1 files changed, 38 insertions, 0 deletions
diff --git a/lib/dup-safer-flag.c b/lib/dup-safer-flag.c
new file mode 100644
index 0000000..f87792a
--- /dev/null
+++ b/lib/dup-safer-flag.c
@@ -0,0 +1,38 @@
+/* Duplicate a file descriptor result, avoiding clobbering
+   STD{IN,OUT,ERR}_FILENO, with specific flags.
+
+   Copyright (C) 2001, 2004-2006, 2009-2022 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert and Eric Blake.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "unistd-safer.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+
+/* Like dup, but do not return STDIN_FILENO, STDOUT_FILENO, or
+   STDERR_FILENO.  If FLAG contains O_CLOEXEC, behave like
+   fcntl(F_DUPFD_CLOEXEC) rather than fcntl(F_DUPFD).  */
+
+int
+dup_safer_flag (int fd, int flag)
+{
+  return fcntl (fd, (flag & O_CLOEXEC) ? F_DUPFD_CLOEXEC : F_DUPFD,
+                STDERR_FILENO + 1);
+}