extern int link (__const char *__from, __const char *__to)
__THROW __nonnull ((1, 2)) __wur;
-#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
+#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED || defined __USE_XOPEN2K
/* Make a symbolic link to FROM named TO. */
extern int symlink (__const char *__from, __const char *__to)
__THROW __nonnull ((1, 2)) __wur;
extern char *ctermid (char *__s) __THROW __nonnull ((1));
#endif
+/* Define some macros helping to catch buffer overflows. */
+#if __USE_FORTIFY_LEVEL > 0 && !defined __cplusplus
+# include <bits/unistd.h>
+#endif
+
__END_DECLS
#endif /* unistd.h */