+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#ifndef _FEATURES_H
+#define _FEATURES_H 1
+
+/* These are defined by the user (or the compiler)
+ to specify the desired environment:
+
+ __STRICT_ANSI__ ISO Standard C.
+ _ISOC99_SOURCE Extensions to ISO C89 from ISO C99.
+ _POSIX_SOURCE IEEE Std 1003.1.
+ _POSIX_C_SOURCE If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2;
+ if >=199309L, add IEEE Std 1003.1b-1993;
+ if >=199506L, add IEEE Std 1003.1c-1995;
+ if >=200112L, all of IEEE 1003.1-2004
+ if >=200809L, all of IEEE 1003.1-2008
+ _XOPEN_SOURCE Includes POSIX and XPG things. Set to 500 if
+ Single Unix conformance is wanted, to 600 for the
+ sixth revision, to 700 for the seventh revision.
+ _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
+ _LARGEFILE_SOURCE Some more functions for correct standard I/O.
+ _LARGEFILE64_SOURCE Additional functionality from LFS for large files.
+ _FILE_OFFSET_BITS=N Select default filesystem interface.
+ _BSD_SOURCE ISO C, POSIX, and 4.3BSD things.
+ _SVID_SOURCE ISO C, POSIX, and SVID things.
+ _ATFILE_SOURCE Additional *at interfaces.
+ _GNU_SOURCE All of the above, plus GNU extensions.
+ _REENTRANT Select additionally reentrant object.
+ _THREAD_SAFE Same as _REENTRANT, often used by other systems.
+ _FORTIFY_SOURCE If set to numeric value > 0 additional security
+ measures are defined, according to level.
+
+ The `-ansi' switch to the GNU C compiler defines __STRICT_ANSI__.
+ If none of these are defined, the default is to have _SVID_SOURCE,
+ _BSD_SOURCE, and _POSIX_SOURCE set to one and _POSIX_C_SOURCE set to
+ 200112L. If more than one of these are defined, they accumulate.
+ For example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE
+ together give you ISO 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_ISOC99 Define ISO C99 things.
+ __USE_ISOC95 Define ISO C90 AMD1 (C95) things.
+ __USE_POSIX Define IEEE Std 1003.1 things.
+ __USE_POSIX2 Define IEEE Std 1003.2 things.
+ __USE_POSIX199309 Define IEEE Std 1003.1, and .1b things.
+ __USE_POSIX199506 Define IEEE Std 1003.1, .1b, .1c and .1i things.
+ __USE_XOPEN Define XPG things.
+ __USE_XOPEN_EXTENDED Define X/Open Unix things.
+ __USE_UNIX98 Define Single Unix V2 things.
+ __USE_XOPEN2K Define XPG6 things.
+ __USE_XOPEN2K8 Define XPG7 things.
+ __USE_LARGEFILE Define correct standard I/O things.
+ __USE_LARGEFILE64 Define LFS things with separate names.
+ __USE_FILE_OFFSET64 Define 64bit interface as default.
+ __USE_BSD Define 4.3BSD things.
+ __USE_SVID Define SVID things.
+ __USE_MISC Define things common to BSD and System V Unix.
+ __USE_ATFILE Define *at interfaces and AT_* constants for them.
+ __USE_GNU Define GNU extensions.
+ __USE_REENTRANT Define reentrant/thread-safe *_r functions.
+ __USE_FORTIFY_LEVEL Additional security measures used, according to level.
+ __FAVOR_BSD Favor 4.3BSD things in cases of conflict.
+
+ The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
+ defined by this file unconditionally. `__GNU_LIBRARY__' is provided
+ only for compatibility. All new code should use the other symbols
+ to test for features.
+
+ 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. */