data/pieceStore: Expose flags in Open method

data/pieceStore/dataBackend/fileCache/backend.go

@@ -39,8 +39,8 @@ func (me *backend) GetLength(path string) (ret int64, err error) {
 	return
 }
 
-func (me *backend) Open(path string) (ret dataBackend.File, err error) {
+func (me *backend) Open(path string, flag int) (ret dataBackend.File, err error) {
-	ret, err = me.c.OpenFile(path, os.O_RDWR|os.O_CREATE)
+	ret, err = me.c.OpenFile(path, flag)
 	return
 }
 

data/pieceStore/dataBackend/http/backend.go

@@ -52,8 +52,8 @@ func (me *backend) GetLength(path string) (ret int64, err error) {
 	return
 }
 
-func (me *backend) Open(path string) (ret dataBackend.File, err error) {
+func (me *backend) Open(path string, flag int) (ret dataBackend.File, err error) {
-	ret = httpfile.Open(me.urlStr(path))
+	ret = httpfile.Open(me.urlStr(path), flag)
 	err = fixErrNotFound(err)
 	return
 }

data/pieceStore/dataBackend/i.go

@@ -8,7 +8,7 @@ import (
 // All functions must return ErrNotFound as required.
 type I interface {
 	GetLength(path string) (int64, error)
-	Open(path string) (File, error)
+	Open(path string, flags int) (File, error)
 	OpenSection(path string, off, n int64) (io.ReadCloser, error)
 	Delete(path string) error
 }
@@ -19,4 +19,5 @@ type File interface {
 	io.Closer
 	io.Seeker
 	io.Writer
+	io.Reader
 }

data/pieceStore/store.go

@@ -141,7 +141,7 @@ func (me *store) pieceWriteAt(p metainfo.Piece, b []byte, off int64) (n int, err
 	defer func() {
 		<-me.requestPool
 	}()
-	f, err := me.db.Open(me.incompletePiecePath(p))
+	f, err := me.db.Open(me.incompletePiecePath(p), os.O_WRONLY|os.O_CREATE)
 	if err != nil {
 		return
 	}
@@ -264,7 +264,7 @@ func (me *store) hashCopyFile(from, to string, n int64) (hash []byte, err error)
 	defer src.Close()
 	hasher := sha1.New()
 	tee := io.TeeReader(src, hasher)
-	dest, err := me.db.Open(to)
+	dest, err := me.db.Open(to, os.O_WRONLY|os.O_CREATE)
 	if err != nil {
 		return
 	}