include/features.h

   1 /* Copyright (C) 1991-2014 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _FEATURES_H
  19 #define _FEATURES_H     1
  20
  21 /* These are defined by the user (or the compiler)
  22    to specify the desired environment:
  23
  24    __STRICT_ANSI__      ISO Standard C.
  25    _ISOC99_SOURCE       Extensions to ISO C89 from ISO C99.
  26    _ISOC11_SOURCE       Extensions to ISO C99 from ISO C11.
  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                         if >=200112L, all of IEEE 1003.1-2004
  32                         if >=200809L, all of IEEE 1003.1-2008
  33    _XOPEN_SOURCE        Includes POSIX and XPG things.  Set to 500 if
  34                         Single Unix conformance is wanted, to 600 for the
  35                         sixth revision, to 700 for the seventh revision.
  36    _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
  37    _LARGEFILE_SOURCE    Some more functions for correct standard I/O.
  38    _LARGEFILE64_SOURCE  Additional functionality from LFS for large files.
  39    _FILE_OFFSET_BITS=N  Select default filesystem interface.
  40    _ATFILE_SOURCE       Additional *at interfaces.
  41    _GNU_SOURCE          All of the above, plus GNU extensions.
  42    _DEFAULT_SOURCE      The default set of features (taking precedence over
  43                         __STRICT_ANSI__).
  44    _REENTRANT           Select additionally reentrant object.
  45    _THREAD_SAFE         Same as _REENTRANT, often used by other systems.
  46    _FORTIFY_SOURCE      If set to numeric value > 0 additional security
  47                         measures are defined, according to level.
  48
  49    The `-ansi' switch to the GNU C compiler, and standards conformance
  50    options such as `-std=c99', define __STRICT_ANSI__.  If none of
  51    these are defined, or if _DEFAULT_SOURCE is defined, the default is
  52    to have _POSIX_SOURCE set to one and _POSIX_C_SOURCE set to
  53    200809L, as well as enabling miscellaneous functions from BSD and
  54    SVID.  If more than one of these are defined, they accumulate.  For
  55    example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE together
  56    give you ISO C, 1003.1, and 1003.2, but nothing else.
  57
  58    These are defined by this file and are used by the
  59    header files to decide what to declare or define:
  60
  61    __USE_ISOC11         Define ISO C11 things.
  62    __USE_ISOC99         Define ISO C99 things.
  63    __USE_ISOC95         Define ISO C90 AMD1 (C95) things.
  64    __USE_POSIX          Define IEEE Std 1003.1 things.
  65    __USE_POSIX2         Define IEEE Std 1003.2 things.
  66    __USE_POSIX199309    Define IEEE Std 1003.1, and .1b things.
  67    __USE_POSIX199506    Define IEEE Std 1003.1, .1b, .1c and .1i things.
  68    __USE_XOPEN          Define XPG things.
  69    __USE_XOPEN_EXTENDED Define X/Open Unix things.
  70    __USE_UNIX98         Define Single Unix V2 things.
  71    __USE_XOPEN2K        Define XPG6 things.
  72    __USE_XOPEN2KXSI     Define XPG6 XSI things.
  73    __USE_XOPEN2K8       Define XPG7 things.
  74    __USE_XOPEN2K8XSI    Define XPG7 XSI things.
  75    __USE_LARGEFILE      Define correct standard I/O things.
  76    __USE_LARGEFILE64    Define LFS things with separate names.
  77    __USE_FILE_OFFSET64  Define 64bit interface as default.
  78    __USE_BSD            Define 4.3BSD things.
  79    __USE_SVID           Define SVID things.
  80    __USE_MISC           Define things common to BSD and System V Unix.
  81    __USE_ATFILE         Define *at interfaces and AT_* constants for them.
  82    __USE_GNU            Define GNU extensions.
  83    __USE_REENTRANT      Define reentrant/thread-safe *_r functions.
  84    __USE_FORTIFY_LEVEL  Additional security measures used, according to level.
  85
  86    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
  87    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
  88    only for compatibility.  All new code should use the other symbols
  89    to test for features.
  90
  91    All macros listed above as possibly being defined by this file are
  92    explicitly undefined if they are not explicitly defined.
