include/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 #define _FEATURES_H     1
  21
  22 /* These are defined by the user (or the compiler)
  23    to specify the desired environment:
  24
  25    __STRICT_ANSI__      ISO Standard C.
  26    _ISOC9X_SOURCE       Extensions to ISO C 89 from ISO C 9x.
  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_ISOC9X         Define ISO C 9X things.
  48    __USE_POSIX          Define IEEE Std 1003.1 things.
  49    __USE_POSIX2         Define IEEE Std 1003.2 things.
  50    __USE_POSIX199309    Define IEEE Std 1003.1b things.
  51    __USE_XOPEN          Define XPG things.
  52    __USE_XOPEN_EXTENDED Define X/Open Unix things.
  53    __USE_BSD            Define 4.3BSD things.
  54    __USE_SVID           Define SVID things.
  55    __USE_MISC           Define things common to BSD and System V Unix.
  56    __USE_GNU            Define GNU extensions.
  57    __USE_REENTRANT      Define reentrant/thread-safe *_r functions.
  58    __FAVOR_BSD          Favor 4.3BSD things in cases of conflict.
  59
  60    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
  61    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
  62    only for compatibility.  All new code should use the other symbols
  63    to test for features.
  64
  65    All macros listed above as possibly being defined by this file are
  66    explicitly undefined if they are not explicitly defined.
  67    Feature-test macros that are not defined by the user or compiler
  68    but are implied by the other feature-test macros defined (or by the
  69    lack of any definitions) are defined by the file.  */
  70
  71
  72 /* Undefine everything, so we get a clean slate.  */
  73 #undef  __USE_ISOC9X
  74 #undef  __USE_POSIX
  75 #undef  __USE_POSIX2
  76 #undef  __USE_POSIX199309
  77 #undef  __USE_XOPEN
  78 #undef  __USE_XOPEN_EXTENDED
  79 #undef  __USE_BSD
  80 #undef  __USE_SVID
  81 #undef  __USE_MISC
  82 #undef  __USE_GNU
  83 #undef  __USE_REENTRANT
  84 #undef  __FAVOR_BSD
  85 #undef  __KERNEL_STRICT_NAMES
  86
  87 /* Suppress kernel-name space pollution unless user expressedly asks
  88    for it.  */
  89 #ifndef _LOOSE_KERNEL_NAMES
  90 # define __KERNEL_STRICT_NAMES
  91 #endif
  92
  93 /* Always use ISO C things.  */
  94 #define __USE_ANSI      1
  95
  96
  97 /* If _BSD_SOURCE was defined by the user, favor BSD over POSIX.  */
  98 #if defined _BSD_SOURCE && \
  99     !(defined _POSIX_SOURCE || defined _POSIX_C_SOURCE || \
 100       defined _XOPEN_SOURCE || defined _XOPEN_SOURCE_EXTENDED || \
 101       defined _GNU_SOURCE || defined _SVID_SOURCE)
 102 # define __FAVOR_BSD    1
 103 #endif
 104
 105 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 106 #ifdef _GNU_SOURCE
 107 # undef  _ISOC9X_SOURCE
 108 # define _ISOC9X_SOURCE 1
 109 # undef  _POSIX_SOURCE
 110 # define _POSIX_SOURCE  1
 111 # undef  _POSIX_C_SOURCE
 112 # define _POSIX_C_SOURCE        199309L
 113 # undef  _XOPEN_SOURCE
 114 # define _XOPEN_SOURCE  1
 115 # undef  _XOPEN_SOURCE_EXTENDED
 116 # define _XOPEN_SOURCE_EXTENDED 1
 117 # undef  _BSD_SOURCE
 118 # define _BSD_SOURCE    1
 119 # undef  _SVID_SOURCE
 120 # define _SVID_SOURCE   1
 121 #endif
 122
 123 /* If nothing (other than _GNU_SOURCE) is defined,
 124    define _BSD_SOURCE and _SVID_SOURCE.  */
 125 #if (!defined __STRICT_ANSI__ && !defined _ISOC9X_SOURCE && \
 126      !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE && \
 127      !defined _XOPEN_SOURCE && !defined _XOPEN_SOURCE_EXTENDED && \
 128      !defined _BSD_SOURCE && !defined _SVID_SOURCE)
