include/features.h

   1 /* Copyright (C) 1991-2016 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_MISC           Define things from 4.3BSD or System V Unix.
  79    __USE_ATFILE         Define *at interfaces and AT_* constants for them.
  80    __USE_GNU            Define GNU extensions.
  81    __USE_REENTRANT      Define reentrant/thread-safe *_r functions.
  82    __USE_FORTIFY_LEVEL  Additional security measures used, according to level.
  83
  84    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
  85    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
  86    only for compatibility.  All new code should use the other symbols
  87    to test for features.
  88
  89    All macros listed above as possibly being defined by this file are
  90    explicitly undefined if they are not explicitly defined.
  91    Feature-test macros that are not defined by the user or compiler
  92    but are implied by the other feature-test macros defined (or by the
  93    lack of any definitions) are defined by the file.  */
  94
  95
  96 /* Undefine everything, so we get a clean slate.  */
  97 #undef  __USE_ISOC11
  98 #undef  __USE_ISOC99
  99 #undef  __USE_ISOC95
 100 #undef  __USE_ISOCXX11
 101 #undef  __USE_POSIX
 102 #undef  __USE_POSIX2
 103 #undef  __USE_POSIX199309
 104 #undef  __USE_POSIX199506
 105 #undef  __USE_XOPEN
 106 #undef  __USE_XOPEN_EXTENDED
 107 #undef  __USE_UNIX98
 108 #undef  __USE_XOPEN2K
 109 #undef  __USE_XOPEN2KXSI
 110 #undef  __USE_XOPEN2K8
 111 #undef  __USE_XOPEN2K8XSI
 112 #undef  __USE_LARGEFILE
 113 #undef  __USE_LARGEFILE64
 114 #undef  __USE_FILE_OFFSET64
 115 #undef  __USE_MISC
 116 #undef  __USE_ATFILE
 117 #undef  __USE_GNU
 118 #undef  __USE_REENTRANT
 119 #undef  __USE_FORTIFY_LEVEL
 120 #undef  __KERNEL_STRICT_NAMES
 121
 122 /* Suppress kernel-name space pollution unless user expressedly asks
 123    for it.  */
 124 #ifndef _LOOSE_KERNEL_NAMES
 125 # define __KERNEL_STRICT_NAMES
 126 #endif
 127
 128 /* Convenience macros to test the versions of glibc and gcc.
 129    Use them like this:
 130    #if __GNUC_PREREQ (2,8)
 131    ... code requiring gcc 2.8 or later ...
 132    #endif
 133    Note - they won't work for gcc1 or glibc1, since the _MINOR macros
 134    were not defined then.  */
 135 #if defined __GNUC__ && defined __GNUC_MINOR__
 136 # define __GNUC_PREREQ(maj, min) \
 137         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
 138 #else
 139 # define __GNUC_PREREQ(maj, min) 0
 140 #endif
 141
 142 /* _BSD_SOURCE and _SVID_SOURCE are deprecated aliases for
 143    _DEFAULT_SOURCE.  If _DEFAULT_SOURCE is present we do not
 144    issue a warning; the expectation is that the source is being
 145    transitioned to use the new macro.  */
 146 #if (defined _BSD_SOURCE || defined _SVID_SOURCE) \
 147     && !defined _DEFAULT_SOURCE
 148 # warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
 149 # undef  _DEFAULT_SOURCE
 150 # define _DEFAULT_SOURCE        1
 151 #endif
 152
 153 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 154 #ifdef _GNU_SOURCE
 155 # undef  _ISOC95_SOURCE
 156 # define _ISOC95_SOURCE 1
 157 # undef  _ISOC99_SOURCE
 158 # define _ISOC99_SOURCE 1
 159 # undef  _ISOC11_SOURCE
 160 # define _ISOC11_SOURCE 1
 161 # undef  _POSIX_SOURCE
 162 # define _POSIX_SOURCE  1
 163 # undef  _POSIX_C_SOURCE
 164 # define _POSIX_C_SOURCE        200809L
 165 # undef  _XOPEN_SOURCE
 166 # define _XOPEN_SOURCE  700
 167 # undef  _XOPEN_SOURCE_EXTENDED
 168 # define _XOPEN_SOURCE_EXTENDED 1
 169 # undef  _LARGEFILE64_SOURCE
 170 # define _LARGEFILE64_SOURCE    1
 171 # undef  _DEFAULT_SOURCE
 172 # define _DEFAULT_SOURCE        1
 173 # undef  _ATFILE_SOURCE
 174 # define _ATFILE_SOURCE 1
 175 #endif
 176
 177 /* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined,
 178    define _DEFAULT_SOURCE.  */
