1 files changed, 58 insertions, 0 deletions
diff --git a/lib/dup2.c b/lib/dup2.c
new file mode 100644
index 0000000..8894481
--- /dev/null
+++ b/lib/dup2.c
@@ -0,0 +1,58 @@
+/* Duplicate an open file descriptor to a specified file descriptor.
+
+   Copyright (C) 1999, 2004, 2005, 2006, 2007 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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* written by Paul Eggert */
+
+#include <config.h>
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+
+#ifndef F_DUPFD
+static int
+dupfd (int fd, int desired_fd)
+{
+  int duplicated_fd = dup (fd);
+  if (duplicated_fd < 0 || duplicated_fd == desired_fd)
+    return duplicated_fd;
+  else
+    {
+      int r = dupfd (fd, desired_fd);
+      int e = errno;
+      close (duplicated_fd);
+      errno = e;
+      return r;
+    }
+}
+#endif
+
+int
+dup2 (int fd, int desired_fd)
+{
+  if (fd == desired_fd)
+    return fd;
+  close (desired_fd);
+#ifdef F_DUPFD
+  return fcntl (fd, F_DUPFD, desired_fd);
+#else
+  return dupfd (fd, desired_fd);
+#endif
+}