fix Chmod/Chown with prefix

object/prefix.go

@@ -86,6 +86,20 @@ func (p *withPrefix) Chown(path string, owner, group string) error {
 	return nil
 }
 
+func (p *withPrefix) Chmod(path string, mode os.FileMode) error {
+	if fs, ok := p.os.(FileSystem); ok {
+		return fs.Chmod(p.prefix+path, mode)
+	}
+	return notSupported
+}
+
+func (p *withPrefix) Chown(path string, owner, group string) error {
+	if fs, ok := p.os.(FileSystem); ok {
+		return fs.Chown(p.prefix+path, owner, group)
+	}
+	return notSupported
+}
+
 func (p *withPrefix) CreateMultipartUpload(key string) (*MultipartUpload, error) {
 	return p.os.CreateMultipartUpload(p.prefix + key)
 }