([]byte, error)
+	Set(data []byte) (ID, error)
+	Delete(id ID) error
+	SetMetadata(id ID, key string, data []byte) error
+	GetMetadata(id ID, key string) ([]byte, error)
+	DeleteMetadata(id ID, key string) error
+}
+
+// fs implements StoreBackend using the filesystem.
+type fs struct {
+	sync.RWMutex
+	root string
+}
+
+const (
+	contentDirName  = "content"
+	metadataDirName = "metadata"
+)
+
+// NewFSStoreBackend returns new filesystem based backend for image.Store
+func NewFSStoreBackend(root string) (StoreBackend, error) {
+	return newFSStore(root)
+}
+
+func newFSStore(root string) (*fs, error) {
+	s := &fs{
+		root: root,
+	}
+	if err := os.MkdirAll(filepath.Join(root, contentDirName, string(digest.Canonical)), 0700); err != nil {
+		return nil, err
+	}
+	if err := os.MkdirAll(filepath.Join(root, metadataDirName, string(digest.Canonical)), 0700); err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+func (s *fs) contentFile(id ID) string {
+	dgst := digest.Digest(id)
+	return filepath.Join(s.root, contentDirName, string(dgst.Algorithm()), dgst.Hex())
+}
+
+func (s *fs) metadataDir(id ID) string {
+	dgst := digest.Digest(id)
+	return filepath.Join(s.root, metadataDirName, string(dgst.Algorithm()), dgst.Hex())
+}
+
+// Walk calls the supplied callback for each image ID in the storage backend.
+func (s *fs) Walk(f IDWalkFunc) error {
+	// Only Canonical digest (sha256) is currently supported
+	s.RLock()
+	dir, err := ioutil.ReadDir(filepath.Join(s.root, contentDirName, string(digest.Canonical)))
+	s.RUnlock()
+	if err != nil {
+		return err
+	}
+	for _, v := range dir {
+		dgst := digest.NewDigestFromHex(string(digest.Canonical), v.Name())
+		if err := dgst.Validate(); err != nil {
+			logrus.Debugf("Skipping invalid digest %s: %s", dgst, err)
+			continue
+		}
+		if err := f(ID(dgst)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Get returns the content stored under a given ID.
+func (s *fs) Get(id ID) ([]byte, error) {
+	s.RLock()
+	defer s.RUnlock()
+
+	return s.get(id)
+}
+
+func (s *fs) get(id ID) ([]byte, error) {
+	content, err := ioutil.ReadFile(s.contentFile(id))
+	if err != nil {
+		return nil, err
+	}
+
+	// todo: maybe optional
+	if ID(digest.FromBytes(content)) != id {
+		return nil, fmt.Errorf("failed to verify image: %v", id)
+	}
+
+	return content, nil
+}
+
+// Set stores content under a given ID.
+func (s *fs) Set(data []byte) (ID, error) {
+	s.Lock()
+	defer s.Unlock()
+
+	if len(data) == 0 {
+		return "", fmt.Errorf("Invalid empty data")
+	}
+
+	id := ID(digest.FromBytes(data))
+	filePath := s.contentFile(id)
+	tempFilePath := s.contentFile(id) + ".tmp"
+	if err := ioutil.WriteFile(tempFilePath, data, 0600); err != nil {
+		return "", err
+	}
+	if err := os.Rename(tempFilePath, filePath); err != nil {
+		return "", err
+	}
+
+	return id, nil
+}
+
+// Delete removes content and metadata files associated with the ID.
+func (s *fs) Delete(id ID) error {
+	s.Lock()
+	defer s.Unlock()
+
+	if err := os.RemoveAll(s.metadataDir(id)); err != nil {
+		return err
+	}
+	if err := os.Remove(s.contentFile(id)); err != nil {
+		return err
+	}
+	return nil
+}
+
+// SetMetadata sets metadata for a given ID. It fails if there's no base file.
+func (s *fs) SetMetadata(id ID, key string, data []byte) error {
+	s.Lock()
+	defer s.Unlock()
+	if _, err := s.get(id); err != nil {
+		return err
+	}
+
+	baseDir := filepath.Join(s.metadataDir(id))
+	if err := os.MkdirAll(baseDir, 0700); err != nil {
+		return err
+	}
+	filePath := filepath.Join(s.metadataDir(id), key)
+	tempFilePath := filePath + ".tmp"
+	if err := ioutil.WriteFile(tempFilePath, data, 0600); err != nil {
+		return err
+	}
+	return os.Rename(tempFilePath, filePath)
+}
+
+// GetMetadata returns metadata for a given ID.
+func (s *fs) GetMetadata(id ID, key string) ([]byte, error) {
+	s.RLock()
+	defer s.RUnlock()
+
+	if _, err := s.get(id); err != nil {
+		return nil, err
+	}
+	return ioutil.ReadFile(filepath.Join(s.metadataDir(id), key))
+}
+
+// DeleteMetadata removes the metadata associated with an ID.
+func (s *fs) DeleteMetadata(id ID, key string) error {
+	s.Lock()
+	defer s.Unlock()
+
+	return os.RemoveAll(filepath.Join(s.metadataDir(id), key))
+}