allow to set umask on *NIX platforms

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/util/util_unix.go

@@ -0,0 +1,38 @@
+// Copyright (C) 2019-2023 Nicola Murino
+//
+// 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, version 3.
+//
+// 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 <https://www.gnu.org/licenses/>.
+
+//go:build unix
+
+package util
+
+import (
+	"strconv"
+	"syscall"
+
+	"github.com/drakkan/sftpgo/v2/internal/logger"
+)
+
+// SetUmask sets the specified umask
+func SetUmask(val string) {
+	if val == "" {
+		return
+	}
+	umask, err := strconv.ParseUint(val, 8, 31)
+	if err != nil {
+		logger.Error(logSender, "", "invalid umask %q: %v", val, err)
+		return
+	}
+	logger.Debug(logSender, "", "set umask to: %d, configured value: %q", umask, val)
+	syscall.Umask(int(umask))
+}