  93    Feature-test macros that are not defined by the user or compiler
  94    but are implied by the other feature-test macros defined (or by the
  95    lack of any definitions) are defined by the file.  */
  96
  97
  98 /* Undefine everything, so we get a clean slate.  */
  99 #undef  __USE_ISOC11
 100 #undef  __USE_ISOC99
 101 #undef  __USE_ISOC95
 102 #undef  __USE_ISOCXX11
 103 #undef  __USE_POSIX
 104 #undef  __USE_POSIX2
 105 #undef  __USE_POSIX199309
 106 #undef  __USE_POSIX199506
 107 #undef  __USE_XOPEN
 108 #undef  __USE_XOPEN_EXTENDED
 109 #undef  __USE_UNIX98
 110 #undef  __USE_XOPEN2K
 111 #undef  __USE_XOPEN2KXSI
 112 #undef  __USE_XOPEN2K8
 113 #undef  __USE_XOPEN2K8XSI
 114 #undef  __USE_LARGEFILE
 115 #undef  __USE_LARGEFILE64
 116 #undef  __USE_FILE_OFFSET64
 117 #undef  __USE_BSD
 118 #undef  __USE_SVID
 119 #undef  __USE_MISC
 120 #undef  __USE_ATFILE
 121 #undef  __USE_GNU
 122 #undef  __USE_REENTRANT
 123 #undef  __USE_FORTIFY_LEVEL
 124 #undef  __KERNEL_STRICT_NAMES
 125
 126 /* Suppress kernel-name space pollution unless user expressedly asks
 127    for it.  */
 128 #ifndef _LOOSE_KERNEL_NAMES
 129 # define __KERNEL_STRICT_NAMES
 130 #endif
 131
 132 /* Convenience macros to test the versions of glibc and gcc.
 133    Use them like this:
 134    #if __GNUC_PREREQ (2,8)
 135    ... code requiring gcc 2.8 or later ...
 136    #endif
 137    Note - they won't work for gcc1 or glibc1, since the _MINOR macros
 138    were not defined then.  */
 139 #if defined __GNUC__ && defined __GNUC_MINOR__
 140 # define __GNUC_PREREQ(maj, min) \
 141         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
 142 #else
 143 # define __GNUC_PREREQ(maj, min) 0
 144 #endif
 145
 146 /* _BSD_SOURCE and _SVID_SOURCE are deprecated aliases for
 147    _DEFAULT_SOURCE.  */
 148 #if defined _BSD_SOURCE || defined _SVID_SOURCE
 149 # warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
 150 # undef  _DEFAULT_SOURCE
 151 # define _DEFAULT_SOURCE        1
 152 #endif
 153
 154 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 155 #ifdef _GNU_SOURCE
 156 # undef  _ISOC95_SOURCE
 157 # define _ISOC95_SOURCE 1
 158 # undef  _ISOC99_SOURCE
 159 # define _ISOC99_SOURCE 1
 160 # undef  _ISOC11_SOURCE
 161 # define _ISOC11_SOURCE 1
 162 # undef  _POSIX_SOURCE
 163 # define _POSIX_SOURCE  1
 164 # undef  _POSIX_C_SOURCE
 165 # define _POSIX_C_SOURCE        200809L
 166 # undef  _XOPEN_SOURCE
 167 # define _XOPEN_SOURCE  700
 168 # undef  _XOPEN_SOURCE_EXTENDED
 169 # define _XOPEN_SOURCE_EXTENDED 1
 170 # undef  _LARGEFILE64_SOURCE
 171 # define _LARGEFILE64_SOURCE    1
 172 # undef  _DEFAULT_SOURCE
 173 # define _DEFAULT_SOURCE        1
 174 # undef  _BSD_SOURCE
 175 # define _BSD_SOURCE    1
 176 # undef  _SVID_SOURCE
 177 # define _SVID_SOURCE   1
 178 # undef  _ATFILE_SOURCE
 179 # define _ATFILE_SOURCE 1
 180 #endif
 181
 182 /* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined,
 183    define _DEFAULT_SOURCE, _BSD_SOURCE and _SVID_SOURCE.  */
 184 #if (defined _DEFAULT_SOURCE                                    \
 185      || (!defined __STRICT_ANSI__                               \
 186          && !defined _ISOC99_SOURCE                             \
 187          && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE  \
 188          && !defined _XOPEN_SOURCE                              \
 189          && !defined _BSD_SOURCE && !defined _SVID_SOURCE))
 190 # undef  _DEFAULT_SOURCE
 191 # define _DEFAULT_SOURCE        1
 192 # undef  _BSD_SOURCE
 193 # define _BSD_SOURCE    1
 194 # undef  _SVID_SOURCE
 195 # define _SVID_SOURCE   1
 196 #endif
 197
 198 /* This is to enable the ISO C11 extension.  */
 199 #if (defined _ISOC11_SOURCE \
 200      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L))
 201 # define __USE_ISOC11   1
 202 #endif
 203
 204 /* This is to enable the ISO C99 extension.  */
 205 #if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
 206      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 207 # define __USE_ISOC99   1
 208 #endif
 209
 210 /* This is to enable the ISO C90 Amendment 1:1995 extension.  */
 211 #if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
 212      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409L))
 213 # define __USE_ISOC95   1
 214 #endif
 215
 216 /* This is to enable compatibility for ISO C++11.
