include/features.h

   1 /* Copyright (C) 1991,92,93,95,96,97,98,99, 2000 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    _ISOC99_SOURCE       Extensions to ISO C89 from ISO C99.
  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                         if >=199506L, add IEEE Std 1003.1c-1995
  31    _XOPEN_SOURCE        Includes POSIX and XPG things.  Set to 500 if
  32                         Single Unix conformance is wanted.
  33    _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
  34    _LARGEFILE_SOURCE    Some more functions for correct standard I/O.
  35    _LARGEFILE64_SOURCE  Additional functionality from LFS for large files.
  36    _FILE_OFFSET_BITS=N  Select default filesystem interface.
  37    _BSD_SOURCE          ISO C, POSIX, and 4.3BSD things.
  38    _SVID_SOURCE         ISO C, POSIX, and SVID things.
  39    _GNU_SOURCE          All of the above, plus GNU extensions.
  40    _REENTRANT           Select additionally reentrant object.
  41    _THREAD_SAFE         Same as _REENTRANT, often used by other systems.
  42
  43    The `-ansi' switch to the GNU C compiler defines __STRICT_ANSI__.
  44    If none of these are defined, the default is all but _GNU_SOURCE.
  45    If more than one of these are defined, they accumulate.
  46    For example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE
  47    together give you ISO C, 1003.1, and 1003.2, but nothing else.
  48
  49    These are defined by this file and are used by the
  50    header files to decide what to declare or define:
  51
  52    __USE_ISOC99         Define ISO C99 things.
  53    __USE_POSIX          Define IEEE Std 1003.1 things.
  54    __USE_POSIX2         Define IEEE Std 1003.2 things.
  55    __USE_POSIX199309    Define IEEE Std 1003.1, and .1b things.
  56    __USE_POSIX199506    Define IEEE Std 1003.1, .1b, .1c and .1i things.
  57    __USE_XOPEN          Define XPG things.
  58    __USE_XOPEN_EXTENDED Define X/Open Unix things.
  59    __USE_UNIX98         Define Single Unix V2 things.
  60    __USE_XOPEN2K        Define XPG6 things
  61    __USE_LARGEFILE64    Define LFS things with separate names.
  62    __USE_FILE_OFFSET64  Define 64bit interface as default.
  63    __USE_BSD            Define 4.3BSD things.
  64    __USE_SVID           Define SVID things.
  65    __USE_MISC           Define things common to BSD and System V Unix.
  66    __USE_GNU            Define GNU extensions.
  67    __USE_REENTRANT      Define reentrant/thread-safe *_r functions.
  68    __FAVOR_BSD          Favor 4.3BSD things in cases of conflict.
  69
  70    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
  71    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
  72    only for compatibility.  All new code should use the other symbols
  73    to test for features.
  74
  75    All macros listed above as possibly being defined by this file are
  76    explicitly undefined if they are not explicitly defined.
  77    Feature-test macros that are not defined by the user or compiler
  78    but are implied by the other feature-test macros defined (or by the
  79    lack of any definitions) are defined by the file.  */
  80
  81
  82 /* Undefine everything, so we get a clean slate.  */
  83 #undef  __USE_ISOC99
  84 #undef  __USE_POSIX
  85 #undef  __USE_POSIX2
  86 #undef  __USE_POSIX199309
  87 #undef  __USE_POSIX199506
  88 #undef  __USE_XOPEN
  89 #undef  __USE_XOPEN_EXTENDED
  90 #undef  __USE_UNIX98
  91 #undef  __USE_XOPEN2K
  92 #undef  __USE_LARGEFILE
  93 #undef  __USE_LARGEFILE64
  94 #undef  __USE_FILE_OFFSET64
  95 #undef  __USE_BSD
