+#if GNULIB_CLOEXEC
+ /* Any new fd created by dup2 must not be cloexec. */
+ ASSERT (close (fd + 2) == 0);
+ ASSERT (dup_cloexec (fd) == fd + 1);
+ ASSERT (!is_inheritable (fd + 1));
+ ASSERT (dup2 (fd + 1, fd + 1) == fd + 1);
+ ASSERT (!is_inheritable (fd + 1));
+ ASSERT (dup2 (fd + 1, fd + 2) == fd + 2);
+ ASSERT (is_inheritable (fd + 2));
+#endif
+
+ /* On systems that distinguish between text and binary mode, dup2
+ reuses the mode of the source. */
+ setmode (fd, O_BINARY);
+ ASSERT (is_mode (fd, O_BINARY));
+ ASSERT (dup2 (fd, fd + 1) == fd + 1);
+ ASSERT (is_mode (fd + 1, O_BINARY));
+ setmode (fd, O_TEXT);
+ ASSERT (is_mode (fd, O_TEXT));
+ ASSERT (dup2 (fd, fd + 1) == fd + 1);
+ ASSERT (is_mode (fd + 1, O_TEXT));
+