features.h

   1 /* Copyright (C) 1991, 92, 93, 95, 96, 97 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #ifndef _FEATURES_H
  20
  21 #define _FEATURES_H     1
  22
  23 /* These are defined by the user (or the compiler)
  24    to specify the desired environment:
  25
  26    __STRICT_ANSI__      ISO Standard C.
  27    _POSIX_SOURCE        IEEE Std 1003.1.
  28    _POSIX_C_SOURCE      If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2;
  29                         if >=199309L, add IEEE Std 1003.1b-1993
  30    _XOPEN_SOURCE        Includes POSIX and XPG things.
  31    _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
  32    _BSD_SOURCE          ISO C, POSIX, and 4.3BSD things.
  33    _SVID_SOURCE         ISO C, POSIX, and SVID things.
  34    _GNU_SOURCE          All of the above, plus GNU extensions.
  35    _REENTRANT           Select additionally reentrant object.
  36    _THREAD_SAFE         Same as _REENTRANT, often used by other systems.
  37
  38    The `-ansi' switch to the GNU C compiler defines __STRICT_ANSI__.
  39    If none of these are defined, the default is all but _GNU_SOURCE.
  40    If more than one of these are defined, they accumulate.
  41    For example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE
  42    together give you ISO C, 1003.1, and 1003.2, but nothing else.
  43
  44    These are defined by this file and are used by the
  45    header files to decide what to declare or define:
  46
  47    __USE_POSIX          Define IEEE Std 1003.1 things.
  48    __USE_POSIX2         Define IEEE Std 1003.2 things.
  49    __USE_POSIX199309    Define IEEE Std 1003.1b things.
  50    __USE_XOPEN          Define XPG things.
  51    __USE_XOPEN_EXTENDED Define X/Open Unix things.
  52    __USE_BSD            Define 4.3BSD things.
  53    __USE_SVID           Define SVID things.
  54    __USE_MISC           Define things common to BSD and System V Unix.
  55    __USE_GNU            Define GNU extensions.
  56    __USE_REENTRANT      Define reentrant/thread-safe *_r functions.
  57    __FAVOR_BSD          Favor 4.3BSD things in cases of conflict.
  58
  59    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
  60    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
  61    only for compatibility.  All new code should use the other symbols
  62    to test for features.
  63
  64    All macros listed above as possibly being defined by this file are
  65    explicitly undefined if they are not explicitly defined.
  66    Feature-test macros that are not defined by the user or compiler
  67    but are implied by the other feature-test macros defined (or by the
  68    lack of any definitions) are defined by the file.  */
  69
  70
  71 /* Undefine everything, so we get a clean slate.  */
  72 #undef  __USE_POSIX
  73 #undef  __USE_POSIX2
  74 #undef  __USE_POSIX199309
  75 #undef  __USE_XOPEN
  76 #undef  __USE_XOPEN_EXTENDED
  77 #undef  __USE_BSD
  78 #undef  __USE_SVID
  79 #undef  __USE_MISC
  80 #undef  __USE_GNU
  81 #undef  __USE_REENTRANT
  82 #undef  __FAVOR_BSD
  83 #undef  __KERNEL_STRICT_NAMES
  84
  85 /* Suppress kernel-name space pollution unless user expressedly asks
  86    for it.  */
  87 #ifndef _LOOSE_KERNEL_NAMES
  88 # define __KERNEL_STRICT_NAMES
  89 #endif
  90
  91 /* Always use ISO C things.  */
  92 #define __USE_ANSI      1
  93
  94
  95 /* If _BSD_SOURCE was defined by the user, favor BSD over POSIX.  */
  96 #if defined _BSD_SOURCE && \
  97     !(defined _POSIX_SOURCE || defined _POSIX_C_SOURCE || \
  98       defined _XOPEN_SOURCE || defined _XOPEN_SOURCE_EXTENDED || \
  99       defined _GNU_SOURCE || defined _SVID_SOURCE)
 100 # define __FAVOR_BSD    1
 101 #endif
 102
 103 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 104 #ifdef _GNU_SOURCE
 105 #undef  _POSIX_SOURCE
 106 #define _POSIX_SOURCE   1