  96 #undef  __USE_SVID
  97 #undef  __USE_MISC
  98 #undef  __USE_GNU
  99 #undef  __USE_REENTRANT
 100 #undef  __FAVOR_BSD
 101 #undef  __KERNEL_STRICT_NAMES
 102
 103 /* Suppress kernel-name space pollution unless user expressedly asks
 104    for it.  */
 105 #ifndef _LOOSE_KERNEL_NAMES
 106 # define __KERNEL_STRICT_NAMES
 107 #endif
 108
 109 /* Always use ISO C things.  */
 110 #define __USE_ANSI      1
 111
 112
 113 /* If _BSD_SOURCE was defined by the user, favor BSD over POSIX.  */
 114 #if defined _BSD_SOURCE && \
 115     !(defined _POSIX_SOURCE || defined _POSIX_C_SOURCE || \
 116       defined _XOPEN_SOURCE || defined _XOPEN_SOURCE_EXTENDED || \
 117       defined _GNU_SOURCE || defined _SVID_SOURCE)
 118 # define __FAVOR_BSD    1
 119 #endif
 120
 121 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 122 #ifdef _GNU_SOURCE
 123 # undef  _ISOC99_SOURCE
 124 # define _ISOC99_SOURCE 1
 125 # undef  _POSIX_SOURCE
 126 # define _POSIX_SOURCE  1
 127 # undef  _POSIX_C_SOURCE
 128 # define _POSIX_C_SOURCE        199506L
 129 # undef  _XOPEN_SOURCE
 130 # define _XOPEN_SOURCE  600
 131 # undef  _XOPEN_SOURCE_EXTENDED
 132 # define _XOPEN_SOURCE_EXTENDED 1
 133 # undef  _LARGEFILE64_SOURCE
 134 # define _LARGEFILE64_SOURCE    1
 135 # undef  _BSD_SOURCE
 136 # define _BSD_SOURCE    1
 137 # undef  _SVID_SOURCE
 138 # define _SVID_SOURCE   1
 139 #endif
 140
 141 /* If nothing (other than _GNU_SOURCE) is defined,
 142    define _BSD_SOURCE and _SVID_SOURCE.  */
 143 #if (!defined __STRICT_ANSI__ && !defined _ISOC99_SOURCE && \
 144      !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE && \
 145      !defined _XOPEN_SOURCE && !defined _XOPEN_SOURCE_EXTENDED && \
 146      !defined _BSD_SOURCE && !defined _SVID_SOURCE)
 147 # define _BSD_SOURCE    1
 148 # define _SVID_SOURCE   1
 149 #endif
 150
 151 /* This is to enable the ISO C99 extension.  Also recognize the old macro
 152    which was used prior to the standard acceptance.  This macro will
 153    eventually go away and the features enabled by default once the ISO C99
 154    standard is widely adopted.  */
 155 #if (defined _ISOC99_SOURCE || defined _ISOC9X_SOURCE \
 156      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 157 # define __USE_ISOC99   1
 158 #endif
 159
 160 /* If none of the ANSI/POSIX macros are defined, use POSIX.1 and POSIX.2
 161    (and IEEE Std 1003.1b-1993 unless _XOPEN_SOURCE is defined).  */
 162 #if (!defined __STRICT_ANSI__ && !defined _POSIX_SOURCE && \
 163      !defined _POSIX_C_SOURCE)
 164 # define _POSIX_SOURCE  1
 165 # if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) != 500
 166 #  define _POSIX_C_SOURCE       2
 167 # else
 168 #  define _POSIX_C_SOURCE       199506L
 169 # endif
 170 #endif
 171
 172 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
 173 # define __USE_POSIX    1
 174 #endif
 175
 176 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
 177 # define __USE_POSIX2   1
 178 #endif
 179
 180 #if (_POSIX_C_SOURCE - 0) >= 199309L
 181 # define __USE_POSIX199309      1
 182 #endif
 183
 184 #if (_POSIX_C_SOURCE - 0) >= 199506L
 185 # define __USE_POSIX199506      1
 186 #endif
 187
 188 #ifdef  _XOPEN_SOURCE
 189 # define __USE_XOPEN    1
 190 # if (_XOPEN_SOURCE - 0) >= 500
 191 #  define __USE_XOPEN_EXTENDED  1
 192 #  define __USE_UNIX98  1
 193 #  undef _LARGEFILE_SOURCE
 194 #  define _LARGEFILE_SOURCE     1
 195 #  if (_XOPEN_SOURCE - 0) == 600
 196 #   define __USE_XOPEN2K        1
 197 #  endif
 198 # else
 199 #  ifdef _XOPEN_SOURCE_EXTENDED
 200 #   define __USE_XOPEN_EXTENDED 1
 201 #  endif
 202 # endif
 203 #endif