 179 #if (defined _DEFAULT_SOURCE                                    \
 180      || (!defined __STRICT_ANSI__                               \
 181          && !defined _ISOC99_SOURCE                             \
 182          && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE  \
 183          && !defined _XOPEN_SOURCE))
 184 # undef  _DEFAULT_SOURCE
 185 # define _DEFAULT_SOURCE        1
 186 #endif
 187
 188 /* This is to enable the ISO C11 extension.  */
 189 #if (defined _ISOC11_SOURCE \
 190      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L))
 191 # define __USE_ISOC11   1
 192 #endif
 193
 194 /* This is to enable the ISO C99 extension.  */
 195 #if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
 196      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 197 # define __USE_ISOC99   1
 198 #endif
 199
 200 /* This is to enable the ISO C90 Amendment 1:1995 extension.  */
 201 #if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
 202      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409L))
 203 # define __USE_ISOC95   1
 204 #endif
 205
 206 /* This is to enable compatibility for ISO C++11.
 207
 208    So far g++ does not provide a macro.  Check the temporary macro for
 209    now, too.  */
 210 #if ((defined __cplusplus && __cplusplus >= 201103L)                          \
 211      || defined __GXX_EXPERIMENTAL_CXX0X__)
 212 # define __USE_ISOCXX11 1
 213 #endif
 214
 215 /* If none of the ANSI/POSIX macros are defined, or if _DEFAULT_SOURCE
 216    is defined, use POSIX.1-2008 (or another version depending on
 217    _XOPEN_SOURCE).  */
 218 #ifdef _DEFAULT_SOURCE
 219 # if !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE
 220 #  define __USE_POSIX_IMPLICITLY        1
 221 # endif
 222 # undef  _POSIX_SOURCE
 223 # define _POSIX_SOURCE  1
 224 # undef  _POSIX_C_SOURCE
 225 # define _POSIX_C_SOURCE        200809L
 226 #endif
 227 #if ((!defined __STRICT_ANSI__                                  \
 228       || (defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 500)) \
 229      && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE)
 230 # define _POSIX_SOURCE  1
 231 # if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 500
 232 #  define _POSIX_C_SOURCE       2
 233 # elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 600
 234 #  define _POSIX_C_SOURCE       199506L
 235 # elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 700
 236 #  define _POSIX_C_SOURCE       200112L
 237 # else
 238 #  define _POSIX_C_SOURCE       200809L
 239 # endif
 240 # define __USE_POSIX_IMPLICITLY 1
 241 #endif
 242
 243 #if (defined _POSIX_SOURCE                                      \
 244      || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 1)       \
 245      || defined _XOPEN_SOURCE)
 246 # define __USE_POSIX    1
 247 #endif
 248
 249 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
 250 # define __USE_POSIX2   1
 251 #endif
 252
 253 #if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199309L
 254 # define __USE_POSIX199309      1
 255 #endif
 256
 257 #if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199506L
 258 # define __USE_POSIX199506      1
 259 #endif
 260
 261 #if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200112L
 262 # define __USE_XOPEN2K          1
 263 # undef __USE_ISOC95
 264 # define __USE_ISOC95           1
 265 # undef __USE_ISOC99
 266 # define __USE_ISOC99           1
 267 #endif
 268
 269 #if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200809L
 270 # define __USE_XOPEN2K8         1
 271 # undef  _ATFILE_SOURCE
 272 # define _ATFILE_SOURCE 1
 273 #endif
 274
 275 #ifdef  _XOPEN_SOURCE
 276 # define __USE_XOPEN    1
 277 # if (_XOPEN_SOURCE - 0) >= 500
 278 #  define __USE_XOPEN_EXTENDED  1
 279 #  define __USE_UNIX98  1
 280 #  undef _LARGEFILE_SOURCE