 107 #undef  _POSIX_C_SOURCE
 108 #define _POSIX_C_SOURCE 199309L
 109 #undef  _XOPEN_SOURCE
 110 #define _XOPEN_SOURCE   1
 111 #undef  _XOPEN_SOURCE_EXTENDED
 112 #define _XOPEN_SOURCE_EXTENDED  1
 113 #undef  _BSD_SOURCE
 114 #define _BSD_SOURCE     1
 115 #undef  _SVID_SOURCE
 116 #define _SVID_SOURCE    1
 117 #endif
 118
 119 /* If nothing (other than _GNU_SOURCE) is defined,
 120    define _BSD_SOURCE and _SVID_SOURCE.  */
 121 #if (!defined __STRICT_ANSI__ && !defined _POSIX_SOURCE && \
 122      !defined _POSIX_C_SOURCE && !defined _XOPEN_SOURCE && \
 123      !defined _XOPEN_SOURCE_EXTENDED && !defined _BSD_SOURCE && \
 124      !defined _SVID_SOURCE)
 125 #define _BSD_SOURCE     1
 126 #define _SVID_SOURCE    1
 127 #endif
 128
 129 /* If none of the ANSI/POSIX macros are defined, use POSIX.1 and POSIX.2
 130    (and IEEE Std 1003.1b-1993 unless _XOPEN_SOURCE is defined).  */
 131 #if (!defined __STRICT_ANSI__ && !defined _POSIX_SOURCE && \
 132      !defined _POSIX_C_SOURCE)
 133 #define _POSIX_SOURCE   1
 134 #ifdef _XOPEN_SOURCE
 135 #define _POSIX_C_SOURCE 2
 136 #else
 137 #define _POSIX_C_SOURCE 199309L
 138 #endif
 139 #endif
 140
 141 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
 142 #define __USE_POSIX     1
 143 #endif
 144
 145 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
 146 #define __USE_POSIX2    1
 147 #endif
 148
 149 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L
 150 #define __USE_POSIX199309       1
 151 #endif
 152
 153 #ifdef  _XOPEN_SOURCE
 154 #define __USE_XOPEN     1
 155 #ifdef  _XOPEN_SOURCE_EXTENDED
 156 #define __USE_XOPEN_EXTENDED    1
 157 #endif
 158 #endif
 159
 160 #if defined _BSD_SOURCE || defined _SVID_SOURCE
 161 #define __USE_MISC      1
 162 #endif
 163
 164 #ifdef  _BSD_SOURCE
 165 #define __USE_BSD       1
 166 #endif
 167
 168 #ifdef  _SVID_SOURCE
 169 #define __USE_SVID      1
 170 #endif
 171
 172 #ifdef  _GNU_SOURCE
 173 #define __USE_GNU       1
 174 #endif
 175
 176 #if defined _REENTRANT || defined _THREAD_SAFE
 177 #define __USE_REENTRANT 1
 178 #endif
 179
 180
 181 /* This macro indicates that the installed library is the GNU C Library.
 182    For historic reasons the value now is 6 and this will stay from now
 183    on.  The use of this variable is deprecated.  Use __GLIBC__ and
 184    __GLIBC_MINOR__ now (see below) when you want to test for a specific
 185    GNU C library version and use the values in <gnu/lib-names.h> to get
 186    the sonames of the shared libraries.  */
 187 #undef  __GNU_LIBRARY__
 188 #define __GNU_LIBRARY__ 6
 189
 190 /* Major and minor version number of the GNU C library package.  Use
 191    these macros to test for features in specific releases.  */
 192 #define __GLIBC__       2
 193 #define __GLIBC_MINOR__ 0
 194
 195
 196 #if !defined __GNUC__ || __GNUC__ < 2
 197 /* In GCC version 2, (__extension__ EXPR) will not complain
 198    about GCC extensions used in EXPR under -ansi or -pedantic.  */
 199 #define __extension__
 200 #endif
 201
 202
 203 /* This is here only because every header file already includes this one.  */
 204 #ifndef __ASSEMBLER__
 205 #include <sys/cdefs.h>
 206 #endif
 207
 208 /* This is here only because every header file already includes this one.  */
 209 #ifndef _LIBC
 210 /* Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
 211    <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
 212    which will always return failure (and set errno to ENOSYS).
 213
 214    We avoid including <gnu/stubs.h> when compiling the C library itself to
 215    avoid a dependency loop.  stubs.h depends on every object file.  If
 216    this #include were done for the library source code, then every object
 217    file would depend on stubs.h.  */
 218
 219 #include <gnu/stubs.h>
 220 #endif
 221
 222 #endif  /* features.h  */