 217
 218    So far g++ does not provide a macro.  Check the temporary macro for
 219    now, too.  */
 220 #if ((defined __cplusplus && __cplusplus >= 201103L)                          \
 221      || defined __GXX_EXPERIMENTAL_CXX0X__)
 222 # define __USE_ISOCXX11 1
 223 #endif
 224
 225 /* If none of the ANSI/POSIX macros are defined, or if _DEFAULT_SOURCE
 226    is defined, use POSIX.1-2008 (or another version depending on
 227    _XOPEN_SOURCE).  */
 228 #ifdef _DEFAULT_SOURCE
 229 # if !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE
 230 #  define __USE_POSIX_IMPLICITLY        1
 231 # endif
 232 # undef  _POSIX_SOURCE
 233 # define _POSIX_SOURCE  1
 234 # undef  _POSIX_C_SOURCE
 235 # define _POSIX_C_SOURCE        200809L
 236 #endif
 237 #if ((!defined __STRICT_ANSI__ || (_XOPEN_SOURCE - 0) >= 500) && \
 238      !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE)
 239 # define _POSIX_SOURCE  1
 240 # if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 500
 241 #  define _POSIX_C_SOURCE       2
 242 # elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 600
 243 #  define _POSIX_C_SOURCE       199506L
 244 # elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 700
 245 #  define _POSIX_C_SOURCE       200112L
 246 # else
 247 #  define _POSIX_C_SOURCE       200809L
 248 # endif
 249 # define __USE_POSIX_IMPLICITLY 1
 250 #endif
 251
 252 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
 253 # define __USE_POSIX    1
 254 #endif
 255
 256 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
 257 # define __USE_POSIX2   1
 258 #endif
 259
 260 #if (_POSIX_C_SOURCE - 0) >= 199309L
 261 # define __USE_POSIX199309      1
 262 #endif
 263
 264 #if (_POSIX_C_SOURCE - 0) >= 199506L
 265 # define __USE_POSIX199506      1
 266 #endif
 267
 268 #if (_POSIX_C_SOURCE - 0) >= 200112L
 269 # define __USE_XOPEN2K          1
 270 # undef __USE_ISOC95
 271 # define __USE_ISOC95           1
 272 # undef __USE_ISOC99
 273 # define __USE_ISOC99           1
 274 #endif
 275
 276 #if (_POSIX_C_SOURCE - 0) >= 200809L
 277 # define __USE_XOPEN2K8         1
 278 # undef  _ATFILE_SOURCE
 279 # define _ATFILE_SOURCE 1
 280 #endif
 281
 282 #ifdef  _XOPEN_SOURCE
 283 # define __USE_XOPEN    1
 284 # if (_XOPEN_SOURCE - 0) >= 500
 285 #  define __USE_XOPEN_EXTENDED  1
 286 #  define __USE_UNIX98  1
 287 #  undef _LARGEFILE_SOURCE
 288 #  define _LARGEFILE_SOURCE     1
 289 #  if (_XOPEN_SOURCE - 0) >= 600
 290 #   if (_XOPEN_SOURCE - 0) >= 700
 291 #    define __USE_XOPEN2K8      1
 292 #    define __USE_XOPEN2K8XSI   1
 293 #   endif
 294 #   define __USE_XOPEN2K        1
 295 #   define __USE_XOPEN2KXSI     1
 296 #   undef __USE_ISOC95
 297 #   define __USE_ISOC95         1
 298 #   undef __USE_ISOC99
 299 #   define __USE_ISOC99         1
 300 #  endif
 301 # else
 302 #  ifdef _XOPEN_SOURCE_EXTENDED
 303 #   define __USE_XOPEN_EXTENDED 1
 304 #  endif
 305 # endif
 306 #endif
 307
 308 #ifdef _LARGEFILE_SOURCE
 309 # define __USE_LARGEFILE        1
 310 #endif
 311
 312 #ifdef _LARGEFILE64_SOURCE
 313 # define __USE_LARGEFILE64      1
 314 #endif
 315
 316 #if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64
