+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* Get declarations of the Win32 API functions. */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+#endif
+
+#if HAVE_DUP2
+
+# undef dup2
+
+int
+rpl_dup2 (int fd, int desired_fd)
+{
+ int result;
+# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+ /* If fd is closed, mingw hangs on dup2 (fd, fd). If fd is open,
+ dup2 (fd, fd) returns 0, but all further attempts to use fd in
+ future dup2 calls will hang. */
+ if (fd == desired_fd)
+ {
+ if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
+ {
+ errno = EBADF;
+ return -1;
+ }
+ return fd;
+ }
+ /* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
+ http://bugs.winehq.org/show_bug.cgi?id=21289 */
+ if (desired_fd < 0)
+ {
+ errno = EBADF;
+ return -1;
+ }
+# elif !defined __linux__
+ /* On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC. */
+ if (fd == desired_fd)
+ return fcntl (fd, F_GETFL) == -1 ? -1 : fd;
+# endif
+ result = dup2 (fd, desired_fd);
+# ifdef __linux__
+ /* Correct a Linux return value.
+ <http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.30.y.git;a=commitdiff;h=2b79bc4f7ebbd5af3c8b867968f9f15602d5f802>
+ */
+ if (fd == desired_fd && result == (unsigned int) -EBADF)
+ {
+ errno = EBADF;
+ result = -1;
+ }
+# endif
+ if (result == 0)
+ result = desired_fd;
+ /* Correct a cygwin 1.5.x errno value. */
+ else if (result == -1 && errno == EMFILE)
+ errno = EBADF;
+# if REPLACE_FCHDIR
+ if (fd != desired_fd && result != -1)
+ result = _gl_register_dup (fd, result);
+# endif
+ return result;
+}
+
+#else /* !HAVE_DUP2 */
+
+/* On older platforms, dup2 did not exist. */
+
+# ifndef F_DUPFD