1 files changed, 59 insertions, 0 deletions
diff --git a/sysdeps/posix/dup2.c b/sysdeps/posix/dup2.c
new file mode 100644
index 0000000000..c0c6b2a0f6
--- /dev/null
+++ b/sysdeps/posix/dup2.c
@@ -0,0 +1,59 @@
+/* Copyright (C) 1991, 1992, 1993, 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <unistd.h>
+
+
+/* Duplicate FD to FD2, closing the old FD2 and making FD2 be
+   open the same file as FD is.  Return FD2 or -1.  */
+int
+DEFUN(__dup2, (fd, fd2), int fd AND int fd2)
+{
+  int save;
+
+  if (fd2 < 0
+#ifdef OPEN_MAX
+      || fd2 >= OPEN_MAX
+#endif
+)
+    {
+      errno = EBADF;
+      return -1;
+    }
+
+  /* Check if FD is kosher.  */
+  if (fcntl (fd, F_GETFL) < 0)
+    return -1;
+
+  if (fd == fd2)
+    return fd2;
+
+  /* This is not atomic.  */
+
+  save = errno;
+  (void) close (fd2);
+  errno = save;
+
+  return fcntl (fd, F_DUPFD, fd2);
+}
+
+weak_alias (__dup2, dup2)