Add size to Save function (#15264) (#15271)

Backport #15264

This PR proposes an alternative solution to #15255 - just add the size to the
save function. Yes it is less apparently clean but it may be more correct.

Close #15255
Fix #15253

Signed-off-by: Andrew Thornton <art27@cantab.net>

modules/storage/storage.go

@@ -65,7 +65,8 @@ type Object interface {
 // ObjectStorage represents an object storage to handle a bucket and files
 type ObjectStorage interface {
 	Open(path string) (Object, error)
-	Save(path string, r io.Reader) (int64, error)
+	// Save store a object, if size is unknown set -1
+	Save(path string, r io.Reader, size int64) (int64, error)
 	Stat(path string) (os.FileInfo, error)
 	Delete(path string) error
 	URL(path, name string) (*url.URL, error)
@@ -80,7 +81,13 @@ func Copy(dstStorage ObjectStorage, dstPath string, srcStorage ObjectStorage, sr
 	}
 	defer f.Close()
 
-	return dstStorage.Save(dstPath, f)
+	size := int64(-1)
+	fsinfo, err := f.Stat()
+	if err == nil {
+		size = fsinfo.Size()
+	}
+
+	return dstStorage.Save(dstPath, f, size)
 }
 
 // SaveFrom saves data to the ObjectStorage with path p from the callback
@@ -94,7 +101,7 @@ func SaveFrom(objStorage ObjectStorage, p string, callback func(w io.Writer) err
 		}
 	}()
 
-	_, err := objStorage.Save(p, pr)
+	_, err := objStorage.Save(p, pr, -1)
 	return err
 }