Add option in readDir to enable symlink following of dirs (#12668)

cmd/os-readdir-common.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package cmd
+
+// Options for readDir function call
+type readDirOpts struct {
+	// The maximum number of entries to return
+	count int
+	// Follow directory symlink
+	followDirSymlink bool
+}
+
+// Return all the entries at the directory dirPath.
+func readDir(dirPath string) (entries []string, err error) {
+	return readDirWithOpts(dirPath, readDirOpts{count: -1})
+}
+
+// Return up to count entries at the directory dirPath.
+func readDirN(dirPath string, count int) (entries []string, err error) {
+	return readDirWithOpts(dirPath, readDirOpts{count: count})
+}