 281 #  define _LARGEFILE_SOURCE     1
 282 #  if (_XOPEN_SOURCE - 0) >= 600
 283 #   if (_XOPEN_SOURCE - 0) >= 700
 284 #    define __USE_XOPEN2K8      1
 285 #    define __USE_XOPEN2K8XSI   1
 286 #   endif
 287 #   define __USE_XOPEN2K        1
 288 #   define __USE_XOPEN2KXSI     1
 289 #   undef __USE_ISOC95
 290 #   define __USE_ISOC95         1
 291 #   undef __USE_ISOC99
 292 #   define __USE_ISOC99         1
 293 #  endif
 294 # else
 295 #  ifdef _XOPEN_SOURCE_EXTENDED
 296 #   define __USE_XOPEN_EXTENDED 1
 297 #  endif
 298 # endif
 299 #endif
 300
 301 #ifdef _LARGEFILE_SOURCE
 302 # define __USE_LARGEFILE        1
 303 #endif
 304
 305 #ifdef _LARGEFILE64_SOURCE
 306 # define __USE_LARGEFILE64      1
 307 #endif
 308
 309 #if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64
 310 # define __USE_FILE_OFFSET64    1
 311 #endif
 312
 313 #if defined _DEFAULT_SOURCE
 314 # define __USE_MISC     1
 315 #endif
 316
 317 #ifdef  _ATFILE_SOURCE
 318 # define __USE_ATFILE   1
 319 #endif
 320
 321 #ifdef  _GNU_SOURCE
 322 # define __USE_GNU      1
 323 #endif
 324
 325 #if defined _REENTRANT || defined _THREAD_SAFE
 326 # define __USE_REENTRANT        1
 327 #endif
 328
 329 #if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0
 330 # if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0
 331 #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
 332 # elif !__GNUC_PREREQ (4, 1)
 333 #  warning _FORTIFY_SOURCE requires GCC 4.1 or later
 334 # elif _FORTIFY_SOURCE > 1
 335 #  define __USE_FORTIFY_LEVEL 2
 336 # else
 337 #  define __USE_FORTIFY_LEVEL 1
 338 # endif
 339 #endif
 340 #ifndef __USE_FORTIFY_LEVEL
 341 # define __USE_FORTIFY_LEVEL 0
 342 #endif
 343
 344 /* Get definitions of __STDC_* predefined macros, if the compiler has
 345    not preincluded this header automatically.  */
 346 #include <stdc-predef.h>
 347
 348 /* This macro indicates that the installed library is the GNU C Library.
 349    For historic reasons the value now is 6 and this will stay from now
 350    on.  The use of this variable is deprecated.  Use __GLIBC__ and
 351    __GLIBC_MINOR__ now (see below) when you want to test for a specific
 352    GNU C library version and use the values in <gnu/lib-names.h> to get
 353    the sonames of the shared libraries.  */
 354 #undef  __GNU_LIBRARY__
 355 #define __GNU_LIBRARY__ 6
 356
 357 /* Major and minor version number of the GNU C library package.  Use
 358    these macros to test for features in specific releases.  */
 359 #define __GLIBC__       2
 360 #define __GLIBC_MINOR__ 23
 361
 362 #define __GLIBC_PREREQ(maj, min) \
 363         ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
 364
 365 /* This is here only because every header file already includes this one.  */
 366 #ifndef __ASSEMBLER__
 367 # ifndef _SYS_CDEFS_H
 368 #  include <sys/cdefs.h>
 369 # endif
 370
 371 /* If we don't have __REDIRECT, prototypes will be missing if
 372    __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */
 373 # if defined __USE_FILE_OFFSET64 && !defined __REDIRECT
 374 #  define __USE_LARGEFILE       1
 375 #  define __USE_LARGEFILE64     1
 376 # endif
 377
 378 #endif  /* !ASSEMBLER */
 379
 380 /* Decide whether we can define 'extern inline' functions in headers.  */
 381 #if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \
 382     && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__ \
 383     && defined __extern_inline
 384 # define __USE_EXTERN_INLINES   1
 385 #endif
 386
 387
 388 /* This is here only because every header file already includes this one.
 389    Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
 390    <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
 391    that will always return failure (and set errno to ENOSYS).  */
 392 #include <gnu/stubs.h>
 393
 394
 395 #endif  /* features.h  */