 129 # define _BSD_SOURCE    1
 130 # define _SVID_SOURCE   1
 131 #endif
 132
 133 /* This is to enable the ISO C 9x extension.  It will go away as soon
 134    as this standard is officially released.  */
 135 #ifdef _ISOC9X_SOURCE
 136 # define __USE_ISOC9X   1
 137 #endif
 138
 139 /* If none of the ANSI/POSIX macros are defined, use POSIX.1 and POSIX.2
 140    (and IEEE Std 1003.1b-1993 unless _XOPEN_SOURCE is defined).  */
 141 #if (!defined __STRICT_ANSI__ && !defined _POSIX_SOURCE && \
 142      !defined _POSIX_C_SOURCE)
 143 # define _POSIX_SOURCE  1
 144 # ifdef _XOPEN_SOURCE
 145 #  define _POSIX_C_SOURCE       2
 146 # else
 147 #  define _POSIX_C_SOURCE       199309L
 148 # endif
 149 #endif
 150
 151 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
 152 # define __USE_POSIX    1
 153 #endif
 154
 155 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
 156 # define __USE_POSIX2   1
 157 #endif
 158
 159 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L
 160 # define __USE_POSIX199309      1
 161 #endif
 162
 163 #ifdef  _XOPEN_SOURCE
 164 # define __USE_XOPEN    1
 165 # ifdef _XOPEN_SOURCE_EXTENDED
 166 #  define __USE_XOPEN_EXTENDED  1
 167 # endif
 168 #endif
 169
 170 #if defined _BSD_SOURCE || defined _SVID_SOURCE
 171 # define __USE_MISC     1
 172 #endif
 173
 174 #ifdef  _BSD_SOURCE
 175 # define __USE_BSD      1
 176 #endif
 177
 178 #ifdef  _SVID_SOURCE
 179 # define __USE_SVID     1
 180 #endif
 181
 182 #ifdef  _GNU_SOURCE
 183 # define __USE_GNU      1
 184 #endif
 185
 186 #if defined _REENTRANT || defined _THREAD_SAFE
 187 # define __USE_REENTRANT        1
 188 #endif
 189
 190 /* We do support the IEC 559 math functionality, real and complex.  */
 191 #define __STDC_IEC_559__                1
 192 #define __STDC_IEC_559_COMPLEX__        1
 193
 194 /* This macro indicates that the installed library is the GNU C Library.
 195    For historic reasons the value now is 6 and this will stay from now
 196    on.  The use of this variable is deprecated.  Use __GLIBC__ and
 197    __GLIBC_MINOR__ now (see below) when you want to test for a specific
 198    GNU C library version and use the values in <gnu/lib-names.h> to get
 199    the sonames of the shared libraries.  */
 200 #undef  __GNU_LIBRARY__
 201 #define __GNU_LIBRARY__ 6
 202
 203 /* Major and minor version number of the GNU C library package.  Use
 204    these macros to test for features in specific releases.  */
 205 #define __GLIBC__       2
 206 #define __GLIBC_MINOR__ 1
 207
 208
 209 #if !defined __GNUC__ || __GNUC__ < 2
 210 /* In GCC version 2, (__extension__ EXPR) will not complain
 211    about GCC extensions used in EXPR under -ansi or -pedantic.  */
 212 # define __extension__
 213 #endif
 214
 215
 216 /* This is here only because every header file already includes this one.  */
 217 #ifndef __ASSEMBLER__
 218 # include <sys/cdefs.h>
 219 #endif
 220
 221 /* This is here only because every header file already includes this one.  */
 222 #ifndef _LIBC
 223 /* Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
 224    <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
 225    which will always return failure (and set errno to ENOSYS).
 226
 227    We avoid including <gnu/stubs.h> when compiling the C library itself to
 228    avoid a dependency loop.  stubs.h depends on every object file.  If
 229    this #include were done for the library source code, then every object
 230    file would depend on stubs.h.  */
 231
 232 # include <gnu/stubs.h>
 233 #endif
 234
 235 #endif  /* features.h  */