1 files changed, 43 insertions, 0 deletions
diff --git a/bits/libc-header-start.h b/bits/libc-header-start.h
new file mode 100644
index 0000000000..c6663074a8
--- /dev/null
+++ b/bits/libc-header-start.h
@@ -0,0 +1,43 @@
+/* Handle feature test macros at the start of a header.
+   Copyright (C) 2016 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 Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This header is internal to glibc and should not be included outside
+   of glibc headers.  Headers including it must define
+   __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION first.  This header
+   cannot have multiple include guards because ISO C feature test
+   macros depend on the definition of the macro when an affected
+   header is included, not when the first system header is
+   included.  */
+
+#ifndef __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
+# error "Never include <bits/libc-header-start.h> directly."
+#endif
+
+#undef __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
+
+#include <features.h>
+
+/* ISO/IEC TR 24731-2:2010 defines the __STDC_WANT_LIB_EXT2__
+   macro.  */
+#undef __GLIBC_USE_LIB_EXT2
+#if (defined __USE_GNU							\
+     || (defined __STDC_WANT_LIB_EXT2__ && __STDC_WANT_LIB_EXT2__ > 0))
+# define __GLIBC_USE_LIB_EXT2 1
+#else
+# define __GLIBC_USE_LIB_EXT2 0
+#endif