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diff --git a/lib/dup-safer-flag.c b/lib/dup-safer-flag.c
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+/* 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);
+}