 317 # define __USE_FILE_OFFSET64    1
 318 #endif
 319
 320 #if defined _BSD_SOURCE || defined _SVID_SOURCE
 321 # define __USE_MISC     1
 322 #endif
 323
 324 #ifdef  _BSD_SOURCE
 325 # define __USE_BSD      1
 326 #endif
 327
 328 #ifdef  _SVID_SOURCE
 329 # define __USE_SVID     1
 330 #endif
 331
 332 #ifdef  _ATFILE_SOURCE
 333 # define __USE_ATFILE   1
 334 #endif
 335
 336 #ifdef  _GNU_SOURCE
 337 # define __USE_GNU      1
 338 #endif
 339
 340 #if defined _REENTRANT || defined _THREAD_SAFE
 341 # define __USE_REENTRANT        1
 342 #endif
 343
 344 #if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0
 345 # if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0
 346 #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
 347 # elif !__GNUC_PREREQ (4, 1)
 348 #  warning _FORTIFY_SOURCE requires GCC 4.1 or later
 349 # elif _FORTIFY_SOURCE > 1
 350 #  define __USE_FORTIFY_LEVEL 2
 351 # else
 352 #  define __USE_FORTIFY_LEVEL 1
 353 # endif
 354 #endif
 355 #ifndef __USE_FORTIFY_LEVEL
 356 # define __USE_FORTIFY_LEVEL 0
 357 #endif
 358
 359 /* Get definitions of __STDC_* predefined macros, if the compiler has
 360    not preincluded this header automatically.  */
 361 #include <stdc-predef.h>
 362
 363 /* This macro indicates that the installed library is the GNU C Library.
 364    For historic reasons the value now is 6 and this will stay from now
 365    on.  The use of this variable is deprecated.  Use __GLIBC__ and
 366    __GLIBC_MINOR__ now (see below) when you want to test for a specific
 367    GNU C library version and use the values in <gnu/lib-names.h> to get
 368    the sonames of the shared libraries.  */
 369 #undef  __GNU_LIBRARY__
 370 #define __GNU_LIBRARY__ 6
 371
 372 /* Major and minor version number of the GNU C library package.  Use
 373    these macros to test for features in specific releases.  */
 374 #define __GLIBC__       2
 375 #define __GLIBC_MINOR__ 19
 376
 377 #define __GLIBC_PREREQ(maj, min) \
 378         ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
 379
 380 /* This is here only because every header file already includes this one.  */
 381 #ifndef __ASSEMBLER__
 382 # ifndef _SYS_CDEFS_H
 383 #  include <sys/cdefs.h>
 384 # endif
 385
 386 /* If we don't have __REDIRECT, prototypes will be missing if
 387    __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */
 388 # if defined __USE_FILE_OFFSET64 && !defined __REDIRECT
 389 #  define __USE_LARGEFILE       1
 390 #  define __USE_LARGEFILE64     1
 391 # endif
 392
 393 #endif  /* !ASSEMBLER */
 394
 395 /* Decide whether we can define 'extern inline' functions in headers.  */
 396 #if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \
 397     && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__ \
 398     && defined __extern_inline
 399 # define __USE_EXTERN_INLINES   1
 400 #endif
 401
 402
 403 /* This is here only because every header file already includes this one.
 404    Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
 405    <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
 406    that will always return failure (and set errno to ENOSYS).  */
 407 #include <gnu/stubs.h>
 408
 409
 410 #endif  /* features.h  */