 204
 205 #ifdef _LARGEFILE_SOURCE
 206 # define __USE_LARGEFILE        1
 207 #endif
 208
 209 #ifdef _LARGEFILE64_SOURCE
 210 # define __USE_LARGEFILE64      1
 211 #endif
 212
 213 #if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64
 214 # define __USE_FILE_OFFSET64    1
 215 #endif
 216
 217 #if defined _BSD_SOURCE || defined _SVID_SOURCE
 218 # define __USE_MISC     1
 219 #endif
 220
 221 #ifdef  _BSD_SOURCE
 222 # define __USE_BSD      1
 223 #endif
 224
 225 #ifdef  _SVID_SOURCE
 226 # define __USE_SVID     1
 227 #endif
 228
 229 #ifdef  _GNU_SOURCE
 230 # define __USE_GNU      1
 231 #endif
 232
 233 #if defined _REENTRANT || defined _THREAD_SAFE
 234 # define __USE_REENTRANT        1
 235 #endif
 236
 237 /* We do support the IEC 559 math functionality, real and complex.  */
 238 #define __STDC_IEC_559__                1
 239 #define __STDC_IEC_559_COMPLEX__        1
 240
 241 /* This macro indicates that the installed library is the GNU C Library.
 242    For historic reasons the value now is 6 and this will stay from now
 243    on.  The use of this variable is deprecated.  Use __GLIBC__ and
 244    __GLIBC_MINOR__ now (see below) when you want to test for a specific
 245    GNU C library version and use the values in <gnu/lib-names.h> to get
 246    the sonames of the shared libraries.  */
 247 #undef  __GNU_LIBRARY__
 248 #define __GNU_LIBRARY__ 6
 249
 250 /* Major and minor version number of the GNU C library package.  Use
 251    these macros to test for features in specific releases.  */
 252 #define __GLIBC__       2
 253 #define __GLIBC_MINOR__ 2
 254
 255 /* Convenience macros to test the versions of glibc and gcc.
 256    Use them like this:
 257    #if __GNUC_PREREQ (2,8)
 258    ... code requiring gcc 2.8 or later ...
 259    #endif
 260    Note - they won't work for gcc1 or glibc1, since the _MINOR macros
 261    were not defined then.  */
 262 #if defined __GNUC__ && defined __GNUC_MINOR__
 263 # define __GNUC_PREREQ(maj, min) \
 264         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
 265 #else
 266 # define __GNUC_PREREQ(maj, min) 0
 267 #endif
 268
 269 #define __GLIBC_PREREQ(maj, min) \
 270         ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
 271
 272 /* This is here only because every header file already includes this one.  */
 273 #ifndef __ASSEMBLER__
 274 #ifndef _SYS_CDEFS_H
 275 # include <sys/cdefs.h>
 276 #endif
 277
 278 /* If we don't have __REDIRECT, prototypes will be missing if
 279    __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */
 280 # if defined __USE_FILE_OFFSET64 && !defined __REDIRECT
 281 #  define __USE_LARGEFILE
 282 #  define __USE_LARGEFILE64
 283 # endif
 284
 285 #endif  /* !ASSEMBLER */
 286
 287 /* Decide whether we can define 'extern inline' functions in headers.  */
 288 #if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ && !defined __OPTIMIZE_SIZE__
 289 # define __USE_EXTERN_INLINES   1
 290 #endif
 291
 292 /* This is here only because every header file already includes this one.  */
 293 #ifndef _LIBC
 294 /* Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
 295    <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
 296    which will always return failure (and set errno to ENOSYS).
 297
 298    We avoid including <gnu/stubs.h> when compiling the C library itself to
 299    avoid a dependency loop.  stubs.h depends on every object file.  If
 300    this #include were done for the library source code, then every object
 301    file would depend on stubs.h.  */
 302
 303 # include <gnu/stubs.h>
 304 #endif
 305
 306 #endif  /* features.h  */