lfsutil: add `Storager` interface and local storage (#6083)

* Add Storager interface

* Add tests

* Add back note

* Add tests for basic protocol routes

* Fix lint errors

1 files changed, 88 insertions, 5 deletions

diff --git a/internal/lfsutil/storage.go b/internal/lfsutil/storage.go
index b2bfe37f..a357b8a8 100644
--- a/internal/lfsutil/storage.go
+++ b/internal/lfsutil/storage.go
@@ -5,9 +5,31 @@
 package lfsutil
 
 import (
+	"io"
+	"os"
 	"path/filepath"
+
+	"github.com/pkg/errors"
+
+	"gogs.io/gogs/internal/osutil"
 )
 
+var ErrObjectNotExist = errors.New("Object does not exist")
+
+// Storager is an storage backend for uploading and downloading LFS objects.
+type Storager interface {
+	// Storage returns the name of the storage backend.
+	Storage() Storage
+	// Upload reads content from the io.ReadCloser and uploads as given oid.
+	// The reader is closed once upload is finished. ErrInvalidOID is returned
+	// if the given oid is not valid.
+	Upload(oid OID, rc io.ReadCloser) (int64, error)
+	// Download streams content of given oid to the io.Writer. It is caller's
+	// responsibility the close the writer when needed. ErrObjectNotExist is
+	// returned if the given oid does not exist.
+	Download(oid OID, w io.Writer) error
+}
+
 // Storage is the storage type of an LFS object.
 type Storage string
 
@@ -15,12 +37,73 @@ const (
 	StorageLocal Storage = "local"
 )
 
-// StorageLocalPath returns computed file path for storing object on local file system.
-// It returns empty string if given "oid" isn't valid.
-func StorageLocalPath(root string, oid OID) string {
-	if !ValidOID(oid) {
+var _ Storager = (*LocalStorage)(nil)
+
+// LocalStorage is a LFS storage backend on local file system.
+type LocalStorage struct {
+	// The root path for storing LFS objects.
+	Root string
+}
+
+func (s *LocalStorage) Storage() Storage {
+	return StorageLocal
+}
+
+func (s *LocalStorage) storagePath(oid OID) string {
+	if len(oid) < 2 {
 		return ""
 	}
 
-	return filepath.Join(root, string(oid[0]), string(oid[1]), string(oid))
+	return filepath.Join(s.Root, string(oid[0]), string(oid[1]), string(oid))
+}
+
+func (s *LocalStorage) Upload(oid OID, rc io.ReadCloser) (int64, error) {
+	if !ValidOID(oid) {
+		return 0, ErrInvalidOID
+	}
+
+	var err error
+	fpath := s.storagePath(oid)
+	defer func() {
+		rc.Close()
+
+		if err != nil {
+			_ = os.Remove(fpath)
+		}
+	}()
+
+	err = os.MkdirAll(filepath.Dir(fpath), os.ModePerm)
+	if err != nil {
+		return 0, errors.Wrap(err, "create directories")
+	}
+	w, err := os.Create(fpath)
+	if err != nil {
+		return 0, errors.Wrap(err, "create file")
+	}
+	defer w.Close()
+
+	written, err := io.Copy(w, rc)
+	if err != nil {
+		return 0, errors.Wrap(err, "copy file")
+	}
+	return written, nil
+}
+
+func (s *LocalStorage) Download(oid OID, w io.Writer) error {
+	fpath := s.storagePath(oid)
+	if !osutil.IsFile(fpath) {
+		return ErrObjectNotExist
+	}
+
+	r, err := os.Open(fpath)
+	if err != nil {
+		return errors.Wrap(err, "open file")
+	}
+	defer r.Close()
+
+	_, err = io.Copy(w, r)
+	if err != nil {
+		return errors.Wrap(err, "copy file")
+	}
+	return nil
 }