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+/* Copyright (C) 1991, 1992, 1993 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. */
+
+#ifndef _FEATURES_H
+
+#define _FEATURES_H 1
+
+/* These are defined by the user (or the compiler)
+ to specify the desired environment:
+
+ __STRICT_ANSI__ ANSI Standard C.
+ _POSIX_SOURCE IEEE Std 1003.1.
+ _POSIX_C_SOURCE If ==1, like _POSIX_SOURCE; if ==2 add IEEE Std 1003.2.
+ _BSD_SOURCE ANSI, POSIX, and 4.3BSD things.
+ _SVID_SOURCE ANSI, POSIX, and SVID things.
+ _GNU_SOURCE All of the above, plus GNU extensions.
+
+ The `-ansi' switch to the GNU C compiler defines __STRICT_ANSI__.
+ If none of these are defined, the default is _GNU_SOURCE.
+ If more than one of these are defined, they accumulate.
+ For example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE
+ together give you ANSI C, 1003.1, and 1003.2, but nothing else.
+
+ These are defined by this file and are used by the
+ header files to decide what to declare or define:
+
+ __USE_POSIX Define IEEE Std 1003.1 things.
+ __USE_POSIX2 Define IEEE Std 1003.2 things.
+ __USE_BSD Define 4.3BSD things.
+ __USE_SVID Define SVID things.
+ __USE_MISC Define things common to BSD and System V Unix.
+ __USE_GNU Define GNU extensions.
+ __FAVOR_BSD Favor 4.3BSD things in cases of conflict.
+
+ The macro `__GNU_LIBRARY__' is defined by this file unconditionally.
+
+ All macros defined by this file are defined as 1.
+ All macros listed above as possibly being defined by this file are
+ explicitly undefined if they are not explicitly defined.
+ Feature-test macros that are not defined by the user or compiler
+ but are implied by the other feature-test macros defined (or by the
+ lack of any definitions) are defined by the file. */
+
+
+/* Undefine everything, so we get a clean slate. */
+#undef __USE_POSIX
+#undef __USE_POSIX2
+#undef __USE_BSD
+#undef __USE_SVID
+#undef __USE_MISC
+#undef __USE_GNU
+#undef __FAVOR_BSD
+
+
+/* If nothing is defined, define _GNU_SOURCE. */
+#if (!defined(_GNU_SOURCE) && !defined(__STRICT_ANSI__) && \
+ !defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE) && \
+ !defined(_BSD_SOURCE) && !defined(_SVID_SOURCE))
+#define _GNU_SOURCE 1
+#endif
+
+
+/* Always use ANSI things. */
+#define __USE_ANSI 1
+
+
+/* If _BSD_SOURCE was defined by the user, favor BSD over POSIX. */
+#ifdef _BSD_SOURCE
+#define __FAVOR_BSD 1
+#endif
+
+
+/* If nothing (other than _GNU_SOURCE) is defined,
+ define _BSD_SOURCE and _SVID_SOURCE. */
+#if (!defined(__STRICT_ANSI__) && !defined(_POSIX_SOURCE) && \
+ !defined(_POSIX_C_SOURCE) && !defined(_BSD_SOURCE) && \
+ !defined(_SVID_SOURCE))
+#define _BSD_SOURCE 1
+#define _SVID_SOURCE 1
+#endif
+
+/* If none of the ANSI/POSIX macros are defined, use POSIX.1 and POSIX.2. */
+#if (!defined(__STRICT_ANSI__) && !defined(_POSIX_SOURCE) && \
+ !defined(_POSIX_C_SOURCE))
+#define _POSIX_SOURCE 1
+#define _POSIX_C_SOURCE 2
+#endif
+
+#if defined(_POSIX_SOURCE) || _POSIX_C_SOURCE >= 1
+#define __USE_POSIX 1
+#endif
+
+#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 2
+#define __USE_POSIX2 1
+#endif
+
+#if defined(_BSD_SOURCE) || defined(_SVID_SOURCE)
+#define __USE_MISC 1
+#endif
+
+#ifdef _BSD_SOURCE
+#define __USE_BSD 1
+#endif
+
+#ifdef _SVID_SOURCE
+#define __USE_SVID 1
+#endif
+
+#ifdef _GNU_SOURCE
+#define __USE_GNU 1
+#endif
+
+
+#undef __GNU_LIBRARY__
+#define __GNU_LIBRARY__ 1
+
+
+#if !defined(__GNUC__) || __GNUC__ < 2
+/* In GCC version 2, (__extension__ EXPR) will not complain
+ about GCC extensions used in EXPR under -ansi or -pedantic. */
+#define __extension__
+#endif
+
+
+/* This is here only because every header file already includes this one. */
+#include <sys/cdefs.h>
+
+/* This is here only because every header file already includes this one. */
+#ifndef _LIBC
+/* Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
+ <stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
+ which will always return failure (and set errno to ENOSYS).
+
+ We avoid including <stubs.h> when compiling the C library itself to
+ avoid a dependency loop. stubs.h depends on every object file. If
+ this #include were done for the library source code, then every object
+ file would depend on stubs.h. */
+
+#include <stubs.h>
+#endif
+
+#endif /* __features.h */